胶北蓬莱群沉积时代、物质来源和大地构造环境研究

胶北隆起区是我国最大的金矿集中区，但其大地构造属性以及相关的华北板块与扬子板块的边界位置等基本地质问题，尚未很好地解决。蓬莱群是发育于胶北隆起区内晚太古宙－古元古代结晶基底之上的唯一沉积盖层，但其沉积时代和物质来源目前均仍未有定论。沉积时代有震旦纪和早古生代两种主要观点；沉积物源有或属于扬子板块，或属于华北板块，或既不属于扬子也不属于华北等多个结论。本项目拟采用野外剖面测制、岩相学、矿物电子显微镜成分与结构分析、主量与微量元素成份分析、全岩Sm-Nd同位素分析、锆石U-Pb年龄和Hf同位素分析等研究手段，通过对蓬莱群的地层比对、岩石地球化学特征和沉积年龄的分析，探讨其沉积时限和物质来源，厘定蓬莱群形成的沉积－构造环境，从而限定胶北隆起的大地构造属性，为探讨胶东地区华北板块南缘与扬子板块北缘的构造分界，及苏鲁超高压变质带区域分布和折返模型，以及胶东金矿成矿背景提供科学依据。

Jiaobei block is one of the most productive areas for gold deposit in China. However, its tectonic affinity and relevant geological issues, such as the boundary between the North China Craton and Yangtze Craton, are still not clear. The Penglai Group is the only overlying strata covering the Archean and early Proterozoic crystallized basement, and its sedimentary age and source are still debatable. Late Proterozoic or Early Paleozoic was proposed for its sedimentary age; Yangtze Craton, North China Craton, or neither of two blocks was proposed for its sedimentary source. Applying of field cross section investigation, petrography, TEM and SEM analyses for mineral composition and structure, major and trace element analyses, Sm-Nd isotope analyses, U-Pb dating and Hf isotope analysis for detrital zircon, this project will study the regional strata correlation, petrochemical characterizing and sedimentary age of the Penglai group to disclose its sedimentary era and source. The understanding of the sedimentary-tectonic regime of the Penglai group will help to constrain the tectonic affinity of the Jiaobei block, contribute to the arguments for the tectonic boundary and spatial distribution of the Sulu UHP metamorphic terrane between North China Craton and Yangtze Craton in the eastern Shandong Peninsula, and provide significant background information for the origin of gold deposits in the area.