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Retrogressive Microstructures of the Eclogites from the Northern Dabie Mountains, Central China: Evidence for Rapid Exhumation
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作者 LiuYican LiShuguang +1 位作者 XuShutong ChenGuanbao 《Journal of China University of Geosciences》 SCIE CSCD 2004年第4期349-354,共6页
The ultrahigh-pressure eclogites from the northern Dabie Mountains in central China occurred as tectonic lens or blocks within granitic gneisses or meta-peridotites. Petrologic studies suggest that the studied eclogit... The ultrahigh-pressure eclogites from the northern Dabie Mountains in central China occurred as tectonic lens or blocks within granitic gneisses or meta-peridotites. Petrologic studies suggest that the studied eclogites experienced strongly retrogressive metamorphism and produced a series of characteristic retrogressive microstructures. The retrograde structures mainly include: (1) oriented needle mineral exsolution, e.g., quartz needles in Na-clinopyroxene and rutile, clinopyroxene and apatite exsolution in garnet formed under decreasing pressure conditions during exhumation; (2) symplectite, especially, two generations of symplectites developed outside the garnet grains, which are called “double symplectite” here; (3) compositional zoning of minerals such as garnet and clinopyroxene; (4) minerals with a reaction rim or retrograde rim, e.g., omphacite with a diopside rim, diopside with an amphibole rim and rutile with a rim of ilmenite. These retrograde textures, especially mineral zoning and symplectite, provide important petrologic evidence for the exhumation process and uplift of high-grade metamorphic rocks such as eclogite in the northern Dabie Mountains, indicating a rapid exhumation process. 展开更多
关键词 retrogressive microstructure rapid exhumation ECLOGITE northern Dabie Mountains China
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Discovery of the eclogite and its petrography in the Northern Dabie Mountain 被引量:39
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作者 XU Shutong LIU Yican +3 位作者 SU Wen WANG Rucheng JIANG Laili WU Weiping 《Chinese Science Bulletin》 SCIE EI CAS 2000年第3期273-278,共6页
Eclogite from the Northern Dabie Mountain is a new finding by the authors. These eclogites in foliated perdotite are enveloped by banded gneiss and occur in the mafic-ultramafic rock belt. They are mainly composed of ... Eclogite from the Northern Dabie Mountain is a new finding by the authors. These eclogites in foliated perdotite are enveloped by banded gneiss and occur in the mafic-ultramafic rock belt. They are mainly composed of omphacite, garnet, diopside, orthopyroxene, amphibole, plagioclase and magnetite, and a small amount of rutile, spinel, olivin and 鏾rundum. The mineral association of peak metamorphism of the eclogite is omphacite+garnet+rutile. The existence of eclogite in the Northern Dabie Mountain implies that there was an eclogitic metamorphism prior to the granulitic facies one in the mafic-ultramafic rock belt. 展开更多
关键词 ECLOGITE PETROGRAPHY NORTHERN DABIE Mountain.
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First occurrence of preiswerkite in the Dabie UHP metamorphic belt 被引量:3
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作者 WANG Rucheng XU Shijin XU Shutong 《Chinese Science Bulletin》 SCIE EI CAS 2000年第8期748-750,共3页
This note reports the preiswerkite that was found as the first occurrence in the UHP metamorphic belt of the Dabie Mountain. It occurs in the quartz jadeitite, and coexists with plagioclase, taramite and magnetite as ... This note reports the preiswerkite that was found as the first occurrence in the UHP metamorphic belt of the Dabie Mountain. It occurs in the quartz jadeitite, and coexists with plagioclase, taramite and magnetite as retrograde symplectite. The calculated temperature of formation for preiswerkite is about 600 -620 ℃ (at P=1.0 -1.5GPa), suggesting that the preiswerkite is an indicator mineral of high-grade greenschist facies retrograded from eclogite-facies rocks. 展开更多
关键词 preiswerkite chemistry quartz-jadeitite DABIE UHP terrain.
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The Fossils in Shangxi Group and Its Implication for Tectonics, Southern Anhui, China 被引量:3
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作者 徐树桐 陈冠宝 +6 位作者 陶正 石永红 孙枢 Kenneth J.Hsu 尹磊明 欧阳舒 廖卓庭 《Science China Chemistry》 SCIE EI CAS 1994年第3期366-376,共11页
The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was re... The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was regarded as a part of the 'Jiangnan old land' of Presinian till it was challenged by the present authors years ago. After we postulated that there may be some strata of Palaeozoic Era in Shangxi Group, some microfossils and then macrofossils of Palaeozoic were found in some part of it. The macrof os-sils, Lingula sp. , Conulariid and the microfossils indicate that most units of the Shangxi Group are Palaeozoic strata. Based on the discovery of these fossils and the recognition of the tectonic-setting of the different tectono-petrologic units in the Shangxi Group, three different stratigraphic sequences (island-arc volcanics, back-arc sediments and the cover of passive margin of Yangtze Continental Plate) are established and the tectonic evolution of them is postulated in the present paper. All the evidences obtained recently from the Shangxi Group indicate that there is no 'Old Land' over the discussed area, but a subduction followed by a collision zone between the island-arc and Yangtze Continental Plate; all these metamorphosed strata were originally island-arc, back-arc basin sediments during the Sinian-late Paleozoic, except the Presinian sandstone distributed in a narrow belt on the northmost margin of the metamorphic terrane. 展开更多
关键词 Jiangnan old land FOSSIL tectono-petrolagic unit.
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Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals
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作者 李曙光 刘贻灿 +1 位作者 徐树桐 郑永飞 《Science China Chemistry》 SCIE EI CAS 2002年第z1期28-37,共10页
The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO... The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin of such CaO-MnO zoning. The tie line of garnet+omphacite from this eclogite gives a Sm-Nd age of (187±5) Ma, which is less significant than the Sm-Nd ages of (221±5)-(228±3) Ma and (210 ±6)-(214±6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northern Dabie zone, respectively. This younger Sm-Nd age could result from the ^(143)Nd/^(144)Nd ratio decrease of the retrograde zone in the garnet. The δ^(80)O values of the garnet and omphacite show that their fractionation values are less than the equilibrium fractionation value between the garnet and om- phacite at 500-900℃, which suggests an oxygen isotopic disequilibrium between them. 展开更多
关键词 eclogite SM-ND ISOTOPIC dating OXYGEN isotope ZONATION of garnet Dabie Mountains.
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Eclogites from the Northern Dabie Mountains, eastern China: Geochemical characteristics, Sr-Nd isotopic compositions and tectonic implications 被引量:12
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作者 刘贻灿 徐树桐 +4 位作者 李曙光 江来利 吴维平 陈冠宝 苏文 《Science China Earth Sciences》 SCIE EI CAS 2000年第S1期178-188,共11页
The petrologic geochemical and Sr-Nd isotopic compositions of the eclogites from the mafic-ultramafic rock belt (MUMRB) in the Northern Dabie Mountains indicate that: (1) the protoliths of most of eclogites are tholei... The petrologic geochemical and Sr-Nd isotopic compositions of the eclogites from the mafic-ultramafic rock belt (MUMRB) in the Northern Dabie Mountains indicate that: (1) the protoliths of most of eclogites are tholeiitic basalt and a few may be gabbro, and most of them produced from the Yangtze subducted continental crust (lower crust and formed during the deep subduction) and a part may be from paleo-oceanic relics between the Yangtze and North China continental plates; (2) their positive Nb anomalies and related trace element characteristics show that they did not form in the island-arc setting; (3) the metamorphosed MUMRB with eclogite and meta-peridotite blocks along the southern part of the Mozitan-Xiaotian fault zone may represent the suture zone produced during the collision between the Yangtze and North China continental plates, which included the Yangtze subducted continental crust and paleo-oceanic relics. 展开更多
关键词 ECLOGITE SR-ND isotopic composition Yangtze subducted continental crust paleo-oceanic RELICS Northern DABIE Mountains.
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DIAMONDS FROM HIGH-PRESSURE METAMORPHIC ROCKS IN EASTERN DABIE MOUNTAIN 被引量:3
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作者 徐树桐 苏文 +4 位作者 刘贻灿 江来利 季寿元 A.I.OKAY A.M.C.SENGOR 《Chinese Science Bulletin》 SCIE EI CAS 1992年第2期140-145,共6页
Diamonds commonly occur in kimberlites, lamproites and relative alluvial sediments. Some examples of diamonds discovered in ultramafics have heen reported. Sobolev and Shatsky reported diamonds from high-pressure meta... Diamonds commonly occur in kimberlites, lamproites and relative alluvial sediments. Some examples of diamonds discovered in ultramafics have heen reported. Sobolev and Shatsky reported diamonds from high-pressure metamorphic rock from northern Kazakhstan and considered it to be the source of the alluvial diamonds in Pridneprovie region of western U. S. S. R. Diamonds reported here show some similarity to those in northern Kazakhstan, and are the second occurrence in the world, but the first one in China. 展开更多
关键词 COESITE JADEITE diamond.
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