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.

国际地球科学中心中国大陆科学钻探项目于2005年完成，目标是中国东部的一个超高压变质地体。超高压地体是扬子克拉通北缘俯冲至中朝克拉通之下150公里深度的产物。完成了东海主孔(MH)(5158m)、预导孔PP1(432m)、PP2(1028m)、PP3(705m)以及荣成、日照超镁铁质岩体3个浅孔(183~350m)的钻探。岩心回收率超过钻井深度的85%，包括未风化的片麻岩、榴辉岩、石榴石橄榄岩、纯橄榄岩和石榴石单斜辉石。根据地表露头的产状，预计会遇到橄榄岩，但没有人预测到通过钻探发现的财源。新的钻芯样本现在可以用于研究，为推进对地幔和俯冲过程的了解提供了一个前所未有的机会。大陆动力学项目资助了斯坦福大学由JG Liou领导的对ICDP-CCSD钻芯样本的多机构、多学科调查，成员包括来自北京中国地质科学院、华盛顿卡内基研究所、台湾中科院、东京工业大学和早稻田大学的同事。PI与30多名中国科学家密切合作，发表了107篇论文。根据汤姆森？S ISI科学网的数据，在1996年至2007年期间，刘建国被评为被引用次数最多的第十位地球科学作者，张荣元被评为前50名，这一点得到了研究界的重视。该奖项提供额外一年的支持，作为基于成就的更新(ABR)，以完成对石榴石橄榄岩核心样品的地球化学研究。将对石榴石橄榄岩中新发现的硫化物矿物进行Re-Os和硫同位素分析。在橄榄岩中发现的锆石是一种罕见但信息量极大的矿物，将对其进行Lu-Hf同位素分析。对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来源。这些新的研究与锆石的U-Pb离子探针分析相结合，将提供大陆次大陆地幔岩石圈形成的详细年代学，并对俯冲在地壳物质污染地幔中的作用提供新的见解。