地球学报Issue(4)：395-402,8.DOI:10.3975/cagsb.2015.04.02
华夏地块龙泉地区发现亚洲最古老的锆石
The Discovery of the Asian Oldest Zircons in Longquan, Cathaysia Block
摘要
Abstract
At present, zircons are the only residual material of the Hadean crust, and constitute a crucial clue to understanding the early crustal evolution. Rencently, we found the two ~4100 Ma detrital zircons from a Paleozoic quartzite in the Longquan area of the Cathaysia Block, through SHRIMP zircon data. One zircon (207Pb/206Pb age of 4127±4 Ma) shows normal oscillatory zonation and constant mantle-like oxygen isotope ratios (δ18O = 5.8‰ to 6.0‰), and might have crystallized in ancient mantle-derived magmas or partial melts of primitive crust. Obviously, this is the oldest age in the reported zircon ages of Asia. The other zircon grain has a ~4100 Ma magmatic core surrounded by a ~4070 Ma metamorphic mantle. The 4070 Ma indicates the most reliable metamorphic age of the earth. Outside the mantle, two overgrowth bands are 3800~3600 Ma, implying that the magmatic core (crust) underwent complex evolutions after ~4100Ma. These data demonstate the diversity of the Earth’s earliest crustal nature and tectonic setting, and provide crucial evidence for us to understand the earliest crustal evolution.关键词
锆石/冥古宙/龙泉/华夏陆块Key words
zircon/Hadean/Longquan/Cathaysia Block分类
天文与地球科学引用本文复制引用
邢光福,杨祝良,陈志洪,姜杨,洪文涛,靳国栋,余明刚,赵希林,段政..华夏地块龙泉地区发现亚洲最古老的锆石[J].地球学报,2015,(4):395-402,8.基金项目
本文由中国地质调查局工作项目“华东基础地质综合调查与片区总结”(编号:1212011220542)和国家自然科学基金项目(编号:41002024 （编号:1212011220542）
41202141)联合资助。获中国地质调查局、中国地质科学院2014年度地质科技十大进展第七名。 （）
