摘要
厘定大别—苏鲁超高压造山带南缘变质岩带的形成时代和地球化学特征有助于区域地层对比研究和对这一造山带演化过程的深入理解。采用单颗粒锆石U-Pb同位素稀释法和蒸发法定年,获得来自苏鲁地体南部海州群上部云台组的3个云母石英片岩样品的碎屑锆石年龄,且集中于800~740Ma之间。全岩初始εNd(800Ma)值变化在-12.8^-8.8之间,两阶段亏损地幔Nd模式年龄为2.1~2.4Ga。这些特征类似于大别山南部宿松地区副片麻岩,指示较单一的沉积物源。结合区域地层对比资料,碎屑锆石年龄限定了海州群云台组的沉积时代可能为新元古代,晚于740Ma左右。其主要沉积物质源自新元古代岩浆岩,归属于扬子陆块。
Constraints of age and isotopic compositions on the metamorphic rock units exposed in the southern part of the Dabie-Sulu ultrahigh pressure orogenic belt are essential for the study of regional stratigraphic comparison and further for understanding tectonic process and evolution of this orogen. In this study, Nd isotopic compositions and ages of detrital zircon of schists from the Haizhou Group in the southern part of the Sulu terrain are presented. Detrital zircon gains of three schist samples collected from the Yuntai Formation of the upper Haizhou Group yielded ages clustering around 740 to 800 Ma. Initial εnd （800 Ma） values and two-stage depleted-mantle Nd modal ages of the schist samples range from - 12.8 to - 8.8 and from 2.1 to 2.4 Ga. These ages and isotopic characteristics of the Yuntai schists are similar to those of paragneisses exposed in the Susong area of the Dabie Mountains and indicate a relatively single sedimentary source. Combined with a regional stratigraphic comparison, ages of the detrital zircons can place a constraint of Neoproerozoic age, later than about 740 Ma, for the deposition time of the Yuntai Formation. The sedimentary material was likely originated from Neoproterozoic magmatic rocks having an affinity of the Yangtze block.
出处
《高校地质学报》
CAS
CSCD
北大核心
2006年第3期365-374,共10页
Geological Journal of China Universities
基金
国家自然科学基金(40525007)
国家重点基础研究发展规划项目(G1999075502)资助
