Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages f...Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages from the diabase of the Aoyougou ophiolite previously put into Upper Lithologic Formation of the Zhulongguan Group are (1 840±2), (1 783±2) and (1 784±2) Ma respectively, whereas the zircon ages from the welded breccias in the Zhulongguan Group are (733±7), (738±4) and (604±6) Ma respectively. These results show that they should belong to the bottom of the middle Proterozoic and the upper part of upper Proterozoic respectively.展开更多
Two-pyroxene-bearing granulites were discovered for the first time in the Hercynian-Indosinian metamorphic belt of the southern Qinling Mountains. The granulites occur in the lower part of the Fuping complex and are d...Two-pyroxene-bearing granulites were discovered for the first time in the Hercynian-Indosinian metamorphic belt of the southern Qinling Mountains. The granulites occur in the lower part of the Fuping complex and are dominated by intermediate-acidic rocks intercalated with a small amount of bands and lenses of basic granulites. The main metamorphic minerals include orthopyroxene, clinopyroxene, biotite, plagioclase and quartz, and orthopyroxenes are often retrogressively transformed into amphiboles. The metamorphic conditions have been estimated to be %T%=720-780℃ and %P%=0.6 GPa. The granulite-bearing Fuping complex probably belongs to early Proterozoic in age. Whether it occurs as the crystalline basement of the southern Qinling Hercynian-Indosinian orogenic belt or as a thrusted slice in the collisional process needs further study.展开更多
The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd is...The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four展开更多
Carbonate liquefied veins in limestone and liquefied mud veins in mudstone are the result by earthquake, which is liquefied in sediments and a strong earthquake event remains clearly records in strata. 24 strata units...Carbonate liquefied veins in limestone and liquefied mud veins in mudstone are the result by earthquake, which is liquefied in sediments and a strong earthquake event remains clearly records in strata. 24 strata units with earthquake events (molar tooth), which are subdivided into 11 seismic periods, have been distinguished from Mid-Proterozoic to Early Paleozoic strata in the Sino-Korean platform. The distributions of them represent paleo-seismic tectonic zones in different periods, which is tallied with convergent continental block before Proterozoic supercontinental Rodinia and the evidence of the breakup or splitting developed in the inner Sino-Korean Platform in 700 Ma.展开更多
Ultrahigh pressure (UHP) metamorphism refers to metamorphism that has occurred at pressures for the stability of coesite. The polycrystalline quartz inclusions showing the characteristic texture within garnets of eclo...Ultrahigh pressure (UHP) metamorphism refers to metamorphism that has occurred at pressures for the stability of coesite. The polycrystalline quartz inclusions showing the characteristic texture within garnets of eclogites indicates the pre-existence of coesites under the peak meta-morphic condition. The unusual exsolution textures in om-pacites and apatites, and the pressure estimations of phengite-bearing eclogites have been taken to provide further proof of eclogite formation under the UHP conditions. Combined with the fact that coesites have been observed in country rocks of eclogites in North Qaidam Mountains, another UHP metamorphic belt cut by the large-scale strike-slip fault in the Altun-North Qaidam area of China is confirmed.展开更多
In order to reveal the nature of deep crust fluids, the phase relations of NaCI-saturated solution at high temperatures and pressures in a hydrothermal diamond anvil cell (HDAC)are investigated. Salinity of the soluti...In order to reveal the nature of deep crust fluids, the phase relations of NaCI-saturated solution at high temperatures and pressures in a hydrothermal diamond anvil cell (HDAC)are investigated. Salinity of the solutions observed is about 35%—50%. The temperatures for the observation range from 25 to 850℃ and the pressures from 1 atm to about 1 GPa. A supercritical single phase, liquid phase (L), vapor phase (V), solid phase (H), L + H, H + V + L and the near-critical phases L + V can be observed. A two-phase (L + V) immiscibility field for the NaCI solution has been discovered to lie in a wide range of temperatures and pressures:from 250( ± 3) to 721℃. Within this field there are two parts, where the upper high temperature part of the two-phase regions is very unstable in character. It is possible to observe a 'critical phenomenon'. In some of our experiments an 'explosion' almost constantly occurred at the interface between the liquid and vapor phases, making the interface obscure, and a展开更多
δ13C of dolostones from the Wumishan Formation (1 310-1 207 Ma) in the Ming Tombs area near Beijing ranges from - 1.5 to 1.5‰ (PDB), and generally, the δ18O ranges from - 4 to - 5‰ (PDB). The secular variation of ...δ13C of dolostones from the Wumishan Formation (1 310-1 207 Ma) in the Ming Tombs area near Beijing ranges from - 1.5 to 1.5‰ (PDB), and generally, the δ18O ranges from - 4 to - 5‰ (PDB). The secular variation of stable carbon isotopic compositions is cyclic. δ13C displays positive shifts from a sequence boundary to 1.5 per mil (PDB), then展开更多
THE huge reserves of submarine polymetallic nodules make them an important kind of potentialmineral resources. It has already been discovered that polymetallic nodules are related withsubmarine vollcanogene hydrotherm...THE huge reserves of submarine polymetallic nodules make them an important kind of potentialmineral resources. It has already been discovered that polymetallic nodules are related withsubmarine vollcanogene hydrothermalism. For example, pyroclasts usually occur as coresubstances of the nodules, and large amounts of mineralizing materials such as manganese aredischarged to form ferromanganese oxides along with the submarine vocanogene hydrothermal-展开更多
Under the same conditions of external force, simulations on differences of deformational energy in structural zones, which have different deformational behavior, and that on the distribution of the differences have be...Under the same conditions of external force, simulations on differences of deformational energy in structural zones, which have different deformational behavior, and that on the distribution of the differences have been carried out by means of finite-element method. Shear deformational energy U_w is higher than volume deformational energy U_T by about one order of magnitude, and deformationat energy U_B( = U_w + U_T) and U_w show a trend to be larger→largest→small in quantity in structural zones of different deformational properties, which correspond to compressive, shear, tensile zones, respectively, but U_T shows a trend to be large→small gradually. This has a considerable significance in the study of tectonic heat and mineral liquid migration in association with the research on tectonic additional hydrostatic pressure.展开更多
The eclogite, discovered in Liuyuan, occurs as lenticular enclave within granitic gneiss. It has typical features of eclogite in petrology and mineralogy. The eclogite provides an important wirdow to reconstruct the t...The eclogite, discovered in Liuyuan, occurs as lenticular enclave within granitic gneiss. It has typical features of eclogite in petrology and mineralogy. The eclogite provides an important wirdow to reconstruct the tectonic border of the Tarim block. The granitoids, located in Baihu area, yield U-Pb zircon ages of 1 660—2 000 Ma (Palaeoproterozoic), which irrplies an early Precambrian basement in the area.展开更多
The differences of thermal conduction and its temperature-varying track of the heat source body at various structural environments have been studied. Hypothetically, geologic heat source body is cut successively into ...The differences of thermal conduction and its temperature-varying track of the heat source body at various structural environments have been studied. Hypothetically, geologic heat source body is cut successively into several segregative bodies with a fixed cubage. With the segmented number increasing, the conductive surface area of heat source body begins to get larger, which separately is similar to the heat geologic body in different tectonic zones that has a various enclosed coefficient η（η=S<sub>0</sub>/sum from i=（1,n）（S<sub>i</sub>））. Finite-element simulation result shows that the thermal conduction speed of spreading from the heat source body to its wall rock is slow→higher→highest, when heat source bodies are situated respectively at compressive, shear and tensile deformation zones, corresponding rates of their temperature drop are low→higher→highest. Research indicates that the temperature’s dropping rate of heat source body has an inverse relationship with enclosed coefficient η for different structural展开更多
New helium isotopic data of ores and rocks from the Altay orogenic zone, Xinjiang,China are reported, which show that the pegmatites from No. 3 vein in the Keketuohai area have high <sup>3</sup>He/<sup&...New helium isotopic data of ores and rocks from the Altay orogenic zone, Xinjiang,China are reported, which show that the pegmatites from No. 3 vein in the Keketuohai area have high <sup>3</sup>He/<sup>4</sup>He ratios up to 1 .795 x 10<sup>-6</sup> and 2.54 x 10<sup>-6</sup>. Such a result suggests that the metallogenic process of rare metal deposits in the Altay orogenic zone might be related to mantle degassing.展开更多
Eclogite was first discovered at the northern margin of the Qaidam Basin in this study. It occurs as pods in the gneiss sequence of Middle to Upper Proterozoic age and is mainly composed of garnet, omphacite, phengite...Eclogite was first discovered at the northern margin of the Qaidam Basin in this study. It occurs as pods in the gneiss sequence of Middle to Upper Proterozoic age and is mainly composed of garnet, omphacite, phengite and rutile. The garnets contain 44%-62% of almandine, 15%-33% of grossular and 12%-30% of pyrope molecules, and the omphacites contain 40%-46% of jadeite. Applying garnet_clinopyroxene thermometry and jadeite geobarometry, the peak conditions of eclogite facies metamorphism occurred at about (722±123)℃ and at the pressure of up to c. 22 ×10 8 Pa.展开更多
Thirteen clinopyroxene megacrysts from Nushan Cenozoic basalts have been investigated by Fourier transform infrared spectrometer(FTIR). The results demonstrate that all samples contain trace amount of structural OH. C...Thirteen clinopyroxene megacrysts from Nushan Cenozoic basalts have been investigated by Fourier transform infrared spectrometer(FTIR). The results demonstrate that all samples contain trace amount of structural OH. Clinopyroxenes from Nushan show four groups of absorption bands, in which, 3 472-3 506 cm -1 is the major characteristic one. It is suggested that the position of major band is probably related to Al content: the position of major characteristic band for high_Al samples is around 3 470 cm -1 , whereas that for low_Al samples around 3 620 cm -1 .展开更多
文摘Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages from the diabase of the Aoyougou ophiolite previously put into Upper Lithologic Formation of the Zhulongguan Group are (1 840±2), (1 783±2) and (1 784±2) Ma respectively, whereas the zircon ages from the welded breccias in the Zhulongguan Group are (733±7), (738±4) and (604±6) Ma respectively. These results show that they should belong to the bottom of the middle Proterozoic and the upper part of upper Proterozoic respectively.
文摘Two-pyroxene-bearing granulites were discovered for the first time in the Hercynian-Indosinian metamorphic belt of the southern Qinling Mountains. The granulites occur in the lower part of the Fuping complex and are dominated by intermediate-acidic rocks intercalated with a small amount of bands and lenses of basic granulites. The main metamorphic minerals include orthopyroxene, clinopyroxene, biotite, plagioclase and quartz, and orthopyroxenes are often retrogressively transformed into amphiboles. The metamorphic conditions have been estimated to be %T%=720-780℃ and %P%=0.6 GPa. The granulite-bearing Fuping complex probably belongs to early Proterozoic in age. Whether it occurs as the crystalline basement of the southern Qinling Hercynian-Indosinian orogenic belt or as a thrusted slice in the collisional process needs further study.
文摘The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four
文摘Carbonate liquefied veins in limestone and liquefied mud veins in mudstone are the result by earthquake, which is liquefied in sediments and a strong earthquake event remains clearly records in strata. 24 strata units with earthquake events (molar tooth), which are subdivided into 11 seismic periods, have been distinguished from Mid-Proterozoic to Early Paleozoic strata in the Sino-Korean platform. The distributions of them represent paleo-seismic tectonic zones in different periods, which is tallied with convergent continental block before Proterozoic supercontinental Rodinia and the evidence of the breakup or splitting developed in the inner Sino-Korean Platform in 700 Ma.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 49902018 and 49732070)the National Key Project for Basic Research on Tibetan Plateau (Grant No. G1998040800)the Key Project of the Ministry of Land and Resources
文摘Ultrahigh pressure (UHP) metamorphism refers to metamorphism that has occurred at pressures for the stability of coesite. The polycrystalline quartz inclusions showing the characteristic texture within garnets of eclogites indicates the pre-existence of coesites under the peak meta-morphic condition. The unusual exsolution textures in om-pacites and apatites, and the pressure estimations of phengite-bearing eclogites have been taken to provide further proof of eclogite formation under the UHP conditions. Combined with the fact that coesites have been observed in country rocks of eclogites in North Qaidam Mountains, another UHP metamorphic belt cut by the large-scale strike-slip fault in the Altun-North Qaidam area of China is confirmed.
文摘In order to reveal the nature of deep crust fluids, the phase relations of NaCI-saturated solution at high temperatures and pressures in a hydrothermal diamond anvil cell (HDAC)are investigated. Salinity of the solutions observed is about 35%—50%. The temperatures for the observation range from 25 to 850℃ and the pressures from 1 atm to about 1 GPa. A supercritical single phase, liquid phase (L), vapor phase (V), solid phase (H), L + H, H + V + L and the near-critical phases L + V can be observed. A two-phase (L + V) immiscibility field for the NaCI solution has been discovered to lie in a wide range of temperatures and pressures:from 250( ± 3) to 721℃. Within this field there are two parts, where the upper high temperature part of the two-phase regions is very unstable in character. It is possible to observe a 'critical phenomenon'. In some of our experiments an 'explosion' almost constantly occurred at the interface between the liquid and vapor phases, making the interface obscure, and a
文摘δ13C of dolostones from the Wumishan Formation (1 310-1 207 Ma) in the Ming Tombs area near Beijing ranges from - 1.5 to 1.5‰ (PDB), and generally, the δ18O ranges from - 4 to - 5‰ (PDB). The secular variation of stable carbon isotopic compositions is cyclic. δ13C displays positive shifts from a sequence boundary to 1.5 per mil (PDB), then
文摘THE huge reserves of submarine polymetallic nodules make them an important kind of potentialmineral resources. It has already been discovered that polymetallic nodules are related withsubmarine vollcanogene hydrothermalism. For example, pyroclasts usually occur as coresubstances of the nodules, and large amounts of mineralizing materials such as manganese aredischarged to form ferromanganese oxides along with the submarine vocanogene hydrothermal-
文摘Under the same conditions of external force, simulations on differences of deformational energy in structural zones, which have different deformational behavior, and that on the distribution of the differences have been carried out by means of finite-element method. Shear deformational energy U_w is higher than volume deformational energy U_T by about one order of magnitude, and deformationat energy U_B( = U_w + U_T) and U_w show a trend to be larger→largest→small in quantity in structural zones of different deformational properties, which correspond to compressive, shear, tensile zones, respectively, but U_T shows a trend to be large→small gradually. This has a considerable significance in the study of tectonic heat and mineral liquid migration in association with the research on tectonic additional hydrostatic pressure.
文摘The eclogite, discovered in Liuyuan, occurs as lenticular enclave within granitic gneiss. It has typical features of eclogite in petrology and mineralogy. The eclogite provides an important wirdow to reconstruct the tectonic border of the Tarim block. The granitoids, located in Baihu area, yield U-Pb zircon ages of 1 660—2 000 Ma (Palaeoproterozoic), which irrplies an early Precambrian basement in the area.
文摘The differences of thermal conduction and its temperature-varying track of the heat source body at various structural environments have been studied. Hypothetically, geologic heat source body is cut successively into several segregative bodies with a fixed cubage. With the segmented number increasing, the conductive surface area of heat source body begins to get larger, which separately is similar to the heat geologic body in different tectonic zones that has a various enclosed coefficient η（η=S<sub>0</sub>/sum from i=（1,n）（S<sub>i</sub>））. Finite-element simulation result shows that the thermal conduction speed of spreading from the heat source body to its wall rock is slow→higher→highest, when heat source bodies are situated respectively at compressive, shear and tensile deformation zones, corresponding rates of their temperature drop are low→higher→highest. Research indicates that the temperature’s dropping rate of heat source body has an inverse relationship with enclosed coefficient η for different structural
文摘New helium isotopic data of ores and rocks from the Altay orogenic zone, Xinjiang,China are reported, which show that the pegmatites from No. 3 vein in the Keketuohai area have high <sup>3</sup>He/<sup>4</sup>He ratios up to 1 .795 x 10<sup>-6</sup> and 2.54 x 10<sup>-6</sup>. Such a result suggests that the metallogenic process of rare metal deposits in the Altay orogenic zone might be related to mantle degassing.
文摘Eclogite was first discovered at the northern margin of the Qaidam Basin in this study. It occurs as pods in the gneiss sequence of Middle to Upper Proterozoic age and is mainly composed of garnet, omphacite, phengite and rutile. The garnets contain 44%-62% of almandine, 15%-33% of grossular and 12%-30% of pyrope molecules, and the omphacites contain 40%-46% of jadeite. Applying garnet_clinopyroxene thermometry and jadeite geobarometry, the peak conditions of eclogite facies metamorphism occurred at about (722±123)℃ and at the pressure of up to c. 22 ×10 8 Pa.
文摘Thirteen clinopyroxene megacrysts from Nushan Cenozoic basalts have been investigated by Fourier transform infrared spectrometer(FTIR). The results demonstrate that all samples contain trace amount of structural OH. Clinopyroxenes from Nushan show four groups of absorption bands, in which, 3 472-3 506 cm -1 is the major characteristic one. It is suggested that the position of major band is probably related to Al content: the position of major characteristic band for high_Al samples is around 3 470 cm -1 , whereas that for low_Al samples around 3 620 cm -1 .
