大别-郯庐-苏鲁造山带复合旋转拼贴作用   总被引：29，自引：0，他引：29  

肖文交  周烑秀  杨振宇  赵西西 《地球科学进展》2000,15(2):147-153

郯庐断裂带的成生演化与含超高压变质带(UHP)的大别及苏鲁造山带存在较密切的时空关系。郯庐断裂带所在的构造位置应是晚二叠世华北与扬子地块碰撞时的根带。UHP岩石的折返过程可能发生于华北、扬子地块的大角度旋转、拼合过程中。在华北与扬子地块的造山后期或者造山期后的构造变形中所记录的构造形迹经晚中生代以来的中国东部构造变形叠加而逐渐呈现复杂的构造组合,所谓“郯庐断裂带”的走滑平移即其中的一种运动方式。华北与扬子地块碰撞造山作用与陆内变形最终造就了大别—郯庐—苏鲁复合造山带。  相似文献   

Carbonate-related parameters of subsurface waters in the West Philippine, South China and Sulu Seas   总被引：3，自引：0，他引：3  

Chen-Tung Arthur Chen  Wei-Ping Hou  Toshitaka Gamo  Shu Lung Wang   《Marine Chemistry》2006,99(1-4):151

Like most other deep basins in Southeast Asia, the deep Sulu Sea (SS) basin is isolated from the neighboring seas by surrounding topography. While the near-surface circulation is mainly governed by the seasonally reversing monsoon winds, below the warm and fresh surface layer, the core of the incoming Subtropical Lower Water from the West Philippine Sea (WPS), by way of the South China Sea (SCS), can be seen, at a depth of around 200 m, to have a distinct salinity maximum. It lies well above the sill depth (420 m) in the Mindoro Strait and thus, its spreading is not hampered by topography. The deep circulation is forced by an inflow of upper North Pacific Intermediate Water (NPIW) from the SCS through the Mindoro Str. Below 1000 m, the physico-chemical properties are remarkably homogeneous. The higher temperature, but lower salinity, oxygen and nutrients, of the deep SS waters, compared to those of the SCS, is indicative of the intrusion of NPIW above the sill depth. The excess, anthropogenic CO₂ penetrates the entire water column, because of the over-spill of the excess CO₂-laden water from the SCS.It has been reported that the bottom of the SS is CaCO₃ rich, relative to the SCS. Previous investigators attribute this to the higher θ in the SS. Indeed, the aragonite does not become undersaturated in the SS until below 1400 m, compared to 600 m in both the WPS and SCS; and the calcite does not become undersaturated until below 3800 m in the SS, compared to 2500 m in the SCS and around 1600 m in the WPS. However, the temperature effect is relatively small. These large differences are, in fact, largely a result of higher CO₃²⁻ concentrations in the SS, relative to the WPS and SCS. The higher CO₃²⁻ concentration in the SS, in turn, is mainly caused by the smaller amounts of organic carbon decomposition.  相似文献   

南苏鲁造山带毛北超高压变质岩体的成因与成矿作用     

张泽明　沈昆刘勇胜  游振东石超　王金丽 《岩石学报》2007,23(12):3095-3115

毛北超高压变质岩体位于苏鲁造山带南部,是由石榴石橄榄岩、榴辉岩、硬玉石英岩和石榴石多硅白云母石英片岩组成的层状岩体.富金红石榴辉岩和富钛铁矿榴辉岩在岩体中呈连续的层状产出,总厚度达200m,深度＞700m,构成了一个大型的钛矿床.岩石学、地球化学和年代学研究表明,毛北岩体的原岩形成在新元古代Rodinia超大陆裂解过程中,基性岩浆经历了强烈的分异结晶作用,形成了由橄榄辉长岩-辉长岩-闪长岩-花岗岩组成的复杂层状侵入体,并在新元古代的全球冰期与高纬度大气降水发生强烈的水-岩交换作用.在印支期的大陆深俯冲过程中,经历了超高压变质作用,其峰期变质温度＞800℃,压力＞4.5GPa,富钛磁铁矿辉长岩转变成了富金红石榴辉岩,形成了超高压变质的钛矿床.  相似文献   

Geochemistry of eclogites from the Dabie–Sulu terrane, eastern China: New insights into protoliths and trace element behaviour during UHP metamorphism     

Hong-Feng Tang  Cong-Qiang Liu  Shun''ichi Nakai  Yuji Orihashi 《Lithos》2007,95(3-4):441-457

The major and trace element compositions of nine eclogites from the Dabie–Sulu ultrahigh pressure (UHP) metamorphic terrane in eastern China were determined for both whole rock and the main constituent minerals, garnet and clinopyroxene. The results indicate that the eclogite protoliths originated from a basaltic magma, which formed in a continental setting as shown by isotopic and immobile element data. Based on the garnet REE characteristics, the eclogites can be roughly divided into two groups. Group 1 has LREE enrichment with no Eu anomaly for whole rock, and smooth LREE depletion but HREE enrichment pattern for garnet, whereas group 2 shows a depletion of LREE with a pronounced positive Eu anomaly and flat HREE pattern for both whole rock and garnet. From these features, we suggest that the protoliths for group 2 are Fe–Ti–gabbros with relatively high cumulus plagioclase and Fe–Ti oxide, whereas the group 1 eclogites are probably from basalts. Therefore, the unusual garnet REE pattern observed in group 2 can be considered as an important signature for identifying gabbro protoliths for eclogites. The identification of gabbro protoliths from the eclogites in the Dabie–Sulu terrane provides evidence for Neoproterozoic rift magmatism in the northern margin of the Yangtze craton. During ultrahigh pressure metamorphism in the Dabie–Sulu terrane, LILEs (including Ba, Rb, Th, U, K) had high mobility, but REEs and HFSEs were immobile, and trace element distribution equilibrium was approached between garnet and clinopyroxene. An estimate of mass balance indicates that garnet and clinopyroxene host the majority of HREEs and Y, and clinopyroxene is a significant host for Sr, but minor and accessory minerals predominantly account for LREEs, Th, U, and Zr.  相似文献   

苏鲁-大别山超高压变质带迟家店和碧溪岭石榴二辉橄榄岩橄榄石组构   总被引：1，自引：0，他引：1  

宋衍茹  金淑燕叶凯 《岩石学报》2007,23(5):1153-1159

大别山碧溪岭和山东荣成分别发育壳源和幔源的石榴二辉橄榄岩。它们在扬子板块向华北板块的俯冲过程中与俯冲板片一起经历了超高压变质作用。这两种原岩来源不同的石榴橄榄岩中的橄榄石具有相似的结晶学优选方位(LPO):[100]轴主板密垂直于面理面,[010]轴主极密平行于线理,这种橄榄石结晶学优选方位明显不同于高温地幔橄榄岩包体中的橄榄石组构,也不同于最近在超高压变质地体中发现的水导致的橄榄石组构。我们认为碧溪岭和荣成石榴二辉橄榄岩中的这种橄榄石组构可能是在相对较干的超高压变质条件下形成的。本研究为大陆深俯冲超高压变质石榴橄榄岩橄榄石组构特征提供了第一手资料。  相似文献   

Ultrahigh-pressure metamorphic records hidden in zircons from amphibolites in Sulu Terrane, eastern China   总被引：8，自引：0，他引：8  

Fulai Liu  Zeming Zhang  Ikuo Katayama  Zhiqin Xu  Shigenori Maruyama 《Island Arc》2003,12(3):256-267

Abstract The amphibolites occur sporadically as thin layers and blocks throughout the Sulu Terrane, eastern China. All analyzed amphibolite from outcrop and drill cores from prepilot drill hole CCSD‐PP1 and CCSD‐PP2, Chinese Continental Scientific Drilling Project in the Sulu Terrane, are retrograded eclogites overprinted by amphibolite‐facies retrograde metamorphism, with characteristic mineral assemblages of amphibole + plagioclase + epidote ± quartz ± biotite ± ilmenite ± titanite. However, coesite and coesite‐bearing ultrahigh‐pressure (UHP) mineral assemblages are identified by Raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from these amphibolites. In general, coesite and other UHP mineral inclusions are preserved in the cores and mantles of zircons, whereas quartz inclusions occur in the rims of the same zircons. The UHP mineral assemblages consist mainly of coesite + garnet + omphacite + rutile, coesite + garnet + omphacite, coesite + garnet + omphacite + phengite + rutile + apatite, coesite + omphacite + rutile and coesite + magnesite. Compositions of analyzed mineral inclusions are very similar to those of matrix minerals from Sulu eclogites. These UHP mineral inclusion assemblages yield temperatures of 631–780°C and pressures of ≥2.8 × 10³ MPa, representing the P–T conditions of peak metamorphism of these rocks, which are consistent with those (T = 642–726°C; P ≥ 2.8 × 10³ MPa) deduced from adjacent eclogites. These data indicate that the amphibolites are the retrogressive products of UHP eclogites.  相似文献   

苏鲁超高压变质带中非超高压花岗质片麻岩的准确识别:来自锆石微区矿物包体及SHRIMP U-Pb定年的证据   总被引：6，自引：0，他引：6  

刘福来  许志琴  宋彪 《地质学报》2003,77(4):533-539

通过隐藏在锆石微区矿物包体激光拉曼的系统鉴定和阴极发光图像特征的详细研究,配合相应的锆石微区SHRIMP U-Pb定年测试,发现苏鲁地体超高压变质带中确实存在非超高压变质的花岗质片麻岩。该类岩石中的锆石晶体自核部到边部所保存的矿物包体以不含超高压矿物为特征,相应的阴极发光图像具有典型岩浆结晶锆石的核部和幔部,以及变质的再生边的特点。其中岩浆结晶锆石微区记录的~(238)U-~(206)Pb年龄为404～748Ma,表明原岩中部分锆石可能经历了Pb丢失,也不排除后期热事件因素的影响,原岩的形成年龄应大于748 Ma;而锆石的再生边所记录的~(238)U-~(206)Pb。年龄为204～214 Ma,与研究区经历超高压变质的副片麻岩和花岗质片麻岩锆石微区所记录的苏鲁地体快速折返过程中角闪岩相退变质年龄(~(238)U-~(206)Pb年龄的平均值为211±4 Ma,刘福来等,2003a)十分相似。上述特征表明,苏鲁地体超高压变质带中的部分花岗质片麻岩在超高压变质事件之前就已经形成,但并未“参与”深俯冲—超高压的变质演化过程,而是在苏鲁地体快速折返的角闪岩相退变质过程中与超高压岩片“拼贴”在一起。该项成果不仅为正确识别非超高压变质岩石提供了一个新的研究方法,而且对进一步深入探讨苏鲁地体超高压和非超高压岩片的“拼贴”机制有着重  相似文献   

苏鲁超高压变质带石榴石橄榄岩中含钛硅镁石出溶体的发现及其意义   总被引：16，自引：3，他引：16  

许志琴  陈晶  杨经绥  李旭平  陈方远 《地质学报》2003,77(4):549-555

在苏鲁超高压变质带南部东海地区的中国大陆超深钻预先孔CCSD-PP1中获得了石榴石橄榄岩样品,在石榴子石内单斜辉石包裹体中首次发现钛斜硅镁石和钛粒硅镁石出溶体结构,钛斜硅镁石和钛粒硅镁石呈出溶棒和出溶片晶产出。根据石榴子石中包裹体的成分计算包裹体的形成温压条件为t=716～914℃;p=4.8～5.1 GPa。根据钛斜硅镁石出溶体的X_(OH)=1,X_F=0,X_(Fe)=0.074～0.094(平均0.082),X_(Ti)=0.41～0.74(平均0.56),估算钛斜硅镁石出溶结构形成在压力>3.5 GPa条件下(>850℃),这种出溶结构记录了该岩石在早期折返过程中仍处在超高压变质环境中。  相似文献   

山东五莲中生代岩浆岩的锆石U-Pb年龄   总被引：17，自引：2，他引：17  

周建波  郑永飞  赵子福 《高校地质学报》2003,9(2):185-194

苏鲁造山带产出一系列中生代岩浆岩 ,但是对它们的确切侵位年龄至今尚无正式报道。对其西北部五莲断裂附近四个花岗质侵入岩体进行了锆石U Pb年龄测定 ,结果得到大店复式岩体中角闪二长岩的谐和年龄为 12 3± 4Ma ,七宝山复式火山 -侵入杂岩体中辉石二长岩的谐和年龄为 12 6± 3Ma。五莲山岩体中晶洞花岗岩的谐和年龄为 116± 4Ma,马耳山岩体中不等粒二长花岗岩的谐和年龄为 115± 1Ma。这些锆石U Pb年龄结果说明 ,苏鲁造山带同样存在侵位时间分别为 115Ma和 12 5Ma左右的早白垩纪侵入体 ,与大别造山带内大面积出露的燕山期岩浆岩年龄基本一致 ,代表了扬子板块与华北板块在三叠纪碰撞折返后的岩浆活动 ,其物质来源可能与俯冲陆壳的部分熔融有关  相似文献   

胶东地块东部变质岩锆石U-Pb定年和氧同位素研究   总被引：18，自引：10，他引：18  

唐俊郑永飞  吴元保查向平　周建波 《岩石学报》2004,20(5):1039-1062

对胶东地块东部高压-超高压变质岩作了系统的锆石U-Ph定年和矿物氧同位素分析,结果对这些变质岩的原岩性质提供了制约。研究得到:(1)区域花岗片麻岩及岩浆锆石普遍不同程度地亏损~(18)O,3个片庥岩样品中岩浆核锆石U-Pb年龄分别为723±36Ma、738±17Ma和744±63Ma,低δ~(18)O值(-0.42～4.14‰)岩浆核锆石说明其原岩为新元古代低δ~(18)O值岩浆岩,石英-石榴石氧同位素温度及少量印支期变质锆石的出现,指示片麻岩与榴辉岩曾经共同经历了印支期超高压变质作用;(2)花岗片麻岩中的榴辉岩原岩年龄有两种,一种是新元古代,其U-Ph年龄为806±79Ma。另一种是古元古代晚期,其 U-Pb年龄为1838±41Ma。这2个榴辉岩的超高压变质年龄分别为229±3Ma和242±21Ma。多数榴辉岩中的变质增生或变质重结晶锆石也具有低δ~(18)O值特征(0.22～3.4‰),指示在榴辉宕相变质作用之前,这些榴辉岩原岩为低δ~(18)O值蚀变岩或低δ~(18)O值基性岩浆岩;(3)大理岩中榴辉岩变质增生锆石δ~(18)O值高达15.9‰,U-Pb年龄为229±4Ma,指示在榴辉岩相变质作用之前,榴辉岩原岩与大理岩一样具有高δ~(18)O值;(4)斜长角闪岩的原岩U-Pb年龄为1719±18Ma,与同时期榴辉岩原岩一起构成扬子板块北缘新元古代岩浆侵位时的裂谷肩部围岩,在三叠纪大陆碰撞时同样受到变质改造。  相似文献