RAPID proposal: Site characterization cruise to document the active and extensive subsurface biosphere in the Guaymas Basin

位于加州湾中部的瓜伊马斯盆地是一个活跃的构造扩张中心，其上覆盖着厚的富含有机质的沉积物。典型的深水洋中脊扩张中心具有非常集中的岩浆活动，很少或没有沉积物，与此相反，瓜伊马斯基底的岩浆活动分布更广。这种广泛分布的岩浆作用显著扩大了富含有机物的沉积物的比例，这些沉积物可能会受到岩浆热的影响，从而大大扩大了支持沉积物中烃类生成和微生物种群的环境范围。认识到岩浆活动并不局限于扩张轴，而是分布在整个瓜伊马斯盆地，表明模型的自然封存碳，形成海洋地壳，生活在地下边缘裂谷盆地应重新考虑，因为这对长期消除大气中的二氧化碳（因此潜在的气候影响）。这个快速建议的主要研究者是国际海洋发现计划（IODP）建议的主要支持者，该计划旨在通过科学的海洋钻探深入研究该系统。为了妥善规划这一昂贵的IODP考察，需要从沉积物取样和地震数据中获得更多的场地特征。该提案要求为主要调查员提供资金，以便参加墨西哥El Puma号研究船（RV）上已经计划的现场调查巡航。这次航行的结果将以极低的投资提供有价值的数据，指导关于瓜伊马斯盆地未来可能进行的科学钻探的决策。该RAPID提案要求为首席研究员提供资金，以参加2014年10月在RV El Puma上进行的墨西哥现场调查巡航，收集横跨瓜伊马斯盆地的广泛沉积物断面的5米重力岩心，并整合测序-基于地下细菌和古菌的微生物群落分析，并结合这些地下沉积物的生化特征。重力取芯和微生物群落分析将针对冷的非热液沉积物以及轴外受热液影响的沉积物。重力取芯活动和地球化学/微生物学研究与热流测量、广泛的二维地震分析和计划中的墨西哥和德国其他航行的高分辨率三维地震绘图相协调。这一多管齐下的战略将提供额外的数据，并完成JOIDES决议适当规划潜在IODP钻探探险所需的现场特征描述。

The Guaymas Basin in the central Gulf of California is an active tectonic spreading center overlain with thick, organic-rich sediments. In contrast to typical deep-water, mid-ocean ridge spreading centers that have very focused magmatism and little or no sediment, magmatism in the Guaymas Basis is more broadly distributed. This broadly-distributed magmatism significantly expands the fraction of organic-rich sediments that may be subject to alteration by the magmatic heat and thus it greatly expands the range of environments that support hydrocarbon generation and microbial populations in the sediments. Recognition that magmatism is not confined to the spreading axis, but instead is distributed throughout Guaymas Basin, suggests that models for the natural sequestration of carbon, the formation of oceanic crust, and life in the subsurface in marginal rift basins should be reconsidered as this has implications for the long-term removal of atmospheric carbon dioxide (and hence potential climatic implications). The Principal Investigator of this RAPID proposal is a lead proponent on an International Ocean Discovery Program (IODP) proposal to study this system in depth through scientific ocean drilling. To properly plan this expensive IODP expedition, additional site characterization gained from sediment sampling and seismic data is required. This proposal requests funds for the Principal Investigator to participate on an already planned site survey cruise aboard the Mexican Research Vessel (RV) El Puma. The results from this cruise will provide valuable data, at an exceptionally low investment, to guide decisions about potential future scientific drilling in the Guaymas Basin.This RAPID proposal requests funds for the Principal Investigator to participate on a Mexican site survey cruise in October 2014 on RV El Puma to collect five-meter gravity cores of an extensive sediment transect across the Guaymas Basin and to integrate sequencing-based microbial community analyses of subsurface bacteria and archaea with biogechemical characterizations of these subsurface sediments. Gravity coring and microbial community analysis will target cold non-hydrothermal sediments as well as off-axis hydrothermally-influenced sediments. The gravity coring campaign and the geochemistry/microbiology studies are coordinated with heatflow measurements and extensive 2D seismic analysis and high-resolution 3D seismic mapping by other planned Mexican and German cruises. This multi-pronged strategy will deliver the additional data and complete the site characterizations that are required to properly plan a potential IODP drilling expedition by the JOIDES Resolution.