Lithology, kinematics and geochronology related to Late Mesozoic basin-mountain evolution in the Nanxiong-Zhuguang area, South China
Lithology, kinematics and geochronology related to Late Mesozoic basin-mountain evolution in the Nanxiong-Zhuguang area, South China
复制标题
DOI：
10.1360/03yd0113
复制
发表时间：
2004-08
期刊：
影响因子：
--
通讯作者：
L. Shu;P. Deng;Bin Wang;Zhengzhong Tan;Xinqi Yu;Yan Sun
中科院分区：
文献类型：
--
作者：
L. Shu;P. Deng;Bin Wang;Zhengzhong Tan;Xinqi Yu;Yan Sun
南雄红层盆地及其毗邻的珠光花岗岩构成南岭地区独特的盆山地貌。研究结果表明，珠光花岗岩是在古特提斯-古亚洲构造体制变质基底上发育的多期复合岩体，具有中上地壳热穹伸展构造的几何学和运动学特征，是印支期碰撞造山作用的岩浆杂岩。燕山早期的俯冲-消耗作用和燕山晚期的陆内玄武岩底侵作用和深部地球动力学作用。南雄盆地是一个北方为断裂边界，南方为不整合边界的晚白垩世-古近纪不对称断陷盆地，其存款中心由南向北逐渐迁移。盆山耦合带的构造运动学研究表明，韧性流变层与脆性流变层剪切方向一致，表明花岗岩穹状伸展构造的形成是一个从中地壳层面的韧性伸展变形、局部左旋走滑剪切到上地壳层面的脆性张性变形的连续过程。诸广花岗岩与南雄断陷盆地构成半地堑构造体系。岩石地球化学研究表明，诸广晚三叠世-侏罗纪花岗岩体具有相似的特征：SiO2、Al 2 O3、K2 O含量高，碱性指数> 2.8，ANKC值> 1.1，LREE富集模式，REE含量高，Eu负异常明显，富集Rb、Th，亏损Ba、Nb，表现出富K、富Al的钙碱性亲和力，反映了晚三叠世至侏罗纪岩浆演化的连续性。南雄盆地的形成和盆山系统的演化受诸广花岗岩穹隆作用和区域伸展构造的双重控制。盆地内橄榄玄武岩的发育表明，熔岩喷发时张拉作用很强。南雄盆地玄武岩中的岩浆型锆石SHRIMP年龄为96± 1 Ma，为南岭地区构造热事件和盆山演化提供了可靠的年代学约束。
The Nanxiong red-bed basin and its adjacent Zhuguang granite form a distinctive basin-mountain landform in the Nanling region, South China. Research results suggest that the Zhuguang granite is a polyphase composite pluton developed on the metamorphic basement of the paleo-Tethys-paleo-Asian tectonic regime and possesses geometrical and kinematic features of hot-doming extensional tectonics at the middle-upper crustal level, which is considered as a magmatic complex that resulted from the collision-orogeny during the Indosinian Period, the subduction-consuming during the Early Yanshanian Period and the intra-continental basaltic underplating and deep-seated geodynamics during the Late Yanshanian Period. The Nanxiong basin is a Late Cretaceous-Paleogene asymmetric faulted basin that is characterized by a fault boundary on the northern side and an uncomformable boundary on the southern side, its deposit center was migrated gradually from south to north. Structural kinematic results on the basin-mountain coupled zone demonstrate that the ductile and the brittle rheological layers show a quite coincident sense of shear, implying that it is a continuous process from the ductile extensional deformation followed by locally sinistral strike-slip shear at a middle-crustal level to the brittle tensional deformation at a upper-crustal level during formation of granitic doming extensional tectonics. The Zhuguang granite and the Nanxiong faulted basin constructed a semi-graben tectonic system. Lithological and geochemical results suggest that the Late Triassic to Jurassic granitic bodies in the Zhuguang have some similar features: high SiO2, Al2O3, K2O contents, alkalinity index > 2.8, ANKC value > 1.1, LREE-enriched pattern with high REE contents, marked negative Eu anomalies, enrichment in Rb and Th, depletion in Ba and Nb, showing a K-rich and Al-rich calc-alkaline affinity, which suggest a continuous magmatic evolution from Late Triassic to Jurassic. Formation of Nanxiong basin and evolution of basin-mountain system were controlled both by the Zhuguang granitic-doming and the regional extensional tectonics. Development of the olivine basalt in the basin suggests that tension action was very strong during lava eruption. The magma-type zircon grains of basalt from the Nanxiong basin yielded the SHRIMP age of 96±1Ma, providing reliable geochronological constraint on the tectono-thermal event and basin-mountain evolution in the Nanling region, South China.