海拉尔盆地呼和湖凹陷南屯组典型砂体的特征分析

根据岩芯、电测曲线、录井、分析化验、地震等资料,分析了呼和湖凹陷下白垩统南屯组沉积相类型、沉积特征以及分布规律。研究表明,南屯组发育扇三角洲、辫状河三角洲、湖底扇和湖泊4种沉积相。扇三角洲主要分布在南一段的西北缓坡带和东南陡坡带,辫状河三角洲主要分布在南二段以及南一段的北部斜坡带,而在深湖-半深湖相中发育湖底扇。指出呼和湖凹陷南部沉积砂体为较有利的勘探区域,其中扇三角洲和辫状河三角洲前缘亚相带是油气聚集的重要相带。     

济阳坳陷青东凹陷新近系沙河街组沉积体系研究

新近系沙河街组是青东凹陷区块油气勘探的主要目的层位,但目前并没有研究者对其中有利沉积相带及沉积体系有过系统的研究,这极大制约了进一步的油气勘探开发。本文以沉积学、地层学理论为指导,依据岩芯、录井、测井及地震等资料,运用沉积学、古生物学、地球化学以及地球物理学的沉积相标志,在青东凹陷区块新近系沙河街组地层内划分出三角洲体系和湖泊体系两类沉积体系,并进一步划分出了扇三角洲、三角洲、滩坝、近岸水下扇、湖底扇、湖泊等6个沉积相及相对应的亚相和微相,为青东凹陷地区有利储层的预测以及进一步的油气开发提供了重要依据。     

北黄海盆地中生界沉积充填及有利生储盖组合

沉积充填生储盖组合中生界北黄海盆地北黄海盆地是我国海域油气勘探的新区,成藏条件及其时空匹配研究薄弱,是制约该区油气勘探取得突破的重要基础地质问题之一。通过岩心、钻井、测井及地震资料等的综合分析,对中生界构造格架下的沉积充填及有利生储盖组合特征进行了系统研究。结果表明,北黄海盆地中生界为断陷湖盆,中侏罗统以湖泊沉积为主,上侏罗统主要发育三角洲-湖泊沉积体系,下白垩统发育扇三角洲-湖泊沉积体系。北黄海盆地中生界发育2套有利的生储盖组合,上侏罗统上部的半深湖相暗色泥岩有机质丰富,构成研究区主力烃源岩,与下白垩统扇三角洲储集砂体及其上部滨浅湖泥岩组成的复合型组合,为空间匹配最好的生储盖组合;上侏罗统烃源岩与其中下部三角洲河道砂体组成的倒灌式间断型组合,为另一套较有潜力的组合,储层物性及断裂-不整合面输导是决定生储盖组合优劣的关键。     

叠合断陷盆地沉积体系分析--以东海丽水-椒江凹陷为例

 丽水-椒江凹陷是我国近海海域典型的叠合断陷盆地。综合分析岩芯、地震、录井、测井等资料,对东海丽水-椒江凹陷沉积体系开展了重点研究。分析认为,古新世研究区主要发育5种沉积体系:扇三角洲体系、三角洲体系、湖泊体系、海洋体系及重力流体系。在此基础上对古新统各组的沉积体系展布进行了深入探讨,其中,断陷初期月桂峰组为湖泊沉积环境,而后断陷继续,海侵发生,沉积环境转变为海洋环境;古新统沉积期三角洲体系主要发育于凹陷西缓坡,以闽浙隆起为物源,扇三角洲主要发育于同沉积断裂控制的东侧陡坡带,在月桂峰及灵峰组沉积期,灵峰潜山出露水面,其两侧形成多个扇三角洲（近岸水下扇）沉积。基于以上研究,预测出研究区的两个有利勘探相带:灵峰潜山两侧扇三角洲（近岸水下扇）及滨浅海（湖）砂体、丽水西次凹西斜坡南部与断块有利构造相匹配的三角洲前缘及滑塌重力流砂体。     

北部湾盆地福山凹陷古近纪湖底扇沉积演化及模式探讨

综合应用地震、测井及岩心观察资料，对福山凹陷古近纪流沙港组的湖底扇沉积进行了详细研究。认为该期的湖底扇沉积主要是由于三角洲前缘带的砂体在重力作用下进入湖泊深水区堆积而形成，部分是由位于湖盆陡坡边缘的河道砂沿水下河道进入湖泊深水区而形成的水下重力流沉积。从空间分布来看，湖底扇主要分布在凹陷的北部和西部，且北部和西部湖底扇的扇体规模较东部大，存活时间较东部长。平面上湖底扇位于三角洲体系的外侧，垂向上由下至上发育着从湖底扇一三角洲前缘远端一三角洲前缘近端的沉积演化序列。湖底扇的总体沉积模式为南部的辫状河三角洲砂岩碎屑体向北推进至深湖区形成孤立的、规模相对较大的湖底扇砂体；而西部及东部的次要物源——辫状河三角洲也在东西两侧活动断层的控制下在湖盆深处形成湖底扇沉积体。     

北黄海东部次盆地下白垩统沉积环境及沉积充填

下白垩统是北黄海东部次盆地目前最重要的油气勘探层位,准确认识下白垩统的沉积特征,对下一步油气勘探战略选区及优化勘探部署具重要意义。依据钻测井、地震资料,利用古生物、地球化学、地球物理等手段,研究了下白垩统的沉积相类型,分析了古气候、古盐度、古水动力、古物源等沉积环境,最终探讨了三级层序地层格架内下白垩统的沉积充填及演化。结果表明,北黄海东部次盆地下白垩统发育扇三角洲-湖泊沉积体系。该时期以亚热带炎热半干旱气候为主,夹短暂温湿气候。古水体为淡水-半咸水性质,接受来自北部、东部、西南等多个方向的物源供给。早期地层分布局限,以滨浅湖亚相、扇三角洲相沉积为主;之后,湖泊水体范围扩大,发育扇三角洲平原-扇三角洲前缘-滨浅湖亚相沉积序列;中晚期地层受区域抬升作用的影响,仅残存于盆地西北部,以滨浅湖相沉积为主。     

内蒙古西部雅布赖盆地侏罗纪沉积-构造演化及油气勘探方向

雅布赖盆地侏罗系为本区主要的勘探目的层。整个侏罗系表现为一个沉积水体由浅—深—浅的演化过程。中—下侏罗统青土井群自下而上划分为3段:第一段为断陷早期沉积的扇三角洲相;第二段为河流、湖盆发育时期产生的冲积扇、扇三角洲、滨浅湖、半深湖亚相等沉积;第三段是在湖泊范围明显增大时期形成的扇三角洲—半深湖亚相沉积。上侏罗统沙枣河组为盆地萎缩时期形成的滨浅湖、冲积扇—河流沉积。认为青土井群二段、三段是主力烃源岩。结合区域构造演化和圈闭条件分析,认为萨尔台凹陷为有利的勘探区,黑沙构造带、黑茨湾地层不整合带为较有利的勘探区带。     

酒泉盆地营尔凹陷下沟组沉积特征及其控制因素

营尔凹陷白垩系下沟组是目前酒泉盆地油气勘探中寻找岩性油气藏最有利的层段之一,对其沉积体系展开系统的研究可为下一步勘探部署提供重要的指导。综合运用岩心、测井、录井等资料,对营尔凹陷下沟组的沉积体系展开了细致的鉴别和演化特征研究,结果表明,下沟组主要发育4种沉积体系:辫状河三角洲沉积体系、扇三角洲沉积体系、湖底扇沉积体系和湖泊沉积体系。辫状河三角洲主要发育于凹陷的西北部缓坡带,越过长2断层坡度变陡、湖盆加深,演化为湖底扇沉积体系。扇三角洲发育于研究区东北、东南和西南部的陡坡背景下,湖相沉积主要发育于北部次凹和南部次凹。沉积体系演化可以划分为3个阶段:下沟组一段沉积时期湖盆快速充填阶段;下沟组二段沉积时期湖盆扩张阶段;下沟组三段沉积时期稳定的三角洲沉积阶段。进一步研究表明,沉积体系类型及展布范围受到不同类型的同沉积断裂及其组合样式的控制,而物源发育和砂体展布样式则受到传递带的影响。     

海-塔盆地中部断陷带南屯组沉积体系配置及有利相带分析

本文充分利用岩芯、测井、地震及分析化验等资料,对海-塔盆地中部断陷带4个主力凹陷的南屯组砂体类型及分布特征进行了详细研究。结果表明,南屯组主要发育扇三角洲、近岸水下扇、辫状河三角洲和湖底扇等4种典型类型砂体,并从沉积背景、发育部位、沉积特征、搬运机制以及地震反射特征等5个方面,分不同角度、不同层次详细阐述了扇三角洲、近岸水下扇、辫状河三角洲和湖底扇的识别标志;其中扇三角洲主要分布在乌尔逊凹陷和贝尔凹陷的陡坡带,近岸水下扇主要分布在南贝尔凹陷和塔南凹陷的陡坡带,而辫状河三角洲主要分布乌尔逊凹陷、贝尔凹陷和南贝尔凹陷的缓坡带。从盆地边部向盆地中心方向,沉积相由扇三角洲、近岸水下扇和辫状河三角洲沉积逐渐过渡为半深湖-深湖相沉积,局部半深湖-深湖相中发育湖底扇沉积体系,整体具有“南北分块、东西分带”的沉积格局。综合研究表明,扇三角洲前缘、近岸水下扇中扇和辫状河三角洲前缘砂体是油气富集的有利沉积相带,而洼槽边缘的湖底扇砂体为岩性油气藏勘探的重点对象。     

内蒙古二连盆地乌兰察布坳陷白垩系特征及铀成矿类型

根据近年在二连盆地乌兰察布坳陷构造类型、沉积体系等方面取得的研究成果,结合前人在本区不同层位发现了不同成因类型的铀矿化,期待企望建立盆地不同构造演化阶段沉积特征与铀成矿类型之间的有机联系。研究认为本区具备多个有利的铀成矿层位和多种铀成矿类型,其中,上白垩统二连组发育冲积(扇)平原和湖泊沉积体系,有利于形成沉积成岩型铀矿床;下白垩统巴彦花群赛汉组发育河流和沼泽沉积体系,有利于形成古河谷型铀矿床;下白垩统巴彦花群腾格尔组发育扇三角洲、辫状河三角洲和湖泊沉积体系,有利于形成同沉积叠加潜水—层间氧化改造型铀矿床。     

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.     

山西五台山区滹沱群变质玄武岩岩石学、地球化学特征及其成因意义

在野外地质调查的基础上,选取滹沱群豆村亚群底部四集庄组玄武岩、顶部青石村组玄武岩和东冶亚群中下部河边村组玄武岩,进行岩石学和地球化学研究。分析结果表明：玄武岩主量元素高TiO2、TFeO,低MgO,具有演化的基性岩浆的特征。稀土元素含量相对较高,具有弱—中等程度的轻稀土元素富集,中等程度的轻重稀土元素分异,轻微的Eu异常;玄武岩中Cr、Ni含量变化较大,但与Mg#具有很好的正相关性。微量元素配分图解中具有明显的Sr负异常,部分样品具有Nb、Ta和Ti负异常,无Zr、Hf负异常,与岛弧火山岩不同;同时Nb、Ta无分异,Zr/Hf值较高,具有板内玄武岩浆的特征。综合分析认为,滹沱群玄武岩可能形成于板内裂谷环境。在岩浆上升过程中发生橄榄石与尖晶石的分离结晶作用,同时不同程度地受到地壳的混染。     

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...     

深港西部通道填海区地下水铜、钒、铊、镉、钨迁移的实验研究

填海工程使滨海地区的地下水物理化学条件改变,导致该区域地下水中重金属浓度升高。本文以深港西部通道填海区为例,采用实验室模拟填海条件的办法,初步探讨了影响填海区地下水重金属迁移的关键因素。模拟实验结果表明,填海区地下水中钨元素含量升高与地下水淡化、淤泥氧化过程以及填料风化有关;铜元素含量升高则与淤泥氧化过程以及填料风化有关;钒元素含量升高与地下水淡化和淤泥氧化过程有关,而其他元素含量升高则主要与填料风化释放有关。     

西藏南木林县秦马弄地区二长花岗岩体岩石成因

以出露在西藏南木林县秦马弄地区二长花岗岩体为研究对象,从野外地质调查、岩石学、LA-ICP-MS锆石U-Pb定年、元素和Lu-Hf同位素地球化学等方面对其进行了分析研究。结果显示：秦马弄地区二长花岗岩体类似于A型花岗岩,形成于古近纪(E1),其LA-ICP-MS锆石U-Pb年龄为(62.0±0.5)~(63.0±0.5) Ma;岩体形成的温度较高(锆石饱和温度为745~805 ℃,平均766 ℃);岩石富SiO2(72.6%~75.0%)、Na2O(2.86%~3.59%)和K2O(4.12%~5.25%),贫CaO(0.72%~1.39%)和MgO(0.26%~0.36%),高FeOT/MgO值(7.26~10.3),属高钾钙碱性系列,弱过铝质;岩石具明显的负Eu异常(Eu/Eu*=0.40~0.70),普遍表现出Ba、Sr、P、Ti元素的亏损和Rb、Th、K、Zr、Hf元素的富集。εHf(t)值为-4.7~-1.8,其两阶段地壳Hf模式年龄tDM2为(1.1~1.3) Ga。秦马弄A型花岗岩体是冈底斯基底地壳物质部分熔融的岩浆产物,形成于古近纪印度板块与欧亚板块俯冲碰撞引起的总体为岛弧背景下的局部拉张构造环境。     

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。     

Geology, mineralogy, and PGE mineralization of the copper-nickel occurrences of the Kvinum ore field, Sredinny Range, Kamchatka

The geology and mineralogy of host metamorphic rocks, the mineralogy of sulfide ores, and the distribution of PGE mineralization were studied in detail for the Kvinum-1 and Kvinum-2 copper-nickel occurrences of the Kvinum ore field, which are the most promising targets for the copper-nickel-PGE mineralization of the Sredinny Range of Kamchatka. It was established that stringer-disseminated and massive copper-nickel ores are localized in amphibole peridotites, cortlandites, and form ore bodies varying from tens of centimeters to 5–20 m thick among the layered cortlandite-gabbroid massifs. The massive sulfide ores were found only at the bottom of cortlandite bodies and upsection grade into stringer-disseminated and disseminated ores. Pyrrhotite, chalcopyrite, and pentlandite are the major ore minerals with a sharply subordinate amount of pyrite, sphalerite, galena, arsenopyrite, and löllingite. Besides pentlandite, the Ni-bearing minerals include sulforasenides (gersdorffite), arsenides (nickeline), and tellurides (melonite) of nickel. It was found that PGE mineralization represented by antimonides (sudburyite) and tellurobismuthides (michenerite) of Pd with sharply subordinate platinum arsenide (sperrylite) is confined to the apical parts of massive sulfide zones and the transition zone to the stringer-disseminated ores. Ore intervals enriched in arsenides and tellurides of Ni, Pd, and Bi contain high-purity gold. In the central parts of the orebodies, the contents of PGE and native gold are insignificant. It is suggested that the contents of major sulfide minerals and the productivity of PGE mineralization in the cortlandites are defined by combined differentiation and sulfurization of ultramafic derivatives under the effect of fluids, which are accumulated at the crystallization front and cause layering of parental magmas with different sulfur contents. The fluid-assisted layering of mafic-ultramafic massifs resulted in the contrasting distribution of PGM in response to uneven distribution of sulfur (as well as As, Te, and Bi) during liquid immiscibility. The productivity of PGE mineralization significantly increases with increasing contents of S, As, Te, and Bi (elements to which Pt and, especially, Pd have high affinity) in fluids.     

Depth of the base of the Jackson aquifer, based on geophysical exploration, southern Jackson Hole, Wyoming, USA

 A geophysical survey was conducted to determine the depth of the base of the water-table aquifer in the southern part of Jackson Hole, Wyoming, USA. Audio-magnetotellurics (AMT) measurements at 77 sites in the study area yielded electrical-resistivity logs of the subsurface, and these were used to infer lithologic changes with depth. A 100–600 ohm-m geoelectric layer, designated the Jackson aquifer, was used to represent surficial saturated, unconsolidated deposits of Quaternary age. The median depth of the base of the Jackson aquifer is estimated to be 200 ft (61 m), based on 62 sites that had sufficient resistivity data. AMT-measured values were kriged to predict the depth to the base of the aquifer throughout the southern part of Jackson Hole. Contour maps of the kriging predictions indicate that the depth of the base of the Jackson aquifer is shallow in the central part of the study area near the East and West Gros Ventre Buttes, deeper in the west near the Teton fault system, and shallow at the southern edge of Jackson Hole. Predicted, contoured depths range from 100 ft (30 m) in the south, near the confluences of Spring Creek and Flat Creek with the Snake River, to 700 ft (210 m) in the west, near the town of Wilson, Wyoming. Received, May 1997 · Revised, February 1998 · Accepted, April 1998     

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.