CO2, organic carbon burial, and global climate change in the Wenlock (Silurian):waired 13 Ccarb and 13 Corg analyses of marine carbonates

本研究的目的是研究显生宙全球碳循环史上最不稳定的系列，以及二氧化碳在全球气候变化中的作用。温洛克系列包含两个主要的（+4%）正碳同位素偏移（早期温洛克Ireviken偏移和晚期温洛克Mulde偏移），并且在文献中都与冰川作用和全球气候变化有关。长期以来，碳循环和二氧化碳在全球气候变化中的作用一直是一个备受争议的话题。然而，二氧化碳的变化通常被认为是显生宙气候变化的主要驱动因素。最近的出版物通过比较各种显生宙尺度的代理记录，将这一争论的焦点集中在长期气候变化上。对古生代二氧化碳变化进行高分辨率（子系统尺度）记录的研究才刚刚开始。在下古生代，最广泛接受的测定古CO2的方法是对碳酸盐和有机碳中的碳同位素进行配对分析。来自北美的最新数据表明，在温洛克早期，13g的负偏移与13g的正偏移相吻合。数据表明，在Ireviken正碳同位素偏移期间，CO2在增加。这种关系对志留纪气候/海洋模式具有重大意义，但目前全球只有一个剖面。到目前为止，仅对一个钻孔的14个样品进行了Wenlock晚期排除的碳碳化合物和碳碳化合物的配对同位素分析。本文提出的研究将为下古生代任何系列的CO2和有机碳埋藏提供最全面（时间和空间）的记录。这将分两个步骤完成：1)高分辨率（每个样品10万年）碳酸碳（¿13Ccarb）同位素地层学；2)全球剖面的温洛克系列碳酸碳和有机碳（¿13Ccarb和¿Corg）同位素地层学配对。由于温洛克期同位素漂移与其他早古生代同位素漂移在地球化学、沉积学和古生物学上有许多显著的相似之处，我们期望对温洛克期乃至整个早古生代的气候系统有新的认识。

The propose of this investigation is to examine the most volatile Series in the Phanerozoic history of the global carbon cycle and the role of CO2 in globale climate change. The Wenlock Series contains two major (+4%) positive carbon isotope excursions (early Wenlock Ireviken Excursion; late Wenlock Mulde Excursion) and both have been associated in the literature with glaciation and global climate change. The role of the carbon cycle and CO2 in global climate change has long been a topic of considerable debate. However, changes in CO2 are most often considered to be the primary driver of Phanerozoic climate change. Recent publications framing this debate have forcused on long-term climate change by comparing various Phanerozoic scale proxy records. Inversitgations to produce high-resolution (sub System scale) records of CO2 change in the Palaeozoic are only just beginning. In the lower Palaeozoic, the most widely accepted method for determining palaeo-¿ CO2 is paired analysis of carbon isotopes in both carbonate and organic carbon. Recent data from North America indicate that a previously unknown negative excursion in ¿ 13Corg coincided with the positive excursion in ¿ 13Corg during the early Wenlock. The data indicate the ¿ CO2 was increasing during the Ireviken positive carbon isotope excursion. This relationship has great implications for Silurian climate/ocean models, but at present is known from only one section globally. Paired isotopic analyses of ¿ 13Ccarb and ¿ 13Corg on the late Wenlock excusion have been carried out so far only on 14 samples on one bore hole. The investigation proposed herein will provide the most comprehensive (both temporally and spatially) record of ¿ CO2 and organic carbon burial of any Series in the lower Palaeozoic. This will be accomplished in two steps: 1) high-resolution (100,000 years per sample) carbonate carbon (¿ 13Ccarb) isotope stratigraphy 2) paired carbonate and organic carbon (¿ 13Ccarb and ¿ Corg) isotope stratigraphy of the Wenlock Series from sections globally. As the Wenlockian isotope excursions have many conspicuous similarities (geochemial, sedimentological, and palaeontological) with other Early Palaeozoic isotope excursions we expect new insights into the climate systems not only for the Wenlock but for the whole Early Palaeozoic.