A new model for a hydrothermal circulation system and limit of the life
A new model for a hydrothermal circulation system and limit of the life
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DOI：
10.5575/geosoc.2017.0014
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发表时间：
2017-04
期刊：
影响因子：
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通讯作者：
J. Ishibashi;K. Yanagawa;K. Takai
中科院分区：
文献类型：
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作者：
J. Ishibashi;K. Yanagawa;K. Takai
综合大洋钻探计划第331次考察于2010年9月进行，提供了一个独特的机会，可以直接进入冲绳海槽中部Iheya North Knoll活跃热液田之下的海底环境。沿着一个小山丘斜坡的五个钻孔点（C 0013-C 0017）的位置覆盖了热液场，以活跃的热液丘NBC的强烈高温流体排出为代表。在C 0016场址的土丘侧翼部分进行的钻探显示，热液硫化物/硫酸盐矿化与黑矿型火山块状硫化物存款中的热液硫化物/硫酸盐矿化相当。从站点C 0013和C 0014位于100和450米以东的土墩，证据的横向侵入的热液成分观察到强烈和广泛的热液蚀变，逐步变化的配置文件的孔隙流体化学，和急剧变化的沉积物的物理性质。另一方面，在距离土堆1550 m的C 0017现场，即使在海底以下50 m处也发现海水向下渗透。这些结果表明，高温和还原性热液环境和低温和氧化性海水占主导地位的环境之间的混合区的活动热液场下面扩展超过公里尺度。此外，微生物学研究表明，地下微生物的栖息地与这一混合区明显重叠。331号考察队成功地为在火山沉积物为主的地质环境中形成的热液循环系统提供了一个新的模型。
Integrated Ocean Drilling Program (IODP) Expedition 331 was conducted in September 2010 and provided an unique opportunity to directly access the subseafloor environment beneath an active hydrothermal field in the Iheya North Knoll in the mid-Okinawa Trough. Localities of five drilled sites (C0013–C0017) along the slope of a knoll cover the hydrothermal field, represented by vigorous high temperature fluid venting from the active hydrothermal mound named NBC. Drilling at Site C0016 at the flank part of the mound revealed hydrothermal sulfide/sulfate mineralization comparable to that in Kurokotype volcanic massive sulfide deposit. From Sites C0013 and C0014 located 100 and 450 m east from the mound, evidence for lateral intrusion of the hydrothermal component was observed by intense and widespread hydrothermal alteration, stepwise change in profiles of pore fluid chemistry, and drastic change in physical properties of the sediment. On the other hand, downward infiltration of seawater was recognized even at 50 m below the seafloor at Site C0017 located 1550 m apart from the mound. These results suggest the mixing region between the high-temperature and reductive hydrothermal environment and the low-temperature and oxidative seawater-dominant environment outspreads over a km scale beneath the active hydrothermal field. Furthermore, microbiological studies revealed that habitat of subvent microorganism significantly overlaps this mixing region. Expedition 331 was successful in providing a new model for a hydrothermal fluid circulation system that develops in a geologic setting dominated by volcanic sediment.