Kema terrane: A fragment of a back-arc basin of the early Cretaceous Moneron–Samarga island-arc system, East Sikhote–Alin range, Russian Far East     

Alexander I.  Malinovsky  Vladimir V.  Golozoubov  Vladimir P.  Simanenko  Ludmila F.  Simanenko 《Island Arc》2008,17(3):285-304

Abstract The Kema terrane is a suite of Barremian(?)–Aptian to Albian volcano-sedimentary rocks of Sikhote–Alin that are interpreted as deposits of the back-arc basin of the Moneron–Samarga island-arc system. Compositional features of the different-type deposits indicate a near-slope depositional environment influenced by volcanic processes. Studies of slump fold orientation testify to the accumulation of material from southeast to northwest by gravitational sliding. Compositional characteristics of terrigenous rocks suggest the major provenance for detrital material was an ensialic volcanic island arc. Petrochemical characteristics of basaltic rocks indicate that the formations studied were confined to the back part of the arc.  相似文献   

Tectonics and sedimentation around Kashinosaki Knoll: A subducting basement high in the eastern Nankai Trough     

Toshihiro  Ike  Gregory F.  Moore  Shin'ichi  Kuramoto  Jin-Oh  Park  Yoshiyuki  Kaneda  Asahiko  Taira 《Island Arc》2008,17(3):358-375

Abstract   When seamounts and other topographic highs on an oceanic plate are subducted, they cause significant deformation of the overriding plate and may act as asperities deeper in the seismogenic zone. Kashinosaki Knoll (KK) is an isolated basement high of volcanic origin on the subducting Philippine Sea Plate that will soon be subducted at the eastern Nankai Trough. Seismic reflection imaging reveals a thick accumulation of sediments (∼1200 m) over and around the knoll. The lower portion of the sedimentary section has a package of high-amplitude, continuous reflections, interpreted as turbidites, that lap onto steep basement slopes but are parallel to the gentler basement slopes. Total sediment thickness on the western and northern slopes is approximately 40–50% more than on the summit and southeastern slopes of KK. These characteristics imply that the basal sedimentary section northwest of KK was deposited by infrequent high-energy turbidity currents, whereas the area southeast of KK was dominated by hemipelagic sedimentation over asymmetric basement relief. From the sediment structure and magnetic anomalies, we estimate that the knoll likely formed near the spreading center of the Shikoku Basin in the early Miocene. Its origin differs from that of nearby Zenisu Ridge, which is a piece of the Shikoku Basin crust uplifted along a thrust fault related to the collision of the Izu–Bonin arc and Honshu. KK has been carried into the margin of the Nankai Trough, and its high topography is deflecting Quaternary trench turbidites to the south. When KK collides with the accretionary prism in about 1 My, the associated variations in sediment type and thickness around the knoll will likely result in complex local variations in prism deformation.  相似文献   

山东东营凹陷东部浊积扇油藏成藏条件与模式   总被引：6，自引：6，他引：0  

孙海宁  夏景生  钟建华  王志坤 《地质力学学报》2008,14(3):221-230

岩性油气藏已成为东营凹陷油气勘探重点。东营凹陷东部在沙三、沙四段沉积时期发育了大量厚层烃源岩, 为圈闭成藏提供了充足的油气资源。勘探证实, 东营凹陷东部发育三角洲前缘滑塌浊积、深水浊积扇等砂体类型, 同时发育断裂型、砂体型、不整合面型等多种输导体系和良好的泥岩盖层。生、储、盖条件在时间、空间上具有良好的组合关系, 为形成砂岩透镜体岩性油气藏和构造-岩性油气藏提供了良好条件。   相似文献   

东营凹陷永55区块沙四上亚段深水浊积扇沉积与油气   总被引：2，自引：1，他引：1  

张晶  王伟锋  荣启宏  史文东 《吉林大学学报(地球科学版)》2007,37(3):519-524

深水浊积扇是东营凹陷北部陡坡带永55区块沙四上亚段最发育的沉积相,也是最有利的砂砾岩储层。在岩心观察基础上,通过薄片鉴定、粒度分析等测试手段,综合地质、物探和测井资料,对永55区块砂砾岩体储层的沉积特征进行了研究。结果表明,本区深水浊积扇沉积具有如下特征：(1)岩石成分成熟度和结构成熟度均较低;(2)碎屑物质以递变悬浮搬运为主;(3)沉积构造具有典型的重力流成因特征;(4)岩心中见典型鲍马沉积序列。建立了深水浊积扇退积型沉积模式,并进一步细分为内扇、中扇和外扇3个亚相及4个微相。位于中扇的辫状沟道砂体物性好,可以构成优质储层,较深湖暗色泥岩为主要的烃源岩和盖层,本区生、储、盖发育齐全,有着良好的勘探开发前景。  相似文献   

南天山萨恨托亥—大山口—带穆龙套型金矿地质及地球化学特征     

孟祥金  叶锦华  王立本 《地球学报》2000,21(4):379-388

南天山中段萨恨托亥大山口成矿带内的金矿赋存在浅变质浊积岩系碎屑岩内。本文以该带内2个典型金矿———大山口金矿和萨恨托亥金矿为例,对其成矿特征进行了初步研究。研究表明,金矿体受韧脆性剪切带控制,产状稳定,矿石类型简单,硫化物种类单一且含量较低。成矿可分为糜棱岩阶段和石英脉阶段,与控矿的韧脆性剪切带的发展演化各阶段相对应。成矿发生于中低温条件下弱酸性向中性环境过渡阶段,成矿流体是以深源流体(含岩浆热液)为主的多源混合热液(构造热液)。成矿作用为构造成岩成矿(韧性剪切带成矿),矿床成因类型为(构造)热液型金矿,  相似文献   

南极利文斯顿岛上三叠统Miers Bluff组及其与相当地层对比     

沈炎彬  邓希光  欧阳舒 《地层学杂志》2000,24(4):291-296

南极南设得兰群岛利文斯顿岛 Miers Bluff组 (MBF)是一套岩层倒转、强烈变形、浅变质的浊流沉积地层 ,主要由砂岩、泥岩、粉砂岩及含砾砂岩组成 ,具有很好的韵律层 ,形成鲍玛序列 ,通常被认为属于近海底扇浊流沉积 ,并当作中新生代火山岩的基底。最近发现的孢粉化石指明其时代属晚三叠世 ,从而解决了久来时代的疑问(石炭—三叠纪 ,二叠—三叠纪 ,或前侏罗纪 )。分布在南极半岛格雷厄姆地的特里尼蒂半岛群、南奥克尼群岛的杂砂岩—页岩组、智利南部乔诺斯群岛乔诺斯变质杂岩的 Potranca组以及新西兰惠灵顿的 Torlesse杂岩应是时代相当、岩性及沉积环境相似的岩层。三叠纪末受太平洋板块俯冲影响 ,这一浊流地层褶皱、变形、隆升 ,具有相同的构造风格 ,是冈瓦纳古陆在侏罗纪早期开始裂解前夕一次构造事件的重要佐证  相似文献   

塔里木盆地塔东凸起西部中上奥陶统地震层序与海底扇沉积   总被引：7，自引：0，他引：7  

钟广法  刘学锋  邓常念  万里皋 《地球科学》2006,31(3):366-371

根据区域地震资料研究塔里木盆地塔东凸起西部中上奥陶统层序地层格架及沉积演化, 在中上奥陶统识别出了2个地震层序, 发现了叠置的丘状前积反射地震单元, 综合岩心观察、岩屑录井和薄片资料, 确认为海底扇沉积体.海底扇沉积主要由块状砂、砾岩, 递变层理砂岩, 平行层理砂岩, 砂纹层理粉砂岩, 变形或包卷层理粉砂岩, 水平层理泥质粉砂岩或粉砂质泥岩, 块状或递变的粉砂质泥岩和泥岩等岩相组成, 形成于中扇和外扇环境, 物源来自研究区南部的岛弧带.海底扇的发现对于塔东凸起乃至整个塔里木盆地中上奥陶统油气勘探具有重要意义.   相似文献   

The soils on the calcareous sand dunes southeast of South Australia     

K. Urushibara-Yoshino 《Environmental Geology》1996,28(3):154-160

 The properties of soils on previously dated sand dunes from Robe to Naracoorte in South Australia were examined. In these areas younger sand dunes are composed of fresh sand, but older sand dunes are composed of calcarenited sand. The soils on the sand dunes developed successionally by the age of sand dunes. The soil properties of these sand dunes differ depending on the ages of the sand dunes. The properties of sand particles in soils are as follows: (1) On the sand dunes of 4300 years B.P., A/C profile developed (Rendzina). On the sand dunes older than 125 000 years B.P. and on the plateau of Tertiary limestone, soil profiles of A₁/AB/B/C on the sand dunes of 83 000 years B.P. and A₁/A₃/B₁/B₂/C (Terra rossa) are well developed. (2) Within the sand of A/C horizons of the sand dunes with the age of 4300 year B.P., the calcite grain content is about 64%, and the quartz content is about 35%. Within the B horizons of soils on the dunes from 83 000 years B.P. to 347 000 years B.P., the calcite grain content is only 1–2%; however, the quartz grain content is about 92%. In the B₂ horizons of soils on the dune of 690 000 years B.P. and on the Tertiary plateau, there are some calcite grains but the quartz grain content is about 96%. (3) The average size of quartz grains in the soils on the sand dunes from 4300 B.P. to 347 000 years B.P. is generally smaller, but the average size of quartz on the sand dunes of 690 000 year B.P. becomes larger and the grains are well rounded. On the Tertiary limestone plateau, the average quartz size becomes again smaller, and the grains are more rounded. (4) Fe_t in B₂ horizon of the soil profiles increases clearly corresponding to the age. Iron activity expressed by Fe_o/Fe_d also shows a close relation to the chronological sequence. The B horizon of the soil profiles shows a drastic decrease of Fe_o/Fe_d according to the age. Iron crystalinity, (Fe_d-Fe_o)/Fe_t, has a tendency for a positive relation with increasing age. Received: 1 June 1995 · Accepted: 4 December 1995  相似文献   

广西隆林县隆或金矿的地质特征和成因分析     

张振贤  吴均贵  曾广海 《南方国土资源》1996,(4)

隆林县隆或金矿属微粒型金矿，具有多层位、层状矿体为主、矿石和矿物成分简单、沉积结构构造特征，属典型层控矿床。矿床成因与生物礁的消失、滑塌事件、深水火山碎屑硅泥质上超盆地的叠覆、以及有机质的热解和分异有关。火山作用提供金的来源，火山～碎屑～浊积岩相为矿源层和含矿层，并受沉积盆地的关闭和开启影响，形成成岩矿床、成岩～后生或后生矿床  相似文献   

Calcareous nannofossil and inoceramid biostratigraphies of a Middle Turonian to Middle Coniacian section from the Opole Trough of SW Poland     

Mariusz K&#x;dzierski 《Cretaceous Research》2008,29(3):451-467

Well-preserved and rich nannofossil assemblages from Turonian-Coniacian (Upper Cretaceous) marlstone deposits of the Opole Trough in SW Poland have been analysed. Nannoplankton zones (and subzones) UC6 through UC10 were determined. Apparent discrepancies between the Turonian substage ages indicated by the nannofossil zones, which are based on correlations with the standard ammonite zones, and those based on inoceramids are revealed. This illustrates poor correlation between the inoceramid and ammonite events used to indicate the substage boundaries, rather than diachroneity in the nannofossil events.  相似文献