Late Cretaceous sea inundation of major continents, surprisingly did not affect Indian block except by two major subaerial events of Large Igneous Provinces （LIPs）. Marion hotspot induced LIP of Mahajanga Flood Bas...Late Cretaceous sea inundation of major continents, surprisingly did not affect Indian block except by two major subaerial events of Large Igneous Provinces （LIPs）. Marion hotspot induced LIP of Mahajanga Flood Basalt （ca. 92Ma） in Madagascar triggered high intensity earthquake along Narmada Lineament and permitted a short lived marine transgression during late Turonian with spectacular estuarine deposits of limited thickness, preserved as archive of “Greenhouse Climatic Record” ？ Reunion hotspot induced LIP of Deccan Flood Basalt, stretching from western to eastern India around Rajahmundry area attracted worldwide attention for the unique fauna and flora preserved in the intertrappean beds straddling Cretaceous-Palaeogene boundary. This massive subaerial LIP （ca. 66Ma） permitted fairly deep penetration of sea along collision facing Subathu-Dogadda Line-ament during late Maastrichtian-Danian, but due to thick vegetation cover, tectonic disturbance and scarce out-crops the evidence is less straightforward than along Narmada rift.展开更多
Solenopsis sp. is an important invader on upland arthropod of Eastern India. This study was conducted to evaluate the role of this insect as potential biocontrol agent against some major pests of rice. The ant populat...Solenopsis sp. is an important invader on upland arthropod of Eastern India. This study was conducted to evaluate the role of this insect as potential biocontrol agent against some major pests of rice. The ant populations were sampled before and during appearance of hibernating larva and pupa of rice yellow stem borer （YSB） Scirpophaga incertulas （Walk.） inside the rice plant. Species richness and diversity of other ant species were also assessed from YSB protected field with insecticides and the crop grown under natural biological control. The maximum value of Barger-Parker index （d = 0.245） indicated that fire ant constituted 24.55% of the total population. Besides, in natural as in agricultural ecosystems, interference between fire ants and mealy bug as well as aphids was also recorded in different altitudes of the Eastern Himalayas and found that the incidence of fire ants Solenopsis sp. decreased the abundance of borer pests, but in contrast it increased the hopper pests in the same ecological niche.展开更多
The Java Island, Indonesia with abundant amount of pyroclastic deposits is located in the very active and dynamic Pacific Ring of Fires. Studying the geochemical weathering indices of these pyroclastic deposits is imp...The Java Island, Indonesia with abundant amount of pyroclastic deposits is located in the very active and dynamic Pacific Ring of Fires. Studying the geochemical weathering indices of these pyroclastic deposits is important to get a clear picture about weathering profiles on deposits resulting from the eruption of Mt. Merapi. Immediately after the first phase of the eruption （March to June 2006）, moist and leached pyroclastic deposits were collected. These pyroclastic deposits were found to be composed of volcanic glass, plagioclase feldspar in various propoitions, orthopyroxene, clinopyroxene, olivine, amphibole and titanomagnetite. The total elemental composition of the bulk samples （including trace elements and heavy metals） was determined by wet chemical methods and X-ray fluorescence （XRF） analyses. Weathering of the pyroelastic deposits was studied using various weathering indices. The Ruxton ratio, weathering index of Parker, Vought resudual index and chemical index of weathering of moist pyroclastic deposits were lower than those of the leached samples, but the alteration indices （chemical and plagioclase） were slightly higher in the moist compared to the leached pyroelastic deposits.展开更多
Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing tem...Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing temperature, and decreasing pressure), the continent-continent collisional process has been divided into three stages, including initial collision, ongoing collision, and tectonic transition. These stages are characterized by normal calc-alkaline andesitic magma(dehydration of the oceanic crust to release fluids), the migration of calc-alkaline magma toward the trench(dehydration of the oceanic crust or an increase in temperature) or small-scale crust-derived peraluminous magma(heat from intra-crustal shearing), and extensive magmatism with compositional diversity induced by slab break-off(increasing temperature and decreasing pressure), respectively.On the basis of the obtained age of slab break-off, the timing of the initial continent-continent collision can be quantitatively back-dated using the convergence rate, depth of slab break-off, and subduction angle. The spatio-temporal migration of the magmatic activity of the Gangdese Batholith, the onset of magmatic flare-up, and the increase of magma temperature at 52–51Ma documented by the volcanic rocks of the Linzizong Pana Formation were most likely the result of the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere at approximately 53 Ma. This proposed age of slab break-off suggests that the initial India-Asia collision likely occurred at approximately 55–54 Ma, which is consistent with the collision ages constrained by other abundant geological data(60–55 Ma). This magmatic method has been applied to the Bitlis orogenic belt in southern Turkey in the Arabia-Eurasia continental collision zone, yielding an age range of approximately 29–22 Ma for the initial Arabia-Asia continental collision that is close to the collision ages recently obtained by apatite fission-track dating(approximately20 Ma) and regional tectonic shortening(approximately 27 Ma). The intense folding of the Upper Cretaceous and the angular unconformity between the overlying Linzizong volcanic rocks in the southern Lhasa Terrane(90.69 Ma) are not related to the initial continental collision between India and Asia, but can be interpreted as the consequences of the strong coupling between the hot and young subducting oceanic crust immediately south of the spreading ridge and the overriding lithosphere or the subduction of the Neo-Tethys oceanic plateaux or seamounts. The tectonic event documented by the angular unconformity between the Linzizong Dianzhong Formation and the Nianbo Formation lasted approximately 3 Ma and likely marks the initial India-Asia collision. The significant deceleration of the Indian continent at approximately 51 Ma can be attributed to the disappearance of the slab pull force in the subduction zone due to the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere. The descent of the eclogitized lower crust of the northern Indian continent provides the main driving force for the current northward motion of Indian plate. The weak deformation of the lithospheric plate in the overriding plate of the India-Asia collisional zone between 60 and 40 Ma can be attributed to the high-angle subduction related to the rollback of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere after the initial India-Asia continental collision, the presence of the thick crust and high elevation on the southern margin of the Lhasa Terrane, and the decoupling between the mid-upper and lower crust and between the lower crust and lithospheric mantle of the Indian continent.展开更多
文摘Late Cretaceous sea inundation of major continents, surprisingly did not affect Indian block except by two major subaerial events of Large Igneous Provinces （LIPs）. Marion hotspot induced LIP of Mahajanga Flood Basalt （ca. 92Ma） in Madagascar triggered high intensity earthquake along Narmada Lineament and permitted a short lived marine transgression during late Turonian with spectacular estuarine deposits of limited thickness, preserved as archive of “Greenhouse Climatic Record” ？ Reunion hotspot induced LIP of Deccan Flood Basalt, stretching from western to eastern India around Rajahmundry area attracted worldwide attention for the unique fauna and flora preserved in the intertrappean beds straddling Cretaceous-Palaeogene boundary. This massive subaerial LIP （ca. 66Ma） permitted fairly deep penetration of sea along collision facing Subathu-Dogadda Line-ament during late Maastrichtian-Danian, but due to thick vegetation cover, tectonic disturbance and scarce out-crops the evidence is less straightforward than along Narmada rift.
文摘Solenopsis sp. is an important invader on upland arthropod of Eastern India. This study was conducted to evaluate the role of this insect as potential biocontrol agent against some major pests of rice. The ant populations were sampled before and during appearance of hibernating larva and pupa of rice yellow stem borer （YSB） Scirpophaga incertulas （Walk.） inside the rice plant. Species richness and diversity of other ant species were also assessed from YSB protected field with insecticides and the crop grown under natural biological control. The maximum value of Barger-Parker index （d = 0.245） indicated that fire ant constituted 24.55% of the total population. Besides, in natural as in agricultural ecosystems, interference between fire ants and mealy bug as well as aphids was also recorded in different altitudes of the Eastern Himalayas and found that the incidence of fire ants Solenopsis sp. decreased the abundance of borer pests, but in contrast it increased the hopper pests in the same ecological niche.
基金supported by the Directorate of Higher Education Department of National Education of Republic of Indonesia under Fundamental Research Grant no: 005/SP3/PP/ DP2M/II/2006-2007, granted to the first authorthe Ministry of Research and Technology of the Republic Indonesia (Fundamental Research Intensive Program with grant no. 97/M/Kp/XI/ 2007) granted to first and second authors
文摘The Java Island, Indonesia with abundant amount of pyroclastic deposits is located in the very active and dynamic Pacific Ring of Fires. Studying the geochemical weathering indices of these pyroclastic deposits is important to get a clear picture about weathering profiles on deposits resulting from the eruption of Mt. Merapi. Immediately after the first phase of the eruption （March to June 2006）, moist and leached pyroclastic deposits were collected. These pyroclastic deposits were found to be composed of volcanic glass, plagioclase feldspar in various propoitions, orthopyroxene, clinopyroxene, olivine, amphibole and titanomagnetite. The total elemental composition of the bulk samples （including trace elements and heavy metals） was determined by wet chemical methods and X-ray fluorescence （XRF） analyses. Weathering of the pyroelastic deposits was studied using various weathering indices. The Ruxton ratio, weathering index of Parker, Vought resudual index and chemical index of weathering of moist pyroclastic deposits were lower than those of the leached samples, but the alteration indices （chemical and plagioclase） were slightly higher in the moist compared to the leached pyroelastic deposits.
基金supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB03010301)the National Key Research and Development Project of China (Grant No. 2016YFC0600304)the National Natural Science Foundation of China (Grant No. 41225006)
文摘Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing temperature, and decreasing pressure), the continent-continent collisional process has been divided into three stages, including initial collision, ongoing collision, and tectonic transition. These stages are characterized by normal calc-alkaline andesitic magma(dehydration of the oceanic crust to release fluids), the migration of calc-alkaline magma toward the trench(dehydration of the oceanic crust or an increase in temperature) or small-scale crust-derived peraluminous magma(heat from intra-crustal shearing), and extensive magmatism with compositional diversity induced by slab break-off(increasing temperature and decreasing pressure), respectively.On the basis of the obtained age of slab break-off, the timing of the initial continent-continent collision can be quantitatively back-dated using the convergence rate, depth of slab break-off, and subduction angle. The spatio-temporal migration of the magmatic activity of the Gangdese Batholith, the onset of magmatic flare-up, and the increase of magma temperature at 52–51Ma documented by the volcanic rocks of the Linzizong Pana Formation were most likely the result of the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere at approximately 53 Ma. This proposed age of slab break-off suggests that the initial India-Asia collision likely occurred at approximately 55–54 Ma, which is consistent with the collision ages constrained by other abundant geological data(60–55 Ma). This magmatic method has been applied to the Bitlis orogenic belt in southern Turkey in the Arabia-Eurasia continental collision zone, yielding an age range of approximately 29–22 Ma for the initial Arabia-Asia continental collision that is close to the collision ages recently obtained by apatite fission-track dating(approximately20 Ma) and regional tectonic shortening(approximately 27 Ma). The intense folding of the Upper Cretaceous and the angular unconformity between the overlying Linzizong volcanic rocks in the southern Lhasa Terrane(90.69 Ma) are not related to the initial continental collision between India and Asia, but can be interpreted as the consequences of the strong coupling between the hot and young subducting oceanic crust immediately south of the spreading ridge and the overriding lithosphere or the subduction of the Neo-Tethys oceanic plateaux or seamounts. The tectonic event documented by the angular unconformity between the Linzizong Dianzhong Formation and the Nianbo Formation lasted approximately 3 Ma and likely marks the initial India-Asia collision. The significant deceleration of the Indian continent at approximately 51 Ma can be attributed to the disappearance of the slab pull force in the subduction zone due to the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere. The descent of the eclogitized lower crust of the northern Indian continent provides the main driving force for the current northward motion of Indian plate. The weak deformation of the lithospheric plate in the overriding plate of the India-Asia collisional zone between 60 and 40 Ma can be attributed to the high-angle subduction related to the rollback of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere after the initial India-Asia continental collision, the presence of the thick crust and high elevation on the southern margin of the Lhasa Terrane, and the decoupling between the mid-upper and lower crust and between the lower crust and lithospheric mantle of the Indian continent.
