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海南岛变碎屑沉积岩锆石SHRIMP U-Pb年龄及地质意义
  • ISSN号:0001-5717
  • 期刊名称:地质学报
  • 时间:0
  • 页码:381-393
  • 语言:中文
  • 分类:P588.133[天文地球—岩石学;天文地球—地质学]
  • 作者机构:[1]中国科学院广州地球化学研究所中国科学院边缘海地质重点实验室,510640, [2]中国科学院研究生院,北京100049
  • 相关基金:注:本文由国家自然科学基金项目(编号40173017)和中国科学院广州地球化学研究所所级创新项目(编号GIGCX03-02,GIGCX-04-04)资助的成果.致谢:评审专家为本文进一步完善和提高提出了许多建设性建议和意见;野外考察得到了海南省有色地质矿产勘查局陈作芬高级工程师的帮助;SHRIMP锆石U-Pb定年得到了北京离子探针中心万渝生研究员的指导;锆石阴极发光成像得到了中国科学院地质与地球物理研究所电子探针室毛骞高级工程师、马云光高级工程师的热助.在此一并致谢!
  • 相关项目:海南岛昌江-琼海断裂带变基性岩成因及构造意义
中文摘要:

CL成像制约下的锆石SHRIMPU—Pb定年结果表明,海南岛北西部中新元古代石碌群的源区岩可能主要为同区的古中元古代抱板群和中元古代花岗质岩,推测其沉积上限约960Ma、下限约1300Ma;而岛中东部早古生代变沉积岩物源较为复杂,可能与新太古宙-古元古代或更老的洋壳基底、同期的基性火成岩及岛北两部的抱板群和中元古代花岗质岩有关,推测其沉积上限约470Ma、下限约514Ma或稍早。锆石SHRIMP年龄谱及Nd模式年龄,虽揭示海南岛东南部与北西部可能具不同的地壳增长历史,但两者约在1000~1200Ma同时经历格林威尔造山事件,并组成Rodinia超大陆一部分。由于晚元古代-寒武纪洋内弧残余在岛中东部可能出现,并于440~509Ma普遍经历一次变质事件,而岛北西则出现中元古代花岗质岩,因而我们认为Rodinia超大陆聚合前,海南岛北西部最可能是劳伧大陆南缘西延部分,而岛东南部更可能位于澳大利亚大陆东部边缘。研究结果还暗示,中新元古代石碌群可能产于陆-陆碰撞有关的前陆盆地,而早古生代火山-碎屑沉积岩可能产于洋内弧相关的环境,因而晚前寒武纪以来海南岛大地构造环境具有由被动大陆边缘经裂谷向活动大陆边缘演化的特点。

英文摘要:

The diopside-tremolite rocks occur as interlayer with iron ore bodies at the top of the late MesoNeoproterozoic Shilu Group in Shilu iron ore mine, the northwest Hainan Island. The Early Paleozoic biotite schists are present probably as interlayer with the Chenxing metabasites in Tunchang area, the East-central Hainan Island. These metaclastics were dated by SHRIMP U-Pb analysis assisted by CL imaging of zircon, respectively. Zircons in the diopside-tremolite rocks of the Shilu Group yielded ^207Pb/^206Pb ages ranging from 1890 Ma to 900 Ma, with a primary cluster between 900 and 1330 Ma. In contrast, zircons in the biotite schists gave an older ^207Pb/^206Pb age of spanning from 2500 Ma to 980 Ma, as well as a younger, weighted concordant U-Pb mean age of 470 ± 16 Ma (MSWD=0.12), respectively. Because the Shilu sequences were deformed and metamorphosed from assembly of Rodinia, deposition probably occurred at ca. 960- 1300 Ma, soon after crystallization of the youngest population of zircons and before or during the onset of Granville deformation. The source rocks for the Group most likely are composed of the Paleo-Mesoproterozoic Baoban Group and the Mesoproterozoic granitoids in the same area. However, the provenances for the Early Paleozoic metaclastics in Tunchang area were rather complex and probably include about 2.5 Ga or older oceanic crust, Paleo-Mesoproterozoic Baoban Group, Mesoproterozoic granitic intrusive and about 514 Ma or earlier basic igneous rocks. Because the unit has a similar metamorphism to the Tasmanian fold belt adjacent to east Australia continent of East Gondwana, deposition probably occurred between about ca. 470 Ma and about . 514 Ma or earlier, soon after crystallization of the youngest population of zircons and before or during the onset of Ross-Delamerian Orogeny (Boger and Miller, 2004). We infer that the southeast Island not only has an older basement than, but also have a less consistent crust growth history with the northwest Island. However, both of them probably had

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期刊信息
  • 《地质学报》
  • 北大核心期刊(2011版)
  • 主管单位:中国科学技术协会
  • 主办单位:中国地质学会
  • 主编:莫宣学
  • 地址:北京户外百万庄26号中国地质学会期刊处
  • 邮编:100037
  • 邮箱:haoziguo@126.com
  • 电话:010-68312410
  • 国际标准刊号:ISSN:0001-5717
  • 国内统一刊号:ISSN:11-1951/P
  • 邮发代号:2-113
  • 获奖情况:
  • 国内外数据库收录:
  • 美国化学文摘(网络版),荷兰地学数据库,荷兰文摘与引文数据库,美国工程索引,美国地质文献预评数据库,美国生物科学数据库,英国动物学记录,日本日本科学技术振兴机构数据库,中国中国科技核心期刊,中国北大核心期刊(2004版),中国北大核心期刊(2008版),中国北大核心期刊(2011版),中国北大核心期刊(2014版),中国北大核心期刊(2000版)
  • 被引量:28314