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2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 224-7
Presentation Time: 9:00 AM-6:30 PM

AN ASTRONOMICAL TIME SCALE FOR TRIASSIC ECOSYSTEM RECOVERY IN SOUTH CHINA


LI, Mingsong1, HUANG, Chunju2, HINNOV, Linda A.3, OGG, James G.4, ZHANG, Yang2, CHEN, Zhong Qiang5 and ZOU, Zhuoyan2, (1)School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, (2)School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China, (3)Dept. Atmospheric, Oceanic and Earth Sciences, George Mason University, 4400 University Avenue, Fairfax, VA 22030, (4)Earth and Atmospheric Sciences, Purdue Univ, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, (5)State Key Laboratory GPMR, China University of Geosciences, Lumo Road 388, Wuhan, 430074, China, mli69@jhu.edu

In the aftermath of the Permian-Triassic mass extinction life experienced a prolonged recovery that lasted several million years. The full recovery of ecosystems dates back to the Middle Triassic Anisian Stage. However, the timeline for the early Triassic recovery is currently understood only in an uncertain framework.

Here we present high-resolution spectral gamma-ray measurements from marine sections of South China ranging from latest Permian to early Late Triassic: the latest Permian-earliest Triassic section at Meishan (Zhejiang), Early Triassic sections at Chaohu (Anhui) and Daxiakou (Hubei), the Olenekian-early Carnian section at Guandao (Guizhou), and Carnian sections at Xiaowa and Laishike (Guizhou). The gamma-ray variations document Milankovitch frequencies that support the astronomical models. Astronomical tuning of the gamma-ray series to orbital eccentricity cycles yields an astronomical time scale for these South China sections.

The main marine end-Permian mass extinction interval at Meishan is constrained to a duration of less than 40 kyr and the negative δ13C excursion is estimated to have lasted less than 6 kyr. The Smithian-Spathian boundary extinction event and δ13C shift lasted 50 kyr. The renowned Chaohu reptiles occurred 4.7 myr after the end-Permian extinction. In the uppermost Spathian approximately 5.0 myr after the end-Permian extinction, the first Triassic Tubiphytes appeared, which later formed the oldest known Triassic metazoan reef in the Anisian. The astronomical time scale provides a detailed timeline for Early Triassic climate upheavals and the recovery of marine ecosystems represented by the Anisian Luoping biota in Yunnan and the Carnian marine Lagerstätte in Guanling area of Guizhou, southwestern China.

Session No. 224--Booth# 331

T150. Early and Middle Triassic Restructuring Following the End-Permian Mass Extinction (Posters)
Tuesday, 3 November 2015: 9:00 AM-6:30 PM
Exhibit Hall (Baltimore Convention Center)
Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.571
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