Collaborative Research: Direct Sampling of the Oceanic Sub-surface Biosphere at Old and Young Seamounts

协作式LEXEN研究：在古老和年轻的海山直接取样海洋表层下生物圈海洋地壳是一个可能的但未经证实的行星比例的微生物生物圈的栖息地。火成岩基底的上部500米是温暖的，多孔的和可渗透的，形成了一个全球规模的含水层，承载着营养丰富的热液流体的循环。热从较低的侵入地壳岩石驱动流体对流细胞内的含水层，甚至在地壳许多数千万年的历史。这种热对流强烈调制的潮汐力，增加流体速度和搅拌的地下孵化器更有力地比以前认为的。将采用两种独特的方法对胡安·德富卡海脊两个截然不同的热液区的未受破坏的地壳流体进行取样。轴向海山目前正直接在海脊轴上形成，山顶和侧面最近有喷发，地质和表面生物变化很大，周期不到一年。在Axial破火山口，1998年用水泥将一个带有重返锥的取样设施直接固定在海底，使人们能够不受污染地进入50摄氏度的扩散喷口。相比之下，BB海山位于海脊轴以东3.5米的地壳上，有一个小的暴露的蚀变岩山顶，完全被低渗透性沉积物包围。该项目将在水/岩石界面以下对Baby Bare流体（40摄氏度）进行取样，使用新开发的分离式取芯仪器将一根3米长的钛管插入生物活性表面区域以下的地下。从Axial和Baby Bare获得的样本将用于研究细菌和古细菌种群的整个光谱，将分析液体的无机和有机化学，并使用温度和流体流量测量将数据置于其完整的环境背景中。该项目首次尝试将无机和有机化学与包括孔隙度和流体流速在内的地球物理参数相结合，以便更好地了解这些地下生物群落的微生物生态。通过研究次表层，特别是与热液系统有关的次表层的化学和微生物生态学及能量学，可以建立一个研究地外生命前景的框架。

COLLABORATIVE LEXEN RESEARCH: DIRECT SAMPLING OF THE OCEANIC SUB-SURFACE BIOSPHERE AT OLD AND YOUNG SEAMOUNTSOceanic crust is a plausible but unproven habitat for a microbial biosphere of planetary proportions. The upper 500 meters of igneous basement is warm, porous and permeable, forming a global-scale aquifer hosting the circulation of nutrient-rich hydrothermal fluids. Heat from the lower intrusive crustal rocks drives fluid convection cells within this aquifer, even in crust many tens of millions of years old. This thermal convection is strongly modulated by tidal forces, increasing fluid velocities and stirring the sub-surface incubator more vigorously than previously believed. Two unique methods will be used for sampling uncompromised crustal fluids from two contrasting hydrothermal areas on the Juan de Fuca Ridge. Axial Seamount is currently forming directly on the ridge axis, with recent eruptions on the summit and flanks, and has considerable geological and surface biological variability with periods of less than a year. At Axial caldera a sampling facility with a re-entry cone was cemented directly to the seafloor in 1998, providing uncontaminated access to a 50 degrees C diffuse vent. In contrast, Baby Bare (BB) Seamount sits on 3.5 My crust east of the ridge axis, with a small exposed summit of altered rock completely surrounded by low permeability sediments. This project will sample Baby Bare fluids (40 degrees C) below the water/rock interface, using a newly developed break-away coring instrument to insert a 3-meter long titanium tube into the sub-surface, below the biologically active surface zone. The samples obtained from both Axial and Baby Bare will be studied for the entire spectrum of bacteria and archea populations, the fluids will be analyzed for their inorganic and organic chemistry, and the data placed in their full environmental context using temperature and fluid flow measurements. This project attempts to integrate for the first time inorganic and organic chemistry with geophysical parameters including porosity and fluid flow rates, so as to better understand the microbial ecology of these sub-surface biotopes. By examining the chemical and microbial ecology and energetics of the sub-surface, and particularly the sub-surface associated with hydrothermal systems, a framework for studying the prospects of extraterrestrial life may be developed.