Helium and Carbon Isotope Studies of Geothermal Fluids Along the North Anatolian Fault and Relationships to Seismicity

北安纳托利亚断层沿线地热流体的氦和碳同位素研究及其与地震活动的关系

• 批准号: 0229508
• 负责人: David Hilton
• 金额: $ 11.32万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0229508&HistoricalAwards=false
• 关键词: Helium; Carbon; Isotope; Studies; Geothermal

HiltonEAR-0229508The present proposal is aimed at understanding relationships between geochemical tracers such as helium and carbon dioxide and the occurrence of seismicity along the North Anatolian Fault Zone (NAFZ) in Turkey. In collaboration with Turkish colleagues, who are monitoring major and minor element geochemistry and other isotope systems (18O, D/H and tritium), we plan to sample fluids for helium and carbon (from production wells and surface springs) from nine previously-monitored geothermal localities sited along an 800-km active segment of the NAFZ. These two geothermal tracers have great utility in their ability to distinguish crustal and mantle inputs to the volatile inventory. We want to test the hypothesis - seen in other studies of earthquake-prone regions - that changes in the balance between mantle- and crustal-derived volatiles have potential as a precursor of impeding seismic activity. The western segment of the NAFZ region experienced two catastrophic earthquakes in 1999 entailing more than 25,000 fatalities: it continues to be seismically active. This work, aimed at understanding how crustal fluids respond to seismic events, has clear societal relevance. In addition, prior work carried out through collaborative efforts with our Turkish colleagues has discovered that mantle-derived 3He occurs in fluids along the entire strike (~800 km) of the active western segment of the NAFZ. The presence of a mantle-derived fluid component indicates leakage across the ductile-brittle transition region of the seismogenic zone. The same observation has been made for the San Andreas Fault System (SAFS) in California. Indeed there are many other parallels between the NAFZ and the SAFS. Information gained in the present study, particularly on the distribution of seismicity along the NAFZ and the westward progression of epicenters (towards the metropolis of Istanbul), may be applicable to the SAFZ.

本提案旨在了解地球化学示踪剂（如氦和二氧化碳）与土耳其北安纳托利亚断层带（NAFZ）沿着地震活动发生之间的关系。我们与土耳其同事合作，他们正在监测主要和次要元素地球化学和其他同位素系统（18 O，D/H和氚），我们计划从位于沿着NAFZ 800公里活动段的九个先前监测的地热地点采集氦和碳（来自生产威尔斯和地表泉水）的流体样本。 这两个地热示踪剂有很大的效用，在他们的能力，区分地壳和地幔输入的挥发性库存。 我们想检验这一假设--在其他地震多发地区的研究中看到的--地幔和地壳衍生挥发物之间平衡的变化有可能成为阻碍地震活动的前兆。1999年，西北非军事区西部地区发生了两次灾难性地震，造成25 000多人死亡：该地区的地震活动仍然很活跃。这项工作旨在了解地壳流体如何对地震事件作出反应，具有明显的社会意义。 此外，通过与我们的土耳其同事的合作努力进行的先前工作已经发现，地幔衍生的3 He出现在流体中沿沿着整个走向（约800公里）的活跃的西部段的NAFZ。 幔源流体成分的存在表明了孕震带韧脆性过渡区的渗漏。在加州的圣安德烈亚斯断层系统（SAFS）也有同样的观测结果。事实上，NAFZ和SAFS之间还有许多其他相似之处。本研究中获得的信息，特别是关于地震活动性沿着NAFZ的分布和震中向西推进（朝向伊斯坦布尔的大都会）的信息，可能适用于SAFZ。