Time-series temperature measurements at high-temperature hydrothermal vents, East Pacific Rise 9°49′-51′N:: evidence for monitoring a crustal cracking event
Time-series temperature measurements at high-temperature hydrothermal vents, East Pacific Rise 9°49′-51′N:: evidence for monitoring a crustal cracking event
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DOI：
10.1016/s0012-821x(98)00101-0
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发表时间：
1998-08-01
影响因子：
5.3
通讯作者：
Lutz, R
中科院分区：
文献类型：
--
作者：
Fornari, DJ;Shank, T;Lutz, R
热液喷口流体的温度测量提供了大洋中脊顶热液和岩浆系统物理和化学状态的重要指标，喷口流体温度和化学性质的变化可对栖息在这些独特生态系统中的生物群落产生巨大影响。为了了解海脊脊顶热液活动的时间变化，因为它与海脊轴线的地质过程有关，在1991年海底火山爆发后的五年中，对东太平洋海隆脊顶北纬9度49 '至9度51'之间的六个高温热液喷口进行了仪器测量和反复取样。位于9 ° 50.2 'N附近的轴向槽底部的Bio 9喷口具有1991 - 1997年最完整的流体温度记录，包括近三年（1994-1997年）的连续温度记录。1991年，Bio 9喷口流体的温度为368摄氏度，1992年第二次火山活动后，温度上升到估计大于或等于388摄氏度，此后在接下来的大约两年时间里下降，1993年12月温度达到365摄氏度。Alvin的热电偶探头进行的连续温度记录和点测量显示，Bio 9喷口流体在365 +/- 1摄氏度下稳定了15个月，直到1995年3月26日。3月26日，该喷口在8天内突然升高了7摄氏度，最高温度372 +/- 1摄氏度持续了14天。在大约3.5个月的时间里，排放流体逐渐冷却到366 +/- 1摄氏度，在记录期结束时的几个月里，温度上升了几度。1995年11月至1997年11月期间，该喷口的流体温度连续记录显示，两年期间上升了5 +/- 1摄氏度。在Bio 9喷口的温度突然升高，同时发生的动物群落结构的变化，和地球化学的喷口流体从这个地区表明，地壳事件发生，无论是在地壳中的开裂前或侵入的一个小岩脉的形式。根据1995年在Bio 9喷口周围进行的微震活动实验的结果[Sohn等人，美国运输部地球物理学家。Union 78（1997）F647; Sohn等人，自然（出版中）]，以及对1995年3月22日发生的一个小震群的鉴定，我们得出结论，震群发生四天后在生物圈9号测得的温度异常是由穿透到火山口下面的热地壳岩石中的裂缝前缘引起的。(C)1998 Elsevier Science B. V.保留所有权利。
Temperature measurements of hydrothermal vent fluids provide an important indicator of the physical and chemical state of mid-ocean ridge crest hydrothermal and magmatic systems, Changes in vent fluid temperature and chemistry can have dramatic effects on biological communities that inhabit these unique ecosystems. In an attempt to understand temporal variability of ridge crest hydrothermal activity as it relates to geological processes at the ridge axis, six high-temperature hydrothermal vents on the East Pacific Rise crest between 9 degrees 49'N and 9 degrees 51'N were instrumented and sampled repeatedly during five years following a submarine volcanic eruption in 1991. Bio9 vent, located on the floor of the axial trough near 9 degrees 50.2'N, has the most complete record of fluid temperatures from 1991 to 1997, including a continuous temperature record of nearly three years (1994-1997). Bio9 vent fluids were 368 degrees C in 1991, increased to an estimated temperature greater than or equal to 388 degrees C after a second volcanic event in 1992, and thereafter declined over the next similar to 2 years reaching a temperature of 365 degrees C in December 1993. Continuous temperature records and point measurements made by Alvin's thermocouple probe show Bio9 vent fluids were stable for similar to 15 months at 365 +/- 1 degrees C, until March 26, 1995. On March 26, an abrupt 7 degrees C increase occurred over a period of eight days at this vent, and a maximum temperature of 372 +/- 1 degrees C persisted for 14 days. The vent fluid cooled gradually over similar to 3.5 months to 366 +/- 1 degrees C, and for several months at the end of the recording period the temperature increased a few degrees. A continuous record of fluid temperature at this vent between November 1995 and November 1997 shows a 5 +/- 1 degrees C increase for the two-year period. The abrupt temperature increase at Bio9 vent, and coincident changes in faunal community structure, and geochemistry of vent fluids from this area suggest that a crustal event occurred, either in the form of a cracking front in the crust or intrusion of a small dike. Based on the results of a microseismicity experiment conducted around the Bio9 vent in 1995 [Sohn et al., Trans. Am. Geophys. Union 78 (1997) F647; Sohn et al., Nature (in press)], and the identification of a small earthquake swarm which occurred on March 22, 1995 we conclude that the temperature anomaly measured at Bio9 four days following the swarm was caused by a cracking front penetrating into hot crustal rocks beneath the vent. (C) 1998 Elsevier Science B.V. All rights reserved.