Subduction and Exhumation of Ultrahigh-Pressure Rocks: Field and Drilling Studies in Eastern China

超高压岩石的俯冲和折返：中国东部的野外和钻探研究

• 批准号: 0810969
• 负责人: Juhn Liou
• 金额: $ 15.35万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810969&HistoricalAwards=false
• 关键词: Subduction; Exhumation; Ultrahigh; Pressure; Rocks

The ICDP Chinese Continental Scientific Drilling project, completed in 2005, targeted an ultrahigh pressure (UHP) metamorphic terrane in eastern China. The UHP terrane resulted from subduction of the northern edge of the Yangtze craton to 150 km depth beneath the Sino-Korean craton. Several drill holes including the main hole (MH) (5158 m depth), pre-pilot holes PP1 (432 m), PP2 (1028 m) and PP3 (705 m) in Donghai, and 3 shallow holes (183-350 m) in ultramafic bodies in Rongcheng and Rizhao were completed. Core recovery was more than 85% of drilling depth including unweathered samples of gneisses, eclogites, garnet peridotites, dunite, and garnet clinopyroxenite. Encountering peridotites was expected based on occurrences in surface outcrops but no one predicted the bonanza that was found by drilling. The new drill core samples, now available for study, offer an unprecedented opportunity to advance understanding of the mantle and subduction processes. The Continental Dynamics program funded a multi-institutional, multidisciplinary investigation of ICDP-CCSD drill core samples led by JG Liou at Stanford University and has included colleagues from the Chinese Academy of Geological Sciences, Beijing, Carnegie Institution of Washington, Academia Sinica (Taiwan), Tokyo Institute of Technology and Waseda University. The PIs have worked closely with more than 30 Chinese scientists, and published 107 papers. The published work on CCSD cores is valued by the research community as recognized by the ranking of J.G. Liou as the tenth most cited geoscience author and R.Y. Zhang as within the top 50 during 1996-2007 according to Thomson?s ISI Web of Science. This award provides one additional year of support as an Accomplishment Based Renewal (ABR) to complete geochemical studies of core samples of garnet peridotite. Newly recognized sulfide minerals in garnet peridotites will be analyzed for Re-Os and Sulfur isotopes. Zircons, a rare but immensely informative mineral found in peridotites, will be analyzed for Lu-Hf isotopes. Analysis of peridotite silicate minerals for oxygen isotopes will be used to test for mantle vs. crustal origin. These new studies, combined with U-Pb ion microprobe analyses of zircon, will provide a detailed chronology of the formation of sub-continental mantle lithosphere and give new insights as to the role of subduction in contaminating the mantle with crustal material.

2005年完成的ICDP中国大陆科学钻探项目，以中国东部的超高压（UHP）变质火山岩为目标。超高压俯冲是扬子克拉通北方边缘向中朝克拉通150 km深处俯冲的结果。完成了东海主孔（MH）（5158 m深）、预先导孔PP 1（432 m）、PP 2（1028 m）和PP 3（705 m）以及荣成和日照超镁铁岩体浅孔（183-350 m）等多个钻孔。岩芯回收率超过钻井深度的85%，包括未风化的片麻岩、榴辉岩、石榴橄榄岩、纯橄榄岩和石榴单辉石岩样品。根据地表露头的出现情况，预计会遇到橄榄岩，但没有人预测钻探发现的富矿。现在可供研究的新钻芯样品为促进对地幔和俯冲过程的了解提供了前所未有的机会。大陆动力学计划资助了一项由斯坦福大学的JG Liou领导的多机构、多学科的ICDP-CCSD岩心样本调查，参与调查的同事包括来自北京中国地质科学院、华盛顿卡内基研究所、中央研究院（台湾）、东京工业大学和早稻田大学的同事。该研究所与30多位中国科学家密切合作，发表了107篇论文。已发表的关于CCSD岩心的工作受到研究界的重视，这一点得到J.G. Liou是第十位被引用最多的地球科学作者，R.Y.根据汤姆森的数据，张在1996-2007年期间进入了前50名？ISI Web of Science。该奖项提供额外一年的支持，作为基于成就的更新（ABR），以完成石榴石橄榄岩岩心样品的地球化学研究。对石榴橄榄岩中新发现的硫化物矿物进行铼-锇和硫同位素分析。 锆石是橄榄岩中发现的一种罕见但信息量巨大的矿物，将进行Lu-Hf同位素分析。 橄榄岩硅酸盐矿物的氧同位素分析将用于测试地幔与地壳起源。 这些新的研究，结合U-Pb离子探针分析的锆石，将提供一个详细的年代学的形成次大陆地幔岩石圈，并提供新的见解俯冲的作用，污染地幔与地壳物质。