喀喇昆仑断裂带走滑过程中伴随的快速隆升作用:热年代学证据

喀喇昆仑断裂带是青藏高原西部的一条大型右旋走滑断裂带,它是喜马拉雅山脉西段北侧重要的地质边界.本文在岩石学、变形构造的研究基础上,对喀喇昆仑断裂带东南段阿伊拉日居山-噶尔盆地地区的喀喇昆仑韧性剪切带中变质岩石的同构造矿物进行了40Ar/39Ar热年代学研究.显微构造研究表明,剪切带中的矿物记录了从高温(>600℃)到低温(<250℃)条件下的连续变形,表现为近水平的右旋剪切运动转变成斜向的右旋正滑,使绿片岩相的变形作用叠加在中-高温变形之上.暗示出走滑过程中存在隆升作用,热年代学结果显示其连续剪切变形作用从早中新世以来至少持续到4Ma,并且出现三个快速冷却阶段:第一个快速冷却阶段为从25～22Ma到21～18Ma期间,可能代表的是浅部高温剪切过程中变形局部停止或减慢的过程;第二个快速冷却时期为从15Ma到12～10Ma,是喀喇昆仑断裂带走滑过程中,阿伊拉日居山的快速隆升、噶尔盆地开始形成以及主要河流深切过程阶段;9Ma以来是第三个快速冷却过程,使阿伊拉日居山脉进一步快速隆升、噶尔盆地定形过程.根据不同年代地表地貌特征的右旋错位距离以及不同层次变形特征,估算出喀喇昆仑断裂带长期滑移速率为8～10mm/a,伴随的隆升速率为1mm/a.从显微构造和热年代学证据表明,晚第四纪以来该断裂经历了强烈的右旋走滑运动的同时伴随强烈的隆升作用.     

华山新生代隆升-剥蚀历史的裂变径迹热年代学分析

综合分析前人的热年代学数据发现华山地区自晚白垩世以来至少经历了三次快速隆升阶段，在120—57Ma间华山经历了缓慢隆升过程，约57Ma以来华山开始相对渭河地堑的快速隆升。其中，57—42Ma间、32—22Ma间和约8Ma以来均为相对快速隆升阶段，视隆升速度约为0．18～0．23mm／a；而42—32Ma问和22～8Ma间则为相对缓慢隆升过程，视隆升速度约为0．01mm／a。约57Ma以来华山的隆升—剥蚀量约为8．5km，平均隆升速度约为0．15mm／a；约32Ma以来的总隆升幅度约为4．5～5．1km，平均视隆升速度约为0．14～0．16mm／a。晚中生代以来华山的隆升过程实际上反映的是东秦岭的隆升过程，与区域地貌结构和周缘断陷盆地的演化过程有密切的成因联系，它表明东秦岭地区的三级等高峰顶面是120—57Ma、42—32Ma和22～8Ma间山脉缓慢隆升—剥蚀的结果，同时反映57—55Ma是渭河盆地开始快速裂陷和秦岭北麓正断层开始强烈活动的时间。     

川东南地区燕山期以来的隆升剥蚀历史研究

川东南地区侏罗系砂岩的磷灰石裂变径迹T—t热史模拟表明,燕山期以来研究区经历了两个阶段的隆升剥蚀。127～105Ma为初始缓慢隆升阶段,隆升剥蚀速率约为5m／Ma,使106m厚的早白垩世地层被剥蚀;105～75Ma间转入快速沉降,75～0Ma由快速沉降转入全面不等速隆升。其中,75—65Ma为快速隆升．隆升剥蚀速率为28m／Ma;65～20Ma为缓慢隆升,隆升剥蚀速率为14m／Ma;20～10Ma期间,研究区由缓慢隆升转为急剧隆升,隆井剥蚀速率为147m／Ma;10Ma到现今,该地区再次由快速隆升转为缓慢隆升。隆升剥蚀速率为10m／Ma。燕山期以来的隆升使大约2580m厚的地层被剥蚀掉。     

燕山山脉隆升的动力学过程

本文应用热年代学方法,测定侵入体的热历史,进而分析燕山山脉的隆升过程。研究结果表明,燕山造山带的隆升过程在时空上具有明显非均匀性。燕山中段南部的盘山岩体约于226.48 Ma侵位,在96～35 Ma期间以3.45 C/Ma的速度冷却,对应于0.115 mm/a的快速隆升过程;燕山中段北部的雾灵山岩体约于132 Ma侵位,在86～45 Ma期间以5.61/Ma的速度冷却,对应于0.186 mm/a的快速隆升过程;燕山西段的云蒙山岩体约于143 Ma侵位,在106～103.95 Ma与20～     

西昆仑及邻区新生代差异隆升的热年代学证据

通过总结和分析有关热年代学的资料, 认为西昆仑及邻区的隆升存在明显的时空差异性.第一, 隆升历史表现出明显的阶段性: 晚渐新世到早中新世(25~16Ma) 的部分隆升阶段、中新世中后期的快速隆升阶段(14~8Ma) 和晚中新世以来的整体强烈隆升阶段(6Ma以来).第二, 隆升在空间上显示出明显的差异性: 塔什库尔干-公格尔山地区的隆升主要集中在9Ma以来, 红其拉甫-库地地区的隆升主要集中在25~16Ma, 康西瓦-普鲁地区的隆升则主要在9Ma以来(集中在9~2Ma) 和25~12Ma.东西方向上表现为东西两端靠近构造结(喜玛拉雅西构造结和西昆仑-阿尔金构造结合部位) 的地方较新(主要在9Ma以来), 中间较老(主要在9Ma以前); 南北方向上, 西昆北地体在20Ma左右发生快速隆升, 西昆南地体在9~5Ma发生快速隆升, 而甜水海地体在5~2Ma发生快速隆升, 由北向南总体上呈现出由老到新的空间差异性.      

湘东南地区中、新生代山体隆升过程的热年代学研究

湘东南地区位于南岭中段北缘。本文应用热年代学方法,测定了湘东南地区5个侵入体的热历史,进而分析湘东南中新生代的隆升过程,并结合区域构造背景,对热演化过程与构造发展过程之间的关系进行了探讨。研究结果表明,湘东南地区中新生代山体隆升过程总体上分为由较快速→快速→缓慢→快速的4个阶段,222～146.Ma期间以0.069mm/a的平均速率较快隆升,146.4～94.11Ma期间以0.113～0.186mm/a的平均速率快速隆升,94.11～14.8Ma期间以0.014～0.028mm/a的平均速率缓慢隆升,14.8Ma～0.0Ma以0.143～0.295mm/a的平均速率快速隆升。晚近时期的隆升总体呈加速趋势。隆升过程在空间上具有非均匀性,不同岩体间隆升过程存在差异。地壳隆升过程在时间上具有明显的互补性,早期具较快速或较大幅度隆升的岩体,通常伴随着晚期相对较慢和较小幅度的隆升。根据热年代学分析结果,结合区域构造背景和其它地质资料,推断五峰仙、大义山、骑田岭等地区在中三叠世后期因构造叠置增厚了4100～7700m以上,证明印支运动早期为强烈的陆内挤压造山运动。燕山晚期岩体隆升和降温由早期构造剥蚀和晚期风化剥蚀造成,并具有良好的盆地沉积响应。湘东南地区晚近时期的快速隆升是区域性整体抬升。     

念青唐古拉花岗岩热演化历史和山脉隆升过程的热年代学分析

念青唐古拉山是青藏高原内部的重要山脉,主体由黑云母二长花岗岩组成,岩体内部发育不同类型的变质岩包体如Lgn、Ygn片麻岩和元古代（Pt）变质岩,岩体东西两侧发育伸展型韧性剪切带。对念青唐古拉黑云母二长花岗岩进行矿物对热年代学分析,良好地揭示了岩浆热演化历史和山脉隆升过程。通过单颗粒锆石离子探针测年,发现65．0～55．0Ma发生早期岩浆侵位事件,形成Lgn、Ygn花岗片麻岩包体;在18．3～11．1Ma期间,在约11km深度的Lgn、Ygn下方发生大规模岩浆侵位和结晶成岩事件,形成念青唐古拉黑云母二长花岗岩（NG）。在11．1～9．3Ma期间,念青唐古拉花岗岩发生快速冷却和隆升过程,平均降温速度约222．2℃／Ma,对应的平均差异隆升速率为5．56mm／a;在9．3～8．6Ma期间,念青唐古拉花岗岩继续发生差异隆升和快速降温,平均降温速率为142．8℃／Ma,对应的差异隆升速率为3．57mm／a;在8．0～5．0Ma期间,念青唐古拉山区发生伸展型韧性剪切变形,导致念青唐古拉花岗岩快速隆升,平均差异隆升速率为3．50mm／a;在5．0～3．7Ma期间,念青唐古拉花岗岩继续发生构造隆升,平均降温速率约92．3℃／Ma,对应的平均差异隆升速率为2．31mm／a。自3．7Ma以来念青唐古拉花岗岩平均降温速度达27．0℃／Ma,平均抬升速度达0．68mm／a。念青唐古拉岩浆集聚、NG花岗岩侵位与INDEPTH-Ⅱ地震深反射亮点揭示的地壳局部熔融存在动力学成因联系,导致上地壳伸展构造变形、NG花岗岩缓慢冷却和念青唐古拉山脉快速隆升。     

中祁连木里盆地古近系ESR年龄及地质意义

对中祁连木里盆地新生代红层进行ESR测年,获得了祁连山地区新生代红层沉积时代及构造变形年代学数据.研究表明,中祁连木里盆地内沉积了巨厚的新生代红层,较好地记录了祁连山隆升历史.盆地最老的新生代地层为始新世由湖相沉积组成的火烧沟组,ESR年龄为40.2～35.3 Ma,与上覆沉积时代为32.6～24.3 Ma的渐新世河湖相沉积组成的白杨河组呈角度不整合接触.构造变形特征与沉积环境的变化说明始新世末与渐新世初木里地区发生了构造变形和山脉的隆升,与祁连山地区新生代早期的隆升有很好的对应关系.     

新生代渭河盆地沉积-构造迁移与渭北隆起及东秦岭耦合关系探讨

渭河盆地、渭北隆起及东秦岭造山带地处青藏块体东北缘、华北克拉通和扬子克拉通的交界处,形成了特有的盆山体系,分布有油气、氦气及地热等多种能源矿产资源。新生代是渭河盆地沉积-构造演化及渭北隆起和东秦岭隆升的重要时期,缺乏该时期盆山体系耦合关系的研究,制约了对区域矿产资源分布规律的认识。盆山耦合体现在时间、空间、物质、构造作用及地表形态等多方面。以大量钻孔资料为依托,运用“回剥法”分析了渭河盆地新生代的沉降幅度及沉降速率,并根据主沉降期新近纪以来不同阶段沉积地层厚度展布特征恢复了盆地沉积演化历史。研究表明渭河盆地新生代以来沉降中心具有自西南方向西安凹陷向北东方向固市凹陷迁移的特征。古近纪始新世以来,渭河盆地发生快速构造沉降,中新世早-中期以西安凹陷为主要沉积、沉降中心,晚中新世以来以西安、固市两个凹陷为主要沉积、沉降中心,晚上新世-早更新世沉降中心转移到东北部固市凹陷,晚更新世以来,西安凹陷和固市凹陷均发生快速沉降。裂变径迹的分析测试结果表明渭北隆起约45～32 Ma整体快速抬升,同步于东秦岭太白山和华山约57～40 Ma的快速隆升阶段,与渭河盆地古近纪始新世约40 Ma的基底快速沉降具有耦合关系。晚中新世约7.3 Ma以来,渭河盆地的持续快速沉降,与渭北隆起上新世约5 Ma及东秦岭太白山约10～9.6 Ma、华山约8～5 Ma以来的快速耦合关系明显。太平洋板块的俯冲、欧亚板块与印度板块始新世约55～45 Ma碰撞及青藏高原约10～8 Ma隆升外扩的远程效应对研究区影响较大。     

黔中隆起金沙地区中新生代隆升剥蚀的裂变径迹分析

对贵州金沙地区取样进行了裂变径迹热史模拟,结合地质分析再现了黔中隆起的沉降和隆升剥蚀作用过程。该地区经历了180～70Ma时期的沉降埋藏增温和70Ma之后的剥蚀冷却降温两大阶段。沉降阶段的增温速率为0.909℃/Ma,对应的T3—K的沉积厚度约为4550m。冷却降温曲线分为三段:70～15Ma,样品温度从120℃降低到60℃,冷却速率为1.09℃/Ma;15～5Ma为一个"平台"期,样品温度维持在60℃左右;5Ma至今,样品温度从60℃快速冷却至20℃,冷却速率达8℃/Ma,这与喜马拉雅期云贵高原的整体隆升和晚期快速崛起相对应。计算表明,晚白垩世以来的隆升剥蚀量达2800m左右。     

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