Zircon SHRIMP U-Pb ages and trace element geochemistry of the Kuhai gabbro and the Dur''''ngoi diorite in the southern east Kunlun tectonic belt, Qinghai, Western China and their geological implications     

LI WangYe  LI ShuGuang  GUO AnLin  SUN YanGui  ZHANG GuoWei 《中国科学D辑(英文版)》2007,50(Z2):331-338

Timing of the intermediate-basic igneous rocks developed in the area of Kuhai-A'nyêmaqên along the southern east Kunlun tectonic belt is a controversial issue. This paper presents new zircon SHRIMP U-Pb dating data for igneous zircons from the Kuhai gabbro and the Dur'ngoi diorite in the Kuhai-A'nyemaqen tectonic belt, which are 555±9 Ma and 493±6 Ma, respectively. The trace element geochemical features of the Kuhai gabbro and the Dur'ngoi diorite are similar to those of ocean island basalts (OIB) and island arc basalts (IAB), respectively. Thus, the Kuhai gabbro with the age of 555±9 Ma and OIB geochemical features is similar to the Yushigou oceanic ophiolite in the North Qilian orogen, whereas the Dur'ngoi diorite with the age of 493±6 Ma and IAB geochemical features is similar to the island arc volcanic rocks developed in the north Qaidam. The Late Neoproterozoic to Early Ordovician ophiolite complex in the area of Kuhai-A'nyêmaqên suggests that the southern margin of the "Qilian-Qaidam-Kunlun" archipelagic ocean in this period was located in the southern east Kunlun tectonic belt. Therefore, the southern east Kunlun tectonic belt in the early Paleozoic is not comparable to the Mianlüe tectonic belt in the Qinling orogenic belt.  相似文献   

Geology and geochemistry of the Bingdaban ophiolitic mélange in the boundary fault zone on the northern Central Tianshan Belt, and its tectonic implications     

DONG YunPeng  ZHANG GuoWei  ZHOU DingWu  LUO JinHai  ZHANG ChengLi  XIA LinQi  XU XueYi  LI XiangMin 《中国科学D辑(英文版)》2007,50(1)

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新疆东昆仑阿其克库勒湖西缘地区蛇绿岩的确证   总被引：6，自引：0，他引：6  

吴峻  兰朝利  李继亮  俞良军 《地质科技情报》2001,20(3):6-10

新疆东昆仑阿其克库勒湖西缘出露了一套超基性—基性岩。该蛇绿岩的野外地质、岩石学以及岩石化学特征表明它们是由变质橄榄岩和堆晶岩两大单元组成的蛇绿岩 ,是否存在蛇绿岩的其它单元值得进一步研究。同时 ,这些特征表明其与青海东昆仑清水泉蛇绿岩相似 ,指示它们可能为同一洋壳的残余。  相似文献   

Soils and Land use on Lithologically Diverse Ophiolitic Alluvia on the Coastal Plain of Palawan,Philippines     

I .C. Baillie  N. B. Inciong  P. M. Evangelista 《Singapore journal of tropical geography》2001,22(1):1-14

The soils on the southeastern coastal plain of Palawan, Philippines are developed on alluvium derived from various lithologies of the Palawan Ophiolitic Complex. There is little lateral mixing of the alluvium. The soil pattern is interpreted as the result of increasing weathering and leaching with age on deposits of different lithological origins. In the ultramafic catchment the younger soils are infertile due to several unfavourable characteristics, including high contents of heavy metals and Mg, deficiencies of P and micro‐nutrients, and impermeability. These soils improve with increased weathering and leaching, and the older soils have better physical and Mg characteristics. In felsic alluvia the reverse is found, and the soils on younger deposits are the most fertile, while the older soils have unfavourable combinations of subsoil compaction, acidity and dominance by aluminium. These patterns are reflected in the current land use, with areas of sparse settlement and cultivation on the less fertile soils on younger ultramafic and older felsic alluvia. These areas have been avoided or abandoned, rather than overlooked, by farmers and cannot be considered as “empty lands”. Their sustainable development will require careful management. Most of the more fertile land is already cultivated.  相似文献   

PGE geochemistry of Jiding ophiolite in Tibet and its constraint on mantle processes   总被引：3，自引：0，他引：3  

XIA Bin  CHEN Genwen  MEI Houjun  GUO Lingzhi  XIAO Xuchang  YU Hengxiang  QI Liang  WANG Guoqiang  Zhong Zhihong 《中国科学D辑(英文版)》2001,44(11):1019-1028

The total PGE amount (σPGE) of mantle peridotite in the Jiding ophiolite is slightly higher than that of the primitive mantle, but the PGE contents of basalt are higher than those of the mid-ocean ridge basalt (MORB), with obviously lower Pd/Ir ratios. The accumulates, dyke swarm and basalts show remarkable negative Pt and positive Rh anomalies, resulting in the special N-type PGE patterns. Mantle peridotite and crustal rocks have similar distribution patterns. It is proposed that the PGE distribution patterns in the Jiding ophiolite are closely related with a higher degree of partial melting of the mantle in this region. Magmatic crystallization-differentiation led to PGE fractionation, thus making the contents of PGE in the accumulates decrease in the ascending direction. The higher content of Au in the Jiding ophiolite is the result of metasomatic alteration at later stages. Pt-Pd fractionation indicates that both the PGEs are controlled by their alloy and sulfide phases. Positive Rh anomalies seem to be related with higher oxygen fugacity in the melts.  相似文献   

Tectonics of Precambrian basement of the Tarim craton   总被引：4，自引：0，他引：4  

GUO Zhaojie  ZHANG Zhicheng  JIA Chengzao  Wei Guoqi 《中国科学D辑(英文版)》2001,44(3):229-236

The Altyn Tagh Mountain is the main area where the Precambrian basements of Tarim craton are exposed. There are two ophiolitic belts in Altyn Tagh: one belt is exposed in the northern margin of Altyn Tagh whose formation age is about (829±60) Ma, the other is situated along the southern margin of Altyn Tagh and has a formation age of about (1449±270) Ma. This paper proposes a simple tectonic model for the Precambrian basement of Tarim craton established from ophiolites in Altyn Tagh area. The south Tarim block had amalgamated with Qaidam block during about 1400-1500 Ma along the present Altyn fault, while the south Tarim-Qaidam united block was still separated from the north Tarim block by an ocean. The united block of south Tarim and Qaidam collided with north Tarim block along the zone of high positive anomaly of central Tarim, Hongliugou and Lapeiquan in about 800 Ma. So since the Sinian (beginning at 800 Ma) there has been an integrated basement for Tarim craton.  相似文献   

Early Carboniferous Radiolarian Fauna from Heiyingshan South of the Tianshan Mountains and Its Geotectonic Significance   总被引：5，自引：0，他引：5  

LIU YuInstitute of Geology  Chinese Academy of Geological Sciences  Baiwanzhuang Ro  Beijing 《《地质学报》英文版》2001,75(1):101-108

Abundant and well-preserved fossil radiolarians found from the Artencasher Formation, Heiyingshan of Baicheng County, Xinjiang Uygur Autonomous Region, are identified, including 15 species and 2 unnamed species in 9 genera. The fauna is dominated by the Family Entactiniidae of Spumellaria. According to the faunal characteristics, the radiolarians may be divided into five assemblages, namely, the Triaenosphaera sicarius, Entatinosphaera palimbola, Entactinia vulgaris, Belowea cf. variabilis and Archocyrtium sp assemblages. The fauna may be correlated with that from the Early Carboniferous of Frankenwald and Rein in Germany. Thus, ophiolite was formed in the Carboniferous, while the age of collision between the Ili plate and the Tarim plate is Early Carboniferous.  相似文献   

新疆北部阿尔泰地区库尔提蛇绿岩：古弧后盆地系统的产物   总被引：40，自引：3，他引：40       下载免费PDF全文

许继峰  陈繁荣  于学元  牛贺才  郑作平 《岩石矿物学杂志》2001,20(3):344-352

位于新疆北部富蕴县库尔提一带的晚古生代变质玄武岩和辉长岩系含有似岛弧火山岩（arc-like)和似洋中脊玄武岩（MORB－like)成分的两种组分，岩石以出现不同程度的LREE亏损和Nb、Ta等元素的负异常为特征，在成分上非常相似于现代弧后盆地（Mariana和Okinawa弧后盆地）的玄武岩。我们厘定这套变质的镁铁质火成岩为弧后盆地蛇绿岩，它们很可能代表了晚古生代古亚洲洋北侧的一个洋内岛弧的弧后盆地系统，表明晚古生代早期新疆北部地区处于与古亚洲洋俯冲有关的岛弧环境，该古洋在晚石炭世－二叠纪消减消失后，两侧西伯利亚和哈萨克－准噶尔板块才开始碰撞和造山。  相似文献   

Petrochemical Investigation of the Antique Ophiolite (Philippines): Implications on Volcanogenic Massive Sulfide and Podiform Chromitite Deposits   总被引：5，自引：0，他引：5  

Rodolfo A. TAMAYO Jr    Graciano P. YUMUL Jr    René C. MAURY  Mireille POLVÉ  Joseph COTTEN  Marcel BOHN 《Resource Geology》2001,51(2):145-164

Abstract: The Antique ophiolite, located in Panay island (west‐central Philippines), corresponds to several tectonic slices within the suture zone between the Philippine Mobile Belt (PMB) and the North Palawan Block (NPB). It includes dismembered fragments of a basaltic sequence, dominantly pillow‐lavas with minor sheet flows, rare exposures of sheeted dikes, isotropic gabbros, subordinate layered mafic and ultramafic rock sequences and serpentinites. Most of the ophiolite units commonly occur as clasts and blocks within the serpentinites, which intrude the whole ophiolitic body, as well as, the basal conglomerate of the overlying Middle Miocene sedimentary formation. The volcanic rock sequence is characterized by chemical compositions ranging from transitional (T)‐MORB, normal (N)‐MORB and to chemistry intermediate between those of MORB and island arc basalt (IAB). The residual upper mantle sequence is harzburgitic and generally more depleted than the upper mantle underlying modern mid‐oceanic ridges. Calculations using whole‐rock and mineral compositions show that they can represent the residue of a fertile mantle source, which have undergone degrees of partial melting ranging from 9‐22.5 %. Some of the mantle samples display chondrite‐nor‐malized REE and extended multi‐element patterns suggesting enrichments in LREE, Rb, Sr and Zr, which are comparable to those found in fore‐arc peridotites from the Izu‐Bonin‐Mariana (IBM) arc system. The Antique ultramafic rocks also record relatively oxidizing mantle conditions (Δlog f_O2 (FMQ)=0.9‐3.5). As a whole, the ophiolite probably represents an agglomeration of oceanic ridge and fore‐arc crust fragments, which were juxtaposed during the Miocene collision of the PMB and the NPB. The intrusion of the serpentinites might be either coeval or subsequent to the accretion of the oceanic crust onto the fore‐arc. Volcanogenic massive sulfide (VMS) deposits occur either in or near the contact between the pillow basalts and the overlying sediments or interbedded with the sediments. The morphology of the deposits, type of metals, ore texture and the nature of the host rocks suggest that the formation of the VMS bodies was similar to the accumulation of metals around and in the subsurface of hydrothermal vents observed in modern mid‐oceanic ridge and back‐arc basin rift settings. The podiform chromitites occur as pods and subordinate layers within totally serpentinized dunite in the residual upper mantle sequence. No large coherent chromitite deposit was found since the host dunitic rocks often occur as blocks within the serpentinites. It is difficult to evaluate the original geodynamic setting of the mineralized bodies since the chemistry of the host rocks were considerably modified by alteration during their tectonic emplacement. A preliminary conclusion for Antique is that the VMS is apparently associated with a primitive tholeiitic intermediate MORB‐IAB volcanic suite, the chemistry of which is close to the calculated composition of the liquid that coexisted with the podiform chromitites.  相似文献   

北祁连石居里地区Cu(Zn)-S矿床地质特征及综合成矿模式     

邬介人  于浦生  任秉琛 《矿床地质》2001,20(4):339-346

文章主要论述了北祁连山西段石居里矿田内Ⅵ号沟、Ⅷ号沟、九个泉等矿床的基本地质特征，并与北祁连山东段老虎山地区银硐沟、猪嘴哑吧等矿床对比。结合其早古生代构造演化历史、古洋脊或弧间、弧后拉张环境确定矿床类型，将上述3个矿床归属为蛇绿岩Cu(Zn）－S型矿床（类塞浦路斯型）。建立综合成矿模式的基本要求：（1）矿床具有一定的时控性，有一定的含矿层位；（2）生长性断裂的积极参与；（3）海底火山喷发、喷气中心与次级盆地双向控制；（4）多元热流体成矿系统。  相似文献