花岗岩浆侵位与结晶固化时差的研究与构造意义:以南岭骑田岭花岗岩基为例   总被引：4，自引：0，他引：4  

章邦桐  吴俊奇  凌洪飞  陈培荣 《高校地质学报》2010,16(1):103-118

通过对南岭中段骑田岭花岗岩基地质-岩石地球化学特征研究, 判明了该岩基的侵位深度（5.5 km）、围岩温度（196℃）及岩浆初始温度（950 ℃ ）,建立起骑田岭花岗岩基的数学计算模型,计算得出： 骑田岭花岗岩熔体侵位后,其初始温度降低至结晶温度所需的时间（Δt col） 为4.1 Ma;由于结晶潜热释放而使结晶过程延长的时间（Δt L）为2.6 Ma; 由于骑田岭花岗岩基放射性元素含量 （U-15.3×10-6,Th-51.35×10-6,K2O-5.02%）是世界平均花岗岩放射性元素含量（U-5×10-6,Th-20×10-6,K2O-2.66%）的2~3 倍,骑田岭花岗岩浆侵位后产生的放射成因热使结晶过程延长的时间（Δt A） 为35.4 Ma,远长于世界平均花岗岩计算的Δt A（2.93 Ma） 。因此, 骑田岭花岗岩基的岩浆侵位- 结晶固化时差 （Δt ECTD）为42.1 Ma, 结合锆石U-Pb 年龄值（161 Ma）, 通过反演计算得出骑田岭花岗岩基侵位年龄值（t E ）为203.1 Ma,从而为骑田岭花岗岩基属于印支期侵位提供了重要的岩浆动力学佐证。  相似文献   

Recurrent mesoproterozoic continental magmatism in South-Central Norway     

Svend Pedersen  Tom Andersen  Jens Konnerup-Madsen  William L. Griffin 《International Journal of Earth Sciences》2009,98(5):1151-1171

We report U–Pb dates and Lu–Hf isotope data, obtained by LAM-ICPMS, for zircons from metamorphic rocks of the Setesdalen valley, situated in the Telemark block south of the classic Telemark region of southern Norway. The samples include infracrustal rocks from the metamorphic basement, metaigneous rocks and metasediments from the Byglandsfjorden supracrustal cover sequence, and metaigneous rocks which intruded the whole succession. The main crustal evolution took place from 1,550–1,020 Ma, beginning with the emplacement of juvenile tonalitic melts; the contribution of older crustal material increased with time. Around 1,320 Ma, further addition of juvenile material occurred, involving both mafic and felsic melts, metamorphism and deformation. Acid magmas with high FeO*/MgO were intruded at 1,215 Ma, coinciding with underplating elsewhere in South Norway. The period starting at 1,215 Ma is represented by supracrustal rocks, principally metarhyolites with minor mafic material and immature sediments of the Byglandsfjorden Group. The crust generation processes ended with the intrusion of diorites and granodiorites at 1,030 Ma, late in the Sveconorwegian orogeny. Regional processes of metamorphism and deformation (around 1,290 and 1,000 Ma) can be related to the assembly of Rodinia. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

胶东金矿成矿构造背景探讨     

李洪奎  禚传源  耿科  梁太涛 《山东地质》2012,(1):5-13

在编制1∶50万山东省大地构造相图基础上,通过对大地构造相研究显示：胶东微地块是经多期增生和碰撞而形成的,其漫长的板块构造演化明显具有阶段性。侏罗纪是该区板块构造演化史上的一个重要转换期,构造演化由原来的南、北分异转变为东、西分异,胶东地区NE向新生构造起了主要作用。胶东地区中生代有2次重要的碰撞造山事件,印支造山作用主要表现为扬子板块向华北板块俯冲,形成苏鲁高压-超高压变质带及同造山花岗岩及后造山高碱正长岩;燕山造山作用的大陆动力学环境起源于中亚-特提斯构造域向滨太平洋构造域转化和太平洋板块的俯冲,在胶东地区表现为3次造山和3次伸展。晚侏罗世造山早期玲珑片麻状花岗岩组合是区域构造挤压导致地壳增厚引起地壳重熔的产物,代表了大陆弧花岗岩特征;早白垩世造山中期郭家岭花岗闪长岩-花岗岩组合代表了造山期大陆弧花岗岩的特点;造山晚期伟德山闪长岩-花岗闪长岩-花岗岩组合表现为大陆弧花岗岩,后造山A型崂山晶洞过碱性碱长花岗岩-正长花岗岩组合为大陆造陆隆升花岗岩与后造山花岗岩,代表燕山构造的结束。胶东地区构造-岩浆事件和金矿成矿作用受控于特提斯、古亚洲洋和太平洋三大构造域的相互作用,金矿形成的动力学背景是中生代构造体制转折和岩石圈减薄,起因与太平洋板块向华北板块的俯冲机制有关。  相似文献   

南盘江盆地中三叠统碎屑锆石地质年代学:物源及其地质意义   总被引：1，自引：0，他引：1  

杨宗永  何斌 《大地构造与成矿学》2012,36(4)

南盘江盆地的物源及其构造性质至今尚未取得较为一致的认识。目前主要的观点认为其物源主要来自盆地东南面的云开大山地区,盆地的性质为古太平洋板块俯冲所形成的前陆盆地。本文采用碎屑锆石年代学方法,首次报道该盆地中三叠统碎屑锆石年龄组成,分析了该盆地的沉积物源,并基于物源分析探讨了成盆机制和板块间动力学关系。该盆地中三叠统碎屑锆石年龄组成最主要的特征性的年龄分布在320～250Ma之间,此区间内存在280Ma和250Ma两个峰值。通过与相邻各块体锆石年龄谱对比,本研究认为:(1)南盘江盆地的主要物源区应为古特提斯北缘(华南一侧)的石炭-二叠纪岩浆弧,SongMa构造带可能是三叠纪的缝合线,而不是因Sibumasu板块增生到印支板块而导致的板内活化带;(2)该盆地三叠纪时为古特提斯闭合在华南形成的前陆盆地,与古特提斯沿SongMa带向北俯冲闭合有关,前人认为的南盘江盆地形成于古太平洋板块向西北俯冲作用的观点值得商榷。  相似文献   

Sedimentary response to the intracontinental orogenic process: insight from the anatomy of a small Mesozoic basin in western Yanshan,northern North China     

《International Geology Review》2012,54(12):1528-1556

ABSTRACT

The intra-continental orogeny and tectonic evolution of the Mesozoic Yanshan fold-thrust belt (YFTB) in the northern North China Craton (NCC) have been strongly debated. Here, we focus on the Shangyi basin, located in the centre of the YFTB. An integrated analysis of sedimentary facies, palaeocurrents, clast compositions, and detrital zircon dating of sediments was adopted to determine the palaeogeography, provenance, basin evolution, and intra-continental orogenic process. The Shangyi basin comprises the well-exposed Early–early Middle Jurassic Xiahuayuan Formation and the Longmen Formation, and the Late Jurassic–Early Cretaceous Tuchengzi Formation. Based on the 18 measured sections, five facies associations – including alluvial fan, fluvial, delta, lacustrine, and eolian facies – have been identified and described in detail. The onset of the Shangyi basin was filled with fluvial, deltaic, and lacustrine deposits controlled by the normal fault bounding the northern basin, corresponding to the pre-orogeny. In the Middle Jurassic, the cobble–boulder conglomerates of alluvial fan, as molasse deposits, were compatible with the syn-orogeny of the Yanshan movement, which played a critical role in northern North China and even East Asia. After the depositional break in the Middle–Late Jurassic, the Shangyi basin, controlled by the normal fault present in the north of the basin, re-subsided and quickly expanded southward with thick sedimentation, which is correlative with the post-orogeny. Combined with A-type granites, metamorphic core complexes, mafic dikes, and rift basins of the Late Jurassic–early Early Cretaceous present in the northern NCC and Mongolia, significant extension was widespread in the northern NCC and even in northeast Asia. Moreover, vertical changes of provenance indicate that the Taihang Mountain and the Inner Mongolia palaeo-uplift (IMPU) present at the west and north of the basin, respectively, experienced uplift twice in the Middle–Late Jurassic and Early Cretaceous, resulting in a regional depositional break.  相似文献   

Kinematics of the Guerrero terrane accretion in the Sierra de Guanajuato,central Mexico: new insights for the structural evolution of arc–continent collisional zones     

《International Geology Review》2012,54(5):574-589

The Guerrero terrane comprises Middle Jurassic–Early Cretaceous arc successions that were accreted to the North American craton in the late Early Cretaceous, producing closure of the Arperos oceanic basin and the formation of an approximately 100 km-wide fold–thrust belt. Such a suture is key to investigating the structural evolution related to Guerrero terrane accretion and, in general, to arc–continent collisional zones. The Sierra de Guanajuato is an exposure of the Guerrero terrane suture belt and consists of a complex tectonic pile that formed through at least three major shortening phases: D1SG, D2SG, and D3SG (SG, Sierra de Guanajuato). During the D1SG and D2SG phases, the Upper Jurassic–Lower Cretaceous successions of the Arperos Basin piled up, forming a doubly vergent imbricate fan of thrust sheets that accommodated substantial NE–SW shortening. Mylonite microtextures, as well as syntectonic minerals, indicate that the D1SG and D2SG deformation events took place under low greenschist-facies metamorphic conditions. We relate these deformation phases to the progressive NE migration of the Guerrero terrane, which triggered the collapse and closure of the Arperos Basin. During D3SG, the El Paxtle arc assemblage of the Guerrero terrane was tectonically emplaced onto the previously deformed successions of the Arperos Basin. However, D3SG structures indicate that during this deformational stage, the main shortening direction was oriented NW–SE and that contraction was accommodated mostly by SE-vergent ductile thrusts formed under low greenschist-facies metamorphic conditions. We suggest that the top-to-the-SE emplacement of the El Paxtle assemblage may be a result of the tectonic escape of the arc produced by the continuous NE impingement of the Guerrero terrane during its collisional addition to the Mexican mainland.  相似文献   

中天山北缘华力西期造山作用——变质岩锆石U-Pb年代学限定   总被引：4，自引：2，他引：2       下载免费PDF全文

林彦蒿张泽明  贺振宇董 昕 于 飞 《中国地质》2011,38(4):820-828

笔者对中天山微陆块北缘托克逊干沟地区角闪岩相变质岩中的锆石进行了U-Pb年代学研究,结果证明变质沉积岩中的碎屑锆石记录了从太古宙至元古宙(3320～530 Ma)的源区岩浆热事件,变质火成岩中的岩浆锆石记录了新元古代晚期(550 Ma)的岩浆作用,而变质锆石记录了晚泥盆纪(385～360 Ma)的变质作用。这一定年结果表明,中天山微陆块北缘的造山作用很可能发生在华力西期,中天山微陆块形成于新元古代以前,但并没有经历前寒武纪变质作用,具有与塔里木克拉通明显不同的前寒武纪构造演化历史。因此,中天山微陆块很可能是一个独立的块体,并不支持其是从塔里木板块分离出来的观点。  相似文献   

滨里海盆地东缘中段盐构造变形特征     

余一欣  郑俊章  汤良杰  王燕锟  杨孝群 《世界地质》2011,30(3):368-374

利用地震剖面解释和构造编图,对滨里海盆地东缘中段下二叠统孔谷阶盐构造变形特征进行了分析。结果表明,孔谷阶含盐层系变形强烈,主要发育盐底辟、盐枕、盐滚、盐焊接、盐边凹陷和龟背构造等多种盐构造变形样式。不同盐构造规模差别较大,隆起幅度自东向西逐渐增大,平面展布具有明显的分带性。盐构造运动对周缘地层变形也产生了重要影响,形成了楔型褶皱地层,并导致盐间和盐上地层发育一些特征各异的断裂。盐构造运动受乌拉尔造山作用影响明显,强烈的盐构造活动主要发生在晚二叠世一三叠纪。  相似文献   

羌塘盆地基底地层及大地构造性质     

祁江豪  郭兴伟  温珍河  郑求根  冯岩  伊飞 《海洋地质前沿》2011,(9):52-59

根据不同学者在盆地基底地层中所得出的锆石同位素测年数据进行统计分析,结合前人对羌塘地区大地构造方面的研究成果得出:羌塘盆地中央隆起带出露的变质岩基底可能经历过泛非时期构造热事件的作用,羌塘块体在演化过程中受到了南部冈瓦纳大陆的影响,这对于了解本地区的大地构造背景以及对古特提斯缝合带的研究有所帮助.  相似文献   

The structural evolution of the Asinara Island (NW Sardinia,Italy)     

《Geodinamica Acta》2013,26(5):309-329

The metamorphic basement of the Asinara island represents a key area of the Sardinia Variscan segment, because it displays an almost complete cross-section through the inner part of the Sardinia Variscan belt, where different tectono-metamorphic complexes have been juxtaposed along narrow belts of high-strain concentration. Detailed field mapping coupled with preliminary studies on the structural and metamorphic features of this small island, allow to draw a better picture of the structural frame issued from the Variscan collision in the inner zone of the belt. Three deformation phases related to crustal thickening in a compressive and transpressive, partitioned tectonic regime, followed by a later phase of extensional deformation have been recognised. In spite of a general HT/LP metamorphic overprint, linked to the post-collisional deformation phases, a relic Barrovian zoneography is still detectable. The Barrovian assemblages are preto syn-kinematic with respect to the D2 deformation phase, and pre-date the third, contractional tectonic event.

The HT/LP assemblage indicates a static growth of weakly deformed by the last deformation events. The complex geometry of the fabric associated to the D2 and D3 deformation events suggests an heterogenous deformation history with a monoclinic geometry characterized by switching of the stretching lineation orientation and a contrasting sense of displacement, probably controlled by a northward partitioned pure shear.  相似文献