摘要
新疆北部石炭—二叠纪存在大规模岩浆成矿作用,但对成矿地球动力学机制缺乏系统认识。在前人工作和我们近年来工作的基础上,文中扼要总结了我们新的初步认识,旨在为深化研究奠定思想基础。文中指出新疆北部泥盆—石炭纪岩浆活动和成矿作用是板块构造的直接产物。石炭纪的板块消减及有关的岩浆作用可能一直持续到三叠纪。地幔柱岩浆作用的起始时间不详,可能在晚石炭世,但集中表现在二叠纪。两种岩浆构造体系在时间上的叠加和空间上的并存造就了成矿作用的集中爆发以及成矿类型上的时空变化。与之有关的成矿作用和相应的成矿类型主要有:赋存于晚泥盆世—早石炭世海相火山岩中的磁铁矿床(有火山岩浆喷溢成因的可能,但更具有夕卡岩型铁矿的特征)、泥盆纪末到早三叠世与中酸性侵入岩有关的斑岩型(夕卡岩型)铜(钼)矿床以及早二叠世与镁铁-超镁铁质侵入岩有关的岩浆铜镍硫化物矿床。后者与南疆塔里木盆地已知溢流玄武岩在时代上((280±5)Ma)的一致性意味着包括该溢流玄武岩的基性大火成岩省可能分布很广泛,波及北疆的相当地域。如这一推论能够证实,那么与之有成因联系的钒钛磁铁矿和铜镍硫化物矿化点/矿床的分布就不应只局限于已知造山带,应该分布更广。这里造山带的"成矿专属性"很有可能只是构造暴露而已。这一思路有助于我们研究新疆北部晚古生代岩浆成矿作用以及与岩浆作用有关的成矿作用,并对寻找同类矿床有战略指导意义。
We report here our new perspectives on magmatism-related mineralization temporally concentrated inthe Carboniferous-Permian periods in the vast region of the northern Xinjiang Autonomous Region.Our broadaim is to provide a conceptual basis for discussion towards an improved understanding of the mineralization andfurther exploration. We confirm the idea that the Devonian-Carboniferous magmatism and relatedmineralization in the region is a consequence of plate tectonics,and such mineralization may have wellcontinued until the Triassic.The onset of the mantle plume activities in the region is poorly constrained,whichmay date back to the Late Carboniferous and prevailed in the Permian.The coexistence and coevality of the twotectonomagmatic processes resulted in the abundant mineralization and its variability in time and space.Themajor types of mineralization include（1）magnetite deposits hosted in the strata of Late Devonian/EarlyCarboniferous age（perhaps formed from volcanic flows as interpreted,but more like skarn/hydrothermaldeposits in character）,（2）porphyry/skarn Cu（and Mo）deposits of Late Devonian through Early Triassicage,and （3）Cu-Ni sulfide and Ti-V-magnetite deposits of Permian age associated with mafic-ultramaficintrusive complexes.The latter deposits that are widespread along orogenic belts are coeval（280±5Ma）withthe hidden flood basalt in the Tarim Basin in southern Xinjiang（interpreted as a large igneous province orLIP）.This observation suggests the possibility that the LIP may in fact be much greater in its spatialdistribution.If proved,this will have profound implications for the Permian Ti-V magnetite and Cu-Ni sulfidemineralization in the region,i.e.,the association of such known deposits with the orogenic belts may reflect the tectonic exposure and more and larger deposits may in fact yet be discovered in more sites and over a muchgreater area away from the orogenic belts.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2012年第4期41-50,共10页
Earth Science Frontiers
基金
国家科技支撑重点项目(2006BAB01A01)
中国地质调查局地质大调查项目(1212010918024
1212011121088
1212011121092
1212010911032)
关键词
新疆北部
石炭—二叠纪
板块构造
大火成岩省
构造体制并存
Northern Xinjiang
Carboniferous-Permian period
plate tectonics
large igneous province
coexis-tence of tectonic regime
