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

合作的LEXEN研究：在年老和年轻的海山海洋地壳中直接取样海洋地下生物圈是一个看似合理但未经证实的行星比例微生物生物圈的栖息地。上500米火成岩基底温热、多孔、渗透性强，形成了一个全球尺度的含水层，容纳了富营养热液的循环。来自较低侵入性地壳岩石的热量驱动着含水层内的流体对流细胞，即使是在数千万年前的地壳中也是如此。这种热对流受到潮汐力的强烈调节，增加了流体速度，并比以前认为的更强烈地搅动了地下培养箱。将使用两种独特的方法对胡安·德·富卡山脊上两个对比鲜明的热液区未受损害的地壳流体进行取样。轴向海山目前直接在脊轴上形成，最近在峰顶和侧翼有喷发，并且具有相当大的地质和表面生物变异性，周期不到一年。1998年，在Axial火山口，一个带有再入锥的采样设施被直接粘接在海底，为50摄氏度的扩散喷口提供了无污染的通道。相比之下，Baby Bare （BB）海山位于3.5 My地壳的脊轴以东，一个小的蚀变岩石暴露的顶部完全被低渗透率沉积物包围。该项目将对水/岩石界面以下的Baby Bare流体（40摄氏度）进行取样，使用新开发的分离式取心仪器将3米长的钛管插入到生物活性表面区域以下的地下。从Axial和Baby Bare获得的样品将被研究细菌和古细菌种群的整个光谱，流体将被分析其无机和有机化学成分，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下。本项目首次尝试将无机化学和有机化学与孔隙度、流体流速等地球物理参数相结合，从而更好地了解这些地下生物群落的微生物生态。通过研究地下，特别是与热液系统有关的地下的化学、微生物生态学和能量学，可以建立一个研究外星生命前景的框架。

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.