Analyses of New High Resolution MCS Data from Guaymas Basin, Gulf of California

加利福尼亚湾瓜伊马斯盆地新的高分辨率 MCS 数据分析

• 批准号: 1658034
• 负责人: Daniel Lizarralde
• 金额: $ 6.69万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-01 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1658034&HistoricalAwards=false
• 关键词: Analyses; New; Resolution; MCS; Data

This research aims to understand the amount of carbon released from sediments, as CO2 and methane, when those sediments are intruded by magmatic sills with injection temperatures of ~1000°C. This understanding has relevance for modern day climate and also for global-scale carbon budgets. The relevance to modern day climate is related to the Paleocence/Eocene thermal maximum, a period of rapid atmospheric warming, thought to be the best ancient analogue to rapid present-day warming. The Paleocence/Eocene event is hypothesized to have been driven by the rapid and voluminous release of carbon from sediments intruded by igneous sills during a regionally large magmatic event around the time of the opening of the North Atlantic between Greenland and Europe. Defining relationships between igneous sill intrusion into sediments and carbon release from those sediments into the ocean and potentially the atmosphere will help place bounds on the volume of carbon available to create the rapid warming under the sill hypothesis and can be compared to modern atmospheric carbon inputs. In addition, many active magmatic systems exist in the present day that involve sill intrusion into organic-rich sediments, units that have generally been thought of as stable carbon sinks. Broader impacts of the work include understanding the reintroduction of carbon into the ocean and potentially into the atmosphere from sediments in these magmatic systems, something that is presently missing from global carbon cycle models. An additional impact is the support of a drilling leg of the International Ocean Discovery Program, a major NSF and international investment in understanding how the Earth system behaves by drilling into the seafloor and examining the rocks and sediments and their stratigraphy and lithologic relationships. The research will analyze a new high-resolution multi-channel seismic dataset from Guaymas Basin in the Gulf of California in order to advance our understanding of the processes of sediment alteration in response to igneous sill intrusion. The work has two main goals: (1) integration of the new high-resolution data into analyses based on lower-frequency 6-kilometer streamer seismic data aimed at quantifying relationships between igneous sill thickness and alteration of overlying sediments. The new data will enable us to confidently identify sills as thin as 12m and evaluate potential drilling sites for the proposed International Ocean Discovery Program in the Guaymas Basin. These new data are the first that look at the second dimension of the crust in the area of the proposed main drill sites and potential alternate sites. Processes driven by the intrusion of igneous sills into sediments during regionally extensive magmatic episodes are increasingly being invoked as triggers for extinction events and global-scale changes in oceanic and atmospheric chemistry. These hypotheses are largely founded on changes in the carbon content of sediments within metamorphic aureoles of igneous sills observed in ancient outcrops and the assumption that carbon and other elements lost from the aureoles are also lost from the entire subsurface system and efficiently released into the ocean or atmosphere. A key objective of the Guaymas drilling proposal, which this research project supports, is to understand the subsurface and seafloor bio/geochemical cycling of carbon released due to sill intrusion. A key objective of the present proposal is to further the work of developing seismic proxies for alteration intensity that can extend knowledge, based on drill cores, to regional scales. Relationships between sill thickness and changes in seismic velocity within overlying sediments may prove to be a useful proxy, and this project will make co-located measurements along existing long-streamer lines in Guaymas Basin with the aid of the new hi-resolution seismic data. The long-streamer data provide the means to estimate changes in sediment properties (seismic velocity) due to contact metamorphism, while the high-resolution data provide a means to estimate sill thickness, which scales with the available thermal energy of the intrusion.

这项研究的目的是了解当沉积物被注入温度约为 1000°C 的岩浆岩床侵入时，沉积物中释放的碳量（二氧化碳和甲烷）这一认识与现代气候以及全球范围的碳有关。与现代气候的相关性与古新世/始新世最热期有关，这是一段大气快速变暖的时期，被认为是与当今快速变暖的最佳古代模拟。古新世/始新世事件被认为是由格陵兰岛和欧洲之间的北大西洋开放期间的一次区域性大型岩浆事件期间火成岩侵入的沉积物中碳的快速大量释放所驱动的。侵入沉积物以及这些沉积物中的碳释放到海洋中，并可能进入大气中，这将有助于限制可用于在窗台下造成快速变暖的碳量此外，当今存在许多活跃的岩浆系统，这些系统涉及对富含有机物的沉积物的侵入，这些单元通常被认为是稳定的碳汇。包括了解碳从这些岩浆系统的沉积物中重新引入海洋并可能进入大气，这是全球碳循环模型目前所缺少的另一个影响是国际海洋发现计划的钻探支队的支持。主要国家科学基金会和国际投资通过钻探海底并检查岩石和沉积物及其地层和岩性关系来了解地球系统的行为，该研究将分析来自加利福尼亚湾瓜伊马斯盆地的新高分辨率多道地震数据集。为了增进我们对火成岩入侵引起的沉积物蚀变过程的理解，这项工作有两个主要目标：（1）将新的高分辨率数据整合到基于低频的分析中。 6 公里拖缆地震数据旨在量化火成岩基岩厚度与上覆沉积物变化之间的关系，新数据将使我们能够自信地识别薄至 12 m 的基岩，并评估拟议的瓜伊马斯盆地国际海洋发现计划的钻探潜力。这些新数据首次研究了拟议的主要钻探地点和火成岩侵入驱动的潜在替代地点区域的地壳第二维度。在区域范围广泛的岩浆活动期间，岩床进入沉积物越来越多地被认为是灭绝事件和海洋和大气化学全球范围变化的触发因素，这些假设主要基于古代观察到的火成岩岩床变质光环内沉积物碳含量的变化。露头以及从光环中损失的碳和其他元素也会从整个地下系统中损失并有效地释放到海洋或大气中的假设是瓜伊马斯钻探提案的一个关键目标。该研究项目支持的目的是了解由于岩床侵入而释放的碳的地下和海底生物/地球化学循环。本提案的一个关键目标是进一步开发可扩展知识的蚀变强度地震代理。钻岩芯，到区域尺度。底床厚度和上覆沉积物内地震速度变化之间的关系可能被证明是一个有用的代理，并且该项目将沿着现有的长拖缆线进行同位测量。在瓜伊马斯盆地，借助新的高分辨率地震数据，长拖缆数据提供了估计由于接触变质作用引起的沉积物特性（地震速度）变化的方法，而高分辨率数据则提供了估计基台的方法。厚度，与入侵的可用热能成比例。