Carboniferous chemostratigraphy: Do epicontinental seas reflect global ocean conditions?

石炭纪化学地层学：陆表海能反映全球海洋状况吗？Deborah J.Thomas、Ethan L.Grossman、Brent V.Miller、Thomas D.Olszewski、Thomas E.YanceyEAR-0643309德克萨斯农工大学摘要石炭纪(3.59-2.99亿年前)是地球历史上构造、气候和生物发生剧烈变化的时期。从地球系统科学的观点来看，石炭纪的几个方面是不同的：全球退缩标志着显著冰川的开始；碳循环的重大变化，表现为古热带地区的煤炭聚集；大陆的重新配置，导致阿勒格尼亚-瓦里斯坎造山运动，盘古大陆的组装，以及Rheic Ocean的关闭，导致北美古热带和特提斯古热带之间的海洋联系被切断。产生了丰富的古生物、古生物地理和古化学数据，最近的重点是应用海洋地球化学指标来解开构造、碳循环和气候之间的潜在联系。从理论上讲，海洋古化学数据提供了温度(增量18氧)、碳循环(增量13碳)和风化作用(34S/32S，87Sr/86Sr)的海洋替代记录，但这些替代记录在古生代的应用受到了混淆，因为它们来自陆表海沉积的海洋沉积物。这些浅海的陆架状环境必须与开阔的大洋盆地(例如，潘塔拉萨和瑞海)有联系，才能支持海洋群落，但有证据表明，浅海陆缘和开阔的海洋之间存在地球化学脱钩。为了更好地了解石炭纪气候变化的原因和后果，PI必须首先确定从海洋地球化学记录中可以推断出什么。因此，他们建议解决这个问题，即石炭纪北美陆缘海在多大程度上记录了全球开阔的海洋条件？他们将使用沿横跨今天墨西哥西南部的Mixteco地体(最具洋性)、阿罗峡谷、美国中大陆、伊利诺伊盆地和阿巴拉契亚盆地(最内陆)的横断面上不同停留时间的放射性和稳定的同位素示踪剂，以限制陆表海和开阔海洋(潘塔拉萨和瑞克海)之间的地球化学耦合程度。

Carboniferous chemostratigraphy: Do epicontinental seas reflect global ocean conditions?Deborah J. Thomas, Ethan L. Grossman, Brent V. Miller, Thomas D. Olszewski, Thomas E. YanceyEAR-0643309Texas A&M UniversityABSTRACTThe Carboniferous Period (359 to 299 million years ago) was a time of dramatic tectonic, climatic, and biologic change in Earth's history. Several aspects of the Carboniferous are distinctive from the standpoint of Earth Systems Science: the onset of significant glaciation, signaled by global regression; a major change in carbon cycling manifested by coal accumulation in the paleotropics; and reconfiguration of the continents resulting in the Alleghanian-Variscan orogeny, assembly of Pangea, and closure of the Rheic Ocean, leading to severing of the marine connection between the North American paleotropics and the Tethyan paleotropics. A wealth of paleobiologic, paleobiogeographic, and paleochemical data has been generated, with recent emphasis on applying marine geochemical proxies to unraveling the potential links between tectonics, carbon cycling, and climate. The marine paleochemical data, in theory, provide oceanic proxy records of temperature (Delta 18 Oxygen ), carbon cycling (Delta 13 Carbon), and weathering (34S/32S, 87Sr/86Sr), but the application of these proxies to the Paleozoic is confounded by the fact that they are derived from marine sediments deposited in epicontinental seas. These shallow, shelf-like environments must have had connections to open ocean basins (e.g., Panthalassa and Rheic Oceans) in order to support marine communities, yet there is evidence to suggest geochemical decoupling between shallow epicontinental seas and the open ocean.In an effort to better understand the causes and consequences of climate change during the Carboniferous, PIs must first establish what can be inferred from marine geochemical records. Thus they propose to address the question, To what degree does the Carboniferous North American epicontinental sea record global open-ocean conditions? They will use radiogenic and stable isotope tracers of varying residence times along a transect spanning the Mixteco terrane in present-day southwestern Mexico (most oceanic), Arrow Canyon, US Midcontinent, Illinois Basin, and Appalachian Basin (most interior) to constrain the degree of geochemical coupling between the epicontinental sea and the open ocean (Panthalassa and Rheic Ocean).