in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
biodiversity of fossil biota may display a pronounced
change. Further analysis is undertaken focused on the
vegetation, sedimentary facies, isotope variation as
well as the ecosystem change. These aspects will be
considered in the frame work of the non-marine T/J
boundary geological and bio-events and their potential
causes. The Jurassic/Cretaceous boundary is uncon-
formity contacted in between the Penglaizhen
Formation (Upper Jurassic) and the Lower Cretaceous
Cangxi Formation in Saitai County of the Sichuan
Basin (Fig.1 G). The Cangxi Formation is characterized
by the pale yellowish grey sandstones and purplish red
sandy mudstones, siltstones, and conglomerates. These
two boundaries are distinct in the field by the
lithological features.
Previous investigations have established diverse
fossil remains and various assemblages for the Upper
Triassic, Lower to Upper Jurassic, including bivalves,
conchastracas, ostracodes, vertebrate fossils, spores-
pollen and plant. These assemblages provide infor-
mative data for understanding the biodiversity and
variation of the Jurassic biota, and are also helpful for
defining the roughly geological ages. These supply
further evidences for our understanding of the
palaeotectonics, palaeoclimate, palaeoenvironmental
and biodiversity aspects of the Sichuan Basin in the
Jurassic period.
Acknowledgements: This work was jointly sup-
ported by the Knowledge Innovation Program of CAS
(KZCX-2-YW-154), the National Key Basic Research
Program of China (2006CB701401), National Natural
Sciences Foundation of China (NSFC 40472004,
40972008) and the special grant of the Jurassic studies
in the Sichuan Basin (No. 07D0020201). This is a
contribution to UNESCO-IUGS project IGCP 506.
Key words: Upper Triassic; Jurassic; Triassic/
Jurassic boundary; Jurassic/Cretaceous boundary;
Fossil biota; The Sichuan Basin
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