The genus and species Yuyuanozoon magnificissimi gen. et sp. nov., a new fossil vetulicolian, is reported from the Early Cambrian Chengjiang Fauna in Yunnan of China. It has a bipartite body plan and five pairs of cha...The genus and species Yuyuanozoon magnificissimi gen. et sp. nov., a new fossil vetulicolian, is reported from the Early Cambrian Chengjiang Fauna in Yunnan of China. It has a bipartite body plan and five pairs of chain-formed gill sacs, showing the general characteristics of Ventulicolia. However, the exclusive 'atrial cavity' and external gill observed indicate that the new form is different from those previously described as vetulicolians, probably representing a lineage developed within deuterostomes and more primitive than urochordates.展开更多
He-Ar isotopic compositions of fluid inclusions trapped in pyrites from some representative PGE-polymetallic deposits in Lower Cambrian black rock series in South China were analyzed by using an inert gas isotopic mas...He-Ar isotopic compositions of fluid inclusions trapped in pyrites from some representative PGE-polymetallic deposits in Lower Cambrian black rock series in South China were analyzed by using an inert gas isotopic mass spectrometer. The results show that the ore-forming fluids possess a low 3He/4He ratio, varying from 0.43×10-8 to 26.39×10-8, with corresponding R/Ra value of 0.003-0.189. The 40Ar/36Ar ratios are 258-287, close to those of air saturated water (ASW). He-Ar isotopic indicator studies show that the ore-forming fluids were mainly derived from the formation water or basinal hot brine and sea water, while the content of mantle-derived fluid or deep-derived magmatic water might be negligible. The PGE-polymetallic mineralization might be related to the evolution of the Caledonian miogeosynclines distributed along the southern margin of the Yangtze Craton. During the Early Cambrian, the formation water or basinal hot brine trapped in Caledonian basins which accumulated giant thick sediments was expelled and migrated laterally along strata because of the pressure generated by overlying sediments. The basinal hot brine ascended along faults, mixed with sea water and finally deposited ore minerals.展开更多
The Cretaceous is among the most unusual eras in the geological past. Geoscience communities have been having great concerns with geological phenomena within this period, for example carbonate platforms and black shal...The Cretaceous is among the most unusual eras in the geological past. Geoscience communities have been having great concerns with geological phenomena within this period, for example carbonate platforms and black shales in the Early and Middle Cretaceous respectively, during the last decades. But few people have paid any attention to the set of pelagic redbeds lying on the black shales, not to mention the applications to paleoclimatology and paleoceanography. It is shown by the sedimentary records of redbeds, that they were deposited around the CCD, with both a higher content of iron and much lower concentrations of organic carbon, which implies conditions with a relatively high content of oxygen. Such redbeds occurred in the global oceans, mainly in the Tethyan realm, with different durations of deposition and a climax from the late Santonian to early Campanian. Global cooling and dramatic changes in ocean currents might help to increase the oxygen flux between the atmosphere and ocean, after the large scale organic carbon burial during the Middle Cretaceous, and therefore lead to the oxygenation of deep ocean and so the occurrence of late Cretaceous oceanic redbeds.展开更多
Human activity duo to rapid increasing of the economy in China has become so wide and intense since 1980s that it comes to the most active factor affecting the earth surface geomorphology process and provoke the most ...Human activity duo to rapid increasing of the economy in China has become so wide and intense since 1980s that it comes to the most active factor affecting the earth surface geomorphology process and provoke the most important impact to environment in recent two decades. Some typical human-induced landslides are introduced. Their generalfeatures,including distribution,types,time series of occurrence and mechanism are summarized. A classification system of landslides is suggested based on their geological backgrounds and formation mechanism. Finally,some aspects of slope management and human activity control are discussed to different types of landslides.展开更多
By means of SEDEX, ASPILA and XRF, depth-dependent changes of different phosphorus forms in sediment cores from specific areas of the offshore Changjiang Estuary (Yangtze Estuary) in 1998 were analyzed. Results show t...By means of SEDEX, ASPILA and XRF, depth-dependent changes of different phosphorus forms in sediment cores from specific areas of the offshore Changjiang Estuary (Yangtze Estuary) in 1998 were analyzed. Results show that contents of total phosphorus (TP), organic-phosphorus (OP) and iron-phosphorus (Fe-P) decreased down-core, while those of absorbed-phosphorus (Ad-P) and calcium-phosphorus (Ca-P) increased. The distribution tendency of detritus-phosphorus (De-P) is not obvious. Results also show that TP, Fe-P and OP contents at Meso station of the Changjiang Estuary and Hangzhou Bay are higher than that of the other stations. This suggests that the pollutants carried by the Changjiang and the Qiantang rivers from inland have affected the natural environment in offshore area. TP, Fe-P and OP contents of each station become higher from bottom to top, indicating the amount of the terrestrial pollutants carried by the two rivers has been enhanced since the last 30-50 years. Ad-P, Ca-P, Fe-P and OP are all active phosphorus in sediments, and their re-cycling in sediment is closely related to each other.展开更多
An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of th...An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140–135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb -Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit. Associated “porphyry” mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.展开更多
Since the eruption of the Tianchi volcano about 1000 years ago, there have been at least 3 to 5 eruptions of small to moderate size. In addition, hazardous avalanches, rock falls and debris flows have occurred during ...Since the eruption of the Tianchi volcano about 1000 years ago, there have been at least 3 to 5 eruptions of small to moderate size. In addition, hazardous avalanches, rock falls and debris flows have occurred during periods between eruptions. A future eruption of the Tianchi volcano is likely to involve explosive interaction between magma and the caldera lake. The volume of erupted magma is almost in a range of 0.1-0.5 km3. Tephra fallout may damage agriculture in a large area near the volcano. If only 1% of the lake water were ejected during an eruption and then precipitated over an area of 200 km2, the average rainfall would be 100 mm. Moreover, lahars are likely to occur as both tephra and water ejected from the caldera lake fall onto flanks of the volcano. Rocks avalanching into the caldera lake also would bring about grave hazards because seiches would be triggered and lake water with the volume equal to that of the landslide would spill out of the existing breach in the caldera and cause flooding downstream.展开更多
This paper presents the special processing methods used for wide-angle land seismic data through both theoretical study and model testing. They are different from conventional ones in the following aspects: separation...This paper presents the special processing methods used for wide-angle land seismic data through both theoretical study and model testing. They are different from conventional ones in the following aspects: separation of reflection and refraction waves, long offset NMO and stacking and forward modeling and inversion. These processing techniques have been applied for the first time to land seismic data from Liaohe areas, resulting in greatly improved quality of the deep formation and better imaging of the shallow layer obtained in the volcanic-shielded area. Wide-angle reflection and refraction seismic surveys were carried out in the Liaohe area using the maximum offset of 6500m and with the target around 2000ms. In the processing, we adopted the τ-p transform and the high-order normal moveout correction.展开更多
A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be furt...A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration.展开更多
This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, stat...This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, static sounding and chemical analysis obtained from the present Hangzhou Bay coastal plain. The incised valleys were formed during the last glacial maximum and were subsequently filled with fluvial facies during the post-glacial period. All commercial gases are stored in the flood plain sand lenses of the incised valleys.展开更多
An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comp...An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comparison of five semivariogram models (Spherical, Exponential, Linear, Gaussian and Rational Quadratic) indicated that kriging fulfills the objective of finding better ways to estimate interpolation weights and can provide error information for monthly rainfall interpolation. ESDA yielded the three most common forms of experimental semivariogram for monthly rainfall in the area. All five models were appropriate for monthly rainfall interpolation but under different circumstances. Spherical, Exponential and Linear models perform as smoothing interpolator of the data, whereas Gaussian and Rational Quadratic models serve as an exact interpolator. Spherical, Exponential and Linear models tend to underestimate the values. On the contrary, Gaussian and Rational Quadratic models tend to overestimate the values. Since the suitable model for a specific month usually is not unique and each model does not show any bias toward one or more specific months, an ESDA is recommended for a better interpolation result.展开更多
We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterize...We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized by an assemblage of garnet, orthopyroxene, spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the or-thopyroxenes have high XMg and A12O3 contents (up to 9.23 wt%). Biotites are enriched in TiO2 and XMg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which show peak melting temperatures of around -56.7℃, indicating a pure CO2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a liquid phase at temperatures around 15.3-23.8℃ translating into CO2 densities of the order of 0.86-0.88 g/cm3. Based on preliminary mineral paragenesis, reaction textures and petrogenetic grid considerations, we infer that the rock was subjected to UHT conditions. The CO2-rich fluids were trapped during exhumation along a clockwise P-T path following isothermal decompression under UHT conditions.展开更多
基金supported by the National Natural Science Foundation of China(Grants 40073007,40173002,40232020)the Natural Scienee Foundation of Yunnan Province(Grant 97D007Z)
文摘The genus and species Yuyuanozoon magnificissimi gen. et sp. nov., a new fossil vetulicolian, is reported from the Early Cambrian Chengjiang Fauna in Yunnan of China. It has a bipartite body plan and five pairs of chain-formed gill sacs, showing the general characteristics of Ventulicolia. However, the exclusive 'atrial cavity' and external gill observed indicate that the new form is different from those previously described as vetulicolians, probably representing a lineage developed within deuterostomes and more primitive than urochordates.
基金the National Natural Sciences Foundation of China(grants40173025,49928201)Trans-century Training Program Foundation for the Talents by the Ministry of Education the Visiting Scholar Foundation of Labs in Universities.
文摘He-Ar isotopic compositions of fluid inclusions trapped in pyrites from some representative PGE-polymetallic deposits in Lower Cambrian black rock series in South China were analyzed by using an inert gas isotopic mass spectrometer. The results show that the ore-forming fluids possess a low 3He/4He ratio, varying from 0.43×10-8 to 26.39×10-8, with corresponding R/Ra value of 0.003-0.189. The 40Ar/36Ar ratios are 258-287, close to those of air saturated water (ASW). He-Ar isotopic indicator studies show that the ore-forming fluids were mainly derived from the formation water or basinal hot brine and sea water, while the content of mantle-derived fluid or deep-derived magmatic water might be negligible. The PGE-polymetallic mineralization might be related to the evolution of the Caledonian miogeosynclines distributed along the southern margin of the Yangtze Craton. During the Early Cambrian, the formation water or basinal hot brine trapped in Caledonian basins which accumulated giant thick sediments was expelled and migrated laterally along strata because of the pressure generated by overlying sediments. The basinal hot brine ascended along faults, mixed with sea water and finally deposited ore minerals.
基金The research is jointly supported by the Key Project of the National Natural Science Foundation of China(No.40332020)Prophase Special Research of Vital Projects in the Basic Research of the Ministry of Science and Technology of China(No.2001CCA01 800)International Geological Correlation Program(IGCP463/494).
文摘The Cretaceous is among the most unusual eras in the geological past. Geoscience communities have been having great concerns with geological phenomena within this period, for example carbonate platforms and black shales in the Early and Middle Cretaceous respectively, during the last decades. But few people have paid any attention to the set of pelagic redbeds lying on the black shales, not to mention the applications to paleoclimatology and paleoceanography. It is shown by the sedimentary records of redbeds, that they were deposited around the CCD, with both a higher content of iron and much lower concentrations of organic carbon, which implies conditions with a relatively high content of oxygen. Such redbeds occurred in the global oceans, mainly in the Tethyan realm, with different durations of deposition and a climax from the late Santonian to early Campanian. Global cooling and dramatic changes in ocean currents might help to increase the oxygen flux between the atmosphere and ocean, after the large scale organic carbon burial during the Middle Cretaceous, and therefore lead to the oxygenation of deep ocean and so the occurrence of late Cretaceous oceanic redbeds.
基金Supported by Key Research Program of the National Science Foundation of China(No.90102002)and the Croucher Foundation of Hong Kong.
文摘Human activity duo to rapid increasing of the economy in China has become so wide and intense since 1980s that it comes to the most active factor affecting the earth surface geomorphology process and provoke the most important impact to environment in recent two decades. Some typical human-induced landslides are introduced. Their generalfeatures,including distribution,types,time series of occurrence and mechanism are summarized. A classification system of landslides is suggested based on their geological backgrounds and formation mechanism. Finally,some aspects of slope management and human activity control are discussed to different types of landslides.
基金The cooperative project between Government of China and Japan
文摘By means of SEDEX, ASPILA and XRF, depth-dependent changes of different phosphorus forms in sediment cores from specific areas of the offshore Changjiang Estuary (Yangtze Estuary) in 1998 were analyzed. Results show that contents of total phosphorus (TP), organic-phosphorus (OP) and iron-phosphorus (Fe-P) decreased down-core, while those of absorbed-phosphorus (Ad-P) and calcium-phosphorus (Ca-P) increased. The distribution tendency of detritus-phosphorus (De-P) is not obvious. Results also show that TP, Fe-P and OP contents at Meso station of the Changjiang Estuary and Hangzhou Bay are higher than that of the other stations. This suggests that the pollutants carried by the Changjiang and the Qiantang rivers from inland have affected the natural environment in offshore area. TP, Fe-P and OP contents of each station become higher from bottom to top, indicating the amount of the terrestrial pollutants carried by the two rivers has been enhanced since the last 30-50 years. Ad-P, Ca-P, Fe-P and OP are all active phosphorus in sediments, and their re-cycling in sediment is closely related to each other.
基金supported by the National Science Foundation of China(grant Nos.49873016,40221301)the Ph.D.Programs Foundation of the Ministry of Education of China(No.20020284035)
文摘An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140–135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb -Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit. Associated “porphyry” mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.
基金The research was funded by the Natural Science Foundation of China(40172033)and the state volcano program of the tenth Five-Year Plan period(2001BA601B06-01-4).
文摘Since the eruption of the Tianchi volcano about 1000 years ago, there have been at least 3 to 5 eruptions of small to moderate size. In addition, hazardous avalanches, rock falls and debris flows have occurred during periods between eruptions. A future eruption of the Tianchi volcano is likely to involve explosive interaction between magma and the caldera lake. The volume of erupted magma is almost in a range of 0.1-0.5 km3. Tephra fallout may damage agriculture in a large area near the volcano. If only 1% of the lake water were ejected during an eruption and then precipitated over an area of 200 km2, the average rainfall would be 100 mm. Moreover, lahars are likely to occur as both tephra and water ejected from the caldera lake fall onto flanks of the volcano. Rocks avalanching into the caldera lake also would bring about grave hazards because seiches would be triggered and lake water with the volume equal to that of the landslide would spill out of the existing breach in the caldera and cause flooding downstream.
文摘This paper presents the special processing methods used for wide-angle land seismic data through both theoretical study and model testing. They are different from conventional ones in the following aspects: separation of reflection and refraction waves, long offset NMO and stacking and forward modeling and inversion. These processing techniques have been applied for the first time to land seismic data from Liaohe areas, resulting in greatly improved quality of the deep formation and better imaging of the shallow layer obtained in the volcanic-shielded area. Wide-angle reflection and refraction seismic surveys were carried out in the Liaohe area using the maximum offset of 6500m and with the target around 2000ms. In the processing, we adopted the τ-p transform and the high-order normal moveout correction.
文摘A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration.
基金This research is financially supported by the China National Natural Science Foundation(Project No．40272063)
文摘This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, static sounding and chemical analysis obtained from the present Hangzhou Bay coastal plain. The incised valleys were formed during the last glacial maximum and were subsequently filled with fluvial facies during the post-glacial period. All commercial gases are stored in the flood plain sand lenses of the incised valleys.
文摘An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comparison of five semivariogram models (Spherical, Exponential, Linear, Gaussian and Rational Quadratic) indicated that kriging fulfills the objective of finding better ways to estimate interpolation weights and can provide error information for monthly rainfall interpolation. ESDA yielded the three most common forms of experimental semivariogram for monthly rainfall in the area. All five models were appropriate for monthly rainfall interpolation but under different circumstances. Spherical, Exponential and Linear models perform as smoothing interpolator of the data, whereas Gaussian and Rational Quadratic models serve as an exact interpolator. Spherical, Exponential and Linear models tend to underestimate the values. On the contrary, Gaussian and Rational Quadratic models tend to overestimate the values. Since the suitable model for a specific month usually is not unique and each model does not show any bias toward one or more specific months, an ESDA is recommended for a better interpolation result.
文摘We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized by an assemblage of garnet, orthopyroxene, spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the or-thopyroxenes have high XMg and A12O3 contents (up to 9.23 wt%). Biotites are enriched in TiO2 and XMg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which show peak melting temperatures of around -56.7℃, indicating a pure CO2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a liquid phase at temperatures around 15.3-23.8℃ translating into CO2 densities of the order of 0.86-0.88 g/cm3. Based on preliminary mineral paragenesis, reaction textures and petrogenetic grid considerations, we infer that the rock was subjected to UHT conditions. The CO2-rich fluids were trapped during exhumation along a clockwise P-T path following isothermal decompression under UHT conditions.
