贵州习水奥陶系牙形石生物地层

贵州习水良村剖面地层发育齐全,是目前所知上扬子地区出露最为完整的奥陶系剖面之一。该剖面海相碳酸盐岩发育,具备优越的牙形石生物地层研究条件。本次,笔者等于此获得了丰富的牙形石标本,经研究建立了16个牙形石带,由下至上分别为Monocostodus sevierensis带,Cordylodus angulatus带,Glyptoconus quadraplicatus带,Tripodus proteus带,Triangulatus bifidus带,Serratognathus diversus带,Oepikodus communis带,Oepikodus evae带,Baltoniodus triangularis带,Baltoniodus navis带,Paroistodus originalis带,Baltoniodus aff.navis带,Lenodus antivariabilis-L.variabilis组合带,Pygodus serra带,Hamarodus brevirameus带以及Protopanderodus insculptus带。     

浙江临安板桥早奥陶世牙形刺新材料及其意义

在浙江临安板桥早奥陶世的留下组、施家头组和荆山组中发现较丰富的牙形刺动物群,自下而上建立Cordylodus angulatus带、Chosonodina herfurthi带、Paltodus deltifer带、Paroistodus proteus带和Prioniodus elegans带等5个牙形刺带,均属于早奥陶世。研究表明,临安板桥一带的早奥陶世碳酸盐岩地层时代局限于早奥陶世特马豆克期—弗洛期,与上覆中奥陶世达瑞威尔期硅质泥岩呈假整合接触关系,其间缺失弗洛晚期—达瑞威尔早期沉积。这一发现对该地区的地层划分对比和古地理研究具有重要意义。     

川西南轿顶山地区中—上奥陶统牙形石生物地层和碳同位素地层研究

以上扬子台地西缘轿顶山地区中—上奥陶统宝塔组灰岩为研究对象,连续不间断采集化石样品,识别出牙形石15属20种,并据此识别出3个可与国内外同期地层直接对比的牙形石带,从下到上依次是Amorphognathus tvaerensis带,Hamarodus brevirameus带,和Protopanderodus insculptus带,研究剖面宝塔组下部与邻区同期地层连续的牙形石带相比缺少1~2个带。另外,通过高精度采集碳、氧同位素样品,在研究剖面宝塔组发现δ13C记录序列中存在同位素正漂移异常,且包含3个次一级峰值,峰值范围在2. 0‰~3. 0‰之间,同期正漂移异常也出现在上扬子台地东部和南部,该异常开始发生层位在上扬子台地均在牙形石Hamarodus brevirameus的首现层位,正漂移异常持续时段跨两个牙形石带(H.brevirameus带和P.inscrulptus带下部)。该同位素异常事件除了可以在上扬子台地内部很好对比外,也可对比塔里木盆地西缘柯坪地区其浪组中的三个次一级峰值的δ13C同位素正漂移异常事件,其浪组发育正漂移事件的地层厚度较大,沉积速率较上扬子台地高。研究地层中牙形石记录和碳、氧同位素曲线均显示,研究区宝塔组下部存在地层缺失,与下伏地层呈不整合接触关系,且地层缺失量比中扬子地区略少。     

新疆塔里木板块台地和斜坡相区奥陶系牙形刺生物地层--揭示沉积间断和大坪阶地层之缺失北大核心CSCD

新疆塔里木板块台地和斜坡相区,如柯坪、巴楚和塔中井下奥陶系牙形刺序列由下而上可综合为:特马豆克阶的Variabiloconus aff.bassleri生物带,Cordylodus angulatus生物带,Chosonodina herfurthi-Rossodus manitouensis生物带,Glyptoconus quadraplicatus生物带和Tripodus proteus生物带;弗洛阶的Serratognathus diversus生物带和Serratognathoides chuxianensis-Erraticodon tarimensis生物带;达瑞威尔阶的Lenodus variabilis生物带,Yangtzeplacognathus crassus生物带,Dzikodus tablepointensis生物带,Eoplacognathus suecicus生物带和Pygodus serra生物带;桑比阶的P.anserinus-Yangtzeplacognathus jianyeensis生物带,Baltoniodus variabilis生物带和B.alobatus生物带下部,以及凯迪阶的Belodina confluens生物带,Yaoxianognathus neimengguensis生物带,Y.yaoxianensis生物带和Aphelognathus pyramidalis生物带。台地和斜坡相区普遍缺失奥陶系大坪阶的牙形刺生物带,在弗洛阶与达瑞威尔阶之间可能由于海平面的下降事件而未接受沉积。柯坪大湾沟和巴楚一间房剖面仅发育Baltoniodus alobatus生物带下部,在B.alobatus生物带与Belodina confluens生物带之间可能也有间断。     

塔里木盆地塔中—巴楚地区奥陶系内幕不整合

塔里木盆地塔中-巴楚地区奥陶系内部存在一期重要的不整合。通过对数十口钻井的地层、古生物研究及与露头剖面的对比,发现该不整合的顶、底层位变化较大,地层缺失量在不同地区有所差异,可大致分为两种情况:其一是塔中地区,上奥陶统良里塔格组覆于鹰山组第三段(下奥陶统上部)之上,且有部分钻井良里塔格组下部也发育不全,缺失了至少11个牙形石带,相当于有17~20Ma的地层缺失;其二是巴楚地区,良里塔格组覆于鹰山组第二段或鹰山组第一段(中奥陶统下部)之上,缺失了至少8个牙形石带,相当于有约14Ma的地层缺失。上述地层缺失主要是由于中奥陶世以后塔里-巴楚地区出水成陆,碳酸盐岩地层受大气淡水溶蚀的结果。在不整合之下碳酸盐岩地层中形成的岩溶是十分重要的油气储层。因此,对该不整合的研究对于塔中、巴楚地区奥陶系,特别是鹰山组的油气勘探具有重要的意义。     

新疆塔里木板块台地和斜坡相区奥陶系牙形刺生物地层——揭示沉积间断和大坪阶地层之缺失

新疆塔里木板块台地和斜坡相区,如柯坪、巴楚和塔中井下奥陶系牙形刺序列由下而上可综合为:特马豆克阶的Variabiloconus aff.bassleri生物带,Cordylodus angulatus生物带,Chosonodina herfurthi-Rossodus manitouensis生物带,Glyptoconus quadraplicatus生物带和Tripodus proteus生物带;弗洛阶的Serratognathus diversus生物带和Serratognathoides chuxianensis-Erraticodon tarimensis生物带;达瑞威尔阶的Lenodus variabilis生物带,Yangtzeplacognathus crassus生物带,Dzikodus tablepointensis生物带,Eoplacognathus suecicus生物带和Pygodus serra生物带;桑比阶的P.anserinus-Yangtzeplacognathus jianyeensis生物带,Baltoniodus variabilis生物带和B.alobatus生物带下部,以及凯迪阶的Belodina confluens生物带,Yaoxianognathus neimengguensis生物带,Y.yaoxianensis生物带和Aphelognathus pyramidalis生物带。台地和斜坡相区普遍缺失奥陶系大坪阶的牙形刺生物带,在弗洛阶与达瑞威尔阶之间可能由于海平面的下降事件而未接受沉积。柯坪大湾沟和巴楚一间房剖面仅发育Baltoniodus alobatus生物带下部,在B.alobatus生物带与Belodina confluens生物带之间可能也有间断。     

浅议上扬子区下奥陶统桐梓组

华南上扬子区桐梓组为下奥陶统最底部的岩石地层单位之一。通过贵州习水吼滩剖面桐梓组的系统分析,并结合上扬子区多个相关剖面的资料,确定桐梓组以中厚层白云岩、白云质灰岩、页岩为主,偶夹薄层生屑灰岩。桐梓组主要形成于浅潮下带至深潮下带环境,其沉积厚度具由西向东逐渐增大的趋势,白云岩所占比例由西向东逐渐减少。通过对白云岩岩石学特征分析,初步得出桐梓组白云岩成因:在台地浅滩附近以混合水白云岩化为主,在台地内部以回流渗透作用为主。整个桐梓组自下而上可以建立5个牙形石带,分别是Cordylodus angulatus带、Glyptoconus quadraplicatus-Scolopodus?pseudoplanus带、Paltodus deltifer-Triangulodus proteus带、Triangulodus bifidus带、Serratognatus divers带。桐梓组上下界线均为穿时界线,底界由西向东向上穿时,顶界向下穿时。     

新疆柯坪大湾沟剖面柯坪塔格组中段底部笔石生物地层初步分析

新疆塔里木盆地西北缘柯坪大湾沟剖面柯坪塔格组中段底部的泥岩夹白云岩地层中发现有较丰富的笔石、腕足类、三叶虫、双壳类等化石,其中笔石有4属8种及2个比较种和1个未定种,可能属笔石Coronograptuscyphus带至Coronograptusgregarius带。从笔石生物地层看,柯坪塔格组中段底部的时代很可能为志留纪兰多维列世鲁丹期末至埃隆期初。     

华南下扬子区下奥陶统仑山组:岩石学、地层学和古地理学*

华南地区下奥陶统仑山组为奥陶系最底部的岩石地层单位之一,其以大套白云岩为主要特征,广泛分布于下扬子区。通过对安徽池州洪家剖面仑山组的系统分析,并结合下扬子区多个相关剖面的资料,进一步确定仑山组岩性为白云岩、灰质白云岩和白云质灰岩,夹有部分亮晶颗粒灰岩和亮泥晶颗粒灰岩。整体上以亮晶生屑灰岩或泥晶生屑灰岩的出现作为仑山组顶界,在下扬子区内部、北部及东南部地区以白云质灰岩或灰质白云岩出现为其底界,而在下扬子区西南部大部分地区则以白云岩化出现为其底界。整个仑山组所含生物化石种类和数量较少,自下而上可建立5个牙形石带,分别是Monocostatus sevierensis带、Acanthodus lineatus-A. costatus带、Scolopodus? pseudoplanus带、Glyptoconus quadraplicatus带和Paltodus deltifer-Tripodus proteus带,推测其时代为早奥陶世特马豆克早期。仑山组主要形成于浅潮下带至深潮下带环境中,其地层总厚度和其中的白云岩厚度受到古地理因素的控制。通过岩石学特征分析,推断仑山组白云岩主要为准同生条件下的多种白云岩化作用叠加中等埋藏条件下的白云岩化形成。     

华南下扬子区下奥陶统仑山组:岩石学、地层学和古地理学

华南地区下奥陶统仑山组为奥陶系最底部的岩石地层单位之一,其以大套白云岩为主要特征,广泛分布于下扬子区。通过对安徽池州洪家剖面仑山组的系统分析,并结合下扬子区多个相关剖面的资料,进一步确定仑山组岩性为白云岩、灰质白云岩和白云质灰岩,夹有部分亮晶颗粒灰岩和亮泥晶颗粒灰岩。整体上以亮晶生屑灰岩或泥晶生屑灰岩的出现作为仑山组顶界,在下扬子区内部、北部及东南部地区以白云质灰岩或灰质白云岩出现为其底界,而在下扬子区西南部大部分地区则以白云岩化出现为其底界。整个仑山组所含生物化石种类和数量较少,自下而上可建立5个牙形石带,分别是Monocostatus sevierensis带、Acanthodus lineatus-A.costatus带、Scolopodus?pseudoplanus带、Glyptoconus quadraplicatus带和Paltodus deltifer-Tripodus proteus带,推测其时代为早奥陶世特马豆克早期。仑山组主要形成于浅潮下带至深潮下带环境中,其地层总厚度和其中的白云岩厚度受到古地理因素的控制。通过岩石学特征分析,推断仑山组白云岩主要为准同生条件下的多种白云岩化作用叠加中等埋藏条件下的白云岩化形成。     

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.     

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.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861