华北克拉通西部古元古代孔兹岩系的地层对比、岩相古地理特征及其地质意义  

Stratigraphic correlation and lithofacies paleogeography of khondalite series in the western North China Craton

作　　者：钟焱 陈雅丽[2] 翟明国[2] 马旭东[3] 

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《岩石学报》2016年第3期713-726,共14页Acta Petrologica Sinica

基　　金：科技部"973"项目(2012CB4166006);国家自然科学基金项目(41530208;41210003);中国地质调查局项目(12120114021701)联合资助

摘　　要：位于华北克拉通西部的孔兹岩系是探讨华北克拉通形成及演化过程的关键对象之一,近年来的研究显示这套富铝质沉积岩系在1.95～1.82Ga期间经历了高压/高温和超高温-高温/中（低）压两期变质作用。已发表的钻井资料表明鄂尔多斯中、新生代盆地的基底岩石在源区特征、沉积时代、岩石矿物组合和变质时代等方面均与孔兹岩系十分类似,暗示孔兹岩系的原岩分布和后期的高级变质作用范围可能涉及到了鄂尔多斯地块内部。然而,目前对于孔兹岩系的原岩分布、等时性和沉积环境等问题仍有争议,这些问题对于约束孔兹岩系的时空分布和理解华北克拉通西部地区的构造演化过程具有十分重要的科学意义。基于地层学角度的尝试,本文选取贺兰山、大青山和集宁地区的孔兹岩系进行了沉积层序的划分及对比,并初步恢复了相应时期鄂尔多斯地块的岩相古地理特征。本文的研究结果表明：（1）鄂尔多斯地块北缘的贺兰山、大青山和集宁等地区的孔兹岩系均由可对比的三个沉积层序组成;（2）这套沉积岩系的分布范围呈面状延伸至鄂尔多斯地块内部,指示华北克拉通西部曾存在一个克拉通内盆地性质的＂鄂尔多斯陆表海＂,其海侵方向可能由贺兰山-鄂尔多斯地块内部指向大青山、集宁等地区;（3）鄂尔多斯陆表海可能发育于2.5～2.3Ga＂构造寂静期＂的某一阶段,此间堆积的孔兹岩系（丰镇群）原岩很可能是代表华北陆块完成克拉通化过程的标志性盖层。The khondalite series,located in the western part of the North China Craton（ NCC）,is one of the most significant objects that are essential for understanding formation and evolution of the NCC. To date,a great number of researches suggested that the khondalite series,a suite of high-grade metamorphic alumina-rich sedimentary rocks,had witnessed two important metamorphic events during 1. 95 ～ 1. 82 Ga,including high pressure / high temperature metamorphism and high to unltra-high temperature / medium to low pressure metamorphism. The available data from drilling samples of the Mesozoic-Cenozoic Ordos Basin revealed that its basement rocks were similar with the khondalite series in petrology,provenance,depositional age and metamorphic timing. It appears that a larger part of the Ordos Block had been covered by the protolithes of the khondalite series and been involved by the subsequent highgrade metamorphic events. However,the debates on the distribution,isochronism and depositional environment of the protolithes of the khondalite series are still ongoing. These points are invaluable for constraining temporal-spatial distribution of the khondalite series and understanding tectonic evolution of the western NCC. As an attempt to facilitate deciphering the protolith basin,three typical sections of the khondalite series in the Helanshan,Daqingshan and Jining areas were chosen for deposition sequence subdivisions,stratigraphic correlation and lithofacies paleogeographic rebuilding. These results in this paper suggest that：（ 1） the khondalite series in the northern margin of the Ordos Block are composed of three correlatable deposition sequences;（ 2） an epeiric sea over the Ordos Block（ Ordos Epeiric Sea） might be responsible for the planar distribution of the khondalite series and its transgressive direction was mainly from the Helanshan-interior of the block to the Daqingshan and Jining areas; and（ 3） the Ordos Epeiric Sea induced accumulation was completed during the inactive period（ 2. 5 ～

关 键 词：孔兹岩系 沉积层序 岩相古地理 鄂尔多斯陆表海 

分 类 号：P539.2[天文地球—古生物学与地层学]