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.

ICDP中国大陆科学钻探项目于2005年完成，目标是中国东部的超高压（UHP）变质地体。超高压地体是扬子克拉通北缘俯冲到中朝克拉通以下150公里深度的产物。完成主孔（MH）（深5 158 m），东海预导孔PP1（432 m）、PP2（1 028 m）、PP3（705 m），荣成、日照超镁铁体浅孔3个（183～350 m）。岩心回收率超过钻探深度的 85%，包括片麻岩、榴辉岩、石榴橄榄岩、纯橄榄岩和石榴石单斜辉石岩的未风化样品。根据地表露头的情况，预计会遇到橄榄岩，但没有人预测到通过钻探发现的富矿。现在可供研究的新钻芯样本为加深对地幔和俯冲过程的了解提供了前所未有的机会。大陆动力学项目资助了一项由斯坦福大学 JG Liou 领导的对 ICDP-CCSD 钻芯样本的多机构、多学科研究，研究人员包括来自北京中国地质科学院、华盛顿卡内基研究所、台湾中央研究院、东京工业大学和早稻田大学的同事。 PI与30多位中国科学家密切合作，发表论文107篇。已发表的 CCSD 核心工作受到研究界的重视，J.G. Liou 是被引用次数排名第十的地球科学作者，R.Y.根据 Thomson 的 ISI Web of Science，张在 1996 年至 2007 年期间名列前 50 名。该奖项作为基于成就的续约 (ABR) 提供额外一年的支持，以完成石榴石橄榄岩核心样品的地球化学研究。将分析石榴石橄榄岩中新发现的硫化物矿物的铼锇和硫同位素。 锆石是一种在橄榄岩中发现的稀有但信息丰富的矿物，我们将对其进行 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的起源。 这些新研究与锆石的 U-Pb 离子微探针分析相结合，将提供次大陆地幔岩石圈形成的详细年代学，并就俯冲在地壳物质污染地幔中的作用提供新的见解。