云南宁蒗县白牛厂金矿成矿地质条件及找矿模式

云南宁蒗县白牛厂金矿断层构造控矿特征十分明显,按产出特征可分为两类:一是产于北东向顺层构造(F_8)破碎蚀变带中的似层状、透镜状矿体;二是沿北北西向断裂带充填的脉状矿体。其成因类型属断层破碎带控制的中-低温热液型矿床。     

福建明溪出水坑银多金属矿地质特征及找矿远景

明溪出水坑银多金属矿位于明溪县中溪乡西南侧,根据矿区老硐调查地质资料,结合区域地质背景、构造分布特征,探索发现的1处矿产地。矿区总体为一倒转背斜褶皱,矿体贮存在背斜褶皱轴部张性断裂带内,断裂构造控矿特征明显。通过对矿体产状、矿石组分及矿化蚀变等特征分析认为,矿床成因属构造蚀变-热液充填型。     

湘东北横洞钴矿矿床地质特征及成因机制探讨

<正>湘东北横洞钴矿产于钦杭结合带中段之湖南省浏阳市境内,受构造控制的蚀变角砾岩型钴矿床。该原生钴矿床的发现在湖南省境内尚属首例。本文通过对矿床地质特征的解剖,并结合成因矿物学研究,探讨了该矿床的成因。该矿床赋存于NE向长(长沙)—平(平江)断裂带构造蚀变角砾岩中。经地表及浅部工程控制,在构造热液蚀变岩带(Gs)中圈出钴矿体一个,该矿体地表出露长约230 m,主要产于构造热液蚀变岩带绿     

黔南独山恒丰早石炭世沉积暴露面的发现及其地质意义

本文报道了黔南恒丰地区首次发现早石炭世沉积暴露面;基于野外地质调查实测剖面,对该剖面进行综合研究,包括岩石地层、沉积相分析及生物化石、全岩微量元素地球化学特征:Sr/Ba、B、U/Th、V/Cr等进行研究。得出研究区早石炭世存在多期次沉积暴露,最后一次暴露的时间与区域上祥摆组至上司组沉积时间相当。早石炭世晚期研究区处于较为封闭的混合潮坪相沉积环境,直到最后一次暴露,海水完全退出,该区成为陆相沉积剥蚀区,导致研究区缺失祥摆组至上司组。剖面下部含鲕状赤铁矿层与"宁乡式"铁矿具相似的沉积环境,为研究区赤铁矿找矿提供了新的信息。     

福建泰宁曹家坊金矿地质特征及成因探讨

泰宁曹家坊金矿位于闽西北隆起带的浦城-洋源隆起与邵武-建宁拗陷的接合部位。区内金矿体主要呈脉状、透镜状赋存于北东东向的断裂破碎蚀变带中。矿体形态、产状严格受到断裂带的控制,矿体与围岩界线较清晰,北东东向断裂带既是导矿构造,也是容矿构造。通过对泰宁曹家坊金矿地质特征的总结与分析,初步认为该矿床的成因类型为变质-热液充填型脉状金矿床。     

福建光泽羊角尖锌多金属矿地质特征及成因探讨

光泽羊角尖锌多金属矿产于加里东期片麻状花岗闪长岩与晚元古代下峰组接触带及下峰组黑云斜长变粒岩中,目前发现的2个矿体,呈似层状、脉状产出.根据矿石矿物组合特征、结构构造及蚀变类型,分析认为矿体与硅化、黄铁矿化、绿帘石化关系密切,属沉积变质-热液改造脉状矿床.     

重庆巫山桃花铁矿床地质特征及成因

通过矿区岩相古地理条件、成矿主要物质来源、赤铁矿鲕粒的形成机制等对重庆巫山桃花铁矿床的地质特征进行描述,探讨铁矿床的成因,认为其属于“宁乡式”铁矿床,赤铁矿鲕粒以胶体化学方式沉积,成因类型系同生沉积成因。     

会泽超大型富锗银铅锌矿床矿化-蚀变分带规律及构造的控制作用

会泽超大型富锗银铅锌矿床是川—滇—黔铅锌多金属成矿区滇东北矿集区的典型代表。基于大量的地表调研和坑道精细编录,通过赋矿白云岩的岩石学、地球化学与矿化蚀变分带规律、构造对矿化-蚀变带控制作用的研究,认为赋矿粗晶白云岩是成矿过程中白云石化的产物,具有典型的热液蚀变成因,与沉积-成岩成因的摆佐组细晶白云岩、白云质灰岩明显不同;根据矿石和蚀变围岩中铅锌矿物组成与矿化、蚀变程度及其分布特征,该矿床矿化-蚀变分带规律:从矿体到围岩依次为铅锌矿石—铅锌矿化黄铁矿带→铅锌矿化/黄铁矿化粗晶白云岩带→灰白色粗晶白云岩带、米黄色粗晶白云岩带、肉红色粗晶白云岩带、网脉状白云石化灰岩带(蚀变残留体)、弱白云石化灰岩带。矿化-蚀变带明显受冲断褶皱构造(矿山厂、麒麟厂、银厂坡斜冲断层及其派生褶皱)上盘的层间断裂带控制,形成了典型的"成矿构造-蚀变白云岩-铅锌矿体"的矿化结构。该认识不仅丰富了会泽型(HZT)铅锌矿床成矿理论,而且对指导滇东北铅锌矿集区,乃至川滇黔成矿区的资源危机矿山的综合地质研究与找矿勘查具有重要的现实意义。     

和龙市星火林场地区银矿点成矿地质特征及找矿标志总结

在阐述星火林场地区银矿点地质特征的基础上,讨论矿点成因,总结找矿标志.矿点位于晚二叠世花岗闪长岩中,目前已发现三条银矿体,Ⅰ号、Ⅱ号矿体受北西向断裂构造带控制;Ⅲ号矿体位于北东向断裂带内.矿石类型为硅化蚀变岩型,矿点成因类型为岩浆热液型.硅化、钾长石化、绢云母化及黄铁矿化是矿化蚀变标志,闪长玢岩是脉岩找矿标志,Ag元素异常及Ag-Pb-Zn组合异常是地球化学找矿标志.     

云南镇雄县安家坝富铁豆鲕状赤铁矿的发现及找矿意义

通过野外调查,在云南镇雄县安家坝发现富铁豆鲕状赤铁矿体。矿体呈透镜状、似层状产出于梁山组上部,矿体产状与地层产状基本一致。通过少量剥土工程初步控制,矿体走向呈南西—北东向,倾向上延伸不明。致密状赤铁矿品位低,不具工业规模,豆鲕状赤铁矿平均品位34.09%,厚度4 m以上,达到赤铁矿最低工业指标要求。镜下显示,豆鲕状赤铁矿样品由鲕豆粒、陆源碎屑及填隙物等构成,鲕豆粒成分占40%以上,分布均匀,成分由粘土矿物构成,具弱褐铁矿化现象。研究认为,本区鲕状赤铁矿的形成经历了叠生成矿作用,原生沉积的铁质石英砂岩,经表生氧化和风化淋滤叠生成矿作用形成原生沉积+风化淋滤叠生赤铁矿床。     

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.     

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.     

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。     

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.     

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.     

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...     

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.