ThermoSill - Effects of local heating due to sill intrusion on subsurface sedimentary microbial activity

中国地质大学学报（自然科学版），2014年9月- 11月。Guaymas盆地是加利福尼亚湾一个年轻的边缘裂谷盆地，其特征是海底扩张活跃，沉积物沉积迅速，包括来自生物高产的上覆水域的富有机沉积物和来自附近大陆边缘的陆源沉积物。考察队采集了具有静止侵入物的富有机质沉积层序。微生物学是这次考察的重点研究课题之一。硫酸盐还原率是海洋沉积物中定量上最重要的电子受体过程，我们收集了一套用于定量的大样本，现在存放在GFZ。拟议的ThermoSill项目将首先关注这些岩心中微生物硫酸盐还原的一般特征以及压力和温度的影响。钻孔岩心经历了不同的地温梯度，范围从200°C到800°C以上，并且船上的地球化学数据已经表明正在发生的生物地球化学过程的多样性。在深海沉积物中，特别是那些深埋的温度较高的沉积物中，短链有机酸等有机基质通常是一个限制因素。由于瓜伊马斯盆地沉积物受水热作用的影响，大分子沉积有机质的热裂解提供了丰富的微生物底物。ThermoSill将研究这种丰富的底物是否会导致特定底物的优先降解，从而揭示在生命上限温度下的过程。将特别注意甲烷的厌氧氧化。在项目的最后部分，将通过加热实验模拟技能的就位和随之而来的温度升高。这些实验将伴随着热解实验和动力学建模，以测试这种短时间加热是否会在地质时间尺度上对微生物群落产生影响。提议的项目与考察的目标直接相关。它还补充了正在进行的研究压力和温度对南开海槽非热液影响沉积物中微生物硫酸盐还原的影响的项目。Exp。370)。

The recent IODP Exp. 385 (Guaymas Basin Tectonics and Biosphere, Sept.-Nov. 2019) drilled eight sites in Guaymas Basin, a young marginal rift basin in the Gulf of California, characterized by active seafloor spreading and rapid sediment deposition, including organic-rich sediments derived from biologically highly productive overlying waters and terrigenous sediments from nearby continental margins. The expedition cored sequences of organic-rich sediments with sill intrusions. Microbiology was one of the key research topics of this expedition. A large sample set for quantification of sulfate reduction rates, the quantitatively most important electron acceptor process in marine sediments, was collected and is now at GFZ. The proposed ThermoSill project will initially focus on the general characteristics of microbial sulfate reduction in these cores as well as the effects of pressure and temperature. The drill cores have experienced vastly different geothermal gradients, ranging from ca. 200 to over 800 °C km-1, and the on-board geochemical data already indicate a great diversity of biogeochemical processes taking place. In deep sea sediments, especially those buried to great depth and therefore temperature, organic substrates like short-chain organic acids are a generally a limiting factor. Because the sediments in Guaymas Basin are hydrothermally influenced, thermogenic cracking of macromolecular sedimentary organic matter provides abundant microbial substrates. ThermoSill will investigate whether this abundance of substrate has an effect leads to a preferential degradation of specific substrates and therefore shed light onto processes at the upper temperature limit of life. Particular attention will be paid to anaerobic oxidation of methane. In the final part of the project, the emplacement of sills and concomitant temperature increase will be simulated by heating experiments. These experiments will be accompanied by pyrolysis experiments and kinetic modelling to test whether such short-time heating can have an effect on the microbial community over geologic timescales. The proposed project is directly relevant to the objectives of the expedition. It is also complementary to an ongoing project that studies the effects of pressure and temperature on microbial sulfate reduction in non-hydrothermally influenced sediments from Nankai Trough (IODP. Exp. 370).