ps418

I'm working on review article on the Permian-Triassic extinction. The review will cover all kinds of things, including radiometric dating, stable isotope stratigraphy, paleosols, biostratigraphy, and possible extinction mechanisms. I already have lots of great stuff ready to go, but I have to wait until Jan. 2 to get the rest of the articles I need from the library. In the meantime though I want to post some of the biostratigraphic information. The text below is quoted from my article. The refs are:

Kobayashi, F., 1999. Tethyan uppermost Permian foraminiferal faunas and their paleogeographic and tectonic implications. Palaeogeography Palaeoclimatology Palaeoecology 150, p. 279-307.

Lai, X, Wignall, P., and Zhang, K., 2001. Paleoecology of the conodonts Hindeodus and Clarkina during the Permian-Triassic transitional period. Palaeogeography Palaeoclimatology Palaeoecology 171, pp. 63-72.

Yin, H.F., 1985. Bivalves near the Permian-Triassic boundary in South China. Journal of Paleontology 59, p. 572-600.

Yin, H.F., and Tong, J.N., 1998. Multidisciplinary High-Resolution Correlation of the Permian-Triassic Boundary. Palaeogeography Palaeoclimatology Palaeoecology 143, pp 199-212.


The P-Tr boundary in marine sediments is formally defined by the first occurence of the conodont Hindeodus parvus.



The P-Tr boundary can also be defined, with less precision, by the first occurences of the bivalve Claraia or the ammonoid Otoceras woodwardi. Since Meishan, China section has been chosen as the P-Tr boundary stratotype, we will describe the biostratigraphy there, and then see how other sections around the world correlate with Meishan. The finest divisions are based on conodonts. Condont zones at the P-Tr boundary at Meishan are as follows (from Lai et al., 2001; Yin and Tong, 1998):

Meishan
I. isarcica
H. parvus
H. typicalis
C. changxingensis
C. deflecta
C. subcarinata

Shangsi
I. isarcica
H. parvus
H. typicalis
C. changxingensis
C. deflecta
C. subcarinata

Armenia
I. isarcica
H. parvus
H. typicalis
C. changxingensis
C. deflecta
C. subcarinata

Spiti, India
I. isarcica
H. parvus
H. typicalis
C. changxingensis
x
x

Kashmir
I. isarcica
H. parvus
H. typicalis
C. changxingensis
x
C. subcarinata

Kuh-e-Ali Bashi, Iran
I. isarcica
H. parvus
H. typicalis
C. changxingensis
x
C. subcarinata

Salt Range, Pakistan
I. isarcica
H. parvus
H. typicalis
x
x
x

Austria
I. isarcica
H. parvus
H. typicalis
x
x
x

Sicily
x
H. parvus
H. typicalis
C. changxingensis
C. deflecta
x

Greenland
x
H. parvus
H. typicalis
x
x
C. subcarinata

Western US
I. isarcica
H. parvus
H. typicalis

West Australia
I. isarcica
H. parvus
H. typicalis

Canadian Arctic
I. isarcica
H. parvus
H. typicalis

Although conodonts are the best zonal fossils for global correlation of the P-Tr boundary, they are not present in all sections, and other fossil zones can be used to mark the boundary. For instance, looking again at the earliest Triassic sediments at the Meishan type section, associated with the condonts H. parvus and I. isarcica, we find the bivalves Pseuodoclaraia wangi and C. griesbachi, followed upsection by the first occerences of C. aurita, C. stachei, and E. multiformis. We find the same sequence, in whole or in part, just above the PTB in sections from the Alps, the western US and Canada, Kashmir, Siberia, Arctic Canada, Greenland, Spitzbergen, and elsewhere (Yin. 1985).

Yet another useful zonal fossil group is the forminifera. For instance, the latest Permian sediments in south China contain the fusulinid genus Paleofusiella. Again, this same genus is found in latest Permian deposits in Japan, north Vietnam, Tibet, and the Carnic Alps, Austria (Kobayashi, 1999). Note that ALL fusulinid forams become extinct by the PTB, although other types of foram do not.

ps418

More Permian condont sorting. These examples are from:

Mei, S., Henderson, C.H., 2001. Evolution of Permian condont provincialism and its significance in global correlation and paleoclimate implications, Palaeogeography Palaeoclimatology Palaeoecology 170, pp. 237-260.

South China sequence

C. subcarinata
C. inflecta
C. orientalis
C. transcaucasia
C. guangyuanensis
C. leveni
C. asymmetrica
C. dukouensis
J. xuanhanensis - Sw. fengshanensis zone
J. prexuanhanensis- Sw. fengshanensis zone
J. altudaensis- Sw. fengshanensis zone
J. shannoni
J. postserrata
J. aserrata
J. nankingensis
x
N. exsculptus - N. pequopensis
M. bisselli - Sw. whitei
x
St. isolatus

Texas sequence

J. xuanhanensis
J. prexuanhanensis
J. altudaensis
J. shannoni
J. postserrata
J. aserrata
J. nankingensis
x
N. exsculptus - N. pequopensis
M. bisselli - Sw. whitei
x
St. isolatus

Abadeh, Iran sequence


C. subcarinata
x
C. orientalis
C. transcaucasia
C. guangyuanensis
C. leveni
C. asymmetrica
C. dukouensis
Sw. fengshanensis

[ January 03, 2002: Message edited by: ps418 ]</p>