The Xiaoyangqiao section, Dayangcha, North China: the new global Auxiliary Boundary Stratotype Section and Point (ASSP) for the base of the Ordovician System

In 2019 the Sub-Commission on the Ordovician System approved the Xiaoyangqiao section, North China as a new ASSP section for the base of the Ordovician System. The sedimentary succession of the section is exposed in a natural outcrop near the Dayangcha Village at a position of 42 degrees 3'24 &...

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Bibliographic Details
Published in:Episodes
Main Authors: Wang, Xiaofeng, Stouge, Svend, Maletz, Jorg, Bagnoli, Gabriella, Qi, Yuping（祁玉平）, Raevskaya, Elena G., Wang, Chuanshang, Yan, Chunbo
Format: Report
Language:English
Published: GEOLOGICAL SOC KOREA 2021
Subjects:
CONODONT IAPETOGNATHUS
JILIN-PROVINCE
GREEN POINT
SEA-LEVEL
STRATIGRAPHY
NEWFOUNDLAND
GSSP
GRAPTOLITE
EVOLUTION
TRILOBITE
Geology
Geosciences
Multidisciplinary
Green Point
Newfoundland
Online Access:http://ir.nigpas.ac.cn/handle/332004/40204
http://ir.nigpas.ac.cn/handle/332004/40205
https://doi.org/10.18814/epiiugs/2020/020091
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Summary:In 2019 the Sub-Commission on the Ordovician System approved the Xiaoyangqiao section, North China as a new ASSP section for the base of the Ordovician System. The sedimentary succession of the section is exposed in a natural outcrop near the Dayangcha Village at a position of 42 degrees 3'24 '' N, 126 degrees 42'21 '' E. It has a well-preserved, abun-dant and diverse fossil record across the boundary with key markers (conodonts and graptolites), which provide improved intercontinental correlation of the Cambrian- Ordovician boundary. The appearance of the first plank -tonic graptolites is immediately below the base of the Cordy-lodus lindstromi Conodont Zone. Other fossils, including acritarchs, brachiopods and trilobites are also present in the Xiaoyangqiao ASSP section. Non-biotic secondary global markers near the base of the Ordovician System include a positive carbon isotopic excursion with the maximum peak (named HSS) below the boundary, a prominent unnamed negative peak immediately below the boundary and a prominent carbon isotope excursion with positive peaks above the boundary. The latter excursion is associated with the appearance of the planktonic graptolites in the Ordo-vician. The strength of the Xiaoyangqiao ASSP section is the correlation between the conodonts and graptolites, correspondence of sea-level lowstands, and the matches of geochemical parameters.

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