The Helanshan tectonic belt is located to the west of the Ordos Basin, and separates the Alxa(or Yinshan)Massif to the west from the Ordos block to the east. Triassic sedimentation in the Helanshan tectonic belt recor...The Helanshan tectonic belt is located to the west of the Ordos Basin, and separates the Alxa(or Yinshan)Massif to the west from the Ordos block to the east. Triassic sedimentation in the Helanshan tectonic belt records important information about tectono-sedimentary process between the Alxa Massif and the Ordos block. Detailed geological mapping and investigation on the lithological package, sedimentary facies and paleocurrent orientation have been conducted on the Middle to Upper Triassic clastic rocks in the Helanshan tectonic belt. The succession is characterized by upward-fining sequence and comprises coarse grained alluvial-fluvial facies in the lower part as well as deltaic-lacustrine facies in the upper part. Based on detailed study and comparisons on the sedimentary sequence along various sections, the Middle to Upper Triassic strata have been revealed that show clear southeastward-deepening sedimentary differentiation and transgression from southwest to northeast, which are consistent with the southeastward flowing paleocurrent. These features indicate a southeastward-dipping paleogeography in the Helanshan tectonic belt, which was original western part of southeastward orientated fluviallacustrine system in the northwestern proto-Ordos Basin. Further to the east, the Triassic succession in the Ordos Basin displays gradually thickening and alluvial-fluvial system flowed from southeast to northwest, showing a huge thick sedimentary wedge in the western basin margin. Together with the Late Permiane Early Triassic closure of the Paleo-Asian Ocean to the north, the Late Triassic extensional structures and diabase dykes in the Helanshan tectonic belt, all the above sedimentary features could be mostly interpreted as records of an extensional basin correlated to post-collisional collapse of the Central Asian Orogenic Belt.展开更多
In this paper, we focus on the characteristics of the landslides developed in the epicentral area of AD 1556 M^8.5 Huaxian Earthquake, and discuss their relations to the active normal faults in the SE Weihe Graben, Ce...In this paper, we focus on the characteristics of the landslides developed in the epicentral area of AD 1556 M^8.5 Huaxian Earthquake, and discuss their relations to the active normal faults in the SE Weihe Graben, Central China. The results from analyzing high-resolution remote-sensing imagery and digital elevation models（DEMs）, in combination with field survey, demonstrate that：（i） the landslides observed in the study area range from small-scale debris/rock falls to large-scale rock avalanches;（ii） the landslides are mostly developed upon steep slopes of ≥30°; and（iii） the step-like normal-fault scarps along the range-fronts of the Huashan Mountains as well as the thick loess sediments in the Weinan area may facilitate the occurrence of large landslides. The results presented in this study would be helpful to assess the potential landslide hazards in densely-populated areas affected by active normal faulting.展开更多
The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data proce...The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data processing of gravity and magnetism, analysis of graben structure, geochemistry, reservoir and composition research. The basin has a double-layered framework and a large thickness of sediments. Gravity highs shown in a residual anomaly map might indicate central uplift zones. There exist at least two sets of mature or low-maturity source rocks corresponding to a certain source rock in the Cretaceous or Paleogene and Neogene strata. The graben has basement rock with potential reservoirs and Tertiary sandstone reservoirs and thus has petroleum exploration potential.展开更多
The detailed geological mapping, conducted in the Damxung-Yangbajain basin, shows that there are many types of deposits formed since the Pliocene. The oldest sediments are formed during the Pliocene. The most prominen...The detailed geological mapping, conducted in the Damxung-Yangbajain basin, shows that there are many types of deposits formed since the Pliocene. The oldest sediments are formed during the Pliocene. The most prominent sediments are three sets of moraines and fluvioglacial deposits. The ESR, U-series and OSL dates indicate they are formed about 700-500 ka B.P., 250-125 ka B.P. and 75-12 ka B.P. respectively and indicate that there are three glacial periods since the mid-Pleistocene in the Nyainqentanglha Range. Along the southeast side of the Nyainqentanglha Range, the main southeast dipping fault zone which bounds the Damxung-Yangbajain Graben on its western edge was mapped. The fault zone consists of three secondary fault zones and their initiation ages that the fault zones became active gradually decrease southeastward. Prominent faulting occurred in about 700-500 ka B.P., 350-220 ka B.P., -140 ka B.P. and 70-50 ka B.P. since the mid-Pleistocene. The height of fault scarps which offset the sediments formed since the mid-Pleistocene suggest that the vertical slip rates change between 0.4 -2 mm/a and the cumulative average vertical movement at rates of 1.1±0.3 mm/a during the Quaternary period and the Holocene vertical throw rate is 1.4±0.6 mm/a along the fault zones on the western side of the Damxung-Yangbajain Graben.展开更多
The Helan Mountain lies in the northwest margin of Ordos Basin and its uplift periods have close relations with the tectonic feature and evolution of the basin.There are many views on the uplift time of Helan Mountain...The Helan Mountain lies in the northwest margin of Ordos Basin and its uplift periods have close relations with the tectonic feature and evolution of the basin.There are many views on the uplift time of Helan Mountain,which is Late Triassic and Late Jurassic.It is concluded by the present strata,magmatic rock and hot fluid distribution that the Helan Mountain does not uplift in Late Triassic to Middle Jurassic but after Middle Jurassic.Through the research of the sedimentary strata and deposit rate in Yinchuan Graben which is near to the Helan Mountain,it is proved that the Helan Mountain uplifts in Eocene with a huge scale and in Pliocene with a rapid speed.The fission track analysis of apatite and zircon can be used to determine the precise uplift time of Helan Mountain,which shows that four stages of uplifting or cooling:Late Jurassic to the early stage of Early Cretaceous,mid-late stage of Early Cretaceous,Late Cretaceous and since Eocene.During the later two stages the uplift is most apparent and the mid-late stage of Early Cretaceous is a regional cooling course.Together with several analysis ways,it is considered that the earliest time of Helan Mountain uplift is Late Jurassic with a limited scale and that Late Cretaceous uplift is corresponding to the whole uplift of Ordos Basin,extensive uplift happened in Eocene and rapid uplift in Pliocene.展开更多
The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang upli...The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang uplift, the rifting block ridge in the northern segment and the ＂Mianhua uplift＂ in the southern segment have possibly preserved characteristics of volcanism and magmatism occurring with those rifting phases. The clockwise rotation of the southern Ryukyu Islands, driven by collision between Luzon and Taiwan, has played a key role in the crustal oceanization, enhancing the crustal extension of the southern segment and inducing volcanic magmatism in those grabens, among which the Yaeyama graben is a typical example of the presence of oceanic crust. Faulting and magmatism were mainly migrating towards the island arc asymmetrically. The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetic anomaly model, which is fit for the symmetric spreading of the mid-oceanic ridges.展开更多
Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanx...Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanxi Graben, we measured the crustal thickness and Vp/Vs ratio beneath each station using the H-K stack of receiver functions. The observed crustal thickness shows obvious lateral variation, increasing gradually from east to west in the Shanxi Graben. Beneath the Shanxi Graben the crust is relatively thicker than both sides of the south and the north. In addition, the Vp/Vs ratio in the north of study zone is higher than that in the south. The highest Vp/Vs ratio exists in the crust of the Xinding basin and the Datong basin. Our study also suggests that high velocity ratio might result from the strong activities of the magmation and volcanism.展开更多
Tangi Mahi-par is a fault valley from previews geological period (Pleistocene) where the Kabul basin was a lake and occupied by water, and after the formation of Tangi Mahi-par fault valley, water was drained from thi...Tangi Mahi-par is a fault valley from previews geological period (Pleistocene) where the Kabul basin was a lake and occupied by water, and after the formation of Tangi Mahi-par fault valley, water was drained from this way. Therefore, this research is essential to elucidate the different rocks types and structures, with no or scarce previous research’s in this mountainous area. The main objective of this study is to selected rock type, rocky structures and different sizes of river sediments transported by rivers discharge from the previous geological periods. There are different types of sediments, terrace remnants, rocks and geological structures which are generally consist of Limestone and Gneiss, where the limestone is likely belonging to the Thythes ocean remnants in Afghanistan and contains Ammonites fossils. In some parts volcanic breccias, it shows the old volcanic eruptions, Stalactite and stalagmite Carbonitic sediments related to limestones are also present there. In addition, there are different types of geological structures such as Anticline, Syncline, dyke, Sill, Apophysis, Graben and Horst. Unconformities and horizontal layers related to Khengal and Cottagay series passing from this area are located one by another.展开更多
Compliance with appropriate flock health program is vital for preventing introduction and minimizing impact of diseases in goat farms. Unfortunately, most goat farms in Uganda, especially in the Albertine Graben Zone ...Compliance with appropriate flock health program is vital for preventing introduction and minimizing impact of diseases in goat farms. Unfortunately, most goat farms in Uganda, especially in the Albertine Graben Zone lack flock health program. The associated frequent outbreaks slow down effort aimed at commercializing goat production. In this study, we documented flock dynamics, identified and prioritized pressing challenges experienced by goat farms during the year 2022 and generated appropriate flock health program and packaged it for dissemination to farmers. Materials and Methods: Using a cross-sectional design, semi-structured questionnaire, data were collected and analyzed with MS Excel 2013. The data included: location and socio-demographics of household, farming system, flock dynamics, housing, feeding system, health management, challenges encountered by goat farm and suggested solutions. Results: Beginning January 2022 to December 2022, the number of goats reared in all the 45 sample farms increased from 2128 to 2220 goats. Results showed that 884 kids were produced and 88 breeding goats were introduced into the farms. Three hundred ninety-nine goats died due to mainly diseases and 435 goats got withdrawn through nondeath. The average farm level and overall mortality rate were 21 goats per 1000 goatmonths and 15 goats per 1000 goatmonths respectively. The most pressing challenges encountered by sample farms were death of goats especially due to diseases, poor access to veterinary extension services, high cost of inputs and feed scarcity. Solutions suggested by sample farms were improved access to veterinary services, improved housing, enhanced vaccination of goats against diseases, and enhanced grazing land management and feed conservation, all of which were incorporated into the flock health program. Conclusion and Recommendations: An appropriate flock health program was generated based on flock dynamics and production constraints which reveal high mortality and limited access to veterinary services res展开更多
We use 15 seismic stations, crossing the Qinling orogen （QO）, Weihe graben （WG） and Ordos block （OB）, to study the crustal structures by receiver functions （RFs） methods. The results show quite a difference in...We use 15 seismic stations, crossing the Qinling orogen （QO）, Weihe graben （WG） and Ordos block （OB）, to study the crustal structures by receiver functions （RFs） methods. The results show quite a difference in crustal structures and materials of three tectonic units （orogenic belt, extentional basin and stable craton）. The average crustal thickness in the northern QO is 37.8 km, and Poisson ratio is 0.247, which indicates the increase of felsic materials in QO. In the southern OB, the average crustal thickness is 39.2 km and Poisson ratio is 0.265. Comparatively high value of Poisson ratio is related with old crystallized base in the lower crust and shallow sediments. The artificial RFs reveal that low-velocity and thick sediments have a significant ef fect on phases of the MohoroviEi6 discontinuity （Moho）. As a result, the Moho phases in WG are tangled. S-wave velocity （Vs） inversion shows that there are shallow sediment layers with 4-8 km＇s thickness and high velocity zones in the middle-lower crust in WG. Complex Moho structure and high velocity zone may have been induced by the activities of the Weihe faults series.展开更多
基金Financial supports for this study were jointly supported by the National Natural Science Foundation of China (Grant Nos.41421002 and 41602109)most special fund from the State Key Laboratory of Continental Dynamics, Northwest University, Shaanxi Postdoctoral Science Foundation, National Science and Technology Special Grant (No. 2016ZX05006-007)China Geological SurveyGrant (No. DD20189614)
文摘The Helanshan tectonic belt is located to the west of the Ordos Basin, and separates the Alxa(or Yinshan)Massif to the west from the Ordos block to the east. Triassic sedimentation in the Helanshan tectonic belt records important information about tectono-sedimentary process between the Alxa Massif and the Ordos block. Detailed geological mapping and investigation on the lithological package, sedimentary facies and paleocurrent orientation have been conducted on the Middle to Upper Triassic clastic rocks in the Helanshan tectonic belt. The succession is characterized by upward-fining sequence and comprises coarse grained alluvial-fluvial facies in the lower part as well as deltaic-lacustrine facies in the upper part. Based on detailed study and comparisons on the sedimentary sequence along various sections, the Middle to Upper Triassic strata have been revealed that show clear southeastward-deepening sedimentary differentiation and transgression from southwest to northeast, which are consistent with the southeastward flowing paleocurrent. These features indicate a southeastward-dipping paleogeography in the Helanshan tectonic belt, which was original western part of southeastward orientated fluviallacustrine system in the northwestern proto-Ordos Basin. Further to the east, the Triassic succession in the Ordos Basin displays gradually thickening and alluvial-fluvial system flowed from southeast to northwest, showing a huge thick sedimentary wedge in the western basin margin. Together with the Late Permiane Early Triassic closure of the Paleo-Asian Ocean to the north, the Late Triassic extensional structures and diabase dykes in the Helanshan tectonic belt, all the above sedimentary features could be mostly interpreted as records of an extensional basin correlated to post-collisional collapse of the Central Asian Orogenic Belt.
基金supported by the National Natural Science Foundation of China (No. 41502203)the Scientific Research Foundation for Returned Overseas Scholars of China (awarded to G. Rao)+1 种基金the Natural Science Foundation of Zhejiang Province (No. LY15D02001)a Science Project (No. 23253002)from the Ministry of Education, Culture, Sports, Science and Technology of Japan
文摘In this paper, we focus on the characteristics of the landslides developed in the epicentral area of AD 1556 M^8.5 Huaxian Earthquake, and discuss their relations to the active normal faults in the SE Weihe Graben, Central China. The results from analyzing high-resolution remote-sensing imagery and digital elevation models（DEMs）, in combination with field survey, demonstrate that：（i） the landslides observed in the study area range from small-scale debris/rock falls to large-scale rock avalanches;（ii） the landslides are mostly developed upon steep slopes of ≥30°; and（iii） the step-like normal-fault scarps along the range-fronts of the Huashan Mountains as well as the thick loess sediments in the Weinan area may facilitate the occurrence of large landslides. The results presented in this study would be helpful to assess the potential landslide hazards in densely-populated areas affected by active normal faulting.
文摘The Albertine Graben in western Uganda is a Mesozoic-Cenozoic rift basin with petroleum exploration potential. A fundamental evaluation of petroleum potential of the graben is given based on field research, data processing of gravity and magnetism, analysis of graben structure, geochemistry, reservoir and composition research. The basin has a double-layered framework and a large thickness of sediments. Gravity highs shown in a residual anomaly map might indicate central uplift zones. There exist at least two sets of mature or low-maturity source rocks corresponding to a certain source rock in the Cretaceous or Paleogene and Neogene strata. The graben has basement rock with potential reservoirs and Tertiary sandstone reservoirs and thus has petroleum exploration potential.
文摘The detailed geological mapping, conducted in the Damxung-Yangbajain basin, shows that there are many types of deposits formed since the Pliocene. The oldest sediments are formed during the Pliocene. The most prominent sediments are three sets of moraines and fluvioglacial deposits. The ESR, U-series and OSL dates indicate they are formed about 700-500 ka B.P., 250-125 ka B.P. and 75-12 ka B.P. respectively and indicate that there are three glacial periods since the mid-Pleistocene in the Nyainqentanglha Range. Along the southeast side of the Nyainqentanglha Range, the main southeast dipping fault zone which bounds the Damxung-Yangbajain Graben on its western edge was mapped. The fault zone consists of three secondary fault zones and their initiation ages that the fault zones became active gradually decrease southeastward. Prominent faulting occurred in about 700-500 ka B.P., 350-220 ka B.P., -140 ka B.P. and 70-50 ka B.P. since the mid-Pleistocene. The height of fault scarps which offset the sediments formed since the mid-Pleistocene suggest that the vertical slip rates change between 0.4 -2 mm/a and the cumulative average vertical movement at rates of 1.1±0.3 mm/a during the Quaternary period and the Holocene vertical throw rate is 1.4±0.6 mm/a along the fault zones on the western side of the Damxung-Yangbajain Graben.
基金Supported by the National Basic Research Program of China(Grant No.2003CB214607)the Development Project of Changjiang River Scholars and the Innovation Research Team in University(Grant No.IRT0559)
文摘The Helan Mountain lies in the northwest margin of Ordos Basin and its uplift periods have close relations with the tectonic feature and evolution of the basin.There are many views on the uplift time of Helan Mountain,which is Late Triassic and Late Jurassic.It is concluded by the present strata,magmatic rock and hot fluid distribution that the Helan Mountain does not uplift in Late Triassic to Middle Jurassic but after Middle Jurassic.Through the research of the sedimentary strata and deposit rate in Yinchuan Graben which is near to the Helan Mountain,it is proved that the Helan Mountain uplifts in Eocene with a huge scale and in Pliocene with a rapid speed.The fission track analysis of apatite and zircon can be used to determine the precise uplift time of Helan Mountain,which shows that four stages of uplifting or cooling:Late Jurassic to the early stage of Early Cretaceous,mid-late stage of Early Cretaceous,Late Cretaceous and since Eocene.During the later two stages the uplift is most apparent and the mid-late stage of Early Cretaceous is a regional cooling course.Together with several analysis ways,it is considered that the earliest time of Helan Mountain uplift is Late Jurassic with a limited scale and that Late Cretaceous uplift is corresponding to the whole uplift of Ordos Basin,extensive uplift happened in Eocene and rapid uplift in Pliocene.
基金The National Major Fundamental Research and Development Project of China under contract Nos G2000046703 and 2007CB411702the Scientific Research Fund of the Second Institute of Oceanography, State Oceanic Administration under contract No.JT0705
文摘The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang uplift, the rifting block ridge in the northern segment and the ＂Mianhua uplift＂ in the southern segment have possibly preserved characteristics of volcanism and magmatism occurring with those rifting phases. The clockwise rotation of the southern Ryukyu Islands, driven by collision between Luzon and Taiwan, has played a key role in the crustal oceanization, enhancing the crustal extension of the southern segment and inducing volcanic magmatism in those grabens, among which the Yaeyama graben is a typical example of the presence of oceanic crust. Faulting and magmatism were mainly migrating towards the island arc asymmetrically. The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetic anomaly model, which is fit for the symmetric spreading of the mid-oceanic ridges.
基金supported by the National Natural Science Foundation of China(No.41230210)the Projects of International Cooperation and Exchanges from the Ministry of Science and Technology of China(Grant No.2010DFB20190)the Fundamental Research Funds for the Institute of Earthquake Science,China Earthquake Administration
文摘Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanxi Graben, we measured the crustal thickness and Vp/Vs ratio beneath each station using the H-K stack of receiver functions. The observed crustal thickness shows obvious lateral variation, increasing gradually from east to west in the Shanxi Graben. Beneath the Shanxi Graben the crust is relatively thicker than both sides of the south and the north. In addition, the Vp/Vs ratio in the north of study zone is higher than that in the south. The highest Vp/Vs ratio exists in the crust of the Xinding basin and the Datong basin. Our study also suggests that high velocity ratio might result from the strong activities of the magmation and volcanism.
文摘Tangi Mahi-par is a fault valley from previews geological period (Pleistocene) where the Kabul basin was a lake and occupied by water, and after the formation of Tangi Mahi-par fault valley, water was drained from this way. Therefore, this research is essential to elucidate the different rocks types and structures, with no or scarce previous research’s in this mountainous area. The main objective of this study is to selected rock type, rocky structures and different sizes of river sediments transported by rivers discharge from the previous geological periods. There are different types of sediments, terrace remnants, rocks and geological structures which are generally consist of Limestone and Gneiss, where the limestone is likely belonging to the Thythes ocean remnants in Afghanistan and contains Ammonites fossils. In some parts volcanic breccias, it shows the old volcanic eruptions, Stalactite and stalagmite Carbonitic sediments related to limestones are also present there. In addition, there are different types of geological structures such as Anticline, Syncline, dyke, Sill, Apophysis, Graben and Horst. Unconformities and horizontal layers related to Khengal and Cottagay series passing from this area are located one by another.
文摘Compliance with appropriate flock health program is vital for preventing introduction and minimizing impact of diseases in goat farms. Unfortunately, most goat farms in Uganda, especially in the Albertine Graben Zone lack flock health program. The associated frequent outbreaks slow down effort aimed at commercializing goat production. In this study, we documented flock dynamics, identified and prioritized pressing challenges experienced by goat farms during the year 2022 and generated appropriate flock health program and packaged it for dissemination to farmers. Materials and Methods: Using a cross-sectional design, semi-structured questionnaire, data were collected and analyzed with MS Excel 2013. The data included: location and socio-demographics of household, farming system, flock dynamics, housing, feeding system, health management, challenges encountered by goat farm and suggested solutions. Results: Beginning January 2022 to December 2022, the number of goats reared in all the 45 sample farms increased from 2128 to 2220 goats. Results showed that 884 kids were produced and 88 breeding goats were introduced into the farms. Three hundred ninety-nine goats died due to mainly diseases and 435 goats got withdrawn through nondeath. The average farm level and overall mortality rate were 21 goats per 1000 goatmonths and 15 goats per 1000 goatmonths respectively. The most pressing challenges encountered by sample farms were death of goats especially due to diseases, poor access to veterinary extension services, high cost of inputs and feed scarcity. Solutions suggested by sample farms were improved access to veterinary services, improved housing, enhanced vaccination of goats against diseases, and enhanced grazing land management and feed conservation, all of which were incorporated into the flock health program. Conclusion and Recommendations: An appropriate flock health program was generated based on flock dynamics and production constraints which reveal high mortality and limited access to veterinary services res
基金supported by National Natural Science Foundation of China(Grant Nos.41174038 and 40474017)
文摘We use 15 seismic stations, crossing the Qinling orogen （QO）, Weihe graben （WG） and Ordos block （OB）, to study the crustal structures by receiver functions （RFs） methods. The results show quite a difference in crustal structures and materials of three tectonic units （orogenic belt, extentional basin and stable craton）. The average crustal thickness in the northern QO is 37.8 km, and Poisson ratio is 0.247, which indicates the increase of felsic materials in QO. In the southern OB, the average crustal thickness is 39.2 km and Poisson ratio is 0.265. Comparatively high value of Poisson ratio is related with old crystallized base in the lower crust and shallow sediments. The artificial RFs reveal that low-velocity and thick sediments have a significant ef fect on phases of the MohoroviEi6 discontinuity （Moho）. As a result, the Moho phases in WG are tangled. S-wave velocity （Vs） inversion shows that there are shallow sediment layers with 4-8 km＇s thickness and high velocity zones in the middle-lower crust in WG. Complex Moho structure and high velocity zone may have been induced by the activities of the Weihe faults series.
