The latest encrinurid trilobites from the Lower Devonian of Xinjiang, Northwest China

IF 2 3区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Geological Magazine Pub Date : 2023-10-09 DOI:10.1017/s0016756823000596

Juan Ma, Jiayi Yin, Yilong Liu, Xiaoqi Du, Shibo Liu, Ruiwen Zong

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引用次数: 0

Abstract

Abstract Encrinurids are common in Ordovician and Silurian strata but whether they survived into the Early Devonian is still controversial. This paper documents the encrinurid Batocara sp. near the Silurian–Devonian boundary in western Junggar, Xinjiang. The highest horizon of Batocara sp. is located above the first appearance datum of the Devonian conodont Caudicriodus , confirming that encrinurids may cross the Silurian–Devonian boundary. The presence of Caudicriodus angustoides bidentatus , Zieglerodina planilingu and plate-type loboliths of scyphocrinoids above the highest horizon of Batocara sp. indicates that encrinurids here extend only into the lower part of the first conodont zone of the Lochkovian (i.e., Caudicriodus hesperius Biozone). Encrinurids are widely distributed and easily recognized, and unlike graptolites and conodonts are not controlled by lithofacies. Therefore, it might be possible to use the highest horizon of encrinurids as indicator fossils to identify the approximate position of the Silurian–Devonian boundary in areas or sections where graptolites and conodonts are not present, and at least in northwest China.

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新疆下泥盆世最新发现的棱叶三叶虫

摘要:在奥陶系和志留系地层中普遍存在着隐石，但它们是否存在于早泥盆世仍存在争议。本文记录了新疆准噶尔西部志留系—泥盆系界线附近的巴托卡拉族。Batocara的最高层位位于泥盆纪牙形刺Caudicriodus的首次出现基准面之上，证实了encrinurids可能跨越志留纪-泥盆纪界线。在Batocara属的最高层位以上，存在着Caudicriodus angustoides bidentatus、Zieglerodina planilingu和scyphocriinoids的板状小石，表明此处的齿形小石仅延伸到Lochkovian第一个牙形带的下部(即Caudicriodus hesperius Biozone)。石屑分布广泛，易识别，与笔石、牙形刺不同，不受岩相控制。因此，在笔石和牙形刺不存在的地区或剖面上，至少在中国西北地区，或许可以利用笔石的最高层位作为指示化石，来确定志留纪-泥盆纪界线的大致位置。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geological Magazine 地学-地球科学综合

CiteScore

4.70

自引率

0.00%

发文量

111

审稿时长

3 months

期刊介绍： Geological Magazine, established in 1864, is one of the oldest and best-known periodicals in earth sciences. It publishes original scientific papers covering the complete spectrum of geological topics, with high quality illustrations. Its worldwide circulation and high production values, combined with Rapid Communications and Book Review sections keep the journal at the forefront of the field. This journal is included in the Cambridge Journals open access initiative, Cambridge Open Option.