GSSP proposal: base of Jurassic System and Hettangian Stage

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GSSP proposal: base of Jurassic System and Hettangian Stage

Postby Junxuan Fan » March 19th, 2009, 11:35 am

BASE HETTANGIAN/JURASSIC GSSP PROPOSAL

FOREWORD

Nicol Morton, Chairman ISJS
Geoffrey Warrington, Convenor TJBWG
Gert Bloos, Secretary TJBWG

This document has been prepared to explain the background and procedures followed by members of the Triassic/Jurassic Boundary Working Group (TJBWG) for selection of the preferred GSSP for the base of the Hettangian Stage and the Jurassic System. It is intended to be a factual account of what happened and to give a reasonably objective account of why the voting went as it did, so that this proposal can be scrutinized objectively. It has some minor revisions from the document submitted to the Jurassic Subcommission.

Background
The basal boundary of the Jurassic has been a long-lasting problem, illustrated for example by the status of the Rhaetian Stage, variously placed in the Triassic or Jurassic, until international agreement was reached to include it as the final stage of the Triassic. The Triassic/Jurassic boundary interval was the time of one of the major evolutionary crises in Earth history, and one that has proved to be complex. It was also a time of active plate tectonics during early stages of the breakup of Pangaea (and therefore rapidly changing palaeogeography), of a major volcanic phase (Central Atlantic Magmatic Province) and apparent major changes of sea-level in many areas, possibly global. This last event resulted in there being very few areas where a continuous sequence of strata across the boundary is preserved.

The Jurassic Subcommission established a Working Group, led by the late René MOUTERDE (France) succeeded by Geoffrey WARRINGTON (UK), to research and eventually propose definition of the boundary at a stratotype (GSSP). More recently, IGCP Project 458 on Triassic/Jurassic Boundary Events, now completed, was set up with leaders Stephen HESSELBO (UK), Christopher McROBERTS (USA) and Jozsef PALFY (Hungary). Both groups contributed a large amount of new data and ideas on the Triassic/Jurassic boundary interval.

By 2003 the Triassic/Jurassic Boundary Working Group (TJBWG) had identified and compared four sections with continuous sedimentation and marine faunas across the boundary interval – St. Audrie’s Bay (SW England), New York Canyon (Nevada), Kunga Island (western Canada) and Chilingote (Peru), but no favoured candidate emerged. Subsequently, two new sections were discovered and proposed as candidates – Kuhjoch (Austria) in 2005, and Waterloo Bay (Northern Ireland) in 2006. Also, a broader range of markers was proposed, including radiolarians and a carbon isotope excursion in addition to ammonites. In September 2006, the 7th International Congress on the Jurassic System, held in Krakow (Poland), enabled discussion of the various proposals; during this the candidature of Chilingote (Peru) was withdrawn.

Candidate sections
In 2007 the following proposals were formally submitted to the members of the TJBWG for comparison, discussion and, eventually, selection:

(a) Ferguson Hill section, New York Canyon, Nevada, USA
By S.G. LUCAS, D.G. TAYLOR, J. GUEX, L.H. TANNER and K. KRAINER
with primary marker the ammonite Psiloceras spelae.

(b) Ferguson Hill section, New York Canyon, Nevada, USA
By C.A. McROBERTS, P.D. WARD and S. HESSELBO
with primary marker a carbon isotope excursion..

(c) Kuhjoch section, Karwendel Mountains, Northern Calcareous Alps, Tyrol, Austria
By A. von HILLEBRANDT, L. KRYSTYN, W.M. KUERSCHNER (with contributions by P.R. BOWN, C. McROBERTS, M. RUHL, M. SIMMS, A. TOMASOVYCH and M. URLICHS
with primary marker the ammonite Psiloceras cf. spelae.

(d) Kunga Island section, Queen Charlotte Islands, British Columbia, Canada
By L.M. LONGRIDGE, E.S. CARTER, J.W. HAGGART and P.L. SMITH
with primary marker a major evolutionary change of radiolarian faunas

(e) St. Audrie’s Bay section, Somerset, England, UK
By G. WARRINGTON, J.C.W. COPE and H.C. IVIMEY-COOK
with primary marker the ammonite Psiloceras planorbis.

(f) Waterloo Bay section, Larne, Northern Ireland, UK
By M.J. SIMMS and A.J. JERAM
with primary marker the ammonite Psiloceras planorbis.

All except the second last were published electronically in the International Subcommission on Jurassic Stratigraphy Newsletter no. 34, part 1. It is planned to publish the St. Audrie’s Bay proposal in a forthcoming Newsletter. They can be downloaded freely from the Jurassic Subcommission website at:
http://www.es.ucl.ac.uk/people/bown/ISJSwebsite.htm
The quality of the science in all these proposals is very impressive and all the authors are to be congratulated on their work.

Selection and voting
In view of the large number of proposed sections and primary markers, the membership of the TJBWG was enlarged by the Convenor and Secretary in consultation with the Subcommission Chairman. All who were known to have an interest and input were invited to participate, to make the Group as representative as possible so that any decisions reached would carry authority. (For a list of those who accepted the invitation see ISJS Newsletter 34,1). To enable discussions, a special password-protected website was established by Christopher McROBERTS, containing the full proposal documents and with facilities to enable TJBWG members to post discussions on the various topics. In the final weeks of the selection processes there was also a huge amount of constructive discussion and exchanges by emails circulated to all WG members.

The selection procedures were organised by the Secretary of the TJBWG in consultation with the Subcommission Chairman. The Convenor withdrew from these in view of his involvement with one of the proposals. Voting was carried out in three stages:



1. Selection of the primary marker
Voting form issued 14th February 2008; response deadline 29 February 2008.
Four different markers were proposed:
(a) A carbon isotope negative excursion identified in several sections; this is the lowest stratigraphically and would have placed some strata traditionally regarded as Triassic in the Jurassic;
(b) A major evolutionary turnover in the radiolarian faunas, slightly predating the first appearance of ammonites traditionally regarded as Jurassic;
(c) The first appearance of the ammonite genus Psiloceras, traditionally regarded as the oldest “Jurassic” ammonite, represented by the species Psiloceras spelae;
(d) The first appearance of the ammonite Psiloceras planorbis, for many decades regarded as the oldest (then known) Jurassic ammonite and index of the Planorbis Zone as basal zone of the Hettangian; this would have placed the boundary at the highest of the levels proposed.

Voting:

Number of TJBWG members = 75; returned voting forms (all valid) = 67 (89.3%)



(i) for Psiloceras spelae/cf.spelae
[Jean Guex and Axel von Hillebrandt agreed that the Ferguson Hill and Kuhjoch ammonites represent the same species, with minor population differences at subspecies level, and concluded that they were contemporaneous within acceptable limits of resolution.]
votes for = 36 (53.7%)
Guex, Lucas, Pienkowski, Kozur, Krystyn, Hillebrandt, Michalik, Meister, Blau, Aberhan, Tanner, Bucher, Hallam, Korte, Yin, Siblik, Urlichs, Haas, Furrer, Bartolini, Bloos, Lathuillere, Tomasovych, Kürschner, Feist-Burkhardt, Vörös, Götz, Page, Vuks, Lindström, Sha, Polubotko, Repin, Hesselbo, Enay, Menning.

(ii) for Psiloceras planorbis
votes for = 13 (19.4%)
Cope, Simms, Hounslow, Stevens, Prinz-Grimm, Warrington, Hall, Ivimey-Cook, Donovan, Jeram, Riccardi, Mancenido, Damborenea.

(iii) for Carbon Isotope Excursion
votes for = 11 (16.4%)
Ward, Olsen, Lord, McRoberts, Cohen, Coe, Bown, Ciarapica, Smith, Longridge, Stanley.

(iv) for Radiolarian faunal turnover
votes for = 7 (10.5%)
Ruckwied, Hirsch, Matsuoka, Hori, Palfy, Carter, Herngreen.




2. Selection of the preferred section
Voting form issued 6 March 2008; response deadline 17 March 2008.
Following the voting, the primary marker chosen by a majority of the TJBWG members was the ammonite Psiloceras spelae, which had been proposed and could be recognised in only two candidate sections – Kuhjoch section (Austria) and Ferguson Hill section (USA). The second stage ballot offered a choice between these two candidate sections.

Number of TJBWG members = 75; returned voting forms (all valid) = 57 (76.0%)

(i) for Kuhjoch section, Austria
votes for = 32 (56.1%)
Hillebrandt, Pienkowski, Aberhan, Feist-Burkhardt, Vörös, Blau, Hounslow, Hallam, Menning, Yin, Meister, Bown, Page, Siblik, Cope, Boomer, Bloos, Michalik, Olsen, Stevens, Haas, Vuks, Repin, Polubotko, Hesselbo, Tomasovych, Longridge, Hall, Furrer, Kürschner, Urlichs, Krystyn.

(ii) for Ferguson Hill section, USA
votes for = 18 (31.6%)
Guex, Lucas, Hirsch, Lord, Matsuoka, McRoberts, Carter, Ruckwied, Korte, Kozur, Götz, Taylor, Hori, Ciarapica, Sha, Mancenido, Enay, Lindström.

(iii) abstain
votes for = 7 (12.3%)
Warrington, Palfy, Riccardi, Damborenea, Ivimey-Cook, Jeram, Smith.


3. Confirmation of majority vote
Voting form issued 19 March 2008; response deadline 7 April 2008.
The majority vote for the Kuhjoch section as preferred GSSP candidate did not achieve the required 60% majority of the votes cast. Therefore, a further ballot was held to seek the approval of TJBWG members for this section to be proposed to the Jurassic Subcommission.

Number of TJBWG members = 75; returned voting forms (all valid) = 61 (81.3%)

(i) YES votes = 48 (78.7%)
Guex, Vuks, Polubotko, Repin, Kürschner, Prinz-Grimm, Stanley, Menning, Hounslow, Bloos, Simms, Pienkowski, Yin, Hallam, McRoberts, Hillebrandt, Korte, Bartolini, Donovan, Tomasovych, Hesselbo, Enay, Stevens, Meister, Haas, Cope, Aberhan, Michalik, Krystyn, Smith, Hall, Herngreen, Boomer, Olsen, Vörös, Longridge, Tanner, Lindström, Furrer, Lathuilière, Feist-Burkhardt, Urlichs, Blau, Götz, Siblik, Gazdzicki, Ruckwied, Bown.

(ii) NO votes = 6 ( 9.8%)
Damborenea, Mancenido, Warrington, Hori, Ward, Palfy.

(iii) ABSTAIN votes = 7 (11.5%)
Kozur, Jeram, Matsuoka, Hirsch, Carter, Ivimey-Cook, Riccardi.

At the same time a ballot was held to ask TJBWG members opinions of a suggestion to propose the Ferguson Hill section as auxiliary stratotype (ASSP).

Number of TJBWG members = 75; returned voting forms (all valid) = 57 (76.0%)

(iv) YES votes = 35 (61.4%)
Guex, Vuks, Polubotko, Repin, Stanley, Menning, Bloos, Pienkowski, Hallam, Hillebrandt, Bartolini, Donovan, Tomasovych, Enay, Kozur, Stevens, Haas, Cope, Aberhan, Michalik, Smith, Hall, Korte, Hori, Herngren, Boomer, Longridge, Tanner, Lindström, Furrer, Hirsch, Carter, Blau, Götz, Ruckwied

(v) NO votes = 9 ( 15.8%)
Kürschner, Hounslow, Simms, McRoberts, Hesselbo, Warrington, Olsen, Lathuilière, Palfy


(vi) ABSTAIN votes = 13 (22.8%)
Damborenea, Prinz-Grimm, Yin, Mancenido, Meister, Krystyn, Jeram, Matsuoka, Vörös, Feist-Burkhardt, Gazdzicki, Riccardi, Bown

Conclusion
The Kuhjoch section, Karwendel Mts., Northern Calcareous Alps, Austria, has been accepted by vote of the members of the TJBWG to be proposed as GSSP for the base of the Hettangian Stage and the Jurassic System. The Ferguson Hill section, New York Canyon, Nevada, USA has been accepted by vote to be proposed as ASSP; an integrated proposal must be prepared for later submission to the Jurassic Subcommission.and to the International Commission on Stratigraphy.

Comments on the result of the votes
This comment does not repeat or evaluate the arguments on the different candidate GSSPs, their boundary definitions and correlation potential, but considers only some general aspects.

The focus of investigation and of discussion was on the boundary itself. Only those sections that have continuous sedimentation and succession of sufficiently preserved fossils through the boundary interval could be considered as candidate GSSPs. Our search for such sections revealed that they are rather rare. Most sections shows deficiencies of one or other kind so that the boundary cannot be recognized.

It is important that even if the boundary itself is not recognizable itself, the ages of the rocks above and below the boundary can be recognized unequivocally. This was the case with traditional boundary levels used in the past, although they have turned out to differ in age, more or less. However, one common characteristic was that the ranges of Choristoceras marshi, Ch. crickmayi and the conodont Misikella posthernsteini, were regarded as latest Triassic, while Psiloceras was regarded as earliest Jurassic wherever found in the world. In complete sections these ranges are separated by an intermediate interval where time-diagnostic fossils are essentially lacking. Thus, an overlap of index fossils of latest Triassic and earliest Jurassic is excluded. Rare exceptions, such as Choristoceras minutum or the late conodont “Neohindeodella” detrei offer no difficulty because these species are known only from sediments above the ranges of the accepted latest Triassic index species. A boundary level at the appearance of Psiloceras spelae is situated between the ranges of the two groups of age-diagnostic fossils referred to above and in this respect continues historical stratigraphical usage.

On the other hand, if the boundary had been placed at a lower level, this would separate the stratigraphic range of, for example, Misikella posthernsteini into a Triassic part and a Jurassic part. Consequently, this important index fossil would lose its unequivocal age-diagnostic character distinguishing latest Triassic from earliest Jurassic.

Similarly, a boundary at a higher level defined by a species within the psiloceratid succession could be correlated only within the faunal province where the GSSP is situated; not all psiloceratids would be Jurassic. In other faunal provinces with different ammonite sequences, only tentative correlations would be possible and stratigraphic allocation of new, hitherto unknown, psiloceratids would remain uncertain.

The investigations of the TJBWG have yielded results that are certainly significant beyond the primary aim, the selection of a GSSP for the base of the Jurassic. Each candidate section will remain an important international stratigraphical reference in the future contributing to the elucidation of a very special important time-span in the history of Earth. Some open questions remain and new ones arise; therefore, investigations must be continued, as indicated below.

Remarks on the Triassic/Jurassic transitional boundary interval
This is essentially an attempt to integrate the results from the six candidate GSSP proposals into an idea on what happened at the end of the Triassic as now understood and where in this history the T-J boundary is defined. The primary causes of the environmental changes across the T-J boundary are not discussed here because they are not yet sufficiently known.

For a long time the late Rhaetian was known as a period of decreasing diversity in important fossil groups, such as ammonoids, bivalves, brachiopods, conodonts, ostracodes, and foraminifers. The immediate transition into the Jurassic, however, was generally obscure, for various reasons. The end-Triassic sea level changes caused regionally widespread gaps in sedimentation and breaks of facies sequence. Moreover, unfavourable facies caused poor records of fossils with regard to frequency, diversity and preservation. Additionally, subsequent influences such as diagenetic processes and thermal metamorphism changed or even deleted biotic and non-biotic signals.

The time of decline in the late Rhaetian ended in a major crisis for the fossil groups referred to above, with a final interval characterized by a minimum of frequency and diversity. It is remarkable that not only the groups mentioned above as being in decline were affected but so also were radiolarians, whose diversity (against the general negative trend) still increased up to the beginning of the final crisis.

Most probably the beginning of the final crisis is indicated by the strikingly rapid extinction of about 70 Triassic species of radiolarians (which were still present in bed 9 of Kunga Island; 57 of them are missing already in bed 10, while 13 short-lived holdovers are absent in bed 13; Longridge et al. 2007 ISJS Newsletter 34(1): 21-33, fig. 4). Only three Triassic species persisted above the extinction level. From bed 10 upwards 20 new species appeared. Thus there was minimal overlap of the earlier and later groups.

There can be little doubt that this turnover reflects a major environmental change. To find out the reason, it seems important that the radiolarians are a pelagic group. Important also is that genera with highly specialised morphology were most concerned. Such forms obviously were adapted to a specialised mode of life that could not be continued after the environmental change. Since calcareous nannoplankton were also concerned it may be that the symbiotic algae were the particularly sensitive element in the radiolarians.

According to Williford et al. (2007 PPP 244: 290-296. fig. 1) the radiolarian turnover is situated within the initial negative Carbon Isotope Excursion (CIE) at Kennecott Point which has a range of about 4 m (110-114 m). Therefore it seems rather probable that the extinction of Triassic radiolarians and the CIE reflect the same environmental change and that this change was the reason for at least the beginning of the final crisis.

Whereas the reaction of the radiolarians to the environmental change was immediate and strong, other latest Triassic fossil groups survived a short time after the CIE. Holdovers into the critical interval are known from the radiolarians (Kunga Island), conodonts (UK), ammonoids (Ferguson Hill: Choristoceras crickmayi), foraminifers, ostracodes, palynomorphs (all Kuhjoch). This means that minimum diversity was reached a short time after the beginning of the crisis.

Of the later part of the critical interval little is known from most of the candidate GSSPs. Since the radiolarian change is completely situated within the CIE according to Williford et al. (2007) it seems that the recovery of the radiolarians began earlier than recoveries of other fossil groups. The reappearance of other fossil groups was clearly later than the CIE.

Most information on the upper part of the critical interval is provided at Kuhjoch and other sections in the same basin (Eiberg Basin). The excellent preservation in these sections (aragonite preserved) indicates that the sections offer the original fossil content without later alteration. The sections show that low diversity persisted almost up to the first appearance of Psiloceras spelae. Near this level also in other fossil groups new forms appeared: ostracodes, aragonitic forams, and palynomorphs.

The increase of diversity around the level of Psiloceras spelae indicates the end of the final crisis. The appearance of Psiloceras spelae at this level is not random. It is at the beginning of a general recovery. The T-J boundary is now proposed at this level. With this definition the final crisis is Triassic. The Jurassic begins with the appearance of new forms that persisted into later Jurassic.

Future plans
It is very evident that in a complex situation such as that summarized above, a single reference section, the GSSP, is inadequate. Of course, the GSSP will remain as the ultimate international point of reference for the base of the Jurassic System. However, further thought must be given as to how best to complement the GSSP with other international points of reference. The following are some topics that require further consideration by the TJBWG and the Jurassic Subcommission:
1. The Ferguson Hill section in New York Canyon (Nevada, USA) provides important supporting information to that of the Kuhjoch section, and its proposal as Auxiliary Stratotype Section and Point (ASSP) has been supported by a vote in the TJBWG. A documented case for this must now be prepared.
2. Current research by Jean Guex and colleagues (see Schaltegger et al. 2008 EPSL 267,266-275) in the Utcubamba Valley, Peru, following up earlier research by Axel von Hillebrandt, has confirmed a similar ammonite succession to that in Nevada and Austria and provided U-Pb ages. Consideration should be given as to whether a selected section should be proposed as an additional Auxiliary Stratotype Section and Point (ASSP).
3. The evolutionary faunal turnover of the radiolaria documented especially in the Kunga Island section provides an important “proxy” for recognition of the base Hettangian/Jurassic, and for interpretation of the biological history of the Earth during this time interval. It provides an important international secondary reference point that merits official recognition.
4. The reference sections in western Europe (St. Audrie’s Bay, S.W. England, and Waterloo Bay, Northern Ireland) document the earliest Psiloceras faunas in a different faunal province. These are also the only sections proposed as candidates where a magnetostratigraphic record appears to be preserved that could enable correlation with the terrestrial record such as that in the Newark Basin and elsewhere. Provided correlation with the GSSP at Kuhjoch, for example using the Carbon Isotope Excursion, can be refined then these sections will also be useful international secondary reference points.
Attachments
Foreword.rev_1.doc
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

2.Jurassic GSSP_proposal

Postby Junxuan Fan » March 20th, 2009, 7:49 am

A CANDIDATE GSSP FOR THE BASE OF THE JURASSIC IN THE NORTHERN CALCAREOUS ALPS (KUHJOCH SECTION; KARWENDEL MOUNTAINS, TYROL, AUSTRIA)

HILLEBRANDT, A. V., KRYSTYN, L. & KüRSCHNER, W. M.
with contributions by
P.BOWN, K. KMENT, CH. MCROBERTS, M. RUHL, M. SIMMS, A. TOMASOVYCH & M. URLICHS
Attachments
2.Jurassic GSSP_proposal.pdf
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

3.Robertinina S.1-8 - Jurassic GSSP_proposal_supplement

Postby Junxuan Fan » March 20th, 2009, 7:53 am

A CANDIDATE GSSP FOR THE BASE OF THE JURASSIC IN THE NORTHERN CALCAREOUS ALPS (KUHJOCH SECTION; KARWENDEL MOUNTAINS, TYROL, AUSTRIA)

HILLEBRANDT, A. V., KRYSTYN, L. & KüRSCHNER, W. M.

SUPPLEMENT

HILLEBRANDT, A. V.
Attachments
3.Robertinina S.1-8 Laptop.pdf
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Last edited by Junxuan Fan on March 20th, 2009, 8:28 am, edited 1 time in total.
Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

4.TRIASSIC-JURASSIC BOUNDARY ASSP_proposal

Postby Junxuan Fan » March 20th, 2009, 7:58 am

TRIASSIC-JURASSIC BOUNDARY ASSP AT FERGUSON HILL, MULLER CANYON (NEVADA, USA)

Jean Guex, Peter D. Ward, Annachiara Bartolini, David G. Taylor, Spencer G. Lucas, Lawrence H. Tanner and Christopher A. McRoberts
Attachments
4.ASSP_proposal.pdf
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

5.Hettangian GSSP general introduction_1.doc

Postby Junxuan Fan » March 20th, 2009, 8:01 am

GENERAL INTRODUCTION

The problem of defining the base of the Jurassic by a GSSP/ASSP has been one of the most difficult to resolve that I have personally come across. I have, as Chairman of the Jurassic Subcommission, and therefore voting member of the International Commission on Stratigraphy, seen a large array of GSSP proposals during the last eight years. Many were the best available on the basis of currently available information; others were very convincing; a few were, to put it politely, questionable but with no clear alternative, so were supported. This one, on the base of the Hettangian/Jurassic, is by far the most complex that I have come across - so many possibilities, so few details, so many unknowns!

The problem of defining the Triassic/Jurassic boundary has been investigated for many years, but the research has been especially active in the last seven years or so with the parallel activities of the Triassic/Jurassic Boundary Working Group of the Jurassic Subcommission and of the IGCP Project 458 on Triassic-Jurassic Boundary Events, both of which have contributed enormous amount of new information. Much of the membership was common to both.

For decades it was accepted generally that the base of the Jurassic should be identified with the first appearance of “typically Jurassic” ammonites and especially the genus Psiloceras. The oldest known at that time was Psiloceras planorbis and this species, and the Planorbis Zone to which it gave its name, was best known in south-west England. Even though no Triassic ammonoids are known from this area, it was generally assumed that these were the oldest “Jurassic” ammonites. Definition of the base of the Jurassic on this basis remains one option, and favoured by some. However, more recent research has shown that older species of Psiloceras, in Britain but more especially elsewhere, exist, stratigraphically above Triassic ammonoids. This was first demonstrated in Nevada, then more recently elsewhere (e.g. Chile, Tibet, Austria).

The question to be answered was whether the base of the Jurassic should be based on these older species of Psiloceras or remain with the traditional basis of Psiloceras planorbis. In the meantime other possibilities for the definition were proposed, namely a major turnover of radiolarian faunas or a carbon-isotope excursion. These were the choices faced by the Triassic/Jurassic Boundary Working Group, as explained in the “Foreword” document.

It was never likely that, given the controversies, there would be unanimous approval of any conclusion. So it has transpired - there remain strongly entrenched, and justifiable, dissenting opinions. Some cannot accept that their personal preference was not successful and are not happy with the final result. Others think that a decision is premature, though when and how further data could become available in the future to enable a better decision is not at all evident. Of course, not all problems have been resolved and there remains work to be done, but the result is considered by most as giving an acceptable definition of this difficult boundary.

In the end, after many discussions by email and other means, the decision was made by at least a two-thirds majority for the Kuhjoch section in Austria to be proposed as GSSP together with the Ferguson Hill section in Nevada, USA as ASSP. The two are complementary and although there are two separate proposal documents because of the circumstances of separate authorship, they are considered by the Jurassic Subcommission as constituting a single proposal.

Nicol Morton
18th August, 2008.
Attachments
5.Hett.GSSP.gen.Intro_1.doc
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Last edited by Junxuan Fan on March 20th, 2009, 8:21 am, edited 1 time in total.
Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

6.base of Jurassic_SC voting_1

Postby Junxuan Fan » March 20th, 2009, 8:13 am

INTERNATIONAL SUBCOMMISSION ON JURASSIC STRATIGRAPHY

DETAILS OF VOTING AND COMMENTS ON PROPOSED GSSP AND ASSP FOR THE BASE OF THE JURASSIC SYSTEM AND HETTANGIAN STAGE

After the results of the voting within the Triassic/Jurassic Boundary Working Group became available the intention was to arrange a ballot on a joint proposal for the GSSP in the Kuhjoch section, Austria, and the ASSP in the Ferguson Hill section, Nevada, USA. Both proposals were revised in the light of discussions and comments during the Working Group voting and a “Foreword” document was prepared explaining the procedures followed and results of the Working Group ballots.

In the event the GSSP proposal for the Kuhjoch section was the first to be ready for distribution and voting by the Voting Members of the Jurassic Subcommission. The “Foreword” document followed and was distributed some days later. Finally a revised summary ASSP proposal for the Ferguson Hill section was distributed and voted on. In retrospect these separate distributions caused some confusion and simultaneous distribution would have been preferable. For consideration of and voting on the GSSP and ASSP proposals by the International Commission on Stratigraphy all documents are being distributed simultaneously.


BALLOT OF VOTING MEMBERS ON HETTANGIAN/JURASSIC GSSP AT KUHJOCH SECTION, AUSTRIA

Distribution of proposal – 4 June 2008 Deadline for votes – 30 June 2008
Number of Voting Members = 22 Votes returned = 21 (95.5%)
[Percentages of returned votes given]

YES votes = 14 (66.7%)
Bown, Cecca, Dietl, Fernandez Lopez, Hesselbo, Hillebrandt, Morton, Ogg, Page, Pavia, Sha, Shi, Shurygin, Wierzbowski.

NO votes = 4 (19.0%)
Carter, Damborenea, Hirsch, Warrington.

ABSTAIN = 3 (14.3%)
Palfy, Smith, Yao.

The proposal has received over the required 60% majority of the votes cast.


INDIVIDUAL VOTES AND COMMENTS:

Bown: YES



Carter: NO
I have voted NO on Kuhjoch because I believe that Ferguson Hill is a far better section for GSSP based on the surrounding geology, lack of tectonics, and ammonite diversity. Furthermore by using C. minutum, Ferguson Hill can be correlated well with the sections in Queen Charlotte Islands and through radiolarian proxy, correlation across the Circum-Pacific region and eastern Tethys is feasible, while not possible in Kuhjoch.
[RESPONSE: This view is not shared by the majority of Working Group members.]

Cecca: YES
In my opinion the proposed ASSP in Ferguson Hill should be voted too because of the good record of ammonite diversity in that section, which helps for inter-regional correlations.

Damborenea: NO
Kuhjoch is potentially a very promising section to fix the base Hettangian GSSP, but it still needs to be studied in detail to meet the requirements for eventual acceptance. As a consequence, there are still serious doubts about the actual correlation of this section with others on the basis of the ammonite fauna (the marker species and its relatives have not been systematically studied in detail and thus their distribution in space and time is not adequately known), the microfossils and the chemostratigraphy. Facilitating strong correlations is one of the main objectives for fixing a GSSP, and I believe the proposal is very weak and incomplete in this aspect. Rather than rushing into a decision which we may regret I prefer to vote no at this stage.
[RESPONSE: This has been a long process and to delay risked loss of momentum when there is no apparently no new information forthcoming in the near or medium future.]

Dietl: YES

Fedan: no response

Fernandez Lopez: YES

Hesselbo: YES
This proposal represents a non-ideal but acceptable compromise between lower and higher levels previously suggested by TJBWG members.
Importantly, though, I think that the von Hillebrandt et al. proposal identifies the 'main negative excursion' in Austria wrongly. This is most certainly not correlatable with our (Hesselbo et al. 2002) ‘main negative excursion’ at St Audrie's Bay, which is a younger feature (extending through at least the whole planorbis Zone). The Austrian 'main negative excursion' may correlate with a small negative kick in the carbon-isotope record at St Audrie's Bay, in the basal 1 m of the Blue Lias where the isotope values decline from the 'initial' negative excursion to the subsequent positive.
This observation has significant implications for the correctness of Figs 28-30 of the proposal.

Hillebrandt: YES

Hirsch: NO
Since the TJB-GSSP members voted in favour of Kuhjoch as GSSP and of Ferguson Hill as Auxiliary GSSP (ASSP), the task of the ISJS voting members should be to accept or reject these chosen GSSP and ASSP section together, and not only that of the GSSP section. It is also in contradiction with the decision reached by the TJB voting members that no ASSP is presented in the Base Jurassic GSSP document, prepared by Hillebrandt & al. (2008).
Without the addition of Ferguson Hill as ASSP for the Base of the Jurassic, I have to formulate my most serious doubts concerning the section proposed herein as GSSP and its submission to the ICS commission for approval.
[Response: A joint proposal by one group of authors was not possible because there were two independent proposals with different authors, and different timetable observed!]

Morton: YES
The difficult question of defining the Triassic/Jurassic boundary was always bound to give a controversial result, even if one could be arrived at! This is a difficult interval of geological time for which it is very difficult to unravel the precise history of events. This is partly because of the complexity of these events and partly because of the relative paucity of continuous sections across the boundary interval. The result is not ideal in several ways, but then very few GSSPs can be claimed to be “ideal”. It is the best available.

Ogg: YES
I provided earlier recommendations to the working group to (1) show the correlation among the different reference sections, and (2) summarize the main events in the boundary interval. They have done this quite nicely (with Gabi Ogg helping on the the final graphics). The philosophy for this GSSP – the recovery from the end-Triassic mass extinctions and other events – is similar that used for the base-Triassic after the end-Permian extinctions. It would be nice to see some magnetic stratiraphy; but otherwise the array of demonstrated correlations are quite good. This is an excellent culmination of a concentrated effort by the international working group.

Page: YES
The Austrian section is really the only viable option.

Palfy: ABSTAIN
There has been an impressive amount of research leading to much useful new information made available from the Kuhjoch section. For this I congratulate Axel von Hillebrandt and his team. Nevertheless for me it is still premature to support a decision for the Kuhjoch +5.80 m level as base-Jurassic GSSP, because:
i) Psiloceras spelae n. spp. has not been formally described yet thus one cannot independently judge the validity of the identification of the primary marker taxon. One can choose to follow the opinion of the three experts quoted but it is a leap of faith rather than a scientific decision;
ii) The carbon isotope curve is clearly of great importance. The negative excursion of delta 13C org at the top of the KossenFormation coincides with a TOC peak hence its interpretation is ambiguous. I would prefer to wait for the results of compound-specific analyses promised in the proposal. There is no discussion whether this and other features of the curve can be produced by the changing ratio of terrestrial vs. marine organic matter in the boundary interval. Yet if confirmed, this negative spike may much better represent the boundary event than the psiloceratid ammonite FOD;. iii) The above concerns highlight my feeling that it is not wise (and likely unprecedented) to rush ahead with voting for a system boundary GSSP for a section about which no peer-reviewed publications have appeared yet. Kuhjoch may very well turn out to be the best section but I’m not convinced yet and in this process we should leave no room for awkward mistakes. I fear that if someone regards the ammonite as a new species, endemic to the Northern Calcareous Alps, than we risk reopening the debate sooner than we want to. It did not reassure me that the ammonite ID has been changed from Psiloceras cf. spelae to P. spelae new ssp. during the different rounds of ballots and the deadlines have always been shorter than required by the ICS statutes. On the positive side, a lot of thoughtful ideas and opinions were expressed in the debates.
[RESPONSE: The leading experts on this group of ammonites were all agreed on the conclusion that the sections could be correlated at the level of ammonite horizon, giving a high degree of resolution. The carbon-isotope events as primary marker were rejected by the majority of Working Group members. Most of the information had been available to Working Group members for over a year, so that long deadlines were not required; 60-day deadlines are no longer applied by ICS.]

Pavia: YES

Sha: YES
I have ever choose Psiloceras spelae as the marker of base-Hettangian. The new proposal sounds good.

Shi: YES
The suggested basal boundary for the Hettangian seems fine, but the new species of Psiloceras may pose some difficultie in correlation, especially those have not been confirmed with wide distribution. Thanks for the great effort for the determination of the GSSP.

Shurygin: YES
GSSP proposal is made excellently. The level with Psiloceras is a fine reference level which relatively confidently is traced in the Siberian sections.

Smith: ABSTAIN
I believe that the incoming of P. spelae is stratigraphically high relative to the actual extinction event as recorded by the microfossils and the chemostratigraphy. As a compromise and in the interests of making progress, I was willing to accept P. spelae as the marker and Kuhjoch as the GSSP site but a recent document by Guex et al. has raised questions as to whether the P. spelae levels in the Americas and Europe are actually correlative. Given such uncertainty I now choose to abstain. This should not detract from the excellent work done by our colleagues who have so quickly and so thoroughly documented the sequence at Kuhjoch.
[RESPONSE: There is further discussion of this in the ASSP proposal and elsewhere.]

Warrington: NO
I am unable to support this proposal for the following reasons (page and figure numbers refer to the proposal document issued with this voting form):
1. Situation and access – the site is at an elevation of 1760 m (5575 feet), near the top of a narrow, debris-strewn gully (Fig. 4). Access from the nearest road is clearly strenuous (1.5 to 2 hours are required to climb 523 m (1716 feet) in a distance of c.1.6 km; p. 4; Fig. 3); conditions (e.g. weather) likely to affect access or limit activity at this altitude are not indicated.
2. Outcrop – the section is described as ‘well-exposed’ (pp. 2, 19) but appears poor (Fig. 7), being situated on a fairly steep, partly grass-covered slope that evidently requires excavation both to expose the candidate section and to facilitate working. Beds at the site are overturned, though this is only admitted in the caption to Fig. 8. The situation limits the extent of the succession accessible at this site though (p. 19) ‘a continuous sequence of sediments of Late Triassic and Jurassic age which is some hundreds of meters thick’ is said to outcrop at Kuhjoch.
3. The appearance of Psiloceras spelae has been selected by the TJBWG as the marker for the base of the Hettangian. Irrespective of this decision attention must be drawn to the statement (p. 7) that ‘the variability of the Alpine species is not known’, suggesting that the boundary marker is, as yet, inadequately researched. The marker characterises ammonite level 2 in the Tiefengraben Member (Kendedlbach Formation) in the Kuhjoch section but the best-preserved psiloceratids at that level are from Hochalpgraben (p. 12), and ammonites have not yet been found in that member in some other sections in the region (p. 13); the choice of GSSP site, and possibly even the marker, is therefore questionable.
4. Inadequate or incomplete documentation – the presentation of records of many of the groups of fossils is inadequate or too generalised.
5. Proposal of this candidate is premature as too many studies (palynology: pp. 6, 11, 16; calcareous nannofossils: p.11; geochemistry: p.11; palaeomagnetism: p.12) are still in progress, incomplete or only planned.
6. Proxies – these are important in relation to the ‘correlatability’ of the proposed GSSP but the few identified comprise only an ostracod LO, the FOs of a miospore, a foraminifer and an ostracod, and a positive δ13Corg excursion. It should be noted that records of other ostracods (p. 14) indicate that these faunas exhibit diachronism between the site and NW Europe. The δ13Corg record, though detailed over some 14m, only extends some 6 m above the proposed GSSP level (Fig. 22); this is insufficient to allow satisfactory comparison and correlation with, for example, the stratigraphically more extensive record available from the UK (Hesselbo et al. 2004). The lack of success in magnetostratigraphic studies is a serious impediment to correlation, particularly to the continental successions present in many parts of the world.
7. The document has not been properly checked; minor typographical errors occur but more importantly, some figure numbers cited on pp. 4, 5, 7-9, 17 and 19 do not relate to appropriate illustrations. Some references cited (Ampferer & Ohnesorge 1912 (p. 4); Kozur & Mock 1991 (p. 10); Hillebrandt 2000c (p. 17); Ruhl et al. (in prep.; figs 21, 22, 23b); Palfy et al. 2002 (figs 28, 29)) are not listed, and some listed (Bonis et al. 2008; Carter & Hori 2005; Fabricius 1966; Guex et al. 1997; Hillebrandt & Krystyn 2007; Hillebrandt (in prep.); Hounslow et al. 2004) are not cited; Hillebrant 1994 should be Hillebrandt 1994, Ward et al. 2001 (p. 12) should be 2007, and Golebiowski is mispelt ‘Golebiowsky’ in the text (pp. 3, 5, 13).
8. For whatever reason, some significant work is not cited; for example, a palynological study (Morbey 1975) of the Kendlbach section (p. 13).
Conclusion: The proposal is premature and exhibits evidence of being prepared hurriedly and without adequate attention to detail. The information provided is inadequate in many respects and some is potentially misleading. The document does not present a convincing case for consideration of the Kuhjoch section as a realistic candidate GSSP for the base of the Hettangian. In many respects Kuhjoch appears inferior to other sites that have been considered by the TJBWG.
References:
Hesselbo, S. P., Robinson, S. A. & Surlyk, F. 2004. Sea-level change and facies development across potential Triassic-Jurassic boundary horizons, SW Britain. Journal of the Geological Society, London, 161 (3): 365-379.
Morbey, S. J. 1975. The palynostratigraphy of the Rhaetian Stage, Upper Triassic in the Kendelbachgraben, Austria. Palaeontographica, B.152 (1-3): 1-75.
[RESPONSE: Most of this is a matter of opinion; other points have been addressed in the revision of the proposal as submitted to ICS.]

Wierzbowski: YES
All the data presented show it is very good proposal.

Yao: ABSTAIN
I think that time is necessary a little more to judge yes or no.



BALLOT OF VOTING MEMBERS ON HETTANGIAN/JURASSIC ASSP AT FERGUSON HILL SECTION, NEVADA, USA

Distribution of proposal – 3 July 2008 Deadline for votes – 3 August 2008

Number of Voting Members = 22 Votes returned = 17 (77.3%)
[Percentages of returned votes given]

YES votes = 14 (82.4%)
Carter, Cecca, Fernandez Lopez, Hillebrandt, Hirsch, Morton, Page, Palfy, Pavia, Sha, Shi, Shurygin, Smith, Wierzbowski.

NO votes = 3 (17.6%)
Damborenea, Hesselbo, Warrington.

ABSTAIN = 0

[No response = 5 (22.7% of Voting Members)
Bown, Dietl, Fedan, Ogg, Yao]


The proposal has received over 80% of the votes cast over the required 60% majority of the membership of the Subcommission.


INDIVIDUAL VOTES AND COMMENTS

Bown: no response

Carter: YES
COMMENTS: In my view, the Kuhjoch section has been too little studied to reign as GSSP for the base of the Jurassic System. There are too many open questions such as the completeness of section, the position of the various proxies etc that need more study. But since Kuhjoch has been voted GSSP by members of the Jurassic Subcommission, the addition of the Ferguson Hill section as ASSP provides the needed complement. Among other features, Ferguson Hill is as continuous as likely possible, and presently it provides the only potential for Circumpacific correlation in that the ammonites can be correlated with those at Kunga Island and Kennecott Point and thus with radiolarians of the Canoptum merum Zone. This correlation can only be achieved through voting the Ferguson Hill section as ASSP, to complement the GSSP section at Kuhjoch.

Cecca: YES

Damborenea: NO
COMMENTS: Ferguson Hill is a well-studied section, key for the correlation of east Pacific regions, which contains a rich ammonite fauna, and is type locality of the agreed marker for the base of Hettangian, namely Psiloceras spelae Guex. In many ways it seems to complement the proposed Kuhjoch section; in fact, Ferguson Hill is indeed better than this one concerning important aspects of a formal GSSP proposal such as exposure, access, abundance/diversity of guide fossils and published research. However, the serious problems posed by the proposal of Kuhjoch section as GSSP, already clearly exposed by several voters on the occasion of the previous voting round (see comments by Warrington, Hesselbo and Pálfy, for instance), are not solved by this belated introduction of Ferguson Hill as its ASSP. The whole voting procedure gave rise to simultaneous serious discussions on several key aspects of the proposals that are still going on (and many of them are not even considered in the proposals as submitted). This shows that the entire proposal is untimely and, as yet, not mature to be presented to the International Commission on Stratigraphy.

Dietl: no response

Fedan: no response

Fernandez Lopez: YES

Hesselbo: NO
COMMENTS: Although the FH section is clearly of great stratigraphic value, the advantage of formal identification as an ASSP is not clear. I see no practical consequence for definition and recognition of the T-J boundary. Other workers will use the FH section as a stepping-stone to Kujoch whether or not it is an ASSP. The only advantage that I can conceive is that ASSP status may help to preserve the section and focus future work upon it – but there may be other, more direct, ways of achieving the same aim.
[RESPONSE: Others emphasise the contrary!]

Hillebrandt: YES
COMMENTS:
1. Additional proxies are not (not yet?) found in the ammonite horizon with P. spelae, contrary to the proposed GSSP (palynomorphs, ostracodes, forams).
2. Below and above the horizon with P. spelae additional ammonite genera and species are found which do not occur at Kuhjoch.
3. Above the P. spelae horizon is possible an ammonite correlation with Kunga Island and Kennecott Point.
4. A correlation of the radiolarian turnover only is possible with help of the initial negative delta13Corg excursion which is also found at Kuhjoch. Canoptum merum was not found at the proposed ASSP.
5. A satisfactory combination of the Lucas et al. proposal with the McRoberts et al proposal does not yet exist.
6. The updated proposal by Guex et al. is in part incomplete and important, already existing informations are lacking (e.g. the exact position of the delta13Corg excursion of McRoberts et al. is not known).
The proposed ASSP contains a high potential of informations which are not described sufficiently in all sectors.
[RESPONSE: Most points rectified in revised proposal to ICS.]

Hirsch: YES
COMMENTS: The correlation between an ASSP at Ferguson Hill and the GSSP at Kuhjoch is presently strongly agreed upon by the "fathers" of the respective proposals. The Ferguson Hill section does immensely complement the base Hettangian/Jurassic.GSSP section at Kuhjoch in several ways. Its wider correlation potential based on the spelae biohorizon, and several proxies allows a worldwide (global) fixation of what is closest to a point, as realistically can be: an ammonite correlation with the Kunga and Kennecott Point sections, where the radiolarian Canoptum merum is anchor to circum-Pacific correlation. The Ferguson Hill Section has further the advantage to be as continuous as a section can be at the first appearance (FA) of P.spelae, a condition that remains uncertain for the first occurrence (FO) of a P.spelae specimen at Kuhjoch. Therefore, I recommend the joint proposal of the Ferguson Hill section as ASSP and the Kuhjoch section as GSSP, to the central ICS committee.

Morton: YES
COMMENTS: In my opinion there is sufficient merit in the proposal for the Ferguson Hill section to be an auxiliary stratotype, ASSP, for the base of the Hettangian/Jurassic. It DOES complement the GSSP section at Kuhjoch in several ways and does help with wider correlation. This correlation should not be regarded as a boundary correlation in the sense of being a time-plane. This would be completely unrealistic and I know of no GSSP-defined boundary for which strict time-plane correlation is claimed. It does give a correlation of a basal unit of the Jurassic that can be shown to be of short duration so that the correlation has a very small errot margin relative to the age of the rocks.

The ASSP proposal is not satisfactory as it stands. It does not give enough of the most significant data published elsewhere for it to stand enough on its own. The primary marker, first appearance of Psiloceras spelae, is clear but precise levels of the most important secondary markers are not given clearly.
[This has been rectified in the revisedproposal to ICS.]

Ogg: no response

Page: YES
COMMENTS: I support Ferguson Hill as an ASSP - the discussion over correlations using the isotopes is some detail which will be resolved at some point, but the ammonite correlation appears good and any slight discrepancy - if it REALLY exits - will be so minor as to be irrelevant at this scale - e.g. sub-biohorizon, less than 50,000 years maybe over 200 million ago?!

Palfy: YES
COMMENTS: I support designating Ferguson Hill (New York Canyon) as an ASSP because it is one of the most important T/J boundary sections and the type locality containing the stratum typicum (type level) of Psiloceras spelae, the ammonite species whose purported first occurrence datum defines the TJB at the Kuhjoch GSSP. The FH/NYC section is the only one where a prominent TJB carbon isotope excursion, for many an important hallmark of the boundary event itself, has been confirmed by two independent research groups. The ASSP section provides crucial correlation for other Pacific sections. I found it frustrating and confusing that the voting form arrived in my mailbox with an incomplete sentence, garbled characters, erroneously (?) referring to the occurrence of the radiolarian Canoptum merum (at least contrary to the proposal by Guex et al. and the relevant paper by Orchard et al. 2007), and again with a much shorter deadline than the 60 days required by ICS.

Pavia: YES
Sha: YES
COMMENTS: This is a very good ASSP of the base-Hettangian as there are both prominent markers of fossils and carbon isotope.

Shi: YES
COMMENTS: This suggested ASSP is acceptable though some minor problems still remained.

Shurygin: YES
COMMENTS: I have attentively read all letters of Jean Guex, Axel von Hillebrandt, comments of Nicol Morton and others. I think that ASSP can be accepted. Some of debatable questions of correlation still remains. Important that Psiloceras spelae occur from the same ammonite biohorizon.. The incontestable proofs of occurrence of Psiloceras spelae at different levels in GSSP and ASSP sections are not present. However it does not prevent to use ASSP which really contains a lot of the additional information.

Smith: YES
COMMENTS: I still have concerns about the Austria-US correlations and the documentation of proxies. However, from earlier discussions, there is enough potential that I am comfortable with voting 'YES' on the Nevada ASSP proposal. Please accept this email as my formal vote. I anticipate that Axel and Jean will be able to formulate a final document that will deal with possible criticisms from the ICS.

Warrington: NO
COMMENTS: In successive votes conducted within the T/J Boundary Working Group I voted against:
a) the selection of the FAD of P. spelae as the criterion for recognising the base of the Hettangian
b) the selection of the Kuhjoch section as the GSSP for the base of the Hettangian, and of Ferguson Hill as an AASP for that level
In the subsequent vote conducted within the ISJS voting membership I voted against acceptance of the Kuhjoch section as the GSSP, and gave my reasons on the voting return.

It is therefore illogical that I should do anything other than vote against the proposal of Ferguson Hill as an AASP.

The discussion that has taken place around the AASP proposal since the ISJS vote has only convinced me that my decision then was the right one. From that discussion it is evident that important uncertainties and differences of opinion remain, particularly relating to the correlatability of what is still only a proposed GSSP.

The ISJS vote received 21 returns of which 14 were in favour of the Kuhjoch proposal and seven (No votes and Abstentions) against. However, five of those in favour made no comment on the proposal, three made comments that are cautious or ambivalent and only six made clearly positive comments. Technically, the 60% in favour criterion was achieved but the above analysis suggests a distinct lack of enthusiasm amongst the ISJS voters regarding the proposal. This situation, where one third of the voters are against and several others, though voting for the proposal, are clearly uneasy with some aspects, is completely unacceptable. It has no parallel in any similar vote that I have been involved in concerning a major stratigraphical boundary.

Wierzbowski: YES

Yao: no response
Attachments
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

7. Becker_03-09-09

Postby Junxuan Fan » April 2nd, 2009, 9:48 am

Date: Mon, 09 Mar 2009 15:04:49 +0100
To: Stan Finney <scfinney@csulb.edu>
From: "Prof. Dr. T. Becker" <rbecker@uni-muenster.de>
Subject: Re: Quaternary discussion

Dear Stan:

On Thursday and Friday I attended the meeting of the German Stratigraphic Commission. Following my proposal and distribution of the Neogene and Quarternary proposals, there has been a discussion and new vote on the Neogene-Quarternary boundary, which I will follow in my future personal vote. The German Commission on Stratigraphy, without exception (even of the German Chairman of the Tertiary Subcommission), voted to define the Quarternary as a system above the Neogene at the base of the Gelasian. The latter should become the future lower Pleistocene stage. This is simply a continuation of the previous decision reported by Manfred Menning, Chairman of the German Comission, at Oslo. In other words, there is no change of opinion.

After careful consideration of the GSSP and ASSP proposals, and after discussions with the Chairman of the German Jurassic Subcommission (Eckard Mönning), I formally vote yes to accept both proposals. Both sections are far from ideal but there is no prospect for any better section and any better solution of the problems at the T/J boundary. It is important not to place typical Triassic fossils (ammonoids, conodonts) into the basal Jurassic. The significance of the Nevada ASSP should be emphasized to IUGS, who has been rather cautious in recent time to accept auxiliary stratotypes.

Please be ware that I will leave to Morocco early tomorrow morning and that I will not be back to my office before the 1st April. There will be no possibility for me to communicate with ICS in that period.

all the best, Thomas
Attachments
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

8. Peng 03-20-09

Postby Junxuan Fan » April 2nd, 2009, 9:57 am

From: "Shanchi Peng" <scpeng@nigpas.ac.cn>
To: "Stan Finney" <scfinney@csulb.edu>
Subject: Re: base Jurassic GSSP proposal
Date: Fri, 20 Mar 2009 22:56:18 +0800

Dear Stan,

I spent plenty of time to digest the GSSP and ASSP proposals of ISJS, and found that I was not satisfied with both sections. The Kuhjoch section, proposed as GSSP, is more or less hard to access and the proposed T/J boundary interval in the section is rather poorly exposed and overturned. In addition, the primary marker Psiloceras spelae is known only from a single level, casting doubt upon if the boundary is really defined at the LO (FAD) of the species (new subspecies). However, I understand that the available sections are rare, and GSSP is placed within an interval of difficult time, and if there is no expectation to have better sections, I probably will vote yes to the proposal of the Kuhjoch section.

I don't think it is a good idea to package two proposals as a single proposal for consideration by ICS voting members as it may make some VMs in a dilemma if they support only one of them. Personally, I am very irresolute to accept, or to recognize formally, the Ferguson Hill section as an ASSP, though the section shows great value in regional correlation. What I am worry about lies that the Jurassic base is defined in this section by a different subspecies from the GSSP candidate Kuhjoch section, and like Psiloceras spelae n ssp. of the Kuhjoch section, Psiloceras spelae spelae in the Ferguson Hill section is also known from a single level, and so far there is no enough evidences convincing us that the levels containing different subspecies in different sections are fully conrrelatable. In this case, a possible risk that we may create double standard for defining Jurassic base exists probably, even if the auxiliary point is considered to be subordinate to the Kuhjoch GSSP. In the current case, if we believe the correlation between Kuhjoch and Ferguson Hill is really or reliably established, then is there any virtual significance in erecting an auxiliary standard.

My second concern is the formal status of the term ASSP (Auxiliary Stratotype Section and Point) in ICS chronostratigraphic nomenclature. As I know, some auxiliary sections had been established previously by some boundary working group or subcommissions, i.g. the Nanbiancun section in China and the Hasselbachtil section in Germany, both selected by the Devonian-Carboniferous Boundary Working Group as the "Auxiliary Stratotype Section" of the boundary and the Prastav Quarry section in Czech had selected by ISDS as "Auxiliary reference section" for the Eifelian Stage (and Middle Devenian), but I didn't know whether these sections had been finally approved or ratified by ICS/IUGS as ASSP or they were only passed in vote within subcommissions/boundary WPs. To my knowledge, in the essential official documents of ICS, i.e. the "International Startigraphic Guide (1st & 2nd editions)", the "Guidelines and Statutes of ICS (Cowie et al., 1986)", and the "Revised guidelines for eastablishing global chronostr. Standard by the ICS (Remane et al., 1996)", a term like ASSP has never been mentioned and, instead, only term ASP (auxiliary stratotype point) was formalized. According to Cowie et al. (1986), the ICS prefers "..to confine nomenclature, for ICS candidates, to two categories of stratotype: (a) global stratotype section and point (GSSP) and (b) auxiliary stratotype point (ASP). This term was confirmed also by Remane et (1996), who said as "if reference section and points seem necessary... , an auxiliary stratotype point may be defined". In the International Strtigraphical Guide (2nd edition, p. 37), an "auxiliary reference section" means "hypostratotype", a term that the ICS is preferable not to accept (Cowie et al., 1986, p. 5).

Conclusion. I would suggest that separate votes could be arranged for the GSSP and the ASSP proposals of Jurassic subcommission; that the term ASP should be used for auxiliary stratotypes until the term ASSP is specified formally by ICS; and that if an ASP or ASPs are needed, we may confine to use them only within ICS or even within certain subcommissions rather then search for formal ratification of IUGS if there are no such ratified precedents existed.

Best wishes,

Shanchi

----- Original Message -----
From: "Stan Finney" <scfinney@csulb.edu>
To: <brian.pratt@usask.ca>; <brichard@NRCan.gc.ca>;
<charles.henderson@ucalgary.ca>; <dharper@savik.geomus.ku.dk>;
<emolina@unizar.es>; <felix.gradstein@geologi.uio.no>;
<fhilgen@geo.uu.nl>; <gehling.jim@saugov.sa.gov.au>;
<isabella.premoli@unimi.it>; <jogg@purdue.edu>;
<Marco.Balini@unimi.it>; <martin.vankranendonk@doir.wa.gov.au>;
<mmelchin@stfx.ca>; <palfy@nhmus.hu>; <plg1@cus.cam.ac.uk>;
<rbecker@uni-muenster.de>; <scpeng@nigpas.ac.cn>; <p.bown@ucl.ac.uk>
Sent: Tuesday, March 17, 2009 4:17 AM
Subject: base Jurassic GSSP proposal


> To: ICS voting members
>
> Besides following the Q-N discussion, I hope that you also have read
> the GSSP proposal for the base of the Jurassic. When I distributed
> it, I indicated that discussion would be open until 16 March, at
> which time ballots would be distributed. I received only one comment
> from Devonian Subcommission Chair Thomas Becker and I attach it here
> (see second paragraph of Becker's letter). I plan to mail out
> ballots on 23 March (Monday). Any comments you might wish to make
> should be made before the ballots are distributed.
>
> Best wishes,
> Stan
> --
> *************************************************************
> Stanley C. Finney, Chair
> Department of Geological Sciences
> California State University - Long Beach
> Long Beach, CA 90840 USA
> Phone: (562) 985-8637
> FAX: (562) 985-8638
> e-mail: scfinney@csulb.edu
> Co-Director, Environmental Science & Policy Program
> Chair, International Commission on Stratigraphy (IUGS)
Attachments
8. Peng 03-20-09.doc
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

9. Morton 03-21-09

Postby Junxuan Fan » April 2nd, 2009, 10:05 am

Cc: Palfy Jozsef <palfy@nhmus.hu>
From: nicol morton <nicol.morton@orange.fr>
Subject: discussion
Date: Sat, 21 Mar 2009 20:56:19 +0100
To: Finney Stan <scfinney@csulb.edu>

Dear Stan,

Thank you for forwarding to me the comments by Becker and Peng - both of whom I know well from my time in ICS and respect. I respond with my comments - please feel free to forward this message if you think it appropriate.

We are all aware that the base of the Jurassic is an extremely difficult case. However, it should be pointed out that the propose boundary definition has a much smaller margin of error than most! The ammonite specialists involved are in agreement that the Kuhjoch and Ferguson Hill subspecies of Psiloceras spelae are in the same ammonite biohorizon - equivalent to an interval of time estimated to be of the order of less than 100k years (see papers by John Callomon - I can give references if required). Please compare this with the precision of other GSSPs. It should give everyone confidence that the two sections proposed are genuinely complementary.

Professor Peng is right to point out that the term ASSP (Auxiliary Stratotype Section and Point) is not yet officially recognised by ICS. It has the same meaning as ASP (Auxiliary Stratotype Point). The important point being made by the Jurassic Subcommission is that the older term "ASP" is very inappropriate because a point in a section has no value other than in its geological context in a section. It is ONLY the time relationship between the underlying and overlying strata that give it meaning. This case was made for the Bathonian (Middle Jurassic) proposal approved by ICS.

We would argue that it is time for ICS to reconsider its terminology and to recognise that a single point in one section may not be sufficient to enable the RECOGNITION and CORRELATION, as distinct from DEFINITION, of a stratigraphical boundary. Stratigraphy must be, above all, a practical aspect of our science.

With best wishes,

Nicol Morton.
Attachments
9. Morton 03-21-09.doc
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Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

10. Palfy 03-22-09.1

Postby Junxuan Fan » April 2nd, 2009, 10:13 am

X-IronPort-AV: E=Sophos;i="4.38,403,1233561600";
d="pdf'?scan'208";a="20155989"
Date: Sun, 22 Mar 2009 20:24:15 +0100 (CET)
Subject: Re: ballot for base Jurassic GSSP
From: "Jozsef Palfy" <palfy@nhmus.hu>
To: "Stan Finney" <scfinney@csulb.edu>
Cc: "Jozsef Palfy" <palfy@nhmus.hu>, nicol.morton@orange.fr
Reply-To: palfy@nhmus.hu

Dear Stan,

I have read the draft ballot you sent me. Here are a few comments as requested.

I advise against using subspecies names until they are officially published, as the International Code of Zoological Nomenclature unambiguously states that a taxonomic name becomes available only when it is published in an appropriate print medium. As we know from Axel von Hillebrandt, this is not expected before July 2009. The ICZN doesn't recognize such thing as in press taxonomic name. The nominate subspecies Psiloceras spelae spelae will also become viable only when another subspecies is explicitly introduced. Thus now we have Psiloceras spelae n. ssp. from Kuhjoch and P. spelae from New York Canyon. It would be unfortunate to ignore the ICZN when the boundary definition is clearly based on biostratigraphy which in turn is rooted in ammonoid taxonomy.

My answer to the second question is yes, I concur with Nicol Morton in that of course the base of the Hettangian Stage is equated not only with that of the Jurassic System but also the Lower Jurassic Series.

The third issue is the one raised by Shanchi Peng, about combining the GSSP and ASSP votes in a single ticket. Here I agree with Shanchi in that I believe it is much preferable to separate the two issues by requiring two votes from our members, one on the GSSP and a separate one on the ASSP. This is also how it was handled within the Jurassic Subcommission and it carries the advantage that, as Shanchi has pointed out, people with differing opinions on the two sections are allowed to vote accordingly.

Beyond this practical question, there are two points worth discussing. One is more general and theoretical, whether or not ASSPs have a useful role in the standardization of chronostratigraphy (this is obviously debated by some), and if yes, what are the criteria of a meaningful ASSP. The other is more specific to the TJB issue, whether an ASSP defined by the FOD of the same species (but represented by supposedly different subspecies, which could be interpreted as either geographic subspecies or chrono-subspecies) enhances the GSSP proposal or rather sanctions another, secondary standard which may lead to ambiguity, should the GSSP-ASSP correlation be questioned by some.

Two minor editorial remarks: Kendelbach vs Kendlbach Formation - both occur in the literature but the GSSP document favors the latter spelling, thus use this consistently in the ballot. Add seconds and W to the longitude of the ASSP coordinates.

I also have a procedural remark about the deadline. The ICS statutes (Paragraph 9.7.) state that: Voting shall be conducted by postal ballot or electronically (email), giving a deadline of sixty (60) calendar days for the receipt of the votes. In the past, I have been frustrated when this rule was not complied with at Task Group or Subcommission level. I was always told that the 60 days rule is from pre-email times, yet email as a medium of communication is explicitly recognized in this paragraph. At the ICS, we of course are in the position to emend our own statutes. But violating a requirement set out in the current statutes sends a wrong message. I realize that you introduced a discussion period before the ballot, which of course may be argued to be counted towards the total time. In this system, however, I would prefer to see the discussion remain open until the final ballot deadline.

In the specific case of the TJB vote, I feel that so far it has not received adequate attention from the ICS voting membership, conceivably because we have been preoccupied with the intense and complex Neogene-Quaternary debate. After several weeks, you have just distributed the second comment, and this one by Shanchi addresses some substantial concerns. I follow these up in a comment in an attached letter, accompanied by a virtual field trip to the GSSP candidate section, both of which I ask you to distribute. I see the lack of more comments so far as a clear indication that we need to keep the discussion open until after the N-Q issue will have settled, so we have a period of undivided attention of our membership. Please consider this request and do not close the discussion on Monday, March 23 as originaly planned. I feel that a reasonable extension will help assure a significantly more informed and careful ICS vote. After all, we are about to fix a system boundary, the second last left undefined in the Phanerozoic, quite a responsibility!

Best wishes,

Jozsef


> Joseph:
>
> I am composing the ballot for the base Jurassic GSSP,
> which will be
> sent out on Monday. As a model I am using a sample that
> Nicol
> prepared when he forwarded the GSSP proposal to ICS. I
> have two
> questions.
>
> First, can I now add the subspecies names to Psiloceras
> spelae now
> that the description of the new subspecies by van
> Hillebrandt &
> Leopold is now in press.
>
> Secondly, does not the GSSP define not only the base
> Jurassic System
> and Hettangian Stage but also the base of the Lower
> Jurassic Series?
>
> See the attached ballot I have prepared and in which I
> include the
> subspecies and the Lower Jurassic Series, and let me know
> what you
> think.
>
> Stan
>
>
> --
> *************************************************************
> Stanley C. Finney, Chair
> Department of Geological Sciences
> California State University - Long Beach
> Long Beach, CA 90840 USA
> Phone: (562) 985-8637
> FAX: (562) 985-8638
> e-mail: scfinney@csulb.edu
> Co-Director, Environmental Science & Policy Program
> Chair, International Commission on Stratigraphy (IUGS)


--
Jozsef Palfy
Head of Department of Geology and Paleontology,
Hungarian Natural History Museum
and Scientific Advisor,
Hungarian Academy of Sciences-Hun. Nat. Hist. Museum,
Research Group for Paleontology

POB 137 Budapest, H-1431 Hungary
Phone: +36 1 210 1075/ext. 2310
or +36 338 3905
Fax: +36 1 338 2728
E-mail: palfy@nhmus.hu
Web: http://www.nhmus.hu/~palfy

Attachment converted: Macintosh
HD:Palfy_TJB_comments.pdf (PDF /«IC») (0019B579)
Attachment converted: Macintosh
HD:Kuhjoch_TJB_GSSP_candidate.pdf (PDF /«IC»)
(0019B57A)
Attachments
10. Palfy 03-22-09.1.doc
(35 KiB) Downloaded 53154 times
Junxuan Fan, Research Professor, Leader of the Geobiodiversity.com database
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
39 East Beijing Road, Nanjing 210008, China
Tel: 0086-25-83282247
Email: fanjunxuan@gmail.com
Junxuan Fan
 
Posts: 45
Joined: February 20th, 2009, 1:17 am

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