广东麒麟新生代玄武质角砾岩筒中岩石包体的研究

本文以广东麒麟玄武质角砾岩筒中的各种岩石包体为研究对象,通过详细的岩石学研究,按岩石类型将包体划分为四类：即橄榄岩、辉石岩、辉长岩质麻粒岩、花岗岩和火山－沉积岩,并依据包体的岩石地球化学特征,讨论了它们的成因;其中辉长岩质麻粒岩是来自本区下地壳的样品,是由上地幔部分熔融产生的熔体“底侵”于地壳底部结晶,又经变质作用的产物。同时,本文结合实测的和计算的地球物理参数,讨论了该区的岩石圈分层。     

南秦岭下地壳组成及岩石圈的拆离俯冲作用

根据新提供的Pb同位素组成及岩石地球化学研究成果，本文进一步证实了位于北秦岭北界的明港地区发育的早中生代安山玄武质火山角砾岩岩筒所携带的下地壳捕虏体属于南秦岭。所恢复的南秦岭下地壳剖面自下而上为：底侵成因的变辉长岩-基性麻粒岩(其中含有榴辉岩及辉石岩的透镜体)-酸性麻粒岩。秦岭造山带总体的岩石因模型为：南秦岭(扬子块体)向北拆离俯冲，北秦岭地壳向华北仰冲，华北岩石因呈楔状插入秦岭造山带，拆离面约在中、下地壳之间。南秦岭俯冲岩片延伸的范围在平面上有可能达到400km。     

壳幔作用与花岗岩成因——以中国东南沿海为例

笔者在近年来的中国东南沿海花岗岩成因研究中,注意到下地壳之下的岩石圈地幔与下地壳之间必然有着十分密切的关系,认识到壳幔作用的重要形式是发生于壳－幔接口的玄武岩浆的底侵作用,它涉及地幔对地壳在“成分”和“热”两方面的贡献。研究表明,本区底侵作用十分发育,是中国东南大陆边缘陆壳演化的重要 过程。中国东南部中生代早期形成的花岗岩多为Ｓ－型花岗岩,它们主要是板块强烈挤压和导致地壳增厚,陆壳重熔形成的岩石。而且这期大规模花岗岩浆活动是与弧后拉张、岩石圈减薄 软流圈上涌作用直接有美．早期太平洋板块向欧亚大陆板块俯冲对大陆裂解起了诱导作用中国东南部晚中生代缝合带的年龄为100～11OMa,可能代表了晚中生代构造－岩浆作用由挤压,地壳增厚,陆壳重熔向扩张岩石圈减薄一双蜂式岩浆作用机制的转变年龄。     

大陆边缘弧岩浆成因与大陆地壳形成

大陆地壳如何形成是国际学术界长期关注并正在持续攻关的一个重大基础科学问题。活动陆缘弧的岩浆成因和密度分选过程是理解大陆地壳形成机制和演化过程的关键。北美白垩纪Cordilleran大陆边缘弧的形成可能经历了与底侵幔源岩浆有关的下地壳部分熔融和岩浆混合,或幔源初始玄武质岩浆的两阶段成分分异过程,以花岗质成分为主的北美内华达地区垂向地壳成分剖面结构可能与榴辉岩相残留体或堆晶岩的拆沉作用密切相关。目前并不清楚亚洲大陆南部以约200 Ma和约90 Ma两个时间断面为代表的中生代冈底斯弧,为何出现大量角闪石岩并具有玄武安山质的平均成分。探究中生代冈底斯弧的岩浆成因、地壳垂向成分结构和地壳形成机制可能有助于或多或少地解决这一问题。     

华北东部岩石圈减薄中的下地壳过程：岩浆底侵、置换与拆沉作用

最近研究表明，华北中生代岩石圈减薄不仅是岩石囤地幔减薄，而且下地壳也发生了一定程度的减薄和置换。本文强调下地壳过程，如岩浆底侵、置换和拆沉作用是理解岩石囤减薄机制的关键因素之一。火山岩及其捕虏体的信息似乎支持在华北东部南、北缘存在局部造山带型的下地壳与岩石囤的拆沉作用。但是华北东部整体上的减薄机制难以用造山带的拆沉模式来解释。华北东部克拉通内部的火山岩中的下地壳捕虏体有两类，一类是经历了麻粒岩相变质的底侵辉长岩和辉石岩以及榴辉岩相变质的石榴辉石岩，形成时代约在140～120Ma；另一类是经过了中生代变质叠加的前寒武纪麻粒岩。中生代华北东部曾发生过大规模的岩浆底侵作用，现今的下地壳很可能已大部分不是前寒武纪的下地壳，它们由中生代变质的辉长岩、镁铁质岩石以及经历了很强烈改造的前寒武纪下地壳麻粒岩组成。此外，在华北东部普遍存在着化学成分类似于“埃达克岩”的中生代高锶花岗岩类岩石，它们的形成与岩浆底侵作用和镁铁质下地壳的部分熔融有关，其熔融残留应是榴辉岩或石榴角闪岩。尽管如此，要通过下地壳部分熔融形成一个厚的密度很大的榴辉岩层，由它的重力不均衡来带动80～120公里厚的岩石圈地幔一起拆沉进入软流圈的机制很难发生在华北克拉通内部。岩浆底侵和置换作用是下地壳过程非常重要的形式，与岩石圈的减薄具有密切联系，其具体机制尚不完善。     

苏鲁地区地壳岩浆底侵的地球物理判识

底侵作用是研究壳幔物质交换与大陆增生演化的重要机制之一，但是对岩浆底侵作用的判识是十分困难的科学问题，中国大陆科学钻探先行项目在苏鲁地区积累的地震学，地热学及地电学资料表明，在苏鲁地区发生过与大陆裂谷同期的地幔岩浆底侵作用，发生了时段主要为始新世，它的发育与沿嘉山－晌水大陆裂谷带在时空上有密切联系，这里的壳幔过渡带厚度可达3km，推测为橄榄岩与基性麻粒岩互层。结合岩石学资料可以推算出由浆底侵作用造成大陆地壳增厚的平均速度约为0.1mm/a.     

桂北—湘南中生代玄武质岩石及其深源包体的地球化学性质和岩石成因探讨

桂北-湘南中生代玄武质岩石中含有丰富的深源包体，它们分别为橄榄岩、变形的辉长岩和中酸性片麻岩三大类，本文在论述上述岩石地球化学性质的基础上，探讨了它们之间的成因关系；寄主的中生代玄武质岩石为地幔楣榄岩部分熔融的产物，与辉长岩和中酸性片麻岩并无成因联系，后者属偶然包体，值得注意的是，深源包体中的变形辉长岩与片麻岩之间为分离结晶的成因关系，它们均为元古宙壳、幔间底侵玄武质岩浆的演化产物，其中辉长岩为底侵岩浆的堆积相，而片麻岩则为底侵岩浆经历分离结晶的堆积作用之后所剩下的残余岩浆的变质产物。     

辽西早白垩世义县组火山岩的起源及壳幔相互作用

对燕山造山带辽西早白垩世义县组火山岩的Nd,Sr,Pb同位素分析,作者认为义县组火山岩起源于岩石圈地幔的部分熔融,岩浆在上侵过程中发生了结晶分异和同化混染作用,即AFC过程.与新生代汉诺坝玄武岩中的中生代镁铁质麻粒岩捕虏体和太古代片麻岩对比研究,发现义县组火山岩与这些镁铁质麻粒岩捕虏体有许多地球化学相似之处,而与长英质麻粒岩捕虏体和太古代各种片麻岩差别较大.作者认为早白垩世燕山板内造山带发生了强烈的岩石圈伸展作用,辽西义县组火山岩和汉诺坝新生代玄武岩中的镁铁质麻粒岩捕虏体均为这一构造背景下的产物,它们属于幔源岩浆喷发与大规模玄武zh质岩浆底侵作用形成的"同质异相体".     

辽西早白垩世义县组火山夺的起源及壳幔相互作用

对燕山造山带辽西早白垩世义县组火山岩的Nd,Sr,Pb同位素分析，作者认为义县组火山岩起源于岩石圈地幔的部分熔融，岩浆在上侵过程中发生了结晶分异和同化混染作用，即AFC过程。与新生代汉诺坝玄武岩中的中生代镁铁质麻粒岩捕虏体和太古代片麻岩对比研究，发现义县组火山岩与这些镁铁质麻粒岩捕虏体有许多地球化学相似之处，而与长英质麻粒岩捕虏体和太古代各种片麻岩差别较大。作者认为早白垩世燕山板内造山带发生了强烈的岩石圈伸展作用，辽西义县组火山岩和汉坝新生代玄武岩中的镁铁质麻粒岩捕虏体均为这一构造背景下的产物，它们属于幔源岩浆喷发与大规模玄武zh质岩浆底侵作用形成的“同质异相体”。     

浙江新昌基性麻粒岩包体初步研究

来自下地壳的基性麻粒岩是壳幔作用过程的产物，蕴含着有关岩浆成因及与壳幔作用之关系的重要信息。位于西太平洋活动大陆边缘的东南大陆沿海（浙闽粤赣诸省）广泛分布中—新生代火山岩，被称为“东南大陆火山岩带”，构成了环太平洋火山岩带中的重要一环。目前关于东南大陆火山岩带的成因及大地构造背景，如岩浆物质来源、岩浆混合作用及岩浆起源的地球动力学机制等，还存在不少争议，这与缺乏深部壳幔作用过程的直接证据有关［1～3］。因此，东南大陆火山岩带中是否存在基性麻粒岩包体，一直受到地质界的关注。以往认为东南大陆沿海地区不…     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Late Wuchiapingian (Late Dzhulfian,early Late Permian) limestone olistolites within the Tertiary flysch of Glypia Unit (Mount Parnon,central–eastern Peloponnesus,Greece)

Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931.     

PALEONTOLOGY

正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.)     

GEOCHEMICAL EXPLORATION

正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.)     

MICROPALAEONTOLOGY

正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.)     

PETROLOGY

正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus.,     

ENVIRONMENTAL GEOLOGY

正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an     

PROSPECTING EXPLORATION

正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of