Mechanisms and Rates of Preservation of Biogenic Remains in Continental Shelf and Slope Environments

陆架和斜坡环境中生物遗迹的保存机制和速度Karla M.Parsons-HubbardOberlin CollegeEAR-0345618摘要陆架和斜坡实验生物学倡议(SSETI)是一项长期的实验，研究海底生物遗骸的命运。人们对死于沉积物-水界面的生物的石化潜力知之甚少，特别是在深海陆架和斜坡环境中。现代陆架和斜坡环境是古代陆表海沉积的合理替代品，很少有人就其石化潜力进行研究。SSETI实验始于1993年，当时软体动物遗骸、甲壳类动物、棘球类动物和木本植物碎片被装在21个不同的EOD中，放在墨西哥湾和加勒比海大陆架和斜坡上的10个主要地点的网袋中。每个站点都有多个重复样本，以便在接下来的几年到几十年内重复采样。这里提出的项目是打捞已经在海底呆了12年的实验阵列。每隔一年(1年、2年、8年)收集样本，以记录割胶速率和过程，并确定不同类型的贝壳、木材、测试层或角质层在不同环境和时间内对割胶活跃区(TAZ)的过程是否有不同的反应。为了回答这些问题，对遗体的反复采样必须伴随着对禁飞区的详细描述。这是通过使用现场微电极采样的孔隙水地球化学分析和通过测量沉积物需氧量来实现的。这项工作的目标是将TAZ中的瞬时化学条件与位于沉积物-水界面或略低于沉积物-水界面的贝壳的长期影响联系起来。第八年的结果表明，孔隙水的地球化学与软体动物物质的溶解之间存在着非常密切的关系。这些发现极大地促进了对海底碳酸盐循环的认识，对古生物学、古生态学具有重要应用，并对碳收支和气候模拟有直接影响。特别是，这项工作的结果对于寻求将海底用作碳汇的规划者来说至关重要。

Mechanisms and Rates of Preservation of Biogenic Remains in Continental Shelf and Slope EnvironmentsKarla M. Parsons-HubbardOberlin CollegeEAR-0345618ABSTRACTThe Shelf and Slope Experimental Taphonomy Initiative (SSETI) is a long-term experiment studying the fate of organism remains on the sea floor. The fossilization potential of organisms that die at the sediment-water interface is poorly understood, particularly in deep offshore shelf and slope environments. The modern shelf and slope setting is a reasonable proxy for ancient epicontinental sea deposits and has only rarely been studied with respect to its fossilization potential. The SSETI experiment began in 1993 when molluscan remains, crustaceans, echinoids, and woody plant debris were deployed in mesh bags in 21 different EODs at 10 major sites on the continental shelf and slope of the Gulf of Mexico and Caribbean. Each site has multiple replicates for repeated sampling over the ensuing years to decades. The project proposed here is to recover experimental arrays that have been on the sea floor for 12 years. Collections of samples have been taken at targeted intervals (1 year, 2 years, 8 years) to document taphonomic rates and processes, and to determine whether different types of shell, wood, test, or cuticle respond differently to processes in the taphonomically active zone (TAZ) in different environments and over time. To answer these questions, repeated sampling of the remains must be accompanied by a detailed characterization of the TAZ. This is accomplished through porewater geochemical analysis using in situ micro-electrode sampling and through measurements of sediment oxygen demand. The goal of this work is to link the instantaneous chemical conditions in the TAZ to the long-term effects on shells residing at, or just below, the sediment-water interface. Results through year eight show a very tight correlation between the porewater geochemistry and dissolution of molluscan material. These findings are greatly advancing knowledge about the cycling of carbonate on the sea floor and has important applications to paleontology, paleoecology, and has direct implications for carbon budgets and climate modeling. In particular, the results of this work are critical to planners seeking to use the sea floor as a carbon sink.