华北克拉通古元古代吕梁群火山沉积作用与构造环境

The Lüliang Mountain, the cradle of the nomenclature named the "Lüliang Movement", is an important component of the North China Craton. Recently, there is considerable disagreement concerning the nature of the "Lüliang Movement", particularly, the tectonic setting of the Precambrian rocks occurred in Lüliang Mountain also remains debated. The Lüliang Group as a key tectonic marker unit in the Lüliang Mountain, composed mainly of metamorphic volcanic, volcaniclastic and sedimentary rocks with economic BIF. These expressions constitute an excellent window through which the Palaeoproterozoic geodynamic and environmental scenarios can be characterized. In this present study, these volcanic, volcaniclastic and sedimentary rocks from the Lüliang Group are chosen as the main research objects. After the geological investigations and volcanic-sedimentary geological section studies for the Lüliang Group, its rock assemblages and volcanic-sedimentary facies associations can be identified,and volcano-sedimetary sequence can be set up. Whole-rock geochemical and isotopic data, coupled with zircon U-Pb-Hf-O isotopes, from these Paplaeoproterozoic rocks of the Lüliang Group, are presented to determine their provenance and tectonic setting, to reconstruct the sedimentary basin type,and to discuss the linkage between the BIF and the volcanic-sedimentation. Overall, this study not only enhances us to understand the tectonic ascription of the Lüliang Mountain during Palaeoproterozoic, but also offers important contributions to the complete picture of Precambrain tectonic processes and environment in the North China Carton, and certainly to the investigations of the iron ore deposit formation and distribution in our country.

著名的"吕梁运动"的发祥地吕梁山是华北克拉通的重要组成部分。迄今，有关"吕梁运动"的性质在认识上有较大的分歧，特别是对吕梁山地区在早前寒武纪时期形成的构造环境也存在较大的争议。本项目拟以吕梁山地区出露的古元古代吕梁群为主要研究对象，把火山岩－火山碎屑岩－沉积岩视为一有机整体，在开展详细的地质调查和剖面测制的基础上，以系统的沉积学和岩石学研究为基础，查明火山－沉积作用形成的岩石组合类型和相组合特征，建立吕梁群火山-沉积序列；通过岩石地球化学、同位素地球化学和锆石U-Pb-Hf-O同位素研究，确定吕梁群源区性质和构造背景，重建吕梁群火山－沉积建造沉积时的盆地类型，探讨产自其中的BIF与火山－沉积作用间可能存在的成生联系。通过这些岩石学、地球化学和同位素地球化学研究，深化吕梁山地区在古元古代时期的构造归宿，为进一步认识华北克拉通前寒武纪构造－环境演化以及我国铁矿的形成和分布规律提供重要依据。