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Geological significance of the former Xiong'er Volcanic Belt on the southwestern margin of the North China Craton

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Frontiers of Earth Science 2019年第1期13卷 191-208页

作者： Guanxu CHEN jinhai luo Huan XU Jia YOU Yifei LI Zichen CHE State Key Laboratory of Continental Dynamics (Northwest University) Department of GeologyNorthwest UniversityXi'an 710069China

The rock association of low-grade metasedimentary rocks and greenschists located within the Meso- Cenozoic Liupanshan Fault system on the southwestern margin of the North China Craton (NCC)is regarded as part of the Paleoproterozoic Xiong'er *** low- grade rocks are separated by normal faults,with the greenschist located in the hanging *** LA-ICP- MS U-Pb ages of the greenschists range from 2455 to 423 Ma,suggesting that they are not Paleoproterozoic in age. The protolith ages (206-194 Ma)of the greenschists were determined by LA-ICP-MS U-Pb dating of zircons from two siltstone *** petrology and geochemistry of the greenschists reveal that their protolith was continental tholeiitic basalt that formed in an extensional environment such as a continental ***,it is proposed that the protolith of the greenschists was a mafic volcanic rock of Late Triassic-Early Jurassic age and was metamorphosed during the Jurassic due to tectonism within the Liupanshan tectonic *** results show that the greenschists should be reclassified and removed from the Xiong'er Group,and explains why they differ so much from those of typical Xiong'er Group successions in other *** formation of the mafic volcanic rocks under conditions of continental rifting differs from that of coeval granitic rocks in the western Qinling Orogen,where the extension occurred during a post-collisional stage in the Late Triassic,which further suggests that the southwestern margin of the NCC became an extensional setting after the Late Triassic.

关键词： southwestern margin of the NCC Paleoproterozoic Xiong'er Group greenschist detrital zircon U-Pb geochronology Late Triassic to Early Jurassic

The evidence of Sm-Nd isochron age for the early Paleozoic ophiolite in Mangya area,Altun Mountains

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Chinese Science Bulletin 1998年第9期43卷 754-756页

作者： Liang Liu Zicheng Che Yan Wang jinhai luo Jianqi Wang Zhangjian Gao NW Univ Xian Dept Geol Xian 710069 Peoples R China

The REE patterns of the basic volcanic rocks in Mangya area, Altun, are slight rich in LREE with (La/Ya)-N=1.69-3.20, (La/Sm)-N=1.37-1.87, other trace element ratios of the rocks are Th/Ta≈1 (for a few samples greater than 1.5), Nb/Y=0.34-0.62, Ti/Y=310-443 (on the average: 381), Ti/V=37-62, Zr/Nb=9.4-12.4, Sr/Rb=12-80 (on the average: 37), and Nb/Th=7.7-16.8. These features are similar to that of E-MORE or OIB. The ε Nd(t) value, being 3.95- 4.12, shows that the source of the volcanic rocks is derived from depleted asthenosphere mantle mixed with materials from enriched mantle. These, together with the information of geological setting and rock assemblages, indicate that the basic volcanic rocks are of ophiolite. The Sm-Nd isotope ages for the eight basic volcanic rock samples construct a straight line with good correlation, and the calculated isochron age is (481.3±53) Ma. Besides, the eight calculated ε Nd(t) and model ages are close to each other, which suggests that they are homologous, so the isochron is not a mixed line. In the meantime, the isochron age ((481.3±53) Ma) is lower than the model ages (T DM=1 004-1 534 Ma) of the samples, suggeting that the isochron age represents the formation age of the basic volcanic rocks and the ophiolite belt in Mangya area, Altun is formed in the early Paleozoic (Cambrian-Ordovician). In spite of the greater uncertainty of the age, it is still reliable because it is consistent with the age constrained by the regional strata.

关键词： Altun mountains Mangya ophiolite Sm-Nd isochron age.

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

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Science China Earth Sciences 2007年第1期50卷 17-24页

作者： DONG YunPeng ZHANG GuoWei ZHOU DingWu luo jinhai ZHANG ChengLi XIA LinQi XU XueYi LI XiangMin The Key Laboratory of Continental Dynamics Ministry of EducationDepartment of GeologyNorthwest UniversityXi’an 710069China Shandong University of Science and Technology Qingdao 266510China Xi’an Institute of Geology and Mineral Resources China Geological SurveyXi’an 710054China

The properties and tectonic significance of the fault bound zone on the northern margin of the Central Tianshan belt are key issues to understand the tectonic framework and evolutionary history of the Tianshan Orogenic Belt. Based on the geological and geochemical studies in the Tianshan orogenic belt, it is suggested that the ophiolitic slices found in the Bingdaban area represent the remaining oceanic crust of the Early Paleozoic ocean between the Hazakstan and Zhungaer blocks. Mainly com-posed of basalts, gabbros and diabases, the ophiolites were overthrust onto the boundary fault be-tween the Northern Tianshan and Central Tianshan belts. The major element geochemistry is charac-terized by high TiO2 (1.50%-2.25%) and MgO (6.64%-9.35%), low K2O (0.06%-0.41%) and P2O5 (0.1%-0.2%), and Na2O>K2O as well. Low ΣREE and depletion in LREE indicate that the original magma was derived from a depleted mantle source. Compared with a primitive mantle, the geochemistry of the basalts from the Bingdaban area is featureded by depletion in Th, U, Nb, La, Ce and Pr, and unfrac-tionated in HFS elements. The ratios of Zr/Nb, Nb/La, Hf/Ta, Th/Yb and Hf/Th are similar to those of the typical N-MORB. It can be interpreted that the basalts in the Bingdaban area were derived from a de-pleted mantle source, and formed in a matured mid-oceanic ridge setting during the matured evolu-tionary stage of the Northern Tianshan ocean. In comparison with the basalts, the diabases from the Bingdaban area show higher contents of Al2O3, ∑REE and HFS elements as well as unfractionated incompatible elements except Cs, Rb and Ba, and about 10 times the values of the primitive mantle. Thus, the diabases are thought to be derived from a primitive mantle and similar to the typical E-MORB. The diabases also have slight Nb depletion accompanying no apparent Th enrichment compared with N-MORB. From studies of the regional geology and all above evidence, it can be suggested that the diabases from the Bingdaban

关键词： geochemistry ophiolite suture zone Bingdaban Tianshan orogenic belt.

TECTONIC SIGNIFICANCE OF THE WEST KUNLUN FOLD-THRUST-BELT AND THE TARIM SOUTHWEST DEPRESSION

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地学前缘 2000年第S1期7卷 84-86页

作者： luo jinhai (Department of Geology, Northwest University, Xi′an 710069,China)

The evolution of the Tarim southwest depression lying at the piedmont of the West Kunlun orogen differs completely from the evolution of the main part of Tarim basin after Later Palaeozoic because the former strongly subsides many times.. Subsidence is related closely to the West Kunlun fold thrust\|belt, thus the evolution of the Depression and the fold\|thrust\|belt reflects clearly the formation and evolution of the West Kunlun and even the Tibet.1 Evolution of the West Kunlun fold\|thrust\|belt\;Thrusting of the fold\|thrust\|belt can be classified into three stages:(1) Devonian thrusting:This is the oldest thrusting distinguished in the northern margin of the West Kunlun while the Silurian—Devonian thrusting was discriminated a few years ago by seismic data in the northern part of the East Kunlun. The Devonian thrusting is proved by the Upper Devonian dynamometamorphic rocks outcropping at the core of the anticline in the Sangzhu lying at the fold\|thrust\|belt. The rocks consist of slightly metamorphic clastic rock and have always been regarded as the Mid\|Proterozoic strata. But they are actually Upper Devonian strata according to the amount of perfect plant fossils that we found recently in the metamorphic rock, and they are overburdened `with an angular unconformity by another reliable Upper\|Devonian conglomerate in the core of the Aqike anticline. A possible explanation for this and its limited lined distribution parallel to the West Kunlun orogen is that they are subjected to metamorphism during the Later Devonian thrusting.

关键词： evolution West Kunlun fold\|thrust\|belt Tarim southw est depression correspondence

Ultra-high pressure metamorphism of granitic gneiss in the Yinggelisayi area, Altun Mountains, NW China

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Science China Earth Sciences 2004年第4期47卷 338-346页

作者： LIU Liang, SUN Yong, luo jinhai, WANG Yan, CHEN Danling & ZHANG Anda The Key Laboratory of Continental Dynamics, Ministry of Education,Department of Geology, Northwest University, Xi抋n 710069, China The Key Laboratory of Continental Dynamics Ministry of Education Department of Geology Northwest University Xi’an China

A study on petrography and mineral chemistry of granitic gneiss from the Yinggeli-sayi area in the Altun Mountains of the northwestern China demonstrates that the granitic gneiss experienced a complicated multi-stage metamorphism. The peak-stage mineral assemblage is garnet+perthite(before exsolution)+titanite(before exsolution)+kyanite+zoisite +quartz/ coesite clinopyroxene with minor apatite and rutile. The exsolution of rod-like plagioclase +amphibole is contained within the core part of coarse-grained titanite, and the Si value per unit formula of the titanite is estimated to be 1.032—1.047, which implies that the titanite contains Si with six-fold coordination and the precursor titanite is hence of supersilicic titanite and suggests that the CaSi2O5 component in the titanite is 3.1%—4.7%. The P-T condition of peak metamorphism is estimated to be 3.7—4.3GPa at 1000. High-Al titanite inclusions are also found in the garnet. All of these suggest that the granitic gneiss underwent UHP metamorphism. The granitic gneiss has SiO2 content (> 70%), Al2O3 (12.58%—14.08%), high K2O content (>5%) with Na2O/K2O ratio of 0.4—0.6, LREE-enriched patterns with (La/Yb)N ratio of 4.3—9.1 and large negative Eu anomaly (d Eu = 0.06—0.59), which indicate that the protolith of the granitic gneiss is the product of anatexis of the middle or upper crustal rock. The UHP granitic gneiss, together with the inter-beds of UHP metamorphic garnet lherzolite and garnet-bearing intermediate-basic gneiss in the outcrops, suggests that they all might undergo continental deep subduction, which will have im-portant bearing for further discussion of the dynamic mechanism of the formation and exhuma-tion of the rocks in this region.

关键词： Altun Mountains, granitic gneiss, supersilicic titanite, UHP metamorphism, continental deep subduction.

鄂尔多斯盆地西南部晚三叠世辉绿岩年代学、地球化学及其构造意义

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地学前缘 2022年第6期29卷 314-324页

作者：罗金海畅莹磊陈卓西北大学地质学系大陆动力学国家重点实验室陕西西安710069

鄂尔多斯盆地西南部中奥陶统马家沟组灰岩内部发育多条辉绿岩脉。辉绿岩富集高场强元素(HFSE)Nb、Ta、Ti、Zr、Hf等,具有板内拉斑玄武岩的地球化学特征,其地球化学数据显示原始岩浆经历过比较强烈的结晶分异演化。对辉绿岩的锆石进行U-P... 详细信息

鄂尔多斯盆地西南部中奥陶统马家沟组灰岩内部发育多条辉绿岩脉。辉绿岩富集高场强元素(HFSE)Nb、Ta、Ti、Zr、Hf等,具有板内拉斑玄武岩的地球化学特征,其地球化学数据显示原始岩浆经历过比较强烈的结晶分异演化。对辉绿岩的锆石进行U-Pb LA-ICP-MS测年获得的^(206) Pb/^(238) U年龄为750~195 Ma。根据峰值年龄并结合区域地质资料,本文把辉绿岩的形成年龄确定为224 Ma(晚三叠世)。辉绿岩反映鄂尔多斯盆地西南部在晚三叠世处于类似大陆裂谷的伸展构造环境,晚三叠世西邻陇山地区发生的强烈碰撞后伸展作用也可能有助于进一步强化鄂尔多斯盆地西南部的伸展构造环境。当时该地区岩石圈的稳定性相对较弱,为该地区后续的早侏罗世和早白垩世岩浆活动提供了物质基础。晚三叠世及后期的岩浆活动提高了鄂尔多斯盆地西南部的地温梯度并加快了该地区烃源岩的热演化进程,可能对该地区的油气成藏条件造成潜在影响。

关键词：鄂尔多斯盆地西南部晚三叠世辉绿岩大陆拉斑玄武岩伸展作用

Discovery of ultrahigh-pressure magnesite-bearing garnet lherzolite (>3.8 GPa) in the Altyn Tagh, Northwest China

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Chinese Science Bulletin 2002年第11期47卷 881-886页

作者： LIU Liang, SUN Yong, XIAO Peixi, CHE Zicheng, luo jinhai, CHEN Danling, WANG Yan, ZHANG Anda, CHEN Liang & WANG YongheKey Laboratory of Continental Dynamics of the Ministry of Education, Northwest University, Xi’an 710069, China The Northwest Institute of Key Laboratory of Continental Dynamics of the Ministry of Education Northwest University Xi’an China The Northwest Institute of Geology and Mineral Resources Xi’an China

Magnesite-bearing garnet Iherzolite from the Altyn Tagh, associated with garnet pyroxenite, and garnet-bearing felsic gneiss, crops out as lenses in Proterozoic gneiss about 100 km east of the Jianggelasayi River. The garnet Iherzolite, together with the eclogite in western Jianggelasayi, composes a high-pressure to ultrahigh-pressure metamorphic belt in the southern margin of the Altyn Tagh. Parageneses of minerals from magnesite-bearing garnet Iherzolite indicate that the rock evolved a multi-stage metamorphism. The peak-stage metamorphism produces an assemblage of Grt+Ol+Opx+Cpx±Mgs, in which A12O3 content of Opxis very low (0.30-0.66wt%). The calculated P-T condition of the peak stage is *** and 880-970°C, some exsolution rods of clinopyroxene and rutile occur in the Grt and magnesite is rimed by dolomite and orthopyroxene, all implying that the peak stage was a UHP metamorphic process. Together with regional geological studies, isotopic dating and the discovery of coesite inclusions in

关键词： garnet lherzolite magnesite UHP metamorphism Altyn Tagh Mountains.

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中亚及中国西部侏罗纪沉积盆地的构造特征

地质科学 2000年第4期35卷 404-413页

作者：罗金海车自成李继亮西北大学地质系西安710069 中国科学院地质研究所北京100029

侏罗纪是中亚和中国西部地区沉积盆地主要形成时期 ,这表现在两个方面 :(1 )先期存在的盆地在此阶段沉积范围持续扩大 ;(2 )形成了许多新的侏罗纪沉积盆地。本文通过对劳亚大陆南部侏罗纪特提斯北带构造特征、诸盆地早 -中侏罗世岩相古... 详细信息

侏罗纪是中亚和中国西部地区沉积盆地主要形成时期 ,这表现在两个方面 :(1 )先期存在的盆地在此阶段沉积范围持续扩大 ;(2 )形成了许多新的侏罗纪沉积盆地。本文通过对劳亚大陆南部侏罗纪特提斯北带构造特征、诸盆地早 -中侏罗世岩相古地理和构造样式的分析 ,表明中国西部与中亚地区在侏罗纪时虽然都处于新特提斯北部被动大陆边缘 ,但由于受帕米尔弧向北推挤的影响 ,以及昆仑构造带与塔拉斯 -费尔干纳断裂和阿尔金大型走滑断裂的存在 ,这两个地区的侏罗纪盆地具有完全不同的构造起因。以塔拉斯 -费尔干纳断裂为界 ,西南侧中亚地区的侏罗纪沉积盆地主要是由新特提斯北部大陆边缘的被动伸展形成 ;东北侧中国西部的侏罗纪沉积盆地则主要发育于区域性挤压构造背景之下 ,形成的主要机制是重力陷落。此外 ,沿塔拉斯 -费尔干纳断裂还存在几个侏罗纪的走滑拉分盆地。

关键词：侏罗纪沉积盆地构造样式中国西部油气藏

中祁连元古代皋兰岩群的解体:古元古代变质事件与早-中寒武世大陆裂谷作用

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岩石学报 2024年第11期40卷 3586-3608页

作者：计波罗金海李向民时超余吉远刘阳大陆动力学国家重点实验室西北大学地质学系西安710069 中国地质调查局西安地质调查中心(西北地质科技创新中心) 中国地质调查局造山带研究中心西安710119 中陕核工业集团公司西安710100

中祁连东段元古代皋兰岩群是一套变质程度极不均一的变质岩系,本次工作根据变质程度将其重新划分为北部的低绿片岩相与南部的高绿片岩相(局部低角闪岩相)两个岩石单元。两者分别具有不同的岩相学、锆石U-Pb年代学和岩石地球化学特征,并... 详细信息

中祁连东段元古代皋兰岩群是一套变质程度极不均一的变质岩系,本次工作根据变质程度将其重新划分为北部的低绿片岩相与南部的高绿片岩相(局部低角闪岩相)两个岩石单元。两者分别具有不同的岩相学、锆石U-Pb年代学和岩石地球化学特征,并以韧性剪切带相隔。低绿片岩相岩石单元中玄武岩和流纹岩的成岩年龄为502.5±3Ma、500.8±3Ma和507.8±4Ma,表明其形成时代为早-中寒武世;高绿片岩相(局部低角闪岩相)岩石单元中的斜长角闪岩变质锆石的U-Pb年龄为1873±10Ma,暗示其形成于古元古代中-晚期中祁连地块基底形成阶段,该岩石单元是中祁连地块对哥伦比亚超大陆聚合事件的物质记录。结合年代学、岩石组合以及区域资料,将低绿片岩相岩石单元从皋兰岩群中解体出来,划归北祁连寒武纪黑茨沟组。岩石地球化学分析显示,新解体出来的黑茨沟组双峰式火山岩形成于大陆裂谷环境,其中玄武质岩浆可能来自软流圈地幔,在上涌过程中受到轻微的地壳混染;流纹岩主要由玄武质岩浆结晶分异而来,并且有少量地壳物质的加入。综合分析祁连山地区原特提斯洋开启时限研究成果,认为新元古代晚期至早古生代早期北祁连地区的裂解作用乃至大洋化过程并非同步进行,而是呈现出西早东晚的特征。

关键词：古元古代皋兰岩群地层单元解体锆石U-Pb年龄构造环境中祁连