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Anticlockwise P-T Path and Zircon U-Pb Dating of HP Mafic Granulites in Yushugou Granulite-Peridotite Complex, Southern Tianshan Mountains, China
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作者 ZHANG Lu ZHANG Lifei +1 位作者 XIA Bin Lü Zeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期252-,共1页
The Yushugou HP granulite-peridotite complex is located at east of northern margin of southern Tianshan mountains,China,which consists of granulite unit and peridotite unit mainly.Because of the rare association of
关键词 Pb China Southern Tianshan Mountains anticlockwise P-T path and Zircon U-Pb Dating of HP Mafic Granulites in Yushugou Granulite-Peridotite Complex HP
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P-T-t Path of Mafic Granulite Metamorphism in Northern Tibet and Its Geodynamical Implications 被引量:8
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作者 HUDaogong WUZhenhan JIANGWan YEPeisheng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第1期155-165,共11页
Mafic granulites have been found as structural lenses within the huge thrust system outcropping about 10 km west of Nam Co of the northern Lhasa Terrane, Tibetan Plateau. Petrological evidence from these rocks indicat... Mafic granulites have been found as structural lenses within the huge thrust system outcropping about 10 km west of Nam Co of the northern Lhasa Terrane, Tibetan Plateau. Petrological evidence from these rocks indicates four distinct metamorphic assemblages. The early metamorphic assemblage (M1) is preserved only in the granulites and represented by plagioclase+hornblende inclusions within the cores of garnet porphyroblasts. The peak assemblage (M2) consists of garnet+clinopyroxene+hornblende+plagioclase in the mafic granulites. The peak metamorphism was followed by near-isothermal decompression (M3), which resulted in the development of hornblende+plagioclase symplectites surrounding embayed garnet porphyroblasts, and decompression-cooling (M4) is represented by minerals of hornblende+plagioclase recrystallized during mylonization. The peak (M2) P-T conditions of garnet+ clinopyroxene+plagioclase+hornblende were estimated at 769-905℃ and 0.86-1.02 GPa based on the geothermometers and geobarometers. The P-T conditions of plagioclase+hornblende symplectites (M3) were estimated at 720-800℃ and 0.55-0.68 GPa, and recrystallized hornblende+plagioclase (M4) at 594-708℃ and 0.26-0.47 GPa. It is impossible to estimate the P-T conditions of the early metamorphic assemblage (M1) because of the absence of modal minerals. The combination of petrographic textures, metamorphic reaction history, thermobarometric data and corresponding isotopic ages defines a clockwise near-isothermal decompression metamorphic path, suggesting that the mafic granulites had undergone initial crustal thickening, subsequent exhumation, and cooling and retrogression. This tectonothermal path is considered to record two major phases of collision which resulted in both the assemblage of Gondwanaland during the Pan-African orogeny at 531 Ma and the collision of the Qiangtang and Lhasa Terranes at 174 Ma, respectively. 展开更多
关键词 continental collision mafic granulite p-t-t path GONDWANALAND Qiangtang and Lhasa Terranes TIBET
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冈底斯岩浆弧东段变泥质岩的逆时针P-T-t轨迹与构造机制 被引量:4
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作者 康东艳 张泽明 +3 位作者 董昕 田作林 向华 莫宣学 《岩石学报》 SCIE EI CAS CSCD 北大核心 2019年第2期349-362,共14页
青藏高原南部冈底斯岩浆弧东段出露的中-高级变质岩代表岩浆弧的中-下地壳,是研究岩浆弧深部组成与形成演化的理想载体。本文对冈底斯弧东段布久地区的变泥质岩,即石榴石夕线石云母片岩进行了岩石学、相平衡模拟和地质年代学研究。岩石... 青藏高原南部冈底斯岩浆弧东段出露的中-高级变质岩代表岩浆弧的中-下地壳,是研究岩浆弧深部组成与形成演化的理想载体。本文对冈底斯弧东段布久地区的变泥质岩,即石榴石夕线石云母片岩进行了岩石学、相平衡模拟和地质年代学研究。岩石学和相平衡模拟表明,片岩由黑云母、白云母、石榴石、夕线石、斜长石、石英及少量的钛铁矿、金红石组成,含或不含蓝晶石,经历了早期的低压麻粒岩相变质与部分熔融,变质温压条件为~7kbar和~770℃,中期的高压麻粒岩相变质与深熔作用,变质温压条件为~10. 5kbar和~775℃,以及晚期的角闪岩相退变质与熔体结晶作用,退变质温压条件为~7. 5kbar和~705℃,具有逆时针型的变质作用P-T-t轨迹。本文和现有年代学研究表明,片岩的早期的低压麻粒岩相变质与部分熔融发生在~70Ma,后续高压麻粒岩相变质与深熔发生在50~45Ma,晚期角闪岩相退变质与熔体结晶开始于45Ma,持续到25Ma。大体积幔源岩浆底侵导致的地壳加热与加厚,以及大陆碰撞导致的地壳缩短与加厚是冈底斯弧表壳岩在晚中生代至早新生代被埋藏到下地壳,经历长期持续高温、高压变质与部分熔融的构造机制,而加厚岩石圈地幔在渐新世的拆沉导致了岩浆弧加厚下地壳的折返。 展开更多
关键词 冈底斯岩浆弧 变泥质片岩 逆时针p-t-t轨迹 麻粒岩相变质作用 部分熔融 地壳加厚
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Metamorphism and geochronology of garnet amphibolite from the Beishan Orogen,southern Central Asian Orogenic Belt:Constraints from P-T path and zircon U-Pb dating
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作者 Wenbin Kang Wei Li +4 位作者 Lei Kang Yunpeng Dong Dazhi Jiang Jiwei Liang Haoqiang Dong 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第4期1189-1201,共13页
Numerous lenses of garnet amphibolite occur in the garnet-bearing biotite-plagioclase gneiss belt in the Baishan area of the Beishan Orogen,which connects the Tianshan Orogen to the west and the Mongolia-Xing’anling ... Numerous lenses of garnet amphibolite occur in the garnet-bearing biotite-plagioclase gneiss belt in the Baishan area of the Beishan Orogen,which connects the Tianshan Orogen to the west and the Mongolia-Xing’anling Orogen to the east.The study of metamorphism in Beishan area is of great significance to explain the tectonic evolution of Beishan orogen.According to the microstructures,mineral relationships,and geothermobarometry,we identified four stages of mineral assemblages from the garnet amphibolite sample:(1) a pre-peak stage,which is recorded by the cores of garnet together with core-inclusions of plagioclase(Pl1);(2) a peak stage,which is recorded by the mantles of garnet together with mantle-inclusions of plagioclase(Pl2)+amphibole(Amp1)+Ilmenite(Ilm1)+biotite(Bt1),developed at temperature-pressure(P-T) conditions of 818.9-836.5℃ and7.3-9.2 kbar;(3) a retrograde stage,which is recorded by garnet rims + plagioclase(Pl3)+amphibole(Amp2)+orthopyroxene(Opx1)+biotite(Bt2)+Ilmenite(Ilm2),developed at P-T conditions of 796.1-836.9℃ and5.6-7.5 kbar;(4) a symplectitic stage,which is recorded by plagioclase(Pl4)+orthopyroxene(Opx2)+amphibole(Amp3)+biotite(Bt3) symplectites,developed at P-T conditions of 732 ±59.6℃ and 6.1 ±0.6 kbar.Moreover,the U-Pb dating of the Beishan garnet amphibolite indicates an age of 301.9 ±4.7 Ma for the protolith and 281.4±8.5 Ma for the peak metamorphic age.Therefore,the mineral assemblage,P-T conditions,and zircon U-Pb ages of the Beishan garnet amphibolite define a near-isothermal decompression of a clockwise P-T-t(Pressure-Temperature-time) path,indicating the presence of over thickened continental crust in the Huaniushan arc until the Early Permian,then the southern Beishan area underwent a process of thinning of the continental crust. 展开更多
关键词 Beishan orogen Garnet amphibolite p-t-t path Zircon U-Pb dating
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攀枝花大田地区康定群咱里组变质杂岩P—T—t轨迹及其构造意义
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作者 张宝玲 陈友良 +3 位作者 欧何琼 付于真 殷桂芹 顾孟娟 《地质论评》 CAS CSCD 北大核心 2023年第3期881-896,共16页
扬子板块西缘的康定杂岩为一套由侵入岩和变质岩共同组成的岩浆—变质混合杂岩,是研究罗迪尼亚超大陆裂解的重要窗口。长期以来对康定杂岩中的岩浆杂岩研究较多,但对变质杂岩研究较为薄弱。为全面了解康定杂岩形成的构造背景及成因机制... 扬子板块西缘的康定杂岩为一套由侵入岩和变质岩共同组成的岩浆—变质混合杂岩,是研究罗迪尼亚超大陆裂解的重要窗口。长期以来对康定杂岩中的岩浆杂岩研究较多,但对变质杂岩研究较为薄弱。为全面了解康定杂岩形成的构造背景及成因机制,笔者等对扬子板块西缘的攀枝花大田地区康定群咱里组石榴夕线黑云斜长片麻岩进行了详细的岩相学、矿物地球化学、变质P—T条件估算研究,同时对同一层位的石榴二云片岩进行了锆石LA-ICP-MS U-Pb年代学分析。结果表明:石榴夕线黑云斜长片麻岩可识别出三期变质矿物组合:进变质阶段矿物组合(M1)为石榴子石变斑晶核部及其核部包裹体(石榴子石核部+第一期黑云母+第一期夕线石+钛铁矿+石英),P—T条件为609~690℃—0.2~0.3 GPa;峰期变质阶段矿物组合(M2)为石榴子石变斑晶幔部及变基质矿物(石榴子石幔部+第二期黑云母+第二期夕线石+斜长石+石英),P—T条件为643~732℃—0.20~0.51 GPa;退变质阶段矿物组合(M3)为石榴子石变斑晶边部及变基质矿物(石榴子石边部+第二期黑云母+第二期夕线石+斜长石+石英),P—T条件为602~687℃—0.27~0.39 GPa。石榴夕线黑云斜长片麻岩记录了具近等压冷却型(IBC)的逆时针P—T演化轨迹;石榴二云片岩锆石U-Pb定年结果表明区内的变质时代为842±10 Ma,综合分析表明:扬子板块西缘的变质杂岩形成于拉张环境,结合区内的同期岩浆活动特征,认为区内新元古代变质事件可能与超级地幔柱引发的岩浆活动有关。 展开更多
关键词 大田地区 康定群变质杂岩 逆时针P—T轨迹 变质时代 构造意义
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海南岛屯昌晨星地区变基性岩体变质特征及构造意义 被引量:14
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作者 许德如 夏斌 +4 位作者 Nonna Bakun-Czubarow 马驰 李鹏春 Robert Bachlinskl 陈广浩 《岩石学报》 SCIE EI CAS CSCD 北大核心 2006年第12期2987-3006,共20页
海南岛屯昌晨星地区变基性岩体原岩可能包括辉长岩(粗粒的斜长角闪岩)、辉长-辉绿岩(中细粒和中粗粒的斜长角闪岩)和枕状熔岩(细粒或块状斜长角闪岩)。由于受多期变质和蚀变作用的影响,组成这些岩石的多数矿物如角闪石、斜长石和绿泥石... 海南岛屯昌晨星地区变基性岩体原岩可能包括辉长岩(粗粒的斜长角闪岩)、辉长-辉绿岩(中细粒和中粗粒的斜长角闪岩)和枕状熔岩(细粒或块状斜长角闪岩)。由于受多期变质和蚀变作用的影响,组成这些岩石的多数矿物如角闪石、斜长石和绿泥石等常表现两个或两个以上的世代。角闪石环带矿物化学分析表明,从核到边,钛、铝、(钠+钾)含量增长,反映了压力和温度同时升高的进变质演化过程;相反,角闪石环带从核部到边部钛、铝和钾+钠含量降低,则暗示温度和压力同时降低而进入另一个退变质演化阶段。所获得的 Sm-Nd 全岩及角闪石的内部等时线年龄为128±12 Ma、Rb-Sr 全岩等时线年龄分别为131.8±6.2 Ma和344±11Ma。根据角闪石环带、矿物共生组合、微结构以及变质温压条件的半定量计算和同位素定年,屯昌晨星地区变基性岩体的变质作用可能经历了三个演化阶段。第一阶段(~527~450 Ma)可能记录了与洋底变质作用有关的(亚)绿片岩相至角闪岩相条件,早期的阳起石、钙质角闪石及镁铁质角闪石残余核为该阶段的产物;第二阶段(~330~240 Ma)进变质作用达到高峰的P=~0.9 GPa、T=~700℃,显示了过渡的高角闪石相-麻粒岩相变质条件。广泛的剪切变形及韭闪质普通角闪石-韭闪石边是该阶段的产物;第三阶段(~130 Ma~90 Ma)显示一个绿片岩相变质条件(P=~0.1~0.3 GPa、7=~300~400℃),可能与区域/热接触变质有关。因而屯昌晨星地区变基性岩体的变质作用演化显示了一个逆时针 P-T-t 轨迹,最可能与古太平洋板块俯冲导致的大陆边缘裂解及洋壳化和随后的年轻洋壳消亡、陆(华南大陆)-陆(印支板块)碰撞事件有关。 展开更多
关键词 变基性岩体 海南岛屯昌晨星地区 角闪石环带 逆时针p-t-t轨迹 洋壳消亡残片
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内蒙石板井—小黄山与蛇绿岩相伴的变质岩及其演化 被引量:10
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作者 周国庆 陈小明 赵建新 《高校地质学报》 CAS CSCD 2001年第3期329-344,共16页
在内蒙古石板井 -小黄山蛇绿岩带发现了具典型热变质特征的红柱石堇青石角岩和以兰绿色角闪石、硬绿泥石、黑硬绿泥石等矿物代表的中高压区域变质角闪片岩。据变质作用时序和相拓朴图两个方面的研究 ,表明石板井和小黄山两地的变质岩属... 在内蒙古石板井 -小黄山蛇绿岩带发现了具典型热变质特征的红柱石堇青石角岩和以兰绿色角闪石、硬绿泥石、黑硬绿泥石等矿物代表的中高压区域变质角闪片岩。据变质作用时序和相拓朴图两个方面的研究 ,表明石板井和小黄山两地的变质岩属同一构造混杂岩 ,其中的变质岩先经过与火成作用有关的热变质作用 ,后又叠加了中高压变质作用 ,即经历过一反时钟PT轨迹。它的热高峰为 6 2 0℃ ,压力高峰近 0 .6 5GPa。 展开更多
关键词 内蒙石板井-小黄山 变质作用时序 反时针PT轨迹 蛇绿台 相拓扑图 热变质作用 火山作用
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佛子岭群逆时针P-T轨迹对大别碰撞造山带构造演化的探究 被引量:2
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作者 杨根山 石永红 +2 位作者 唐虎 李秋立 侯振辉 《岩石学报》 SCIE EI CAS CSCD 北大核心 2020年第12期3654-3672,共19页
佛子岭群位于大别造山带最北缘,处于华北和扬子两大板块结合部位,构造位置十分关键,是解析两大板块精细耦合过程和探究大别造山带晚古生代构造事件的重要单元。然而,由于长期以来佛子岭群一直被视为"浅变质"复理石沉积单元,... 佛子岭群位于大别造山带最北缘,处于华北和扬子两大板块结合部位,构造位置十分关键,是解析两大板块精细耦合过程和探究大别造山带晚古生代构造事件的重要单元。然而,由于长期以来佛子岭群一直被视为"浅变质"复理石沉积单元,因而对其变质演化过程的解析较为薄弱,制约了对大别造山带形成过程的全面理解。本次通过对老虎场-龚店地质剖面细致的观测,石榴黑云母片麻岩精细的岩相学、矿物化学分析、热力学评价和年代学研究,建立了佛子岭群一个逆时针P-T变质演化型式。研究显示,佛子岭群记录了Ⅰ、Ⅱ、Ⅲ和Ⅳ四个变质阶段,温压变化依次为:(1)T=658~663℃、P=1.08~1.16GPa→(2)T=755~762℃、P=1.21~1.45GPa→(3)T=549~554℃、P=1.08~1.19GPa→(4)P标定=0.3~0.6GPa、T=477~499℃,(1)至(3)为近等压升温和降温过程,(3)至(4)则表现为近等温降压型式。锆石U-Pb定年显示了1484±64Ma^1180±192Ma、995±35Ma^606±14Ma和370±14Ma^331±8Ma三组年龄,前两组代表了碎屑锆石年龄;第三组共计7颗锆石,年龄集中,Th/U比值0.01~0.03,加权平均年龄为344±11Ma,代表了主期变质年龄。结合此次地质剖面结构特征和岩石类型,以及前人白云母40Ar-39Ar的270~255Ma变质年龄,表明佛子岭群记录了两期变质事件,早期为晚古生代的拉张背景下的岛弧根部变质,晚期为晚古生代末的较为快速抬升构造热事件,并据此推测大别造山带可能为增生和碰撞复合型造山带。 展开更多
关键词 佛子岭群 浅变质 逆时针P-T轨迹 锆石U-PB 岛弧拉张环境
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The Himalayan Collisional Orogeny:A Metamorphic Perspective 被引量:12
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作者 WANG Jiamin WU Fuyuan +2 位作者 ZHANG Jinjiang Gautam KHANAL YANG Lei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第6期1842-1866,共25页
This paper introduces how crustal thickening controls the growth of the Himalaya by summarizing the P-T-t evolution of the Himalayan metamorphic core.The Himalayan orogeny was divided into three stages.Stage 60–40 Ma... This paper introduces how crustal thickening controls the growth of the Himalaya by summarizing the P-T-t evolution of the Himalayan metamorphic core.The Himalayan orogeny was divided into three stages.Stage 60–40 Ma:The Himalayan crust thickened to~40 km through Barrovian-type metamorphism(15–25°C/km),and the Himalaya rose from<0 to~1000 m.Stage 40–16 Ma:The crust gradually thickened to 60–70 km,resulting in abundant high-grade metamorphism and anatexis(peak-P,15–25°C/km;peak-T,>30°C/km).The three sub-sheets in the Himalayan metamorphic core extruded southward sequentially through imbricate thrusts of the Eo-Himalayan thrust,High Himalayan thrust,and Main Central thrust,and the Himalaya rose to≥5,000 m.Stage 16–0 Ma:the mountain roots underwent localized delamination,causing asthenospheric upwelling and overprinting of the lower crust by ultra-high-temperature metamorphism(30–50°C/km),and the Himalaya reached the present elevation of~6,000 m.Underplating and imbricate thrusting dominated the Himalaya’growth and topographic rise,conforming to the critical taper wedge model.Localized delamination of mountain roots facilitated further topographic rise.Future Himalayan metamorphic studies should focus on extreme metamorphism and major collisional events,contact metamorphism and rare metal mineralization,metamorphic decarbonation and the carbon cycle in collisional belts. 展开更多
关键词 continental collision crustal thickening mountain uplift critical taper wedge and channel flow p-t-t path HIMALAYA
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Metamorphic P-T-t Path of UHT Granulites from the North Tongbai Orogen, Central China 被引量:3
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作者 Hua Xiang Zeming Zhang +2 位作者 Liming Zhao Zengqiu Zhong Hanwen Zhou 《Journal of Earth Science》 SCIE CAS CSCD 2018年第5期1116-1131,共16页
Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate- to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature (P-T) cond... Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate- to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature (P-T) conditions. In this study, zircon trace elements and Hf isotopes and REE partitioning between zircon and garnet are adopted to track the formation condition of zircon in the granu- lites from North Tongbai Orogen, Central China. Combined with previous metamorphic P-T path results, a quantitative integrated anticlockwise P-T-t path was established for Tongbai granulites. These grauulites recorded an early low-P heating followed by a dramatic pressure increase. Evidence for the prograde history (M1) is provided by cordierite, orthopyroxene and biotite inclusions in garnet. The prograde metamorphism occurred at around 443±3 Ma, with P-T conditions of ca. 730-820 ℃ and 〈6 kbar. The peak metamorphic (M2) condition is 〉920 ℃ and 8.5-10 kbar and the peak metamorphism age is ca. 432±4 Ma. At around 419 Ma, the granulites suffered an amphibolite-facies retrograde metamorphism (M3), represented by the replacement of garnet by biotite and plagioclase, and clinopyroxene by amphibole, with metamorphic condition of ca. 700℃ and ca. 7 kbar. The last retrograde metamorphism (M4) is a greenschist-facies overprint with an age of ca. 404 Ma. It is concluded that the meta- morphism of Tongbai granulite lasted for more than 40 Ma, including a stage of more than 20 Ma granulitc-facies metamorphism. The prolonged granulite-facies metamorphism resulted from the continuous northward subduction of the Shangdan oceanic crust beneath the North Qinling terrane. 展开更多
关键词 GRANULITES zircon U-Pb dating p-t-t path trace element Ln-Hf isotope Tongbai Orogen.
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Permo-Triassic high-pressure metamorphism in the central western Korean Peninsula, and its link to Paleo-Tethyan Ocean closure: Key issues revisited 被引量:2
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作者 Hyeong Soo Kim Sanghoon Kwon +1 位作者 Sung Won Kim M.Santosh 《Geoscience Frontiers》 SCIE CAS CSCD 2018年第5期1325-1335,共11页
Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic colli... Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic collisional orogeny in northeast Asia. The metamorphic pressureetemperatureetime(P-T-t)paths of these rocks, however, remain poorly constrained and even overestimated, owing to outdated geothermobarometers and inaccurate isopleth techniques. Here we evaluate the metamorphic Pe T conditions of Triassic HP mafic granulites including those in Baekdong, Sinri and Daepan and the Bibong Triassic retrogressed eclogite in the Hongseong area, and the Permo-Triassic Samgot mafic granulite in the Imjingang Belt of the central western Korean Peninsula through the application of modern phase equilibria techniques. The Baekdong and Samgot mafic granulites and the Bibong retrogressed eclogite yield a range of 12.0 -16.0 kbar and 800 -900℃, representing HP granulite facies conditions. The Sinri and Daepan granulites from the Hongseong area show relatively lower grade metamorphic conditions between HP granulite and normal granulite facies, and are characterized by sub-isothermal decompression during exhumation. The similarities in the metamorphic ages and the post-collisional igneous activity from the central western Korean Peninsula indicate that the Triassic ages represent the retrograde stage of the metamorphic Pe T paths. In contrast, the Late Permian metamorphic ages, which are older than protolith ages of the post-collisional igneous rocks, correspond to the possible prograde stage of metamorphism. The P-T-t paths presented in this paper, together with the metamorphic ages and post-orogenic igneous events reported from these areas suggest trace of the subduction, accretion and exhumation history, and indicate a tectonic linkage among the northeast Asian continents during the Paleo-Tethyan Ocean closure. 展开更多
关键词 HP GRANULITE Retrogressed ECLOGITE Petrology and phase equilibria Metamorphic p-t-t paths CENTRAL WESTERN Korean Peninsula
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Petrological Investigations and Zircon U-Pb Dating of High Pressure Felsic Granulites from the Yushugou Complex, South Tianshan, China 被引量:1
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作者 ZHANG Lu ZHANG Lifei +3 位作者 ZHU Jianjiang XIA Bin LU Zeng Thomas BADER 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2018年第1期144-161,共18页
As a window of insight into the lower crust, high pressure granulite has received much attention since last decade. Yushugou high pressure granulite-peridotite Complex was located in the northeast margin of Southern T... As a window of insight into the lower crust, high pressure granulite has received much attention since last decade. Yushugou high pressure granulite-peridotite Complex was located in the northeast margin of Southern Tianshan, NW China. Previous ideas agreed that the peridotite unit in Yushugou, combined with the ultramafic rocks in Tonghuashan and Liuhuangshan, represent an ophiolite belt. However, the metamorphic evolution and tectonic mechanism of the Yushugou high pressure (HP) granulite remain controversial. Petrological investigations and phase equilibrium modelling for two representative fclsic granulitc samples suggest two stages metamorphism of the rocks in Yushugou Complex. Granulite facies metamorphism (Stage I) with P-T conditions of 9.8-10.4 kbar at 895-920℃ was recorded by the porphyroblastic garnet core; HP granulite facies metamorphism (Stage II) shows P-T conditions of 13.2-13.5 kbar at 845-860℃, based on the increasing grossular and decreasing pyrope contents of garnet rims. The Yushugou HP felsic granulites have recorded an anti- clockwise P-T path, characterized by the temperature decreasing and pressure increasing simultaneously. The LA-ICP-MS isotopic investigations on zircons from the felsic granulite show that the protolith ages of the granlulites are -430 Ma, with two age groups of-390 Ma and 340-350 Ma from the metamorphic rims of zircon, indicating the Stage I and II metamorphic events, respectively. A tectonic model was proposed to interpret the processes. The investigated felsic granulite was derived from deep rooted hanging wall, with Stage I granulite facies metamorphism of -390 Ma, which may he related to the Devonian arc magmatic intrusion; Stage II HP granulite facies metamorphism (340-350 Ma) may due to the involvement of being captured into the subducting slab and experienced the high pressure metamorphism. 展开更多
关键词 anticlockwise P-T path HP felsic granulites P-T pseudosection U-Pb zircon dating SouthTianshan
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Re-evaluating monazite as a record of metamorphic reactions 被引量:2
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作者 Kyle P.Larson Sudip Shrestha +4 位作者 John M.Cottle Carl Guilmette T.Alex Johnson H.Daniel Gibson Félix Gervais 《Geoscience Frontiers》 SCIE CAS CSCD 2022年第2期237-254,共18页
This study presents a re-examination of historical specimens(DG136 and DG167)from the Monashee complex in the southeastern Canadian Cordillera that are critical to the current understanding of rare earth element(REE)d... This study presents a re-examination of historical specimens(DG136 and DG167)from the Monashee complex in the southeastern Canadian Cordillera that are critical to the current understanding of rare earth element(REE)distribution between garnet and monazite(and other accessory minerals)during metamorphism.Nine-hundred and fifty-one new monazite petrochronology spot analyses on 29 different grains across two specimens outline detailed(re)crystallization histories.Trace element data collected from the same ablated volume,interpreted in the context of new phase equilibria modelling that includes monazite,xenotime and apatite,link ages to specific portions of the pressure-temperature(P-T)paths followed by the specimens.These linkages are further informed by garnet Lu-Hf geochronology and xenotime petrochronology.The clockwise P-T paths indicate prograde metamorphism was ongoing by ca.80 Ma in both specimens.The structurally deeper specimen,DG136,records peak P-T conditions of~755-770℃and 8.8-10.4 kbar,interpreted to coincide with(re-)crystallization of low Y monazite at~75-70 Ma.Near-rim garnet isopleths from DG167 cross in the observed peak assemblage field at~680℃ and 9.3 kbar.These conditions are interpreted to correspond with low Y monazite(re-)crystallisation at~65 Ma.Both specimens record decompression along their retrograde path coincident with high Y 70-55 Ma and 65-55 Ma monazite populations in DG136 and DG167,respectively.These findings broadly agree with those initially reported~20 years ago and confirm early interpretations using trace elements in monazite as generally reliable markers of metamorphic reactions.Modern phase equilibria modelling and in situ petrochronological analysis,however,provide additional insight into monazite behaviour during anatexis and the effects of potential trace element buffering by REE-bearing phases such as apatite. 展开更多
关键词 Monazite petrochronology Phase equilibria modelling GEOCHRONOLOGY p-t-t paths
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P-T-t path of metamorphism for the Julin Group and its geodynamical implications in Yuanmou,Yunnan 被引量:2
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作者 邓尚贤 王江海 朱炳泉 《Science China Earth Sciences》 SCIE EI CAS 2001年第7期609-620,共13页
The metamorphic complex of the Julin Group occurs in the Yuanmou area of Yunnan Province on the western margin of the Yangtze Platform, and connects with the Kangdian metamorphic complex to the north. Based on the det... The metamorphic complex of the Julin Group occurs in the Yuanmou area of Yunnan Province on the western margin of the Yangtze Platform, and connects with the Kangdian metamorphic complex to the north. Based on the detailed petrographic observations and studies of garnet growth zoning, a P-T-t path has been reconstructed for the staurolite-kyanite zone in the Julin Group. This path is characterized by (1) a counter-clockwise evolutional trend, (2) a quicker increase of temperature than that of pressure in the initial prograde metamorphism, but slower near the peak, then temperature and pressure simultaneously reaching the peak metamorphic conditions, and (3) a slow near-isobaric cooling during the retrograde process. The P-T-t path for prograde metamorphism is closely related to magmatic accretion in the arc setting. The magmatic accretion model, metamorphism type and tectonic setting may be compared with the global Grenville tectono-metamorphic events, and related to the assembly of the Rodinia at the late Meso-proterozoic-early Neoproterozoic (~1.0 Ga). The retrograde P-T-t path shows a slow near-isobaric cooling, indicating sustained heat supplies from the upper mantle and no rapid erosion. This heat source may be originated from the Neoproterozoic (~0.82 Ga) breakup of the Rodinia. 展开更多
关键词 p-t-t path garnet growth zoning the Julin Group RODINIA Yunnan Province
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Metamorphic petrology and geology in China:A review 被引量:4
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作者 Yuan-sheng Geng Qi-han Shen Hui-xia Song 《China Geology》 2018年第1期137-157,共21页
The development of metamorphic petrology to metamorphic geology in China has a long history.Ancient basement metamorphic rocks are distributed primarily in the North China Craton,the Yangtze Block and Tarim Craton.The... The development of metamorphic petrology to metamorphic geology in China has a long history.Ancient basement metamorphic rocks are distributed primarily in the North China Craton,the Yangtze Block and Tarim Craton.They are mainly made up of plutonic gneiss and metamorphosed supercrust rock,transformed to granulite facies through Archean Paleoproterozoic.Many of the Paleoproterozoic metamorphic rocks have undergone high-pressure granulite facies metamorphism with a clockwise metamorphic evolution path.The ultrahigh temperature (UHT)granulites from the Late Paleoproterozoic are found in North China Craton.Many high-precision chronological data have allowed preliminary construction of the formation and evolutionary framework of different metamorphic basements.Primarily there are low-temperature and high-pressure blue schist,high-temperature and high-pressure granulite and ultrahigh-pressure (UHP)eclogite facies metamorphic rocks in the Phanerozoic orogenic belt.The discovery of eclogite in the Sulu orogen and a large quantity of coesite in its country rocks show that there was a deep subduction of voluminous continental materials during the collision process between the Yangtze block and the North China Craton in the Early Mesozoic phase.From the studies of,for instance,organic matter vitrinite reflectance,illite crystallinity,illite (muscovite)polytype and illite (muscovite)b dimension,the Late Paleozoic strata in the eastern region of Inner Mongolia and the north-central region of NE China have only experienced diagenesis to an extremely low-grade metamorphism.The discovery of impact-metamorphosed rocks in Xiuyan area of Liaoning province has enriched the type and category of metamorphic rocks in China.The phase equilibrium method has been widely used in the study of metamorphism of middle and high-grade metamorphic rocks.On the basis of existing geologic surveys and monographic study results, different scholars have respectively compiled 1:1500000 Metamorphic Geological Map and Specifications of Qinghai Tibet Plateau and its Adjacent Areas,1:2500000 Metamorphic Tectonic Map of China, and the 1:5000000 Metamorphic Geological Map and Specifications of China,among others repectively, which have systematically summarized the research results of metamorphic petrology and metamorphic geology in China. 展开更多
关键词 METAMORPHIC PETROLOGY METAMORPHIC GEOLOGY METAMORPHIC p-t-t path Ultrahigh pressure METAMORPHIC pock GRANULITE
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Evidence for Mesoproterozoic collision,deep burial and rapid exhumation of garbenschiefer in the Namaqua Front,South Africa 被引量:3
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作者 Valby Van Schijndel David HCornell +1 位作者 Robert Anczkiewicz Anders Schersten 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第2期511-531,共21页
Metamorphic provinces such as the^1 Ga Grenvillian,~400 Ma Caledonide and Triassic Qinling Provinces often contain rocks with high-pressure assemblages such as eclogites,which formed at mantle depths in subduction zon... Metamorphic provinces such as the^1 Ga Grenvillian,~400 Ma Caledonide and Triassic Qinling Provinces often contain rocks with high-pressure assemblages such as eclogites,which formed at mantle depths in subduction zones.These are evidence of the accretion of terranes by subduction of oceans and collision to form large tectonostratigraphic provinces.The Mesoproterozoic Namaqua-Natal Province comprises a number of terranes thought to have been assembled by plate-tectonic processes,but they have generally yielded metamorphic pressures below 5 kbar,corresponding to<20 km,crustal depths,lacking evidence for subduction processes.The Kaaien Terrane in the Namaqua Front contains two large garbenschiefer units with the unusual paragenesis garnet-hornblende-epidote-white mica-plagioclase-ilmenite-quartz.Their protoliths are graywackes influenced by andesitic volcanism during their deposition at^1870 Ma,in a passive margin of the Rehoboth Province or Kaapvaal Craton.Prograde garnet growth dated at 11655 Ma culminated in peak metamorphic conditions of 64530C and 10.40.7 kbar,corresponding to 40 km depth.This is attributed to subduction of these rocks before collision between the overriding arc-related Areachap Terrane,the Kaaien Terrane and the Kaapvaal-Rehoboth cratonic block during the Namaqua orogeny.Exhumation of the garbenschiefer slabs was followed by rapid cooling,as the 11435 Ma argon dates of hornblende and white mica,with closure temperatures^540C and^440C respectively,are the same within error.This was probably due to tectonic juxtaposition of the garbenschiefer slab with much cooler rock units.The exhumation was accommodated along the Trooilapspan-Brakbosch Shear Zone due to ongoing transpression.Other components of the Namaqua Front have distinctly different P-T-t paths,exemplified by greenschist metamorphism in the 1300 Ma Wilgenhoutsdrift Group,and medium-pressure metamorphism in the Areachap Terrane.They were juxtaposed by late-tectonic uplift and transpressional movements.The^40 km depth of garbenschiefer peak metamorphism is the deepest yet found in the Namaqua-Natal Province and strengthens the plate tectonic model of accretion by collision of terranes at the end of a Wilson cycle.The high pressure paragenesis of the garbenschiefer was preserved due to its location in the Namaqua Front,whereas most other parts of the Namaqua-Natal Province were overprinted by 1100–1020 Ma thermal events after the collision events. 展开更多
关键词 Collision orogeny p-t-t path Garbenschiefer Lu–Hf garnet U–Pb zircon 40Ar/39Ar dating
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Petrological study of the western Iratsu mass from the Sambagawa metamorphic belt, central Shikoku, Japan
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作者 厉子龙 TAKASU Akira 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第7期649-655,共7页
The western Iratsu mass, the largest tectonic body in the Sambagawa metamorphic belt, central Shikoku, is mainly composed of epidote amphibolite with minor amounts of eclogite. Systematically, a majority of garnets sh... The western Iratsu mass, the largest tectonic body in the Sambagawa metamorphic belt, central Shikoku, is mainly composed of epidote amphibolite with minor amounts of eclogite. Systematically, a majority of garnets show bell-shaped chemical zoning of pyrope contents and Mg/(Mg+Fe2+) monotonously increasing outward. The grossular component in zonal garnet increases outwards, maximizes at an intermediate part, and then decreases towards the outermost rim, reflecting a process from increasing to decreasing pressure conditions during the prograde metamorphism. Jadeite contents of omphacite range from 25~20mole% within the cores to 15~10 mole% at the rims, implying a pressure-decreasing process (from 11 × 105 Pa to 8 × 105 Pa). The peak pressure-temperature (P-T) condition of 630~680 ℃ and ca. 15× 105 Pa in the western Iratsu mass is much higher than that of (610±25) ℃ and (10± 1)× 105 Pa of the Sambagawa oligoclase-biotite zone schists. The authors suggest a clockwise P-T-t path for the western Iratsu mass. 展开更多
关键词 PETROLOGY p-t-t path Western Iratsu mass Sambagawa belt
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Tectonic implication of UHP rocks from the Dabie Mountains 被引量:14
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作者 王清晨 从柏林 《Science China Earth Sciences》 SCIE EI CAS 1996年第3期311-318,共8页
Petrological, mineralogical, isochronological data accumulated in the last 4 years are summarized. The variations of lithology and protolith. as well as block-in-matrix structure of UHP (uHrahigh-pressure) rocks imply... Petrological, mineralogical, isochronological data accumulated in the last 4 years are summarized. The variations of lithology and protolith. as well as block-in-matrix structure of UHP (uHrahigh-pressure) rocks imply a metamorphic melange. Clockwise P-T paths of UHP rocks indicate that their formation and exhumation are related to collisional orogeny. Isochronological data indicate that the peak UHP metamorphism was during the Middle-Late Triassic. The exhumation rates, estimated according to P-T-t paths, show a multiple exhumation stages, with a high exhumation rate (3.3-3.6 mm/a) in the Middle-Late Triassic, a lower rate (0.7-1.1 mm/a) in the Early Jurassic, and a very low rate (0.15 mm/a) in the Middle Jurassic to Early Cretaceous. With these constraints, a hypothetical cross-section of the Dabie orogenic belt is constructed. 展开更多
关键词 UHP ROCKS p-t-t path EXHUMATION rate DABIE OROGENIC belt.
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Multistage exhumation and partial melting of high-T ultrahigh-pressure metamorphic rocks in continental subduction-collision zones 被引量:3
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作者 LIU Yi Can DENG LiangPeng GU XiaoFeng 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第7期1084-1099,共16页
High-temperature(HT, >850℃) metamorphism in continental collision orogens, particularly for those ultrahigh-pressure(UHP) metamorphic rocks, has become one of the remarkable topics in Earth science. It has bearing... High-temperature(HT, >850℃) metamorphism in continental collision orogens, particularly for those ultrahigh-pressure(UHP) metamorphic rocks, has become one of the remarkable topics in Earth science. It has bearing on the element and isotope behaviors of UHP rocks, their partial melting and related geodynamic effects during exhumation. In this paper, five representative continental collision orogens with typical HT/UHP rocks, including the Dabie orogen in China, the Kokchetav in Kazakhstan, the Caledonides in Greenland, the Rhodope in Greece, and the Erzgebirge in Germany are introduced, and their HT/UHP metamorphism and evolution processes are summarized. In addition, metamorphic P-T-t paths, multistage exhumation processes, and partial melting and preservation and retrogression of UHP index minerals during exhumation and their possible mechanisms are discussed. On this basis, the forthcoming key fields and scientific subjects of HT/UHP rocks within continental subduction channel are proposed. 展开更多
关键词 continental subduction-collision zone high-T ultrahigh-pressure rock p-t-t path multistage exhumation partial melting
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Jadeitic rocks within high pressure metamorphic zone from northeastern Jiangxi Province and their forming and surviving conditions 被引量:1
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作者 周国庆 《Science China Earth Sciences》 SCIE EI CAS 1997年第5期477-484,共8页
There is a close relation in time, space and origin between the NEJXO, NEJXDFZ and HPMZ from NEJXP which are located in and constrained by both Yangtze Craton and Cathaysia. These HPMRs principally include (i) Jd-Q-Ab... There is a close relation in time, space and origin between the NEJXO, NEJXDFZ and HPMZ from NEJXP which are located in and constrained by both Yangtze Craton and Cathaysia. These HPMRs principally include (i) Jd-Q-Ab schist, (ii) Lw-Jd-Ab schist, (iii) Jd-Ab schist, and (iv) Gl-schist. The Jd is nearly pure (Jd91-98). Jd surrounded by Ab is separated from Q and survived due to the reaction between Jd and Q, while Lw encircled by Ab remains as a pseudomorph composed of CZo+ An. The minerals associated with Jd are Lw, Gl, Ab, Q, CZo, An, Pa, Il, Ru, Sp, Ap, and Zr. According to the textures, the mineral paragenesis is classified into four groups (i) Pl-Am-Q, (ii) Jd-Lw-Gl-Q. (iii) CZo-An-Ab-Q, (iv) Ab-Ana-Ser-Ur, corresponding to (i) 1.0-0.93 Ga, 250℃, 2-3×10 8Pa; (ii) 0.93-0.79 Ga, 300-350℃, 5-12×10 8 Pa; (iii) 0.79-0.223 Ga, 350-400-120℃ , 12-5-3×10 8 Pa; and (iv)<0.223 Ga, < 120-50℃ , <3×108 Pa, in time, temperature and pressure respectively. Aclockwise P-T-t path is isothermal increasing in P (up to 45 km)-isothermal decreasing in P (up to 5 km)-nearly isobar decreasing in T. 展开更多
关键词 NEJXP HPMR JD p-t-t path
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