碰撞造山过程中热-构造状态演化与陆壳岩石熔融的关系

碰撞造山作用过程中陆壳岩石馆融形成花岗岩浆主要出现在加热期和伸展抬升期，是碰任后岩石田热状态调整引起陆壳物质化学分界的结果。陆壳碰撞前的构造历史、大陆岩石国的热参数和地幔过程、造山带的几何学特征和运动学性质等制约了造山带花岗岩类的发育，尤其是与各种造成地慢高热流叠加于下部地壳的岩石圈调整过程关系密切。大别造山带中生代花岗岩类的形成可能就是华北、扬子陆块碰撞后，底侵和垂向分离过程作用于造山带伸展抬升期，引起下部地壳岩石相继发生两次馆融的结果。     

中国东南大陆中、新生代岩浆作用与壳幔演化动力学

本文论述了中国东南大陆中、新生代岩浆作用的多旋回性和迁移性，构造演化与岩石系列和岩石组合的关系。前寒武纪岩石圈制约本区中、新生代岩浆作用和成矿作用，并在三种岩石围岩石学一地球物理综合模型中反映。总结了四个主要构造期岩浆作用源区特征和构造背景，并根据不同大地构造单元在碰撞造山后近南北向刊近北东向伸展裂解，从造山带挤压碰撞向伸展裂解机制转换过程探讨了中、新生代岩浆作用和壳幔演化动力学。     

喀喇昆仑-昆仑山脉北侧的深部构造

本文就和田地震台所接受的5张深源远震体波观测图波形的理论计算拟合讨论塔里木盆地的西南边缘、昆仑山脉北麓的深部地壳结构,在30km以下存在一高速夹层,地壳厚度约53km左右,由于透射地震射线来自不同方向,显示了速度结构的小差异,表明存在横向的变化。     

The geological setting of lode-gold deposits in the central southern Urals: a review

The late-Paleozoic Uralides represent one of the largest lode-gold metallogenic provinces in the world. In the southern Urals, gold distribution is heterogeneous and is confined mainly to two tectonostratigraphic zones, namely the Main Uralian fault and the East Uralian zone. The important lode-gold districts within and in the immediate hangingwall of the first-order crustal suture of the Main Uralian fault are characterized by a complex tectonic history of earlier compressional tectonics involving thrusting, folding and reverse faulting and later transcurrent shearing. Gold mineralization is hosted by second- and third-order brittle to brittle–ductile strike-slip faults that developed late during the kinematic history of the Main Uralian fault. Strike-slip reactivation of earlier compressional structures was related to the late-stage docking of the passive margin of the East European platform with island-arc complexes of the southern Urals, an event that is tentatively related to changes in plate motion during the final stages of terrane accretion during the upper Permian and lower Triassic. Gold mineralization was controlled by the permeability characteristics of the hydrothermal conduits, as well as by competence contrasts and geochemistry of the mainly volcanic host rocks. Mineralization occurred at relatively shallow crustal levels (2–6 km) and largely post dates peak-metamorphism of the host rocks. The large and very large (up to 300 to Au) gold deposits of the East Uralian zone are hosted by upper-Paleozoic granitoid massifs. Gold mineralization is temporally associated with the main phase of regional-scale compressional tectonics and granite plutonism during the upper Carboniferous and lower Permian. Controlling structures have a dominantly east–west strike and occur as hybrid shear-tensional vein systems in competent granitoids subjected to east/west-directed regional shortening. Deformation textures and alteration mineral assemblages indicate lower-amphibolite-facies conditions of mineralization close to peak metamorphic conditions that are associated with the mid-Permian regional metamorphism and tectonism. Gold deposits in the southern Urals are, therefore, polygenetic and are temporally and genetically distinct in each of the two major mineralized tectonostratigraphic zones of this well-preserved collisional orogenic belt. The different timing of ore fluid generation and fluid discharge is interpreted to be the result of the different tectonic, metamorphic and magmatic evolution of terranes in the southern Urals.     

A 2.5-D interpretation of the Basque country magnetic anomaly (northern Spain): geodynamical implications

The Basque country magnetic anomaly follows a NW-SE trend over the Basque country (northern Spain) with intensities up to 250 nT measured at 3000 m above sea level. The paired negative part of the anomaly is located to the north and presents intensities down to −60 nT. A model of the magnetic properties of the crust in the area, taking into account previous geological and geophysical data, indicates a wedge of material with a magnetic susceptibility of 0.07 SI emplaced along a NE-directed basal thrust. The anomalous wedge is composed of basic and/or ultrabasic Cretaceous intrusives and lower crustal rocks, and reaches a minimum depth which increases towards the northwest from 5–7 to 12 km. According to previous works, geological features of the rocks on top of the anomalous wedge indicate that during the Cretaceous this zone constituted a deep marine environment which underwent important crustal thinning related to rifting. The transition towards the southwest was to a normal continental platform. Alpine deformation gave rise to displacement on a basal thrust, which can be correlated with the lower contact of the magnetic wedge, and emplacement of this wedge towards the northeast. The southeastern termination of the anomaly can be related to the lateral termination of the basic rocks which constitute the anomalous wedge in a transform fault related to the rifting event.     

东大别地区重大地震事件深部地壳结构特征

本文应用东大别地区层析成像研究结果,对研究区重大地震事件的深部地壳结构特征进行了研究,结果表明：霍山地区的2次MS≥6.0级地震在深部地壳结构上具有一定的相似性;1970年以来的12次MS≥4.0地震在25 km深度的地壳速度结构特征比较接近。     

对壳幔二元混合模型的讨论

壳幔二元混合模计算结果的意义是多解的。对该模型所获得的“壳幔比”,并不象一些研究者所认为并强调的那样具有定量意义。所以,将f_M视为岩浆形成时地幔物质直接参与的质量比是不正确的;实质上,它只能被用来定性地反映岩浆源区岩石的成熟程度。     

Late Paleozoic gabbroic rocks of the Bridge River accretionary complex, southwestern British Columbia: geology and geochemistry

Gabbroic bodies in the Bralorne-Gold Bridge area of southwestern British Columbia are associated with the oceanic Bridge River complex of the western Canadian Cordillera, one of the suspect terranes accreted to North America in the Jurassic. The gabbros are locally cut by tonalites and are structurally interleaved with ultramafic rocks, phyllites, graphitic cherts, and carbonate lenses that comprise the lower part of the Bridge River complex. Their late Carboniferous crystallization age overlaps the depositional age of affiliated supracrustal rocks (Mississippian-Jurassic), some of which have been metamorphosed to blueschist facies. Compositionally, the gabbros resemble mafic plutonic rocks of ophiolitic complexes and gabbroic rocks of the nearby Shulaps Range. They display some affinity to oceanic island arc tholeiitic suites. The Bralorne and Shulaps gabbros include cumulates and appear to have been derived from a single, light REE-depleted, peridotitic source by melting and subsequent fractional crystallization/accumulation of various combinations of plagioclase, pyroxenes, and olivine. The tonalites are compositionally distinct from typical ophiolitic plagiogranites, but might be related to the associated gabbros. The gabbroic bodies occur within tectonic slivers derived from the oceanic crust that floored a deep ocean basin that existed during the late Paleozoic and early Mesozoic. The Bridge River complex comprises fragments of oceanic crust that were tectonically incorporated into an east-verging accretionary prism during a middle/late Triassic to Jurassic collisional event.     

Cadomian terranes, wrench faulting and thrusting in the central Europe Variscides: geophysical and geological evidence

Sixty five per cent of the Paleozoic basement of western and central Europe is hidden by a sedimentary cover and/or sea. This work aims to remove that blanket to detect new structures which could used to build a more comprehensive model of the Variscan orogeny. It is based on the interpretation of various forms of data: (a) published gravity maps corrected for the effects of the crust–mantle boundary topography and light sedimentary basins; (b) aeromagnetic maps; (c) measurements of densities; and (d) induced and remanent magnetizations on rocks from Paleozoic outcrops of the upper Rhenish area. From the northern Bohemian Massif to the eastern Paris Basin, the Saxothuringian is characterized by a 500?km long belt of gravity highs, the most important being the Kraichgau high. Most of the corresponding heavy bodies are buried under a post-early Viséan cover. They are interpreted as relics of Late Proterozoic terranes overlain by an Early to Middle Paleozoic sequence, equivalent to the Bohemian terrane in the Bohemian Massif. The most probable continuation of these dense Bohemian terranes toward the west is the Southern Channel–Northern Brittany Cadomian terrane. The gravity lows are correlated with Variscan granites and pre- and early Variscan metagranites. Gravity and magnetic maps demonstrate large-scale displacement in Devonian–Early Carboniferous times along the parallel and equidistant, NW–SE striking, Vistula, Elbe, Bavarian, Bray and South Armorican dextral wrench faults. In the Vosges–Schwarzwald and Central Massif the faults continue with the east–west striking Lalaye-Lubine–Baden-Baden and Marche faults and with south vergent thrusts. The Bavarian faults shift the Kraichgau terrane by 150?km relative to the Bohemian terrane, whereas the offset of the Northern Brittany Cadomian relative to the Northern Vosges–Kraichgau terranes is estimated at 400?km along the Bray fault. Sinistral wrench faults are the NE–SW striking Sillon Houiller, Rheingraben, Rodl, Vitis and Diendorf faults. The southern Vosges–Schwarzwald Devonian–Dinantian basin is interpreted as a pull-apart basin at the south-easterly extremity of the Bray fault. The Bohemian and Kraichgau body form allochthonous terranes which were thrust over the Saxothuringian crust. Thrusting to the north-west was accompanied by back-thrusting and led to the formation of pop-up structures. Contemporaneous dextral and sinistral wrench faulting resulted in transpressive strain during collision. The zonal structure of the Variscides in the sense of Kossmat (1927) is relevant only to the Rhenohercynian Foreland Belt. Kossmat (1927) already spoke of a Moldanubian Region because it displays no real zonal structure. The Saxothuringian Zone was formed by terrane accretion. Their apparent zonal structure is not a pre-collisional feature, but only the result of accretion and collision.     

安徽及邻区震源深度分布特征研究

本文利用安徽及邻区（29°～35°N,114°～120°E）1976年1月—2009年7月重新定位后的地震目录,统计分析了不同空间范围内的震源深度分布特征,结果表明：安徽及邻区平均震源深度8 km,优势深度分布为5～15 km,其中霍山地区震源深度优势分布为3～8 km。中小地震震源深度在空间分布是不均匀的,安徽中西部...     

南太平洋社会群岛塔希提岛(TAHITI)火山岩——一种典型的大洋岛屿玄武岩

塔希提岛火山岩属典型的大洋岛屿玄武岩(OIB)。该岛是法属波利尼西亚群岛中社会群岛链之一部分,火山活动可分三期:早期(1.7—1.3Ma),中期(1.3—0.6Ma)和晚期(0.6—0.3Ma)。早期火山岩兼有碱性和拉斑系列岩石,包括苦橄玄武岩、碱性玄武岩、拉斑玄武岩及少量玄武安山岩;中期火山岩主要有粗面玄武岩—粗面岩、碱性玄武岩和少量碧玄岩;晚期则以碧玄岩为主,并有部分碱玄岩出现。火山岩的这种岩性变化表明其岩浆由早到晚从富镁、硅弱不饱和向富碱和硅强烈不饱和演化。 社会群岛火山链的火山活动以平均11cm/a的速率从西北向东南迁移,与MORB相比,所有塔希提的岩石皆富大离子亲石元素并有较高的~(87)Sr/~(66)Sr比值,这一特征可能与其特殊的源区成分有关,即富集的地幔热柱或大洋岩石圈。早期岩石是地幔热柱和少量洋壳的部分熔融产物的混合体,故既有拉斑系列又有碱性系列。随着火山活动远离存在热柱的热点区域,洋壳部分熔融的程度逐渐降低,因而其产生的熔融体也越来越富碱,~(87)Sr/~(66)Sr比值也相应有所降低。     

盐结皮对艾比湖湿地土壤特性的影响及其自然要素分析

为探讨艾比湖湿地内土壤盐结皮(SSC)与土壤特性的相互作用关系,以及影响SSC厚度的 自然要素.采用野外调查与室内试验相结合的方法,在湿地内选取30个具有代表性的样点,并在其周围选取无SSC的样点(30个)作对比,对研究区内有SSC和无SSC覆盖的土壤特性(有机质、容重、质量含水量、总盐、全氮、全磷和pH)进行对比分析...     

新疆诺尔特地区石炭纪火山岩的成岩机制

诺尔特地区位于阿尔泰北部山区 ,西伯利亚板块西南缘。诺尔特地区石炭纪火山岩赋存于下石炭统红山嘴组中 ,火山岩属钙碱性系列 ,主要是酸性陆相火山岩。火山岩岩浆起源于诺尔特地区中地壳位置 ,成岩物质来源于地壳。痕量元素协变关系、皮尔斯元素比值、元素丰度关系及氧同位素特征的研究表明 ,石炭纪火山岩具有明显的部分熔融成岩机制的特点 ,而结晶分异作用特点不明显 ,无混合作用特点的显示。石炭纪火山岩为部分熔融作用的产物。     

应用地球物理方法研究撞击坑

陨石的撞击作用使靶岩形成一个特殊的地球物理场，具有低密度、低电阻率、低速度、磁力异常等不同于周边的岩性。因此，可利用重力、电法、磁法、地震等地球物理方法探测撞击坑的形态特征和寻找新的冲击构造。     

浙东南中生代酸性岩浆的形成与喷发

浙江东南部中生代酸性火山岩其成因类型为同熔型岩类;岩浆起源于成分为安山质的中下地壳(16-25km)的部分熔融,属古老大陆变质基底构造活化的产物。在弱挤压—弱拉张这样的总体构造背景下,因火山喷发之岩浆房的深度。过饱和水含量等物理化学因素的变化,从而导致不同旋回甚或同一旋回的火山产物在产状、组份、结构构造等发生变化。     

Passive and active margin history of the northern Tatricum (Western Carpathians, Slovakia)

The Tatricum, an upper crustal thrust sheet of the Central Western Carpathians, comprises pre-Alpine crystalline basement and a Late Paleozoic–Mesozoic sedimentary cover. The sedimentary record indicates gradual subsidence during the Triassic, Early Jurassic initial rifting, a Jurassic–Early Cretaceous extensional tectonic regime with episodic rifting events and thermal subsidence periods, and Middle Cretaceous overall flexural subsidence in front of the orogenic wedge prograding from the hinterland. Passive rifting led to the separation of the Central Carpathian realm from the North European Platform. A passive margin, rimmed by peripheral half-graben, was formed along the northern Tatric edge, facing the Vahic (South Penninic) oceanic domain. The passive versus active margin inversion occurred during the Senonian, when the Vahic ocean began to be consumed southwards below the Tatricum. It is argued that passive to active margin conversion is an integral part of the general shortening polarity of the Western Carpathians during the Mesozoic that lacks features of an independent Wilson cycle. An attempt is presented to explain all the crustal deformation by one principal driving force – the south-eastward slab pull generated by the subduction of the Meliatic (Triassic–Jurassic Tethys) oceanic lithosphere followed by the subcrustal subduction of the continental mantle lithosphere.     

Crustal evolution in the silicate planets

This paper reviews recent discoveries from space missions to the Moon, Mercury, Mars, and Venus, and their implications for planetary development. It appears that all these planets have undergone similar sequences of crustal evolution, the chief difference among them being how far each has evolved. All have apparently undergone a first differentiation in which a global crust was formed. This crust was partly disrupted by heavy impact bombardment some 4·10⁹ years ago. A second differentiation, resulting in basalt eruptions, followed. The Moon and Mercury essentially stopped evolving at this point; Mars and Venus continued to a stage of incipient plate tectonics, with crustal fracturing and vulcanism. Terrestrial Precambrian geologic evidence is consistent with a similar but further-advanced evolutionary sequence for the Earth as well, and the theory is proposed that terrestrial continents are the greatly altered and redifferentiated remnants of an originally global igneous crust of intermediate composition. The ocean basins of today are the multi-cyle descendants of mare-like basins localized by a late heavy bombardment about 4·10⁹ years ago analogous to that which formed the lunar mare basins and similar basins on other planets.     

人工生物结皮的发育演替及表土持水特性研究

为了解接种蓝藻对荒漠地区表土持水特性的改善作用,对库布齐沙漠东缘达拉特旗地区人工接种蓝藻后形成的生物结皮进行了发育演替及持水特性研究.结果表明,在人工接种荒漠蓝藻之后,藻结皮能够很快形成,并在一些微环境下藻结皮直接演替为藓结皮(接种2~3 a后).随着结皮的发育演替,表土生物量、多糖含量、厚度以及孔隙度增加,而土壤容重减小;同时,形成结皮之后表土质地也发生了明显的变化,其中沙粒含量逐渐减少,粉粒、黏粒含量增加.实验还发现随着结皮的发育演替,表土含水量与饱和持水量都呈增加的趋势,即:藓结皮>藻结皮>流沙,藻结皮中的含水量(饱和持水量)为流沙中的1.1~1.3倍,藓结皮中的含水量(饱和持水量)为流沙中的1.8~2.2倍.相关分析表明表土含水量及饱和持水量与表土生物量、多糖含量、厚度、容重、粉粒和黏粒含量呈正相关,与表土孔隙度和沙粒含量呈负相关.通过逐步回归分析发现影响含水量的主要因素为表土黏粒的含量,而影响饱和持水量的主要因素为表土孔隙度.     

中─高级变质相中水热流体的形成与作用

固体地壳中流体是普遍存在的，中—高级变质相中的矿物并非只发生晶体塑性变形，溶解和溶移作用在非糜棱岩化岩石中占主导地位，因为高温高压环境下存在的水热流体，在变质变形作用中起着至关重要的作用。在周围分布有网络状进进剪切带的递进缩短带中，与应交梯度有直接关系的单个矿物的位错密度梯度在其晶体边缘形成，产生了化学位梯度，从而使矿物边缘发生溶解。变形分解作用是产生这一过程的动力，并为流体汇聚形成水热循环系统提供了空间。     

大别山超高压变质杂岩的折返

作为世界上规模最大的一个超高压变质带，大别山超高压变质杂岩是扬子板块 与中朝板块在三叠纪碰撞造山的产物，表现为扬子板块呈北北东向斜向俯冲到中朝板块之下。 超高压变质杂岩的折返机制是个复杂的动力学过程，折返速率也随时间推移而变慢。早期阶段 （三叠纪－早侏罗纪）同碰撞期浮力驱动下高压－超高压变质杂岩在俯冲带内沿道冲－韧性剪 切断裂快速挤侵（ｅｘｔｒｕｓｉｏ）到地壳层位，折返速率高达４ｍｍ／年；中期伴随着巨厚造山带山根的 拆沉，上部发生拉张塌陷，使超高压变质杂岩进一步减压，但折返速率缓慢，～(４０)Ａｒ／~(３９)Ａｒ年代学显 示１１７Ｍａ前它们仍处在地壳的较深部；晚期伴随着晚侏罗－早白垩纪花岗质岩浆的上升侵位， 超高压变质杂岩进一步抬升，同时低角度正断层发育，此阶段的折返机制类似于变质核杂岩模 型。整个折返过程中剥蚀一直在起作用。