胶莱盆地白垩系林寺山组砾岩沉积特征及盆地演化意义

胶莱盆地下白垩统莱阳群底部林寺山组主要由砾岩组成。通过对盆地及周缘18个地点林寺山组砾岩系统的调查,从砾岩组分、砾径和长轴排列方向的统计分析出发,研究该砾岩沉积相类型、盆地物源区、古水流及林寺山组上覆地层中砂岩碎屑锆石U-Pb年龄谱特点,并进一步讨论了盆地演化的意义。研究表明,林寺山组底部砾岩以冲积扇相为主,但不同地点亚、微相类型又有差异。原型胶莱盆地由莱阳、海阳-即墨和诸城-五莲3个独立盆地组成,被6个隆起区所分隔。莱阳盆地的物源主要来自胶北隆起和苏鲁造山带北部;海阳-即墨盆地以苏鲁造山带北部隆起区、即墨-牟平隆起、胶南隆起为主物源区;诸城-五莲盆地以胶南隆起和马山-李党家低隆起为主要物源区。林寺山组砾岩的出现标志着苏鲁造山带大规模塌陷和胶莱盆地的形成。     

苏鲁地体折返与郯庐断裂活动:莱阳盆地中生界碎屑锆石年代学的制约

胶莱盆地位于苏鲁造山带的北缘,其莱阳群沉积对反演郯庐断裂和苏鲁造山带中生代的折返过程具有重要的制约作用。本文利用LA-ICP-MS方法对莱阳盆地的莱阳群碎屑岩和青山群火山岩进行锆石U-Pb年龄测定,分析其年龄谱特征,探讨其沉积物源区,进而为苏鲁造山带的折返机制提供依据。(1)莱阳盆地发育莱阳群和青山群为代表的中生代沉积岩,锆石年龄测试得到莱阳群形成时代为125±0.6Ma;青山群形成时代为119±1Ma,表明两者都是早白垩世中-晚期的沉积产物;(2)超高压带北缘莱阳盆地与合肥盆地的碎屑锆石年龄谱对比表明,莱阳盆地的沉积物无论沉积时代还是物源区均明显不同与郯庐断裂西侧的合肥盆地,表明郯庐断裂应该形成于两个盆地形成之前,可能为三叠纪-早侏罗世之间;(3)莱阳盆地内发育大量的华北型碎屑物质,进一步表明在扬子大陆板块俯冲过程中华北板块曾经仰冲到扬子板块之上;(4)莱阳盆地发育少量的新元古代岩浆和印支期变质锆石的年龄,表明早白垩世苏鲁超高压变质岩已经折返到地表;(5)超高压变质岩与中生代岩浆岩同时作为莱阳盆地的物源,结合五莲拆离断层的同期活动和莱阳盆地的同时代沉积,说明苏鲁超高压带中生代的折返具有与变质核杂岩类似的大型伸展构造背景。     

山东诸城晚白垩世王氏群恐龙化石层碎屑锆石定年和物源示踪

山东东部诸城晚白垩世王氏群大面积、高密度集群埋藏的恐龙化石是近年研究的热点,但其沉积物源与精确沉积时限目前尚不明确。本文通过对山东诸城王氏群恐龙化石层中6个砂岩样品的碎屑锆石U-Pb定年表明,样品090414-24-D中最年轻的单颗粒锆石年龄(YSG)为77.3 Ma,应代表王氏群恐龙化石层的最大沉积时限(下限),结合前人对王氏群红土崖组的年代学研究表明,其沉积时限应老于73.5 Ma(上限),也说明赋存恐龙化石层的王氏群上部红土崖组为Campanian期沉积;碎屑锆石定年揭示物源的锆石年龄组成分布在100～130 Ma之间,6个样品的年龄主峰值多在110 Ma或120 Ma左右,与下伏的早白垩世青山群火山岩年龄主峰较为吻合。王氏群恐龙化石层砾岩的砾石成分和古水流研究显示,其中3组砾石统计表明砾岩层砾石成分主要由火山岩或火山碎屑岩组成,3组古水流数据表明,诸城地区王氏群红土崖组砾岩层的古流向以南和南东方向为主,尚有1组显示古流向为向北,表明王氏群物源主要来自盆地北侧莱阳和北西侧沂沭断裂带的青山群火山岩,其次为盆地南缘。本研究为诸城王氏群化石层沉积时限的限定和沉积物源的判断,以及胶莱盆地王氏群时期古地理格局的恢复等提供了重要的依据。     

山东青岛地区灵山岛早白垩世碎屑岩锆石U-Pb-Hf同位素特征及其大地构造意义

苏鲁造山带东缘的灵山岛上发育有早白垩世碎屑岩,目前人们对其沉积的精确时代、成因机制和大地构造环境仍然存在着广泛的争议.利用LA-ICP-MS的方法对灵山岛上两套碎屑岩进行了锆石U-Pb测年,并对特征年龄谱中的代表性碎屑锆石进行了Lu-Hf同位素分析.结果表明:（1）碎屑锆石U-Pb测年结果显示,莱阳群法家茔组和青山群八亩地组下部的碎屑岩沉积时代分别为127±3 Ma和128±4 Ma,表明两套碎屑岩都是早白垩世中晚期的沉积产物;（2）灵山岛上两套碎屑岩具有完全相似的年龄谱以及锆石Hf同位素组成,表明发育软沉积变形的粉砂岩、泥岩和上覆的含砾粗砂岩具有相似的物源,并且源区组成较为单一,主要以亲华北的胶北地体为主,其次的物源区为苏鲁造山带;（3）胶莱盆地下白垩统莱阳群和灵山岛下白垩统莱阳群的碎屑锆石年龄谱对比表明,灵山岛上的莱阳群碎屑岩明显不同于胶莱盆地的莱阳群,暗示在早白垩世时,灵山岛上的两套碎屑岩可能受到区域断裂的控制,沉积于一个相对独立的盆地.综合结果表明,灵山岛地区莱阳群法家茔组可能沉积于断陷湖盆的萎缩期,早期的沉积以湖相为主,晚期主要以河流相为主,在此期间遭受到了强烈的火山地震作用,诱发了下部的湖相的砂泥岩发生大规模的滑塌和软沉积变形.      

胶莱盆地沉积-沉降史分析与构造演化

基于地表典型露头剖面观察、地震剖面和测井资料解释、沉降史分析,并运用叠合盆地和改造盆地的研究思路,恢复了胶莱盆地白垩纪不同演化阶段的盆地原型及其构造性质。结果表明,该盆地经历了3个显著不同的沉积-沉降阶段。早白垩世莱阳群沉积时期,盆地原型表现为两个NE至NNE向延伸的断陷槽:一个沿苴县—诸城断陷发育,另一个沿牟平—即墨构造带发育,其沉积-沉降中心分别受苏鲁造山带北缘断裂带和牟平—即墨断裂带控制;该阶段沉积-沉降速率发生显著的空间分异,最大沉积-沉降速率在断陷槽,为230～370m/Ma,沿两侧斜坡地带沉积-沉降速率减小,约60m/Ma。早白垩世青山群对应一套中基性至中酸性火山岩,在沂沭裂谷盆地中堆积了一套大盛群河湖相沉积,这个时期是典型的大陆裂谷作用阶段,胶莱盆地演化为火山盆地,盆地沉降速率为35～70m/Ma。晚白垩世盆地原型表现为受东西向断裂控制的不对称箕状断陷,由诸城凹陷、高密凹陷和莱阳凹陷组成,其构造性质属于受西侧郯庐断裂和东侧牟平—即墨断裂控制的右旋拉分盆地;该阶段沉积-沉降速率总体一致,在63～73m/Ma。最后探讨了白垩纪盆地不同伸展阶段的动力学机制。     

胶莱盆地白垩纪构造演化

胶莱盆地是位于胶东半岛的白垩纪盆地,前人对该盆地的沉积-构造演化进行了相关研究,也取得了重要进展。但是关于盆地初始形成阶段古构造应力场状态还存在一些争论。本文通过对盆地内部断层滑动矢量数据的反演及节理、同沉积断层指示意义分析,将胶莱盆地白垩纪构造演化划分为五个阶段:早白垩世早期NWW-SEE向伸展,控制了莱阳群初始沉积;莱阳群沉积末期近E-W向挤压;早白垩世晚期E-W向伸展,形成了青山群;早白垩世末期NW-SE向挤压;晚白垩世近N-S向至NNE-SSW向伸展,形成了王氏群。大量的野外现象与前人研究成果均与本文得到的盆地初始成盆阶段NWW-SEE向伸展应力场相吻合。NWW-SEE向伸展作用可能是在古太平洋板块向欧亚板块俯冲过程中,古太平洋板块后撤与苏鲁造山带后造山作用的共同作用下发生的,代表胶莱盆地形成初期,受苏鲁造山带造山后期作用的影响;而青山期伸展方向的变化可能指示盆地主要受到古太平洋板块后撤的影响。盆地在白垩纪古构造应力场的作用下,分别受到早白垩世裂谷作用与晚白垩世走滑拉分作用控制,两种作用的叠加使胶莱盆地成为一个复合型盆地。     

胶莱盆地早白垩世瓦屋夼组砂岩中碎屑锆石U-Pb-Hf同位素组成及其构造意义

本文报道了胶莱盆地莱阳群最底部瓦屋夼组长石石英砂岩中碎屑锆石的LA-ICP-MS U-Pb年代学和原位Hf同位素分析结果,进而约束了瓦屋夼组砂岩的沉积时代和物源及其构造意义。碎屑锆石多数呈自形–半自形晶,发育岩浆生长环带,暗示它们为岩浆成因;少数晚三叠世锆石呈均匀无结构的阴极发光特点,缺乏岩浆环带,暗示它们为变质锆石。82个谐和年龄的峰值分别为129 Ma、158 Ma、224 Ma、253 Ma、461 Ma、724 Ma、1851 Ma和2456 Ma。上述定年结果结合原位Hf同位素分析表明:(1)瓦屋夼组的沉积时代为早白垩世(129~106 Ma);(2)1851 Ma、2456 Ma年龄的锆石主要来源于华北克拉通前寒武纪基底岩石;新元古代(729~721 Ma)岩浆锆石和晚三叠世(226~216 Ma)变质锆石来源于苏鲁造山带;晚古生代锆石记录了华北克拉通北缘同时代的岩浆事件;晚三叠世(231~223 Ma)岩浆锆石和158~129 Ma锆石则与胶北、胶东同时期的岩浆事件相对应;(3)胶莱盆地与合肥盆地具有不同的沉积时代和物源属性;(4)瓦屋夼组中苏鲁造山带物源的存在,暗示苏鲁高压–超高压变质岩石至少在早白垩世时期已经出露地表。     

鲁西隆起区晚中生代地层碎屑石榴石分析及物源区构造演化示踪

以鲁西淄博、临朐、平邑、蒙阴盆地为重点研究区,通过盆地中生界砂岩中碎屑石榴石的成分分析,探讨鲁西隆起及周边地区中生代构造演化历史。研究表明,鲁西盆地砂岩中石榴石成分在早中侏罗世和中晚侏罗世期间出现变化,暗示着物源的转变,早中侏罗世时期主要物源是鲁西隆起,中晚侏罗世时期转变为胶东地区和鲁西隆起。侏罗纪时期石榴石的物源转变显示,苏鲁苏鲁造山带可能在中晚侏罗世时期已经抬升至地表。白垩纪鲁西盆地物源主要为胶东地区,鲁西隆起的物源贡献较小,但是青山组中段和王氏组中段物源略有波动。白垩纪鲁西盆地石榴石物源显示,控制鲁西盆地沉积的主要是苏鲁造山带,古地理格架显示东高西低的特征,盆地物源的波动暗示鲁西隆起可能在早白垩世中晚期和晚白垩世中期经历过抬升。     

胶莱盆地沉积-沉降史分析与构造演化

基于地表典型露头剖面观察、地震剖面和测井资料解释、沉降史分析，并运用叠合盆地和改造盆地的研究思路，恢复了胶莱盆地白垩纪不同演化阶段的盆地原型及其构造性质。结果表明，该盆地经历了3个显著不同的沉积-沉降阶段。早白垩世莱阳群沉积时期，盆地原型表现为两个NE至NNE向延伸的断陷槽：一个沿苴县-诸城断陷发育，另一个沿牟平-即墨构造带发育．其沉积-沉降中心分别受苏鲁造山带北缘断裂带和牟平-即墨断裂带控制；该阶段沉积-沉降速率发生显著的空间分异．最大沉积-沉降速率在断陷槽，为230～370m／Ma，沿两侧斜坡地带沉积-沉降速率减小．约60m／Ma。早白垩世青山群对应一套中基性至中酸性火山岩，在沂沭裂谷盆地中堆积了一套大盛群河湖相沉积，这个时期是典型的大陆裂谷作用阶段．胶莱盆地演化为火山盆地，盆地沉降速率为35～70m／Ma。晚白垩世盆地原型表现为受东西向断裂控制的不对称箕状断陷．由诸城凹陷、高密凹陷和莱阳凹陷组成，其构造性质属于受西侧郯庐断裂和东侧牟平-即墨断裂控制的右旋拉分盆地：该阶段沉积-沉降速率总体一致，在63～73m／Ma。最后探讨了白垩纪盆地不同伸展阶段的动力学机制．     

胶莱盆地蛇窝泊地区白垩纪林寺山组沉积时代与物源特征:来自碎屑锆石U-Pb测年与稀土元素组成的新证据

林寺山组是胶莱盆地莱阳群底部重要的地层单元之一.准确限定其沉积时代与物源性质对于客观重建华北陆块东部晚中生代大地构造格局以及周缘造山带/前寒武纪变质基底晚中生代的折返过程具有重要的制约作用.以莱阳盆地蛇窝泊地区莱阳群林寺山组细砾岩为研究对象,对其开展了野外地质调查、岩相学观察、锆石U-Pb测年与锆石稀土元素分析等综合研究,并获得了如下初步认识.（1）林寺山组细砾岩中最小一组碎屑锆石加权平均年龄分别为129±1 Ma与127±5 Ma,结合区域上不整合于莱阳群之上青山群火山岩锆石谐和年龄为119±1 Ma,推测蛇窝泊地区林寺山组沉积时代介于127~119 Ma.（2）蛇窝泊地区林寺山组细砾岩的碎屑锆石年龄变化于2 858~126 Ma之间,并以新太古代晚期与白垩纪早期碎屑锆石为主.前古元古代的碎屑锆石主要来源于胶北前寒武纪变质岩,表明胶北太古宙-古元古代变质岩至少在白垩纪早期已折返至近地表.（3）160~120 Ma岩浆型碎屑锆石主要来源于胶东同时代的中酸性侵入体,暗示在白垩纪早期至少部分160~120 Ma中酸性侵入体已抬升至地表.（4）林寺山组发育少量的二叠纪（280 Ma）和印支期（213 Ma）变质锆石,表明胶东地区可能存在二叠纪约280 Ma区域变质-变形事件,同时暗示早白垩世苏鲁超高压变质岩已经折返到地表.      

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