Heat and Chemical Exchange During the Early Stages of Backarc Rifting in a Polar Region: Hydrothermal Activity in Bransfield Strait, Antarctica

NSF表格1358(1/94)该奖项由国家科学基金会极地计划办公室提供，支持研究南设得兰群岛和南极半岛之间的布兰斯菲尔德海峡的热液喷发。之前在海峡的勘探工作发现了几个海底散发出高温热液的地点。这些发现是利用专门设计的仪器包来探测和绘制热液活动给上覆水柱带来的热和化学异常的。海峡中的热液地点的水深从200米到1300米不等，发生在火山露头上，这些火山露头周期性地沿着裂谷带的走向穿过沉积物盖层。这些遗址与欺骗岛的火山口结盟，那里有活跃的温泉。这是在南极洲发现的第一批海底热液地点，因此代表着独特的研究机会。该项目将返回海峡，进一步绘制这些地区的地图并进行采样。有几个令人信服的理由相信，对布兰斯菲尔德喷口系统的进一步勘探将产生令人兴奋的新信息：(1)布兰斯菲尔德海峡是一个弧后裂谷系统，与该环境中的喷口相关的喷口流体和矿物沉积很可能不同于迄今从海底喷口采集的任何样品。(2)初步证据表明，布兰斯菲尔德火山喷发有两种不同的底质：安山岩和流纹岩。这种情况为研究基质化学对喷口流体成分的影响提供了一个天然的实验室。(3)布兰斯菲尔德海峡独立于大洋中脊体系，裂谷历史相对较短(约4My)。因此，虽然该地区横跨大西洋和太平洋，但海峡的喷口生物群很可能有一个独特的谱系。有关布兰斯菲尔德喷口物种的生物化学信息将增加我们对深海生命扩散的了解。在过去，这样的发现导致了新物种的鉴定和以前未知的生化化合物的分离。(4)布兰斯菲尔德热液遗址的火和冰环境可能被证明是与地球和地外天体原始环境最相似的。布兰斯菲尔德海峡是世界上海洋生产力最高的地区之一，靠近南极大陆，远离大洋中脊系统。富含有机物质的沉积物和火山作用在弧后环境中产生的热量相结合，创造了一种有利于不寻常的流体、独特的喷口生物群和外来热液沉积的环境。协作奖：OPP 9725972和OPP 9813450

NSF FORM 1358 (1/94) This award, provided by the Office of Polar Programs of the National Science Foundation, supports research to investigate hydrothermal venting in Bransfield Strait, between the South Shetland Islands and the Antarctic Peninsula. Previous exploratory work in the Strait identified several sites where hot hydrothermal fluids emanate from the sea floor. These discoveries were made using an instrument package specially designed to detect and map the thermal and chemical anomalies that hydrothermal activity imparts on the overlying water column. Hydrothermal sites in the Strait range in water depth from 200 to 1300 meters and occur on the volcanic outcrops that periodically protrude through the sediment cover along the strike of the rift zone. These sites are alligned with the caldera at Deception Island which has active hot springs. These are the first submarine hydrothermal sites discovered in Antarctica and as such represent unique research opportunities. This project will return to the Strait to further map and sample these areas. There are several compelling reasons to believe that further exploration of vent systems in the Bransfield will yield exciting new information: (1) Bransfield Strait is a back-arc rift system and it is likely that the vent fluids and mineral deposits associated with venting in this setting are unlike anything sampled so far from submarine vents. (2) Preliminary evidence suggests that venting in the Bransfield occurs in two different volcanic substrates: andesite and rhyolite. This situation provides a natural laboratory for investigating the effects of substrate chemistry on vent fluid composition. (3) Bransfield Strait is isolated from the system of mid-ocean ridges and has a relatively short history of rifting (approximately 4 my). So, while the region straddles the Atlantic and Pacific, vent biota in the Strait may well have a distinct genealogy. Biochemical information on vent species in the Bransfield will add to our knowledge of the dispersal of life in the deep ocean. In the past such discoveries have led to the identification of new species and the isolation of previously unknown biochemical compounds. (4) The fire and ice environments of hydrothermal sites in the Bransfield may prove to be the closest analog for primordial environments on Earth and extraterrestrial bodies. The Bransfield Strait is one of the most productive areas of the world's oceans and lies close to the Antarctic continent, far removed from the mid-ocean ridge system. The combination of organic-rich sediment and heat produced by volcanism in this back- arc setting creates a situation conducive to unusual fluids, unique vent biota, and exotic hydrothermal deposits. Collaborative awards: OPP 9725972 and OPP 9813450