A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based ...A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based on the textural relations and compositions of minerals,especially of zoned garnet and potassic white mica,a P-T path was reconstructed using contoured P-T pseudosections.The U-Th-Pb dating of monazite in the micaschist was undertaken with the electron microprobe.The micaschist experienced P-T conditions along a clockwise path between 16 kbar at 510℃and 5 kbar at 555℃followed by isobaric heating to about 600℃.Monazite ages range between 315 and 480 Ma with the most prominent maxima and side maxima at 346.0±1.1(2σ),357.3±2.3,and 368.3±1.7 Ma.Ages older than 380 Ma were related to detrital monazite pointing to a Devonian sedimentary protolith.Other ages around 325 Ma were assigned to the isobaric heating by nearby post-tectonic granites.The high-pressure event,being the result of the collision of Laurussia and Gondwana after closure of the Rheic Ocean,occurred in the Late Devonian.The exhumation to 15-20 km(5 kbar)ended probably in the Early Carboniferous.The high-pressure micaschists from the Fichtelgebirge to the Erzgebirge crystalline complexes are suggested to represent a single nappe within a metamorphic nappe pile.This nappe is composed of metasedimentary slices,which experienced different peak pressures rather than representing a coherent crustal section.展开更多
利用偏光显微镜、X射线衍射(XRD)、拉曼光谱分析(Raman)、扫描电镜和能谱分析(SEM and EDS)等,从矿物学角度对潭柘寺东山红庙岭组中硬绿泥石特征进行了研究。结果表明,该区硬绿泥石属单斜晶系,发育接触双晶,呈玫瑰花状或束状集合体。硬...利用偏光显微镜、X射线衍射(XRD)、拉曼光谱分析(Raman)、扫描电镜和能谱分析(SEM and EDS)等,从矿物学角度对潭柘寺东山红庙岭组中硬绿泥石特征进行了研究。结果表明,该区硬绿泥石属单斜晶系,发育接触双晶,呈玫瑰花状或束状集合体。硬绿泥石中有部分Fe2+被氧化为Fe3+,并替换了Al3+,其化学式可写为(Fe2+,Mg)(Al,Fe3+)2SiO5(OH)2。该区硬绿泥石与钠云母共存,形成温度为350～500℃,呈定向排列,为受构造应力影响而形成的应力矿物,其形成还可能与受构造控制的深部热液活动有关。展开更多
文摘A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based on the textural relations and compositions of minerals,especially of zoned garnet and potassic white mica,a P-T path was reconstructed using contoured P-T pseudosections.The U-Th-Pb dating of monazite in the micaschist was undertaken with the electron microprobe.The micaschist experienced P-T conditions along a clockwise path between 16 kbar at 510℃and 5 kbar at 555℃followed by isobaric heating to about 600℃.Monazite ages range between 315 and 480 Ma with the most prominent maxima and side maxima at 346.0±1.1(2σ),357.3±2.3,and 368.3±1.7 Ma.Ages older than 380 Ma were related to detrital monazite pointing to a Devonian sedimentary protolith.Other ages around 325 Ma were assigned to the isobaric heating by nearby post-tectonic granites.The high-pressure event,being the result of the collision of Laurussia and Gondwana after closure of the Rheic Ocean,occurred in the Late Devonian.The exhumation to 15-20 km(5 kbar)ended probably in the Early Carboniferous.The high-pressure micaschists from the Fichtelgebirge to the Erzgebirge crystalline complexes are suggested to represent a single nappe within a metamorphic nappe pile.This nappe is composed of metasedimentary slices,which experienced different peak pressures rather than representing a coherent crustal section.
文摘利用偏光显微镜、X射线衍射(XRD)、拉曼光谱分析(Raman)、扫描电镜和能谱分析(SEM and EDS)等,从矿物学角度对潭柘寺东山红庙岭组中硬绿泥石特征进行了研究。结果表明,该区硬绿泥石属单斜晶系,发育接触双晶,呈玫瑰花状或束状集合体。硬绿泥石中有部分Fe2+被氧化为Fe3+,并替换了Al3+,其化学式可写为(Fe2+,Mg)(Al,Fe3+)2SiO5(OH)2。该区硬绿泥石与钠云母共存,形成温度为350～500℃,呈定向排列,为受构造应力影响而形成的应力矿物,其形成还可能与受构造控制的深部热液活动有关。
