The Motuo area is located in the east of the Eastern Himalayan Syntaxis.There outcrops a sequence of high-grade metamorphic rocks,such as metapelites.Petrology and mineralogy data suggest that these rocks have experie...The Motuo area is located in the east of the Eastern Himalayan Syntaxis.There outcrops a sequence of high-grade metamorphic rocks,such as metapelites.Petrology and mineralogy data suggest that these rocks have experienced three stages of metamorphism.The prograde metamorphic mineral assemblages （M1） are mineral inclusions （biotite ＋ plagioclase ＋ quartz ± sillimanite ± Fe-Ti oxides） preserved in garnet porphyroblasts,and the peak metamorphic assemblages （M2） are represented by garnet with the lowest Xsps values and the lowest XFe# ratios and the matrix minerals （plagioclase ＋ quartz ± K-feldspar ＋ biotite ＋ muscovite ＋ kyanite ± siilimanite）,whereas the retrograde assemblages （M3） are composed of biotite ＋ plagioclase ＋ quartz symplectites rimming the garnet porphyroblasts.Thermobarometric computation shows that the metamorphic conditions are 562-714℃ at 7.3-7.4 kbar for the M1 stage,661-800℃ at 9.4-11.6 kbar for the M2 stage,and 579-713℃ at 5.5-6.6 kbar for the M3 stage.These rocks are deciphered to have undergone metamorphism characterized by clockwise P-T paths involving nearly isothermal decompression （ITD） segments,which is inferred to be related to the collision of the India and Eurasia plates.展开更多
Sanjiang (Jinshajiang River,Lancangjiang River and Nujiang River) concentration area in southwest China is within the Tethys\|Himalayan tectonic domain,and it is the main area where develops Himalayan movement and rel...Sanjiang (Jinshajiang River,Lancangjiang River and Nujiang River) concentration area in southwest China is within the Tethys\|Himalayan tectonic domain,and it is the main area where develops Himalayan movement and relative ore deposits,such as Yulong super large Cu\|Mo deposit,Jinding super large Pb\|Zn deposit,etc ,in West China.So it is a best place to study Himalayan movement and metallogeny.1 Metallogenic geological background Sanjiang concentration area has passed complex Tethys tectonic development before Cainozoic era,and it begins Himalayan inland basin\|mountain tectonic development at the end of Yanshan movement.It commonly accepts autochthonous platform type deposits since Mesozoic era,and the basin\|mountain tectonic pattern has already appeared.Old metamorphic terrains and paleo\|Tethys orogenic belts become “mountains”,as well as microplateforms sink to become “basins”.Comparing to Mesozoic basins,Eogene basins are many smaller garben\|type extension basins or strike\|slip extension basins on the background of big large basins.展开更多
Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isoc...Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isochron age shown on the spectra are 56.53± 0.43 Ma, 55.52± 1.78 Ma and 55.90± 0.29 Ma respectively. The age data are consistent with each other within 1σ uncertainties. Because the given initial 40Ar/ 36Ar value of 294.7± 1.14 is very close to Nier’s value ( 295.5±5), both plateau and isochron ages may be considered as the forming time of quartz. So the age of 55.90- 56.53 Ma represents the forming age of ore deposits. It is obvious that the ore deposits were formed during the Early Himalayan period.展开更多
基金supported by the National Natural Science Foundation of China (40921001)the Geological Survey of China (1212010818094)
文摘The Motuo area is located in the east of the Eastern Himalayan Syntaxis.There outcrops a sequence of high-grade metamorphic rocks,such as metapelites.Petrology and mineralogy data suggest that these rocks have experienced three stages of metamorphism.The prograde metamorphic mineral assemblages （M1） are mineral inclusions （biotite ＋ plagioclase ＋ quartz ± sillimanite ± Fe-Ti oxides） preserved in garnet porphyroblasts,and the peak metamorphic assemblages （M2） are represented by garnet with the lowest Xsps values and the lowest XFe# ratios and the matrix minerals （plagioclase ＋ quartz ± K-feldspar ＋ biotite ＋ muscovite ＋ kyanite ± siilimanite）,whereas the retrograde assemblages （M3） are composed of biotite ＋ plagioclase ＋ quartz symplectites rimming the garnet porphyroblasts.Thermobarometric computation shows that the metamorphic conditions are 562-714℃ at 7.3-7.4 kbar for the M1 stage,661-800℃ at 9.4-11.6 kbar for the M2 stage,and 579-713℃ at 5.5-6.6 kbar for the M3 stage.These rocks are deciphered to have undergone metamorphism characterized by clockwise P-T paths involving nearly isothermal decompression （ITD） segments,which is inferred to be related to the collision of the India and Eurasia plates.
文摘Sanjiang (Jinshajiang River,Lancangjiang River and Nujiang River) concentration area in southwest China is within the Tethys\|Himalayan tectonic domain,and it is the main area where develops Himalayan movement and relative ore deposits,such as Yulong super large Cu\|Mo deposit,Jinding super large Pb\|Zn deposit,etc ,in West China.So it is a best place to study Himalayan movement and metallogeny.1 Metallogenic geological background Sanjiang concentration area has passed complex Tethys tectonic development before Cainozoic era,and it begins Himalayan inland basin\|mountain tectonic development at the end of Yanshan movement.It commonly accepts autochthonous platform type deposits since Mesozoic era,and the basin\|mountain tectonic pattern has already appeared.Old metamorphic terrains and paleo\|Tethys orogenic belts become “mountains”,as well as microplateforms sink to become “basins”.Comparing to Mesozoic basins,Eogene basins are many smaller garben\|type extension basins or strike\|slip extension basins on the background of big large basins.
文摘Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isochron age shown on the spectra are 56.53± 0.43 Ma, 55.52± 1.78 Ma and 55.90± 0.29 Ma respectively. The age data are consistent with each other within 1σ uncertainties. Because the given initial 40Ar/ 36Ar value of 294.7± 1.14 is very close to Nier’s value ( 295.5±5), both plateau and isochron ages may be considered as the forming time of quartz. So the age of 55.90- 56.53 Ma represents the forming age of ore deposits. It is obvious that the ore deposits were formed during the Early Himalayan period.
文摘鄂西渝东地区是中国南方海相油气勘探的重要区块,又是目前页岩气勘探的热门地区,该地区晚燕山-喜马拉雅期以来长期遭受隆升剥蚀.剥蚀量是烃源岩热演化、油气藏形成与演化、资源量计算和盆地模拟中不可缺少的基础参数.考虑到剥蚀量恢复方法固有的局限性和适用条件,本文在分析了古温标镜质体反射率Ro剖面特征之后,采用古地温梯度反演法进行钻井剥蚀量恢复,然后分析钻井剥蚀量与钻井开孔层位之间的相关性,再与地质图相结合编制剥蚀量平面分布图.结果表明：鄂西渝东地区古温标Ro剖面不存在明显的＂错断＂、＂跳跃＂现象。记录的古地温为达到最大埋深时的古地温;钻井剥蚀量与钻井开孔层位之间具有明显的相关性,开孔层位越老,剥蚀量越大,反之亦然;晚燕山—喜马拉雅期剥蚀量总体上从东往西逐渐变小.东部的利川复向斜剥蚀量为2000-4000 m,中部的石柱复向斜为1500-2500 m,方斗山以西为1000-1500 m.
