Magmatism, Deep Processes and Gold Deposits in Eastern Hebei, China

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沂沭断裂带及其近区的地震成因岩石新认识

将沂沭断裂带及其附近地区的地震成因岩石划分为四种类型,它们是具有地震成因构造的震积岩、震断层构造岩、震火山岩及隐爆地震角砾岩.前两类是构造地震的记录,而后两类是火山地震及隐爆火山地震的记录.由于震断层构造岩沿长期活动性断层分布,大多遭受了若干期强地震活动的改造,所以不易确定其最初的形成时期.因此,笔者重点对分布于沂沭断裂地震带及附近的其它三类地震成因岩石(包括震积岩、震火山岩和隐爆地震角砾岩)作了研究,论述了三类地震成因岩石的特征、时空分布、反映的地震作用机理及意义.认为:地震成因岩石不仅是强地震事件和激烈构造活动的记录;而且,因为由强地震形成的不同等级断层和裂隙构成了一个高渗透性的能够沟通不同深度石油和成矿流体的网络,所以深入研究地震成因岩石有助于完善大断裂地震带及近区的石油聚集与成矿理论.     

沂沭断裂带及其近区不同地质时期地震液化脉构造对比

在沂沭断裂带及其近区,已发现震旦纪石旺庄组、寒武纪馒头组、古近纪朱壁店组和沙河街组四个层位发育震积岩,它们均是具有地震液化脉构造和其它地震成因层内构造的震积岩层。通过对比与分析,确认不同地层层位的液化脉构造具有某些共同特征,这反映了不同层位的液化脉构造的成因具同一性。笔者认为将具有地震液化脉构造共同特征的前寒武纪“molar tooth构造”,称作“泥亮晶灰岩液化脉构造”为宜。     

沂沭断裂带中南段钾质火山岩的元素地球化学与Sr-Nd-Hf同位素组成及其对岩石成因的制约

本文以沂沭断裂带中南段莒南-大店一带的钾质火山岩为对象,系统研究了它们的岩石学、元素地球化学和Sr-Nd-Hf同位素组成特征,据此探讨了源区地幔富集机制及岩石成因。莒南钾质火山岩主要为一套安粗质火山-潜火山岩组合,大店多发育粗面质火山岩,二者的锆石LA-ICP-MS U-Pb年龄基本一致,均约为118Ma。在化学组成上,这套火山岩均偏碱性,里特曼指数(σ)介于4.10~5.07,且富钾(K_2O=4.21%~5.77%),在SiO_2-K_2O和K_2O-Na_2O关系图上,均投影在钾玄岩系区。安粗质和粗面质火山岩均富大离子亲石元素(Cs,Rb,Th,U,Pb)和轻稀土元素,贫高场强元素(Nb,Ta,P,Ti),但粗面质火山岩具较显著的Ba、Eu负异常,且轻重稀土比值较低。二类火山岩均具有富集且较均一的Sr-Nd同位素组成(I_(Sr)=0.7086~0.7091,ε_(Nd)(t)=-16.9~-18.2),锆石ε_(Hf)(t)值均为显著的负值(安粗质岩:-22.3~-24.3,粗面岩:-19.7~-23.6)。元素和同位素组成的综合分析表明,区内钾质火山岩的源区地幔极可能遭受了因扬子板块深俯冲和华北克拉通岩石圈拆沉等多次富集事件的影响。至早白垩世,随着郯庐断裂引张的加剧,诱发了软流圈地幔上涌,同时在断裂减压作用的影响下,促使了这一经叠次改造的富集地幔的部分熔融,由此产生的岩浆经进一步分异演化,导致了区内钾质火山岩的形成。     

晚中生代沂沭断裂带左旋韧性剪切与岩浆迁移规律

沂沭断裂带内部的岩浆侵入与断裂活动关系密切,开展沂沭断裂带内部岩浆年代学研究,对于沂沭断裂带构造背景研究具有积极的参考意义。选取沂沭断裂带内部的莒县浮来山正长岩体、边部的莒南官坊石英正长岩体及侵入该岩体的闪长玢岩脉,开展岩石学及年代学研究。首次发现晚中生代沂沭断裂带左旋韧性剪切,获得浮来山岩体的LA-ICP-MS锆石U-Pb年龄为(125.1±1.7) Ma,官坊岩体年龄为(125.6±2.0) Ma, 发生韧性变形的闪长玢岩脉年龄为(122.8±2.1) Ma。获得的125 Ma岩浆活动年龄与沂沭断裂带东侧的五莲变质核杂岩快速剥露(122~128 Ma)、诸城断陷盆地快速沉降的时间相吻合,该时期沂沭断裂带处于岩石圈减薄与破坏强烈的时期;闪长玢岩脉的122.8 Ma结晶年龄,与五莲变质核杂岩后构造岩体(石场、坊子岩体等)结晶年龄一致,该时期沂沭断裂带处于弱伸展状态,同时也说明胶东半岛岩石圈减薄具有时间上的一致性。晚中生代时期,沂沭断裂带两侧岩浆活动具有逆时针迁移的规律,这一规律可能与伊佐奈岐板块向欧亚板块俯冲的方向、角度、速度的变换有关。     

Metallogeny of Shoshonite-Hosted Copper-Gold Deposits in Middle-South Parts of Tancheng-Lujiang Deep Fault Zone and Its Vicinity,Eastern China

ＩＮＴＲＯＤＵＣＴＩＯＮＳｈｏｓｈｏｎｉｔｅｓａｒｅｐｏｔａｓｓｉｃｉｇｎｅｏｕｓｒｏｃｋｓｗｈｉｃｈｏｃｃｕｒｍａｉｎ－ｌｙｉｎｓｕｂｄｕｃｔｉｏｎ－ｒｅｌａｔｅｄｔｅｃｔｏｎｉｃｓｅｔｔｉｎｇｓ（Ｍｏｒｒｉｓｏｎ,１９８０）．Ｔｈｅｙａｒｅｃｏｍ...     

太平洋板块俯冲与中国东部中生代地质事件

中国东部至少自侏罗纪开始就一直处于俯冲大洋板块之上,但是有关俯冲板块对其影响程度一直有不同的认识。最近的研究表明,太平洋海山岛链的时空分布显示太平洋板块的漂移方向曾发生多次转折,这些转折与白垩纪中国东部的构造演化和岩浆事件有着密切的时空耦合关系。从时代和力学性质上看,太平洋板块俯冲方向的改变在很大程度上控制着中国东部中生代的盆地演化和郯庐断裂活动等重要地质事件。这些认识为理解中国东部构造演化提供了新的视角,包括岩石圈减薄的机制、郯庐断裂的演化,以及燕山期大规模岩浆活动等。本文重点分析了太平洋板块俯冲与中国东部中生代岩浆活动的对应关系。在125～140Ma太平洋板块向南西方向俯冲,造成中国东部岩石圈减薄,软流圈卸载上涌,发生减压部分熔融;约125Ma,太平洋板块漂移方向发生了大幅度转折,形成安第斯式的俯冲挤压,岩石圈停止减薄和减压部分熔融,出现岩浆宁静期。随着俯冲的深入,到110Ma前后俯冲板块后撤,形成弧后拉张,岩浆活动又重新开始。     

中国东部燕山期岩浆活动的几个问题

中国东部中酸性燕山期岩浆活动非常发育。文中讨论了中国东部燕山期岩浆岩的分区、岩浆系列、埃达克质岩（adakite-like）、花岗岩源区、花岗岩形成环境、I型和S型花岗岩的含义等问题。认为目前使用的花岗岩判别图不能用来讨论花岗岩形成的构造环境，按照花岗岩源区深度，至少可以分出来自地幔下地壳和中上地壳的3个深度层次的花岗岩类，强调源区深度对花岗岩性质的制约。认为中国东部燕山期大规模岩浆活动可能与地壳拉张环境下大规模拆沉作用导致的软流圈地幔上涌及其引发的玄武岩底侵作用有关，而与古太平洋板块的俯冲作用无关，中国东部不属于环太平洋构造－岩浆带。但拆沉作用发生的时间、原因和机制仍然不清楚。     

长乐-南澳断裂带晚中生代岩浆活动 与变质-变形关系

长乐-南澳断裂带是东南沿海地区陆内强烈变质-变形带。带内沉积岩、火山岩和早白垩世的钙碱性角闪石黑云花岗岩和花岗闪长岩都已发生可达角闪岩相的变质和石英-长石相韧性剪切变形。鉴于高温矿物和强烈韧性变形多出现在深成岩附近;远离深成岩,变质和变形就逐渐减弱,故本文认为,至少有一部分变质变形的热源是由岩浆提供的。韧剪组构和糜棱质花岗岩是在岩浆侵位的晚期或长乐-南澳断裂带左旋走滑时,在中地壳部位同时形成的,长乐断裂带中花岗岩的组构记录了一期同走滑变形的岩浆作用,“软变形”作用。据此,长乐-南澳带内花岗岩的形成是受走滑剪切应力和岩浆热双重制约的,是在走滑过程中实现的。其动力来源可能与晚中生代的太平洋板块沿日本中央构造线—台湾纵谷带朝东亚陆缘的斜向俯冲有关。     

中国东南部晚中生代岩浆作用的深部条件制约

通过对中国东南部区域地质条件的分析和地球物理资料的研究,获得了如下认识：1．区域构造作用和基底物质成分影响并制约着晚中生代岩浆活动,岩浆岩的分区性具有很好的地表与深部一致性;2．按岩浆岩类型可分为三区,即沿海钙碱性中酸性火山－侵入杂岩区、武夷山弱过铝花岗质火山－侵入杂岩区和赣江以西强过铝花岗岩区,三者之间分别被政和－大埔断裂与赣江断裂所分隔;3．在沿海地区,存在局部高导层,推测与拉开裂解有关。玄武岩浆底侵和碱性花岗岩形成与晚白垩世拉张作用关系密切;4．政和－大埔、赣江和长乐－南澳三大断裂是重力梯度带或梯度宿突变带,且深部地球物理存在明显差异,可能是壳幔作用剧烈的场所;5．存在中地壳低速带,厚2－4km,为地壳部分熔融或韧性变形产物,推测是部分晚中生代花岗岩浆的策源地;6．支持中国东南部晚中生代岩浆作用的板块俯冲＋陆内玄武岩浆底侵的成因模式,日本中央构造线－台湾纵谷带是中生代太平洋板块朝东亚陆缘消减的俯冲带和缝合带。     

Tectonic Taphrogenesis and Paleoseismic Records from the Yishu Fault Zone in the Initial Stage of the Caledonian Movement

The Yishu fault zone (mid-segment of the Tanlu fault zone) was formed in the Presinian. Periodic tectonic activities and strong seismic events have occurred along the fault zone. During the initial stage of the Caledonian Movement, with the proceeding of the marine transgression from the Yishu paleo-channel to the western Shandong, uneven thick sediments, composed mainly of sand, mud and carbonates of littoral, lagoon, and neritic facies, were deposited in the Yishu fault zone and western Shandong, and constructed the bottom part of the Lower Cambrian consisting of the Liguan and Zhushadong formations. Through field observations and the lab-examinations, various paleoseismic records have been discovered in the Liguan Formation and the Zhushadong Formations of the Yishu fault zone and its vicinity, including some layers with syn-sedimentary deformation structures that were triggered by strong earthquakes (i.e. seismite, seismo-olistostrome, and seismo-turbidite). Paleoseismic records developed in the Zhushadong Formation are mainly seismites with soft-sediment deformation structures, such as liquefied diapir, small liquefied-carbonate lime-mud volcano, liquefied vein, liquefied breccia, convolute deformation (seismic fold), graded fault, soft siliceous vein, and deformation stromatolite, as well as seismites with brittle deformation structures of semiconsolidated sediments. Paleoseismic records preserved in the Liguan Formation are not only seismo-olistostrome with a slump fold, load structure, and ball-and-pillows, but also seismo-turbidite with convolution bedding, graded bedding and wavy-bedding. However, in the western Shandong area, the closer to the Yishu fault zone, the greater the thickness of the Liguan Formation and the Zhushadong Formation, the greater the number and type of layers with paleoseismic records, and the higher the earthquake intensity reflected by associations of seismic records. This evidence indicates that tectonic taphrogenesis accompanied by strong earthquake events occurred in the Yishu fault zone during the initial stage of the Caledonian Movement, which embodied the break-up of the Sino-Korean Plate along the Paleo-Tanlu fault zone at that time.     

Granitic Magmatism in Eastern Tethys Domain (Western China) and their Geodynamic Implications

Western China locates in the eastern section of the Tethys domain, granitic rocks in this region with variable formation ages and geochemistry record key information about the crust-mantle structure and thermal evolution during the convergent process of Tethys. In this study, we focus on some crucial granitic magmatism in the western Yangtze, Qinling orogen, and western Sanjiang tectonic belt, where magma sequence in the convergent orogenic belt can provide important information about the crust-mantle structure, thermal condition and melting regime that related to the evolution processes from Pre- to Neo-Tethys. At first, we show some features of Pre-Tethyan magmatism, such as Neoproterozoic magmatism (ca. 870–740 Ma) in the western margin of the Yangtze Block were induced by the assembly and breakup of the Rodinia supercontinent. The complication of voluminous Neoproterozoic igneous rocks indicated that the western Yangtze Block underwent the thermodynamic evolution from hot mantle-cold crust stage (ca. 870–850 Ma) to hot mantle and crust stage (ca. 850–740 Ma). The Neoproterozoic mantle sources beneath the western Yangtze Block were progressively metasomatized by subduction-related compositions from slab fluids (initial at ca. 870 Ma), sediment melts (initial at ca. 850 Ma), to oceanic slab melts (initial at ca. 825–820 Ma) during the persistent subduction process. Secondly, the early Paleozoic magmatism can be well related to three distinctive stages (variable interaction of mantle-crust to crustal melting to variable sources) from an Andeans-type continental margin to collision to extension in response to the evolution of Proto-Tethys and final assembly of Gondwana continent. Thirdly, the Paleo-Tethys magmatism, Triassic granites in the Qinling orogenic display identical formation ages and Lu-Hf isotopic compositions with the related mafic enclaves, indicate a coeval melting event of lower continental crust and mantle lithosphere in the Triassic convergent process and a continued hot mantle and crust thermal condition through the interaction of subducted continental crust and upwelling asthenosphere. Finally, the Meso- and Neo-Tethyan magmatism: Early Cretaceous magmatism in the Tengchong Block are well responding to the subduction and closure of Bangong-Nujiang Meso-Tethys, recycled sediments metasomatized mantle by subduction since 130 Ma and subsequently upwelling asthenosphere since ca. 122 Ma that causes melting of heterogeneous continental crust until the final convergence, this process well recorded the changing thermal condition from hot mantle-cold crust to hot mantle and crust; The Late Cretaceous to Early Cenozoic magmatism well recorded the processes from Neo-Tethyan ocean slab flat subduction, steep subduction, to initial collision of India-Asia, it resulted in a series of continental arc magmatism with enriched mantle to crustal materials at Late Cretaceous, increasing depleted and/or juvenile materials at the beginning of early Cenozoic, and increasing evolved crustal materials in the final stage, implying a continued hot mantle and crust condition during that time. Then we can better understand the magmatic processes and variable melting from the mantle to crust during the evolution of Tethys, from Pre-, Paleo-, Meso-, to Neo-, both they show notably intensive interaction of crust-mantle and extensive melting of the heterogeneous continent during the final closure of Tethys and convergence of blocks, and thermal perturbation by a dynamic process in the depth could be the first mechanism to control the thermal condition of mantle and crust and associated composition of magmatism.     

Late Cretaceous Transpressional Fault System: A Case Study of the Yishu Fault Belt, Shandong Province, Eastern China

On the basis of field observations of the structures of three profiles from the Linshu region, deformation characteristics and the tectonic background of the Yishu fault belt in the Late Cretaceous–Early Cenozoic have been discussed in detail.Three structural profiles, whose deformations consist mainly of earlier transpressional faults and later normal faults, were developed for the Mengtuan Formation of the Lower Cretaceous Dasheng Group.Typical positive flower structures, duplex structures, and break-through faults were found in these profiles.On the basis of analyses of the structural deformation and previous geochronological studies, it was concluded that the earlier transpressional faults of the profiles were triggered by the sinistral transpression of the Yishu fault belt in the Late Cretaceous–Early Paleogene, and that the later normal faults, formed during the Late Paleogene–Neogene extension, truncated the earlier transpressional faults.With consideration of the tectonic evolution of the Tan-Lu fault belt and the different drift directions of the Pacific plate since the Cretaceous, we suggest that the major tectonic events of the Late Cretaceous–Neogene in eastern China were mainly controlled by the subduction of the Pacific plate.     

华北东部中生代构造格局转换过程中的深部作用与浅部响应

华北晚中生代构造岩浆岩带作为一个新的构造格局,以其鲜明的ＮＮＥ走向跨在古域不同的构造单元之上。在华北东部清楚地保留了标志早中生代格局转换过程的各种信息。本文所列举的晚三叠世超镁铁－－镁铁质和碱性侵入岩、堆晶岩、麻粒岩就是下地壳底部壳幔相互作用的产物;早－－中侏罗世的辉绿岩岩墙群、玄武岩粗岩系列的火山岩是中、上部地壳岩浆的表现,与此同时的受裂陷槽控制的含煤类磨拉石及火山磨拉石建造则是表的响应。由沉积     

Carboniferous Highly Fractionated I‐type Granites from the Kalamaili Fault Zone,Eastern Xinjiang,NW China: Petrogenesis and Tectonic Implications

Carboniferous magmatism is one of the most important tectonothermal events in the Central Asian Orogenic Belt(CAOB). However, the final closure time of the Kalamaili Ocean between East Junggar and Harlik Mountain is still debated. Early Carboniferous(332 Ma) and late Carboniferous(307–298 Ma) granitic magmatism from Kalamaili fault zone have been recognized by LA-ICP-MS zircon U-Pb dating. They are both metaluminous highly fractionated I-type and belong to the high-K calc-alkaline. The granitoids for early Carboniferous have zircon ε_(Hf)(t) values of-5.1 to +8.5 with Hf model ages(T_(DM2)) of 1.78–0.83 Ga, suggesting a mixed magma source of juvenile material with old continental crust. Furthermore, those for late Carboniferous have much younger heterogeneous zircon ε_(Hf)(t) values(+5.1 to +13.6) with Hf model ages(T_(DM2)=1.03–0.45 Ga) that are also indicative of juvenile components with a small involvement of old continental crust. Based on whole-rock geochemical and zircon isotopic features, these high-K granitoids were derived from melting of heterogeneous crustal sources or through mixing of old continental crust with juvenile components and minor AFC(assimilation and fractional crystallization). The juvenile components probably originated from underplated basaltic magmas in response to asthenospheric upwelling. These Carboniferous highly fractionated granites in the Kalamaili fault zone were probably emplaced in a post-collisional extensional setting and suggested vertical continental crustal growth in the southern CAOB, which is the same or like most granitoids in CAOB. This study provides new evidence for determining the post-accretionary evolution of the southern CAOB. In combination with data from other granitoids in these two terranes, the Early Carboniferous Heiguniangshan pluton represents the initial record of post-collisional environment, suggesting that the final collision between the East Junggar and Harlik Mountain might have occurred before 332 Ma.     

南雄断裂带岩石地球化学特征及其与铀成矿的关系

粤北南雄陆相红色盆地及其紧邻的诸广山花岗岩区,是中国重要的花岗岩型铀成矿带。研究表明,南雄断裂带属于伸展体系下的低角度剥离断层,为浅层次的热隆伸展构造,断裂带上部为脆性变形层,下部为韧性变形层,既是导矿构造。又是储矿构造。钻孔岩心揭露表明,断裂带岩石包括构造角砾岩、碎裂岩和糜棱岩。岩石具有显著的碱交代蚀变特征,部分糜棱岩后期遭受构造作用产生破碎,且有基性岩脉穿插。样品地球化学特征分析表明,碱交代和糜棱岩化程度与铀元素的富集有对应关系。这一规律性说明岩石的碱交代和糜棱岩化对铀富集的空间分布有重要作用。     

山东龙泉站金矿区稳定同位素特征及其地质意义

山东龙泉站金矿区的金矿产于沂水-汤头断裂主裂面下盘的糜棱岩化碎裂岩和花岗质碎裂岩中。对区内典型金矿床硫、氢、氧、碳和铅等稳定同位素的研究资料表明:黄铁矿的δ34S值的变化为 2.7‰- 4.4‰,δ18OH2O值为-1.78‰- 4.07‰,δD(SMOW)值为-74‰--77‰,δ13C平均值为-4.18‰--5.1‰,铅同位素具有正常铅的特点,说明区内金矿的成矿物质来源于地下深处,成矿流体以岩浆水为主,大气降水为辅。     

从水系的分布形态探讨沂沭断裂带的运动特征

郯城-庐江断裂带是纵贯中国大陆东部,长达2 000 km以上的大断裂带。该研究利用DEM数据和ETM,以及谷歌卫星影像来分析郯城-庐江断裂带中段的沂沭断裂带周边的水系的几何分布形态特征。三维卫星图像解译和野外调查的结果显示：(1)沿断裂带周边发育的水系的几何分布形态主要受由F1-F4 4条主要断层所组成的沂沭断裂带构造所制约;(2)沿断裂带发育的水系不具有典型的走滑断层的系统化的同步转折和位错的变形特征;(3)沂沭断裂带东侧的F1和F2断裂是现今的活动断裂,而F3和F4断裂在第四纪基本没有明显的活动迹象;(4)F1和F2断裂以垂向运动为主,具有高角度的逆断层或正断层的运动特征。该研究结果显示沿断裂发育的水系地貌和几何分布特征可作为评价断裂的活动性和运动特征的地貌标志。     

东昆仑祁漫塔格地区构造岩浆作用与成矿关系初步探讨

以钾、钠含量变化为主要指标获取祁漫塔格地区各个地史时期花岗岩类的成因类型.结果表明,区内构造岩浆作用在时间上具有明显的阶段性,加里东中晚期是本区第一次侵入岩浆作用的高峰期,印支中晚期为本区花岗岩浆作用的鼎盛时期,加里东中晚期和印支中晚期也是区内两次区域成矿作用的大爆发期.岩体分布具有明显的方向性.主要由北东向和北西向两...