The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of par...The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of partially serpentinized dunite, peridotite, gabbro, basalt, minor plagiogranite,diorite dyke and marine sediments. The basalts are mainly composed of fine grained plagioclase feldspar, clinopyroxene and orthopyroxene and show quenching and variolitic textures. The gabbros are characterized by medium to coarse grained plagioclase, orthopyroxene and clinopyroxene with ophitic to sub-ophitic textures. The ultramafic cumulates are represented by olivine, Cpx and Opx.Geochemically, the basalts and gabbros are sub-alkaline to alkaline and show tholeiitic features.The basalts are characterized by 44.1-45.6 wt.% of SiO_2 with 28-38 of Mg#, and the gabbros by38.7-43.7 wt.% of SiO_2, and 26-79 of Mg#. The ultramafic rocks are characterized by 37.4-52.2 wt.% of SiO_2, and 80-88 of Mg#. In multi-element diagrams(spidergrams) both basalts and gabbros show fractionated trends with strong negative anomalies of Zr. Nb. Sr and a gentle negative anomaly of P.However, the rare earth element(REE) plots of the basalts and gabbros show two distinct patterns. The first pattern, represented by light REE(LREE) depletion, suggests N-MORB features and can be interpreted as a signature of Paleo-Tethyan oceanic crust. The second pattern, represented by LREE enrichment with negligible negative Eu anomaly, conforms to E-MORB, and may be related to an arc tectonic setting. In V vs. Ti/1000, Cr vs. Y and AFM diagrams, the basalts and gabbros plot within Island Arc Tholeiite(IAT) and MORB fields suggesting both ridge and arc related settings. The ultramafic rocks exhibit two distinct patterns both in spidergrams and in REE plots. In the spidergram, one group displays highly enriched pattern, whereas the other group shows near flat pattern compared to primordial mantle. In the REE plot, one group displays steeper slopes [(La/Yb)N = 4.340-4.341], whereas the other displays moderate to flat slopes [(La/Yb)N = 0.97-1.67] and negative Eu-anomalies. Our study suggests that the ultramafic rocks represent two possible mantle sources(fertile and refractory).展开更多
The Fossil Hill Formation of the type section composed chiefly of the sedimentary-volcaniclastic breccia and tuffites can be divided into two cycles of sedimentation. The thermal fluid was active in the coarse volcani...The Fossil Hill Formation of the type section composed chiefly of the sedimentary-volcaniclastic breccia and tuffites can be divided into two cycles of sedimentation. The thermal fluid was active in the coarse volcaniclastic deposits of the lower cy-cle, it led to the formation of laumontite,analcite,albite and regularly hybrid mineral of interlayered chlorite and montmorillonite .which are absent from the upper cycle, and to the transportation and concentration of some of trace elements between the coarser tuffites and the overlying fine tuffite bed at the upper part of this cycle. So-called 'rainprint' and 'mud crack' actually are non-sedimentary originally, they were formed respectively by sheddillg of the small zeolitized concretions on the bedding plane and tectonic pressed stress. The evidences indicate that the Fossil Hill Formation of the Fossil Hill section was deposited in an intermontane lake affected by both volcanic action andseasonal flail under the condition of worm and moist climate.展开更多
An oil flow obtained from the Middle Ordovician Fengfeng Formation carbonate reservoir in the well KG-3, Kongxi burial-hill zone in 1993 marked a breakthrough in petroleum exploration of the high-mature Lower Palaeozo...An oil flow obtained from the Middle Ordovician Fengfeng Formation carbonate reservoir in the well KG-3, Kongxi burial-hill zone in 1993 marked a breakthrough in petroleum exploration of the high-mature Lower Palaeozoic strata, North China. Both the Lower member of the Fengfeng Formation and the Second Member of the Upper Majiagou Formation in the Middle Ordovician are supposed to be the main source beds. Oil generation peaks range from 1.0% to 1.6% in Ro, showing a “lag effect” of oil generation in high-mature carbonate source rocks under multicyclic tectonic movement conditions. The Kongxi burial-hill zone adjoins a potential Ordovician source kitchen. The KG-3 Ordovician burial-hill reservoir has undergone two oil filling events, i.e., an early event in the Late Carboniferous-Permian and a more significant late event in the early Eogene.展开更多
Bozhong oilfield which is abbreviated as BZ oilfield is the first oilfield with deep metamorphic buried hill that is discovered reserves of billion-ton in Bohai Bay. Affected by multi-stage tectonic movements, the dis...Bozhong oilfield which is abbreviated as BZ oilfield is the first oilfield with deep metamorphic buried hill that is discovered reserves of billion-ton in Bohai Bay. Affected by multi-stage tectonic movements, the distribution of fractures is very complex in this area, therefore it is significant to study the evolution of structures for understanding the distribution of fractures. In view of the complexity on the tectonic evolution of the buried hill region in the study area, the influence of tectonic movements on the formation of fractured reservoir is analyzed, and the research results lay the foundation for the efficient development in this type of the oilfield. The results show that main faults, which is formed during early Indosinian and Yanshanian period, are mainly developed in the BZ oilfield area, and the fracture strike has mainly east-west and north-east-east trend. Based on the analysis of the relationship among tectonic evolution, regional stress field and fracture development, it is considered that Indosinian extrusion is the main reason for the formation of main direction faults in the study area. Yanshanian strike-slip transformation and Himalayan reactivation further controlled the development of the fractured reservoirs in the later stage, and formed the present fracture network system. Well block 5 is located in passive plate system during Indosinian period, it is affected by Himalayan stretching and long-term activation of large faults in the later stage, so that the effective fractures are relatively developed. The result plays an important role in guiding the overall plan deployment of the BZ oilfield.展开更多
Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and ...Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and rhythmite of the Krol Formation are the main rock types. The present study focuses on the investigation of slope stability in the region in terms of potential seismicity and landslide. Geological and geotechnical mapping indicates that the major portion of the area is characterized by slope wash materials and buildings. The combination of 3-4 joint sets with one random joint is the main structure at outcrops.The major geological structures of this area are Nainital lake fault passing from the center of the lake, Main Boundary Thrust at SW, and Khuriya Fault passing from the SE direction of Nainital City. This work finds that different types of discontinuities(e.g. joints and faults), overburden due to unplanned civil structures,and neotectonic activity in the vicinity of this ara affect the stability of the city. The slate forms the base of the city, dipping slightly towards the lake side along the NW direction, thus accelerating the instability of this area. Rock mass rating(RMR), slope mass rating, factor of safety(FOS) and graphical analysis of the discontinuity for slope kinematics indicate that the study area is a landslide-prone zone. This study can facilitate reducing the risk of human life, and contribute to the ongoing construction works in the area.展开更多
[Objective] To select excellent pioneer species of better ecological and economical comprehensive benefits from the common rock hill plants in Karst area in northwestern Guangxi Province.[Method] Determine the content...[Objective] To select excellent pioneer species of better ecological and economical comprehensive benefits from the common rock hill plants in Karst area in northwestern Guangxi Province.[Method] Determine the contents of malondialdehyde and proline in leaves of 65 strains of plants by thiobarbituric acid method and sultosalicylic acid method,analyze the relevance of the contents of malondialdehyde and proline by mathematics statistics and analyze the 65 kinds of rock hill plants by clustering [Result] The contents of malondialdehyde and proline are 0.005 2-0.038 1 μmol/g.There are comparably significant differences in the contents of malondialdehyde in different plants;The determination of proline contents in plant＇s leaves are 4.347-374.956 μg/ml.There are also significant differences in proline of different leaves of rock hill plants.The contents of malondialdehyde and proline can be used as a reference point in selecting pioneer plants in Karst area.But when we select the pioneer plants,not only the biological characters of the species themselves should be taken into consideration,but also the differences of Karst area environment,ecological and biological benefits and the reasonable distribution of species.[Conclusion] Pistacia chinensis,Zenia insignis,Acacia confusa,Itoa orientalis and Sophora japonica can be used as the first choices of excellent pioneer plants in Karst area in northwestern area which comparably consists with the real situation of afforestation of rock hills and recovery of plants in Guangxi.展开更多
文摘The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of partially serpentinized dunite, peridotite, gabbro, basalt, minor plagiogranite,diorite dyke and marine sediments. The basalts are mainly composed of fine grained plagioclase feldspar, clinopyroxene and orthopyroxene and show quenching and variolitic textures. The gabbros are characterized by medium to coarse grained plagioclase, orthopyroxene and clinopyroxene with ophitic to sub-ophitic textures. The ultramafic cumulates are represented by olivine, Cpx and Opx.Geochemically, the basalts and gabbros are sub-alkaline to alkaline and show tholeiitic features.The basalts are characterized by 44.1-45.6 wt.% of SiO_2 with 28-38 of Mg#, and the gabbros by38.7-43.7 wt.% of SiO_2, and 26-79 of Mg#. The ultramafic rocks are characterized by 37.4-52.2 wt.% of SiO_2, and 80-88 of Mg#. In multi-element diagrams(spidergrams) both basalts and gabbros show fractionated trends with strong negative anomalies of Zr. Nb. Sr and a gentle negative anomaly of P.However, the rare earth element(REE) plots of the basalts and gabbros show two distinct patterns. The first pattern, represented by light REE(LREE) depletion, suggests N-MORB features and can be interpreted as a signature of Paleo-Tethyan oceanic crust. The second pattern, represented by LREE enrichment with negligible negative Eu anomaly, conforms to E-MORB, and may be related to an arc tectonic setting. In V vs. Ti/1000, Cr vs. Y and AFM diagrams, the basalts and gabbros plot within Island Arc Tholeiite(IAT) and MORB fields suggesting both ridge and arc related settings. The ultramafic rocks exhibit two distinct patterns both in spidergrams and in REE plots. In the spidergram, one group displays highly enriched pattern, whereas the other group shows near flat pattern compared to primordial mantle. In the REE plot, one group displays steeper slopes [(La/Yb)N = 4.340-4.341], whereas the other displays moderate to flat slopes [(La/Yb)N = 0.97-1.67] and negative Eu-anomalies. Our study suggests that the ultramafic rocks represent two possible mantle sources(fertile and refractory).
文摘The Fossil Hill Formation of the type section composed chiefly of the sedimentary-volcaniclastic breccia and tuffites can be divided into two cycles of sedimentation. The thermal fluid was active in the coarse volcaniclastic deposits of the lower cy-cle, it led to the formation of laumontite,analcite,albite and regularly hybrid mineral of interlayered chlorite and montmorillonite .which are absent from the upper cycle, and to the transportation and concentration of some of trace elements between the coarser tuffites and the overlying fine tuffite bed at the upper part of this cycle. So-called 'rainprint' and 'mud crack' actually are non-sedimentary originally, they were formed respectively by sheddillg of the small zeolitized concretions on the bedding plane and tectonic pressed stress. The evidences indicate that the Fossil Hill Formation of the Fossil Hill section was deposited in an intermontane lake affected by both volcanic action andseasonal flail under the condition of worm and moist climate.
文摘An oil flow obtained from the Middle Ordovician Fengfeng Formation carbonate reservoir in the well KG-3, Kongxi burial-hill zone in 1993 marked a breakthrough in petroleum exploration of the high-mature Lower Palaeozoic strata, North China. Both the Lower member of the Fengfeng Formation and the Second Member of the Upper Majiagou Formation in the Middle Ordovician are supposed to be the main source beds. Oil generation peaks range from 1.0% to 1.6% in Ro, showing a “lag effect” of oil generation in high-mature carbonate source rocks under multicyclic tectonic movement conditions. The Kongxi burial-hill zone adjoins a potential Ordovician source kitchen. The KG-3 Ordovician burial-hill reservoir has undergone two oil filling events, i.e., an early event in the Late Carboniferous-Permian and a more significant late event in the early Eogene.
文摘Bozhong oilfield which is abbreviated as BZ oilfield is the first oilfield with deep metamorphic buried hill that is discovered reserves of billion-ton in Bohai Bay. Affected by multi-stage tectonic movements, the distribution of fractures is very complex in this area, therefore it is significant to study the evolution of structures for understanding the distribution of fractures. In view of the complexity on the tectonic evolution of the buried hill region in the study area, the influence of tectonic movements on the formation of fractured reservoir is analyzed, and the research results lay the foundation for the efficient development in this type of the oilfield. The results show that main faults, which is formed during early Indosinian and Yanshanian period, are mainly developed in the BZ oilfield area, and the fracture strike has mainly east-west and north-east-east trend. Based on the analysis of the relationship among tectonic evolution, regional stress field and fracture development, it is considered that Indosinian extrusion is the main reason for the formation of main direction faults in the study area. Yanshanian strike-slip transformation and Himalayan reactivation further controlled the development of the fractured reservoirs in the later stage, and formed the present fracture network system. Well block 5 is located in passive plate system during Indosinian period, it is affected by Himalayan stretching and long-term activation of large faults in the later stage, so that the effective fractures are relatively developed. The result plays an important role in guiding the overall plan deployment of the BZ oilfield.
文摘Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and rhythmite of the Krol Formation are the main rock types. The present study focuses on the investigation of slope stability in the region in terms of potential seismicity and landslide. Geological and geotechnical mapping indicates that the major portion of the area is characterized by slope wash materials and buildings. The combination of 3-4 joint sets with one random joint is the main structure at outcrops.The major geological structures of this area are Nainital lake fault passing from the center of the lake, Main Boundary Thrust at SW, and Khuriya Fault passing from the SE direction of Nainital City. This work finds that different types of discontinuities(e.g. joints and faults), overburden due to unplanned civil structures,and neotectonic activity in the vicinity of this ara affect the stability of the city. The slate forms the base of the city, dipping slightly towards the lake side along the NW direction, thus accelerating the instability of this area. Rock mass rating(RMR), slope mass rating, factor of safety(FOS) and graphical analysis of the discontinuity for slope kinematics indicate that the study area is a landslide-prone zone. This study can facilitate reducing the risk of human life, and contribute to the ongoing construction works in the area.
基金Supported by Natural Science Foundation of Guangxi(Guangxi Sci-ence8032273)Key Laboratory of Colleges and Universities.(Guangxi Education and Scientific Research NO.2010[6])~~
文摘[Objective] To select excellent pioneer species of better ecological and economical comprehensive benefits from the common rock hill plants in Karst area in northwestern Guangxi Province.[Method] Determine the contents of malondialdehyde and proline in leaves of 65 strains of plants by thiobarbituric acid method and sultosalicylic acid method,analyze the relevance of the contents of malondialdehyde and proline by mathematics statistics and analyze the 65 kinds of rock hill plants by clustering [Result] The contents of malondialdehyde and proline are 0.005 2-0.038 1 μmol/g.There are comparably significant differences in the contents of malondialdehyde in different plants;The determination of proline contents in plant＇s leaves are 4.347-374.956 μg/ml.There are also significant differences in proline of different leaves of rock hill plants.The contents of malondialdehyde and proline can be used as a reference point in selecting pioneer plants in Karst area.But when we select the pioneer plants,not only the biological characters of the species themselves should be taken into consideration,but also the differences of Karst area environment,ecological and biological benefits and the reasonable distribution of species.[Conclusion] Pistacia chinensis,Zenia insignis,Acacia confusa,Itoa orientalis and Sophora japonica can be used as the first choices of excellent pioneer plants in Karst area in northwestern area which comparably consists with the real situation of afforestation of rock hills and recovery of plants in Guangxi.
