Yuxuan Wang, Paul Wignall, Yijun Xiong, D. Loydell, Jeffrey Peakall, Jaco H. Baas, Benjamin J. W. Mills, S. Poulton
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引用次数: 0
Abstract
The early Silurian Llandovery–Wenlock boundary interval was marked by significant marine perturbations and biotic turnover, culminating in the Ireviken Extinction Event (IEE) and the Early Sheinwoodian Carbon Isotope Excursion (ESCIE). Here, we apply multiple independent redox proxies to the early Wenlock Buttington section, which was deposited in a mid-shelf location in the Welsh Basin, UK. To account for regional geochemical variability in marine sediments due to factors such as sediment provenance, we first define oxic baseline values for the Welsh basin, utilizing deeper water, well-oxygenated intervals of late Llandovery age. Our approach documents unstable, oscillating redox conditions on the mid shelf at Buttington. We suggest that these dynamic redox fluctuations are likely to relate to changes in the position of the chemocline or a migrating oxygen minimum zone. Benthic biota such as trilobites, brachiopods, bivalves and gastropods appear to have been relatively unaffected by fluctuating oxic-ferruginous conditions, but were more severely impacted by the development of euxinia, highlighting the inhibiting role of toxic sulfides. By contrast, the redox perturbations appear to have placed extreme stress on graptolites, causing many extinction losses regardless of the specific development of euxinia.
Thematic collection:
This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at:
https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.7165009
早志留纪兰德发现期-文洛克边界区间的特点是显著的海洋扰动和生物更替,最终导致了伊雷维肯大灭绝事件(IEE)和早志留纪碳同位素激变(ESCIE)。在此,我们将多个独立的氧化还原代用指标应用于沉积于英国威尔士盆地中陆的早期温洛克布廷顿剖面。为了考虑沉积物产地等因素造成的海洋沉积物的区域地球化学变异性,我们首先利用兰德塞斯晚期的深水富氧区间,定义了威尔士盆地的氧化基线值。我们的方法记录了布廷顿大陆架中部不稳定的、振荡的氧化还原条件。我们认为,这些动态氧化还原波动可能与化学跃层位置的变化或氧最小区的迁移有关。底栖生物群(如三叶虫、腕足类、双壳类和腹足类)似乎相对不受缺氧-铁锈色波动条件的影响,但却受到缺氧状态发展的严重影响,这凸显了有毒硫化物的抑制作用。相比之下,氧化还原扰动似乎对石龙子造成了极大的压力,导致许多石龙子灭绝,而与具体的蜕皮发育无关。 专题文集:本文是《中古生代地球系统的化学演化与生物响应》(Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response)文集的一部分,可从以下网站获取: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system 补充材料: https://doi.org/10.6084/m9.figshare.c.7165009