塔里木板块奥陶系鹰山组的地质时代北大核心CSCD

塔里木板块碳酸盐岩相的鹰山组地质时代有3种观点,分别为早奥陶世、早-中奥陶世、中奥陶世。归纳塔里木下奥陶统-中奥陶统界线附近的相关古生物资料,根据牙形石Serratognathoides chuxianensis等的延展时限,认为前人在柯坪、巴楚地区所建立的牙形石Paroistodus originalis带,Baltoniodus aff.navis带证据不足;原Tangshanodus带不能对比华北板块下马家沟组的Tangshanodus tangshanensis带,原定的Tangshanodus sp.已厘定为Erraticodon tarimensis,层位在Aurilobodus leptosomatus-Loxodus dissectus带之下和Serratognathus diversus带之上;Serratognathoides chuxianensis层位只限于下奥陶统弗洛阶的Oepikodus evae带,在塔里木该牙形石种亦仅见于A.leptosomatus-L.dissectus带之下。根据全球下奥陶统-中奥陶统界线的确认标准,宜将鹰山组上部牙形石Serratognathoides chuxianensis-Scolopodus euspinus-Erraticodon tarimensis组合划归下奥陶统弗洛阶,鹰山组时代应为早奥陶世特马豆克晚期至弗洛期。鹰山组与上覆地层之间存在沉积间断。     

塔里木盆地奥陶系牙形石带及沉积层序

通过对塔里木盆地西部柯坪、巴楚及东部却尔却克奥陶系露头剖面及盆地覆盖区钻井岩心的大量牙形石样品分析,分别建立了塔里木盆地中西部及东部地区奥陶系牙形石带序列。盆地中西部地区牙形石带共计22个,由老到新分别为Variabiloconusaff.bassleri带、Rossodusmanitouensis-Cordylodusrotundatus-Chosonodinaherfurthi组合带、Scolopodusquadraplicatus带、Glyptoconusfloweri带、Tripodusproteus/Paltodusdeltifer带、Glyptoconusunicostatus带、Serratognathusdiversus/Paroistodusproteus带、Serratognathoideschuxianensis-Scolopoduseuspinus-Erraticodontarimensis组合带、Aurilobodusleptosomatus-Loxodusdissectus组合带、Amorphognathusvariabilis带、Eoplacognathussuecicus带、Pygodusserrus带、Pygodusanserinus带、Eoplacognathusjianyeensis/Baltoniodusva-riabilis带、Eoplacognathuselongatus带、Baltoniodusalobatus带、Belodinacompressa/Periodongrandis带、Phrag-modusundatus带、Belodinaconfluens带、Yaoxianognathusneimengguensis带、Yaoxianognathusyaoxianensis带和Aphelognathuspyramidalis带;盆地东部地区下奥陶统属于深水盆地相,其特有的牙形石带主要有5个,由老到新分别为Cordyloduslindstromi带、Cordylodusangulatus带、Prioniodusgilberti带、Paroistodusproteus带和Prionio-duselegans带。同时初步建立了塔里木盆地奥陶系三级层序地层格架,并探讨了上述牙形石带与盆地奥陶系主要构造单元岩石地层单位以及全盆地可对比的6个三级层序之间的关系。     

乐山范店牙形石的发现及寒武-奥陶系界线——兼论牙形石色变指数与含油气关系

本文对四川乐山范店寒武、奥陶系界线上下的牙形石进行了研究,已发现有5属11种.其组合面貌与我国华北、南方地区下奥陶统最底部的牙形石组合大体一致,从而为该地寒武-奥陶系界线的重新划分提供了生物化石依据.确认该地白云岩与灰岩的界线并不是真正的寒武-奥陶系分界线,正确的分界线应在原岩性界线之下约5m的白云岩处.因此,本剖面中-上寒武统洗象池组顶部约5m的白云岩不是寒武系,应属奥陶系.最后,对界线上下牙形石的颜色进行鉴定,其色变指数低,属2级,为生成液态烃适宜的成熟度范围,提出是有利的生油区之一     

贵州北部中奥陶统的牙形石

贵州北部中奥陶统碳酸盐地层发育良好,笔者在毕节、仁怀、桐梓、正安、德江、秀山等地试作了牙形石生物地层工作,获得了较多的牙形石资料,为牙形石带的建立和对比提供了依据(图1)。 一、剖面介绍 1.毕节燕子口剖面 上覆地层 涧草沟组 整合 宝塔组 35—39 浅灰至深灰色中原 至厚层泥晶龟裂纹灰岩,含少许 泥质,局部为粘土质灰岩.产角石:Sinoceras chinense,Michelinoceras sp.,Richardsonoceras sp. 等;牙形石:Dapsilodus similaris,D.procerus,Protopanderodus。liripipus,Panderodus gracilis,     

沿河土地坳中奥陶统牙形石生物地层

本文论述了贵州沿河土地坳中奥陶统牙形石生物地层，该地中奥陶统（十字铺组和宝塔组）地层发育，岩性以碳酸盐类为主，牙形石较丰富，其牙形石组合面貌与扬子地区基本一致，系属北大西洋生物地理区。     

宜昌地质矿产研究所2002年度地调科研项目重要进展综述

20 0 2年度 ,我所共承担各类地调科研项目 2 4个。经广大科技人员的艰苦努力 ,各项目进展顺利 ,取得了一批重要的地质成果。现综述如下 :1　地层古生物成果举世瞩目1 .1　宜昌黄花场剖面有望成为全球中下奥陶统界线的“金钉子”全球中下奥陶统界线的划分和层型剖面的选择 ,是目前国际奥陶系分会研究和讨论的重点。1 999年由美国推荐的全球中下奥陶统界线层型Whiterock Narrow剖面 ,经进一步研究发现 ,国际奥陶系分会规定的界线生物标志——牙形石Tripoduslaevis,在该剖面上的产出层位并非是该种的首现层位 ,较之所期望的层位要高得多。为…     

塔里木盆地阿克库勒地区下奥陶统古岩溶及油气分布

下奥陶统碳酸盐岩是阿克库勒地区主要含油气层,岩溶作用是影响奥陶系储层发育的最主要因素。本文详细论述了该区下奥陶统发育多期岩溶,海西早期是主岩溶期,该期岩溶主要形成于表生大气淡水条件下,岩溶作用深度和范围受志留-泥盆系和上奥陶统隔水层限制。指出岩溶斜坡区的地表岩溶带及潜流岩溶带上部是有利的储层发育和油气主要富集区带。     

全球下奥陶统-中奥陶统界线层型候选剖面——宜昌黄花场剖面研究新进展

湖北宜昌黄花场剖面是我国奥陶系大湾阶的界线层型剖面，高精度生物地层以及岩石、层序地层和碳同位素地球化学的综合研究表明，该剖面完全符合关于建立全球下奥陶统一中奥陶统界线（即奥陶系第三个尚待正式命名的阶）界线层型剖面和点位（GSSP）的条件。建议以该剖面牙形石Baltoniodus？triangularis的首现层位，作为划分全球下奥陶统一中奥陶统界线的GSSP。所建议的GSSP交通方便，位于距宜昌市北北东22km的公路旁，地层出露完美无缺，界线生物层位于大湾组下段SHod-16层底部，距大湾组底部10．57m；界线上下发育了B．？triangularis的完整演化序列，并伴生有极好的Baltoniodus、Trapezognathus、Periodon和Microzarkodina等牙形石属种演化序列来作为佐证；界线之上0．2m所出现的世界广布的Microzarkodina abellum可作为划分此界线的辅助标志。界线生物层位于低位海侵序列之中，界线之下0．6m处所显示的从高位到低位的层序转换面和碳同位素最大偏移，与全球此时所发生低位事件密切相关，可作为识别该界线的物理和化学标志。所建议的界线生物层与笔石Azygograptus suecicus生物带上下组合之间的界线接近，与几丁虫Belonechitina cf．henryi生物带底界几乎一致，因此，所建议的界线易于在全球，无论浅水碳酸盐相、还是深水笔石相，识别和进行精确对比。同样的生物组合序列和层序及碳同位素异常亦在黄花场剖面之北5km的陈家河（即大坪）剖面得到了验证．     

塔河油田加里东期岩溶储层特征及分布预测

岩溶储层是塔河油田奥陶系碳酸盐岩的主要储层，是海西早期与加里东期岩溶作用的结果。海西期岩溶储层主要发育在石炭系直接覆盖于中下奥陶统之上的地区，上奥陶统覆盖区的岩溶储层主要是加里东期岩溶作用形成的。地震剖面奥陶系反射波组底部上超、顶部削切特征，牙形剌化石带的缺失、志留系层序地层对比均证实奥陶系在加里东中期有过隆升剥蚀，说明塔河油田具备有加里东岩溶作用的地质条件，锶同位素特征证实了加里东期岩溶洞穴的存在。在上奥陶统覆盖区，岩溶储层主要发育于加里东不整合面(T47和T27)下300 m之内，岩溶储层中，岩溶洞穴高度主要为0～30 m之间，最大可达75 m，显然是加里东中期岩溶作用的产物。加里东期断裂控制了加里东岩溶储层的发育，由此预测了加里东期岩溶储层的发育区带。     

华南下/中奥陶统界线附近笔石相的分异与全球下/中奥陶统界线生物标志的选择

通过对宜昌黄花场(扬子地台中部)大湾组剖面和重庆城口(扬子地台北部)的湄潭组剖面笔石动物群特征的分析,结合江西崇义地区(盆地相)、江南过渡带笔石动物群的研究成果,讨论了华南下／中奥陶统界线附近笔石相分异的现象,并探讨了下／中奥陶统界线附近笔石动物和牙形石的相互关系。认为宜昌黄花场剖面完全具备建立全球下／中奥陶统界线层型剖面和点(GSSP)的条件,牙形石B.triangularis的首次出现(FAD)是良好的界线生物标志。     

Police, politics, and the right to the city

Space and spatiality have recently been at the core of debates concerning the political possibilities of the city. The arguments advanced in this paper might be seen as an attempt to contribute to these debates through a reflection on the spatiality of (in) justice, politics, and the right to the city. The case of French urban policy, with its focus on distressed urban areas, and the `suburban problem' in France are used as examples to make arguments more concrete.     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

This paper reports the first results of a study of 11 isotope systems (³He/⁴He, ⁴⁰Ar/³⁶Ar, ³⁴S/³²S, ⁶⁵Cu/⁶³Cu, ⁶²Ni/⁶⁰Ni, ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ^206–208Pb/²⁰⁴Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.     

Influences of the unsaturated,saturated, and riparian zones on the transport of nitrate near the Merced River,California, USA

Transport and transformation of nitrate was evaluated along a 1-km groundwater transect from an almond orchard to the Merced River, California, USA, within an irrigated agricultural setting. As indicated by measurements of pore-water nitrate and modeling using the root zone water quality model, about 63% of the applied nitrogen was transported through a 6.5-m unsaturated zone. Transport times from recharge locations to the edge of a riparian zone ranged from approximately 6 months to greater than 100 years. This allowed for partial denitrification in horizons having mildly reducing conditions, and essentially no denitrification in horizons with oxidizing conditions. Transport times across a 50–100-m-wide riparian zone of less than a year to over 6 years and more strongly reducing conditions resulted in greater rates of denitrification. Isotopic measurements and concentrations of excess N₂ in water were indicative of denitrification with the highest rates below the Merced River. Discharge of water and nitrate into the river was dependent on gradients driven by irrigation or river stage. The results suggest that the assimilative capacity for nitrate of the groundwater system, and particularly the riverbed, is limiting the nitrate load to the Merced River in the study area.     

扬子北缘马元铅锌矿床闪锌矿微量元素及S-Pb-He-Ar-C同位素地球化学研究

马元铅锌矿床是近年扬子陆块北缘铅锌找矿的新突破。矿体呈层状、似层状产于碑坝隆起翼部震旦系灯影组角砾状白云岩层间构造带中,围岩蚀变很弱。矿石中硫化物以闪锌矿、方铅矿为主,中粗粒晶质结构,充填于白云岩角砾间。闪锌矿富集Cd、Ge、Ag,贫In、Tl、Se,Ga/In为6~132,Ge/In多1000,成矿温度以中-低温为主。金属硫化物ε~(34)S值相对集中,为12.9‰~19.4‰,平均为17.4‰,来自于海相硫酸盐的还原。铅同位素组成稳定,~(206)Pb/~(204)Pb为17.858~17.918:~(207)Pb/~(204)Pb为15.603~15.694;~(208)Pb/~(204)Pb为37.756~38.046,具有造山带和上地壳铅的特征,震旦系可能提供了金属成矿物质。闪锌矿中流体包裹体的~3He/~4He为0.03Ra~1.05Ra,~(40)Ar/~(36)Ar为326.1~765.1,~(38)Ar/~(36)Ar为0.183~0.204,表明成矿流体主要为地壳流体和饱和大气水(大气降水或海水)的混合。闪锌矿内流体包裹体挥发分δ~(13)C_(CH_4)值为-36.01‰~-28.80‰,δ~(13)C_(C_2H_6)值为-27.72‰~-22.44‰,δ~(13)C_(CO_2)值为-23.24‰~-9.68‰,表明有机流体参与了成矿作用。石英、方解石的H-O同位素结果表明具有海水和有机水混合的特征。可见,成矿流体具有两种流体混合的特征,一为蒸发海水与围岩反应所形成的盆地卤水,二为有机流体。推测矿区可能存在一个古油气藏,由于TSR生成一高硫气藏,为区内还原性有机流体的主要来源。当富含Pb、Zn等成矿物质的成矿流体运移至富含CH_4和H_2S的还原性流体的矿区角砾岩带时,两种流体混合,Pb、Zn等遇到H_2S发生反应而沉淀成矿,并伴生热液白云石等,形成了马元铅锌矿床。综上所述,我们认为马元矿床属MVT型铅锌矿床。     

Rb-Sr, K-Ar, H-and O-Isotope systematics of the Middle Riphean shales from the Debengda Formation, the Olenek Uplift, North Sibera

Clay subfractions (SFs) of <0.1, 0.1–0.2, 0.2–0.3, 0.3–0.6, 0.6–2 and 2–5 μm separated from Middle Riphean shales of the Debengda Formation are studied using the TEM, XRD, K-Ar and Rb-Sr isotopic methods. The oxygen and hydrogen isotope compositions in the SFs are studied as well. The low-temperature illite-smectite is dominant mineral in all the SFs except for the coarsest ones. The XRD, chemical and isotopic data imply that two generations of authigenic illite-smectite different in age are mixed in the SFs. The illite crystallinity index decreases in parallel with size diminishing of clay particles. As compared to coarser SFs, illite of fine-grained subfractions is enriched in Al relative to Fe and Mg, contains more K, and reveals higher K/Rb and Rb/Sr ratios. The Rb-Sr age calculated by means of the leachochron (“inner isochron”) method declines gradually from 1254-1272 Ma in the coarsest SFs to 1038-1044 Ma in finest ones, while the K-Ar age decreases simultaneously from 1225–1240 to 1080 Ma. The established positive correlation of δ¹⁸O and δD values with dimensions of clay particles in the SFs seems to be also consistent with the mixing systematics. The isotopic systematics along with data on mineral composition and morphology lead to the conclusion that mixedlayer illite-smectite was formed in the Debengda shales during two periods 1211–1272 and 1038–1080 Ma ago. The first period is likely close to the deposition time of sediments and corresponds to events of burial catagenesis, whereas the second one is correlative with the regional uplift and changes in hydrological regime during the pre-Khaipakh break in sedimentation.     

Delivery of Trace Metals (Al,Fe, Mn,V, Co,Ni, Cu,Cd, Ag,Pb) from the Trinity River Watershed Towards the Ocean

The Trinity River (Texas, USA) contains in its watershed 23 different reservoir lakes, the largest one being Lake Livingston situated in the lower Trinity River watershed and two potentially polluting metroplexes, Dallas and Houston. In order to determine fluxes of nutrients and trace metals to Galveston Bay, a survey that included 24 discreet samples collected over a year and at various stages of discharge was carried out during 2000–2001. Geochemical (i.e., sorption by Fe oxyhydroxides), biological (i.e., seasonal uptake by sinking algae in Lake Livingston), and hydrological (i.e., dilution effects by increasing flow rates) controls were found to be mainly responsible for variations in dissolved trace metal concentrations rather than pollution sources. The Trinity River loads of suspended sediments and pollutant trace metals entering Galveston Bay at Anahuac were <20% of those reaching Lake Livingston, and only a few percent of the total upstream trace metal load is entering the Gulf of Mexico. Thus, during the transit through the 23 man-made lakes and an estuary, >96% of the pollutant trace metal load is lost to sediments.     

海南长塘岭矿区大坡岩体岩石学、地球化学特征及其含矿性初探

海南大坡岩体位于五指山褶皱带内,主要受昌江—琼海构造带、琼西构造带与潭爷断陷构造带控制.岩石地球化学及岩石学研究表明,大坡岩体形成于海西-印支晚期,岩性单一,主要为中细粒似斑状黑云母二长花岗岩.岩体显示为Ⅰ型花岗岩与S型花岗岩的混合,主体以地壳物质部分熔融为主,形成过程有少量地幔物质加入.元素对的比值及稀土元素配分特征说明岩体钨锡等多金属含矿性可能较差.     

贵州岑巩羊桥罗家塘杷榔动物群的发现及其后生动物早期演化的意义

岑巩县羊桥乡罗家塘杷榔组仅出露中-上部地层,岩性单一,均为青灰、灰绿色粉砂质泥、页岩.在其上部层位发现了俞氏贵州始海百合(Guizhoueocrinus yui Zhao,Parsley et Peng,2007),计有棘皮动物始海百合、腕足动物、软体动物-软舌螺、节肢动物-三叶虫等8属9种,包括了2个未定名的新种和1...     

Breakthroughs in the biodiversity, biogeography, biostratigraphy, and basin analysis of the Beaufort group

Over the past decade researchers working on the rocks of the Beaufort Group in the main Karoo Basin of South Africa have vastly increased our understanding of this important Permo-Triassic sequence. Many new fossil forms have been discovered, allowing for breakthroughs into the biodiversity, biogeography and biostratigraphy of the group. Taxonomic and phylogenetic advances are many and varied, and cover most of the vertebrate taxa, but with emphasis placed on the temnospondyl amphibians, archosauriforms and non-mammalian synapsids, in particular the anomodontia. Biostratigraphic breakthroughs have centered on the Middle Permian Eodicynodon and Tapinocephalus assemblage zones, the Late Permian Dicynodon Assemblage Zone, and the Triassic Lystrosaurus and Cynognathus assemblage zones. Correlation of these biozones with better dated sequences in Europe, Russia and China has allowed for many chronostratigraphic refinements, which are in turn vital for sequence stratigraphical analysis of the basin fill. Based on fossil data, both the lower (Ecca–Beaufort) and upper (Beaufort–Molteno) contacts of the group have been proved to be highly diachronous. The refined chronostratigraphic framework has also allowed for a better analysis of the basin evolution through time, particularly in terms of the correlation of external stimuli that affect basin sedimentation patterns.