陕西凤太晚古生代拉分盆地动力学与金-多金属成矿   总被引：3，自引：0，他引：3  

方维萱  黄转盈 《沉积学报》2012,30(3):405-421

采用沉积盆地构造-古地理位置恢复重建和构造-岩相学等新方法研究认为,凤太晚古生代沉积盆地属于受板块斜向俯冲碰撞动力学控制下的拉分盆地。在中泥盆世初期,凤太沉积盆地被周缘垂向基底隆起分隔,其成盆构造动力学主要受四组同生断层,晚古生代沉降中心和沉积中心不断发生迁移。中泥盆世中期在盆地北部形成了北西向沉降中心和沉积中心,晚泥盆世末期沉积盆地萎缩,沉降中心和沉积中心收缩于沉积盆地中心。石炭纪沉降中心和沉积中心从盆地中心迁移到盆地四周边缘的同生断裂带附近,在沉积盆地北侧边缘商丹带南侧,形成了石炭纪-早三叠世与俯冲消减带有关的楔状沉积充填体。在凤太拉分盆地中形成的近东西向、北北东向、近南北向和北西向网状同生断裂带系统共同控制了凤太泥盆纪拉分盆地形成与演化过程。其中,商丹带（西段）、礼县-凤县-凤镇-山阳同生断裂带（中段）和酒奠梁-镇安-板岩镇同生断裂带（西段）三个主控同生断裂带不但在泥盆纪期间对于凤太泥盆纪拉分盆地形成具有显著控制作用,而且石炭纪-早三叠世拉分盆地演化过程也具有十分重要的控制作用,石炭纪-早三叠世同生断裂带发生构造反转并控制了沉降中心和沉积中心。采用沉积盆地动力学和构造-岩相学等新方法研究认为,在凤太晚古生代拉分盆地具有分级特征,西部凤县二级盆地为金-多金属成矿集中区,东部太白二级盆地为金矿成矿集中区。在八方山-银母寺三级拉分盆地中,八方山和银母寺等多金属矿床与八卦庙超大型金矿床具有矿田尺度上成矿分带,主要由于三级盆地、同生断裂、热水沉积岩相和构造热流体叠加岩相控制了矿田和矿床尺度上金与多金属成矿分带。凤太拉分盆地北部和东部金矿矿源层和初步富集成矿形成主要与泥盆纪钠长岩相和钠质热水沉积岩相有关,并受钠长碳酸质角砾岩-铁白云石钠长石角砾岩等石炭纪构造-热流体岩相叠加;凤太拉分盆地南部温江寺三叠系浊积岩系中热水硅质岩相和层状英安质凝灰岩是卡林型金矿重要赋矿层位;凤太拉分盆地中部热水沉积-改造型铅锌矿主要与硅质岩相和菱铁矿铁白云岩相等热水沉积相密切有关。  相似文献   

郯庐断裂带北段构造样式解析   总被引：9，自引：0，他引：9  

王书琴  孙晓猛  杜继宇  王英德  许强伟  田景雄 《地质论评》2012,58(3):414-425

郯庐断裂带(郯城—庐江断裂带)北段在中—新生代发生多期不同性质活动,形成各具特色的构造样式.各种构造样式和地层间切割或覆盖关系的匹配研究,为限定断裂带活动期次及时代,建立郯庐断裂带北段变形序列提供了第一手资料.不同构造样式反映了断裂带由老至新经历了以下5个重要的变形事件:①密山县知—镇韧性剪切带黑云母40 Ar/39 ...  相似文献   

Evolution Features of Depositional and Tectonic Setting from Late Paleozoic to Meso-Cenozoic in the Yong' an Basin     

ZU Fuping  SHU Liangshu  LI Cheng 《地质论评》2012,58(1)

永安盆地发育在前泥盆纪基底之上,位于华夏块体南缘,沿NE向政和—大埔断裂带展布.利用层序地层学方法,辅之以野外调查,研究了永安盆地的地层序列和岩石组合:①对晚古生代至早三叠世地层格架及柱状剖面的分析表明,伴随海平面的升降,海相沉积序列具有阶段性,不同沉积相在盆地东、中、西区段分布不均,盆地沉积沉降中心大致位于龙岩和梅县地区;②对横贯盆区的地质剖面及盆内辅助剖面的研究表明,中—新生代,盆内以断块作用为主,改造了晚古生代地层,代之以断褶复合地层;③有机碳质层为盆地的海陆变迁作了时域界定,并且其赋存部位和形态也在空间上表征了盆地构造演化的力学机制.通过分析构造事件、古地理及物源区、深部构造、边界构造等盆地要素,研究了盆地的沉积构造环境演化及其应力机制,结果表明:①晚古生代,海进海退的快慢受控于不同时期构造事件的强弱变化,由此产生的沿岸隆起区的剥蚀以及拉张背景的山体风化剥蚀为盆地提供了物源,存在北、南两个物源区;中—新生代,盆地总体为火山活动背景下的山前及河湖相沉积环境.②盆地具有隆起—伸展构造发育的特点,主要经历了华力西期海陆交互相巨厚沉积阶段,印支期稳定的台地向活动大陆边缘转变阶段并伴随挤压隆升,以及印支期后中—新生代由挤压向拉张机制转换的构造改造阶段.以上认识为中国东南部盆地的薄弱基础研究提供了新的基础参考信息.  相似文献   

永安盆地晚古生代—中—新生代沉积构造环境演化特征     

祖辅平  舒良树  李成 《地质论评》2012,58(1):126-148

永安盆地发育在前泥盆纪基底之上,位于华夏块体南缘,沿NE向政和—大埔断裂带展布。利用层序地层学方法,辅之以野外调查,研究了永安盆地的地层序列和岩石组合：① 对晚古生代至早三叠世地层格架及柱状剖面的分析表明,伴随海平面的升降,海相沉积序列具有阶段性,不同沉积相在盆地东、中、西区段分布不均,盆地沉积沉降中心大致位于龙岩和梅县地区;② 对横贯盆区的地质剖面及盆内辅助剖面的研究表明,中—新生代,盆内以断块作用为主,改造了晚古生代地层,代之以断褶复合地层;③ 有机碳质层为盆地的海陆变迁作了时域界定,并且其赋存部位和形态也在空间上表征了盆地构造演化的力学机制。通过分析构造事件、古地理及物源区、深部构造、边界构造等盆地要素,研究了盆地的沉积构造环境演化及其应力机制,结果表明：① 晚古生代,海进海退的快慢受控于不同时期构造事件的强弱变化,由此产生的沿岸隆起区的剥蚀以及拉张背景的山体风化剥蚀为盆地提供了物源,存在北、南两个物源区;中—新生代,盆地总体为火山活动背景下的山前及河湖相沉积环境。② 盆地具有隆起—伸展构造发育的特点,主要经历了华力西期海陆交互相巨厚沉积阶段,印支期稳定的台地向活动大陆边缘转变阶段并伴随挤压隆升,以及印支期后中—新生代由挤压向拉张机制转换的构造改造阶段。以上认识为中国东南部盆地的薄弱基础研究提供了新的基础参考信息。  相似文献   

西藏冈底斯带东段石炭纪构造环境讨论   总被引：3，自引：0，他引：3  

冉明佳  钟康惠  罗明非  刘肇昌 《地质论评》2012,58(2):250-258

冈底斯带东段石炭纪构造环境存有争议。本文通过岩石地球化学分析,发现石炭纪诺错组和来姑组火山岩具有碱性系列向拉斑系列过渡的特征,具有双峰火山岩特点;石炭纪玄武岩样品的平均化学成分与大陆拉斑玄武岩的平均值较为接近;微量元素除Ti、Yb、Y之外,其他元素都富集,其中Rb、Th、Ce富集程度相对较高;稀土元素特征表现为轻稀土富集,铕、铈异常不明显。显示出石炭纪玄武岩的地球化学特征均与大陆拉斑玄武岩相似。构造环境判别图解显示,石炭纪玄武岩样品主要落入板内环境的大陆拉张带(或初始裂谷)玄武岩区。因而认为冈底斯东段在石炭纪属于陆内裂谷或被动陆缘裂谷环境。  相似文献   

Review Section     

《International Geology Review》2012,54(6):737-755

ABSTRACT

The petrology, geochronology, and geochemistry of the early Permian volcanic rocks from Houtoumiao area, south Xiwuqi County in central Inner Mongolia of China, are studied to elucidate the early Permian tectonic setting of the region. The volcanic rocks, which are interbedded with sandstone, feature both mafic and felsic compositions and show a bimodal nature. Zircon U–Pb dating reveals that the volcanic rocks formed at 274–278 Ma, similar to the ages of bimodal magmatism in neighbouring areas. The mafic rocks are composed of tholeiitic basalt, basaltic andesite, basaltic trachyandesite, and trachyandesite. They are rich in Th, U, and LILEs, depleted in HFSEs Nb, Ta, and Ti, and have positive ε_Nd(t) values (+3.6 to +7.9). Geochemical analyses indicate that the mafic rocks originated from metasomatized lithospheric mantle. The felsic volcanic rocks are mainly rhyolite, with minor trachyte and dacite. They have different evolutionary tendencies of major elements, chondrite-normalized REE patterns, and isotopic compositions from the mafic volcanic rocks, which preclude formation by fractional crystallization of mafic melts. The ε_Nd(t) values of the felsic rocks are similar to those of the Carboniferous Baolidao arc rocks in the region. It is suggested that Permian felsic melts originated from the partial melting of Carboniferous juvenile arc-related rocks. By comparison with typical Cenozoic bimodal volcanism associated with several tectonic settings, including rift, post-collisional setting, back-arc basin, and the Basin and Range, USA, the bimodal volcanic rocks in central Inner Mongolia display similar petrological and geochemical characteristics to the rocks from back-arc basin and the Basin and Range, USA. Based on the analysis of regional geological data, it is inferred that the early Permian bimodal volcanic rocks in the study area formed on an extensional continental margin of the Siberian palaeoplate after late Carboniferous subduction–accretion.  相似文献   

Zircon U–Pb ages and Hf isotopic compositions of two types of supracrustal rocks in the Northeastern Sulu UHP terrane: constraints on the surface boundary between South China and North China     

《International Geology Review》2012,54(5):539-561

ABSTRACT

There are voluminous ultrahigh pressure-related orthogneisses and minor metamorphic supracrustal rocks in the northeastern Sulu UHP terrane (NSL), East China. The tectonic affinities of the supracrustal rocks are crucial for unravelling the deep continental subduction processes and locating the tectonic suture between the South China (SCB) and North China (NCB) blocks. In this contribution, we report new zircon U–Pb ages and Hf isotope data for the supracrustal rocks and metagabbros in the Zeku region of the NSL. In the Zeku region, the supracrustal rocks are spatially associated with granitic gneisses, metagabbros, and eclogites. Detrital zircon U–Pb analyses yield ages between 3.39 and 0.65 Ga that cluster as three major age populations including (1) 2.15–1.68 Ga with two subpeaks at ~1.83 Ga and~1.97 Ga, (2) 2.45–2.15 Ga with a peak at ~2.37 Ga, and (3) 0.79–0.65 Ga. In addition, there is a small age population between 3.39 and 2.61 Ga. The youngest age population of 0.79–0.65 Ga indicates that the Zeku supracrustal rocks must have been deposited after 650 Ma rather than during the Palaeoproterozoic as previously thought. The 210–190 Ma metamorphic ages suggest that the Zeku rocks were affected by Triassic collision–subduction and exhumation. Most of the Archaean-Palaeoproterozoic zircons have negative ε_Hf(t) values and two-stage Hf model ages concentrating at 2.4–3.4 Ga (peak at ~2.9 Ga), indicating that source rocks of these zircons were mainly derived from recycling of ancient crustal material. These ages, together with the Hf isotopic compositions and rock assemblages, indicate that the Zeku supracrustal rocks were mainly derived from the Precambrian basement rocks of the northern Yangzte Block and have a tectonic affinity to the SCB, rather than the NCB. Our results, together with previously published data, suggest that there are two types of supracrustal rocks with different zircon U–Pb ages and tectonic affinities in the NSL. On the basis of new data, we suggest that the surface boundary between the SCB and NCB in the Jiaodong Peninsula is a complicated tectonic mélange zone rather than a single fault.  相似文献   

The tectono-magmatic evolution of the West Junggar terrane (NW China) unravelled by U–Pb ages of detrital zircons in modern river sands     

《International Geology Review》2012,54(5):607-621

ABSTRACT

The West Junggar terrane (WJT) is an outstanding laboratory for studying the tectonic evolution of the Junggar–Balkhash Ocean, because it contains widespread Paleozoic magmatism in different tectonic settings. We attempt to reconstruct the tectono-magmatic evolution of WJT through U–pb analysis of detrital zircons from three modern river sand samples from the Harabura, Baibuxie, and Aletengyemule rivers in the Barleik Mountains of the central WJT. A total of 232 concordant spots show Th/U ratios of 0.14–1.69, typical of igneous origin, and they contain abundant Paleozoic (96%) and few Precambrian (4%) ages, with major age populations at 450–530, 400–430, 320–380, and 265–320 Ma. The first two groups may be derived from the early subduction- and accretion-related magmatic rocks of the WJT, whereas the third group is congruent with magmatic activities related to the final subduction and basin-filling processes within a framework of the remnant Junggar–Balkhash Ocean. By combining with the regional data, the last group of magmatic events is referred to as post-subduction magmatism. The missing Mesozoic–Cenozoic magmatism clearly indicates a pre-Permian closure for the Junggar–Balkhash Ocean, nearly coeval with the closure of other oceans in the southwestern Palaeo-Asian Ocean.  相似文献   

中国西部叠合盆地油气藏形成、演化与分布预测     

庞雄奇  周新源  姜振学  王招明  李素梅  田军  向才富  杨海军  陈冬霞  杨文静  庞宏 《地质学报》2012,86(1):1-103

中国西部叠合盆地经历了多期构造变动和多旋回的油气成藏作用,研究叠合盆地油气藏的形成、演化和分布预测具有重要的意义。叠合盆地指不同时期形成的不同类型的沉积盆地或地层在同一地理位置上的叠加和复合,具有地层沉积不连续、地层构造不连续、地层应力应变作用不连续等三大标志性特征,依据构造剖面上地层年代的关联性,将叠合盆地分为五种类型,即连续沉积型叠合盆地、中晚期地层叠合盆地、早晚期地层叠合盆地、早中期地层叠合盆地、长期暴露型叠合盆地。叠合盆地普遍发育复杂油气藏,三种作用（剥蚀作用、断裂作用、褶皱作用）六种机制（渗漏、扩散、溢散、氧化、降解和裂解）形成复杂油气藏,依据成因特征分为五类,原成型油气藏,圈闭调整型油气藏,组分变异型油气藏,相态转换型油气藏,规模改造型油气藏。研究表明,复杂油气藏中天然气的地下产状特征和分布特征与地表产状特征和分布特征有很大差异。中国西部叠合盆地油气分布主要受烃源灶、古隆起、沉积相、断裂带、构造变动和区域盖层等六大因素的控制。其中烃源灶（S）、古隆起（M）、沉积相（D）和盖层（C）等四大要素控制着油气成藏的形成和分布,并建立了多要素匹配（T-CDMS）成藏模式,用以预测有利成藏领域。油气藏形成之后,多期的构造变动对早成的油气藏进行调整、改造和破坏,主要受构造变动强度、构造变动时间、构造变动次数、构造变动时盖层的封油气性能等四大要素控制,并以此建立了多期构造变动破坏油气藏后剩余潜力评价模型,利用这一模型可以预测出有利勘探区带并评价出有利勘探区带中的剩余资源潜力。油气藏经过改造,表现出晚期成藏效应,并受相势耦合作用的控制最后定位,利用晚期成藏效应和相势耦合理论可以预测有利勘探目标,并指出潜在有利勘探目标。  相似文献   

中国古亚洲域沉积盆地火山岩油气藏储层特征比较及其差异分析   总被引：2，自引：0，他引：2  

杨明慧  兰朝利 《地质学报》2012,86(8):1198-1209

在中国古亚洲域沉积盆地火山岩储层母岩年代和岩性、储集空间类型以及火山岩岩相综合分析的基础上,探讨了火山岩油气藏的储层特征及其差异性。研究表明,中国古亚洲域火山岩储层的母岩发育年代西早东晚,西部的准噶尔、三塘湖和吐哈盆地发育晚古生代海相、海陆交互相的中基性安山岩、玄武岩及火山碎屑岩;东部的松辽、二连和海拉尔盆地发育中生代陆相中酸性流纹岩、安山岩。火山岩原生储集空间包括气孔、孔洞以及冷凝收缩裂缝等;次生储集空间包括各种溶蚀孔及构造裂缝、风化裂缝等。火山岩岩相可分喷出相、火山通道相、次火山相和火山沉积相。其中中基性岩类多以溢流相开始,相序类型为溢流相、爆发相/火山沉积相;中酸性岩类多以爆发相或火山通道相发端,主要相序为爆发相、溢流相/侵出相。溢流相一般发育原生气孔、构造缝;爆发相多为粒间孔,而侵出相以角砾间孔和原生裂缝为主。火山岩储层的差异受多因素影响,包括岩性岩相、喷发环境以及后期构造、成岩作用等。前者奠定火山岩储层形成与分布的基础和储集空间的发育程度;后者则改造储层的储渗性能。  相似文献