Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun (spots and solar flares...Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun (spots and solar flares) during eleven years cycle, as well as knowledge of possible flooding of the Nile and the periods of increase and decrease of the extent necessary to meet the soil around Lake Qarun in Fayoum-Egypt. From historical records in ancient Egypt and Muslim countries, the possible link between periods of the disappearance of sunspots on the solar disc for several years and is known to inch lower level and role of the minimum level of Mandour creeping ice on Southern Europe to the Mediterranean Sea, and the offset of the drought in North Africa and the Sahel region of Africa during the last thousand years. Analyzed pollen fossils of the overlapped layers of soil in two areas of the Delta were Avaris in Sharkiya Province and Mendes in Dakahliya Province. The study pointed out that there are differences due to environmental conditions, demonstrated by the analysis of soil pH, increased electrical connectivity also, the evidence of sulfates and chlorides indicate high salinity of Mendes and Avaris. Also the analysis of fossil pollen of successive layers of soil for both regions resulted in findings of fossil pollen of the species Chenopodiaceae by 51.2%, in Mendes, while, 7% in the Avaris. This is strong evidence of the existence conditions of salt in Mendes than Avaris archaeological sites.展开更多
Groundwater is the water located beneath the earth's surface in the soil pore spaces and in the fractures of rock formations. As one of the most important natural resources, groundwater is associated with the environ...Groundwater is the water located beneath the earth's surface in the soil pore spaces and in the fractures of rock formations. As one of the most important natural resources, groundwater is associated with the environment, public health, welfare, and long-term economic growth, which affects the daily activities of human beings. In modern urban areas, the primary contaminants of groundwater are artificial products, such as gasoline and diesel. To protect this important water resource, a series of efforts have been exerted, including enforcement and remedial actions. Each year, the TGPC (Texas Groundwater Protection Committee) in US publishes a "Joint Groundwater Monitoring and Contamination Report" to describe historic and new contamination cases in each county, which is an important data source for the design of prevention strategies. In this paper, a DDM (data dependent modeling) approach is proposed to predict county-level NCC (new contamination cases). A case study with contamination information from Harris County in Texas was conducted to illustrate the modeling and prediction process with promising results. The one-step prediction error is 1.5%, while the two-step error is 12.1%. The established model can be used at the county-level, state-level, and even at the country-level. Besides, the prediction results could be a reference during decision-making processes.展开更多
This paper reviews the history and progress of research on active tectonics in China and overseas.By giving a brief introduction on the history of active tectonic research in China and other countries,the paper sums u...This paper reviews the history and progress of research on active tectonics in China and overseas.By giving a brief introduction on the history of active tectonic research in China and other countries,the paper sums up the process and development of quantitative investigation of active tectonics since the 1980s.The focus is on the main efforts and progress made in China on certain aspects of research,such as basic surveys and applied investigation of active tectonics,the study of theories related to regional active tectonics and their kinematics and geodynamics,surveys on coupling relations between deep and shallow structures,active fault surveys and prospecting and seismic hazard assessment in urban areas,as well as the efforts made using Quaternary geochronology.Furthermore,the paper looks back on Chinese quantitative investigation of active tectonics in China and sums up cognitions derived from studies on the determination of several basic and measurable parameters of active tectonics.These parameters include the length of fault and fault segmentation,coseismic slip and cumulative slip,fault slip rate,the sequence of paleoearthquake events and the time elapsed since the most recent event.At the same time,efforts and progress made in China on assessing the long-term seismic potential for active faults and evaluating the risk from potential active fault movement have been reviewed by summarizing research on developing theories,models,methods and the application of time-dependent seismic potential to probabilistic assessment,magnitude estimation for potential earthquakes on active faults,and the forecast of potential risk caused by active fault movement.Finally,in consideration of the realities and problems in the research of active tectonics in China,the authors put forward several suggestions for issues worthy of more attention for further investigation in the future.展开更多
The thermal history of the Jiaodong region and adjacent provinces (Shandong and northem Jiangsu) have been extensively studied, particularly by apatite fission track (AFT) dating. However, the AFT ages from surfac...The thermal history of the Jiaodong region and adjacent provinces (Shandong and northem Jiangsu) have been extensively studied, particularly by apatite fission track (AFT) dating. However, the AFT ages from surface outcrops range broadly and do not show an apparent relationship between age and elevation. This work provides a multiple low temperature thermochronological dataset including zircon and apatite (U-Th)/He ages (ZHe and AHe), and AFT ages from a 1000-m-deep borehole at the Jiaojia goldfield in the northwest of Jiaodong Peninsula. ZHe, AFT and AHe ages range from -100-70, -85-50 and -65-50 Ma, respectively. These data conform to the principles of age vs. closure temperature and age vs. elevation and thus can be employed to estimate the exhumation history. Based on the density histogram of fission track length calculation, thermal history modeling, and previously published AFT ages from the Chinese Continental Science Drill program, this work concludes that compared to the AFT ages from surface outcrops, the low temperature thermochronological ages from the boreholes show a better relationship between age, elevation and closure temperature, and the age becomes younger with increasing depth. In addition, the exhumation history in the Jiaodong and adjacent areas can be divided into two distinct stages: a short, rapid tectonic exhumation (-100-95 Ma) and a long, slow exhumation since 95 Ma. The rate and amount of tectonic exhumation since 95 Ma are inferred as -30 m Ma-1 and -3 km, respectively.展开更多
This paper presents a review on the rock associations, geochemistry, and spatial distribution of Mesozoic-Paleogene igneous rocks in Northeast Asia. The record of magmatism is used to evaluate the spatial-temporal ext...This paper presents a review on the rock associations, geochemistry, and spatial distribution of Mesozoic-Paleogene igneous rocks in Northeast Asia. The record of magmatism is used to evaluate the spatial-temporal extent and influence of multiple tectonic regimes during the Mesozoic, as well as the onset and history of Paleo-Pacific slab subduction beneath Eurasian continent. Mesozoic-Paleogene magmatism at the continental margin of Northeast Asia can be subdivided into nine stages that took place in the Early-Middle Triassic, Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, Late Cretaceous, and Paleogene, respectively. The Triassic magmatism is mainly composed of adakitic rocks,bimodal rocks, alkaline igneous rocks, and A-type granites and rhyolites that formed in syn-collisional to post-collisional extensional settings related to the final closure of the Paleo-Asian Ocean. However, Triassic calc-alkaline igneous rocks in the Erguna-Xing'an massifs were associated with the southward subduction of the Mongol-Okhotsk oceanic slab. A passive continental margin setting existed in Northeast Asia during the Triassic. Early Jurassic calc-alkaline igneous rocks have a geochemical affinity to arc-like magmatism, whereas coeval intracontinental magmatism is composed of bimodal igneous rocks and A-type granites. Spatial variations in the potassium contents of Early Jurassic igneous rocks from the continental margin to intracontinental region, together with the presence of an Early Jurassic accretionary complex, reveal that the onset of the PaleoPacific slab subduction beneath Eurasian continent occurred in the Early Jurassic. Middle Jurassic to early Early Cretaceous magmatism did not take place at the continental margin of Northeast Asia. This observation, combined with the occurrence of low-altitude biological assemblages and the age population of detrital zircons in an Early Cretaceous accretionary complex,indicates that a strike-slip tectonic regime existed between the continental margin and Paleo-Pacific slab during the Middle Jurassic to early Early Cretaceous. The widespread occurrence of late Early Cretaceous calc-alkaline igneous rocks, I-type granites, and adakitic rocks suggests low-angle subduction of the Paleo-Pacific slab beneath Eurasian continent at this time. The eastward narrowing of the distribution of igneous rocks from the Late Cretaceous to Paleogene, and the change from an intracontinental to continental margin setting, suggest the eastward movement of Eurasian continent and rollback of the PaleoPacific slab at this time.展开更多
Chinese scientists make history by editing humangenes with new technologyIs it possible for humans to wall off a branch of knowledge that is deemed too dangerous,risky or formidable to pursue?That is what James Burke...Chinese scientists make history by editing humangenes with new technologyIs it possible for humans to wall off a branch of knowledge that is deemed too dangerous,risky or formidable to pursue?That is what James Burke,the science historian,asked in his 1985 documentary series,展开更多
The NE-to NNE-striking Tan-Lu Fault Zone(TLFZ) is the largest fault zone in East China, and a typical representative for the circum-Pacific tectonics. Its late Mesozoic evolution resulted from subduction of the Paleo-...The NE-to NNE-striking Tan-Lu Fault Zone(TLFZ) is the largest fault zone in East China, and a typical representative for the circum-Pacific tectonics. Its late Mesozoic evolution resulted from subduction of the Paleo-Pacific Plate,and can be used for indication to the subduction history. The TLFZ reactivated at the end of Middle Jurassic since its origination in Middle Triassic. This phase of sinistral motion can only be recognized along the eastern edge of the Dabie-Sulu orogenis,and indicates initiation of the Paleo-Pacific(Izanagi) Plate subduction beneath the East China continent. After the Late Jurassic standstill, the fault zone experienced intense sinistral faulting again at the beginning of Early Cretaceous under N-S compression that resulted from the NNW-ward, low-angle, high-speed subduction of the Izanagi Plate. It turned into normal faulting in the rest of Early Cretaceous, which was simultaneous with the peak destruction of the North China Craton caused by backarc extension that resulted from rollback of the subducting Izanagi Plate. The TLFZ was subjected to sinistral, transpressive displacement again at the end of Early Cretaceous. This shortening event led to termination of the North China Craton destruction. The fault zone suffered local normal faulting in Late Cretaceous due to the far-field, weak backarc extension. The late Mesozoic evolution of the TLFZ show repeated alternation between the transpressive strike-slip motion and normal faulting. Each of the sinistral faulting event took place in a relatively short period whereas every normal faulting event lasted in a longer period, which are related to the subduction way and history of the Paleo-Pacific Plates.展开更多
文摘Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun (spots and solar flares) during eleven years cycle, as well as knowledge of possible flooding of the Nile and the periods of increase and decrease of the extent necessary to meet the soil around Lake Qarun in Fayoum-Egypt. From historical records in ancient Egypt and Muslim countries, the possible link between periods of the disappearance of sunspots on the solar disc for several years and is known to inch lower level and role of the minimum level of Mandour creeping ice on Southern Europe to the Mediterranean Sea, and the offset of the drought in North Africa and the Sahel region of Africa during the last thousand years. Analyzed pollen fossils of the overlapped layers of soil in two areas of the Delta were Avaris in Sharkiya Province and Mendes in Dakahliya Province. The study pointed out that there are differences due to environmental conditions, demonstrated by the analysis of soil pH, increased electrical connectivity also, the evidence of sulfates and chlorides indicate high salinity of Mendes and Avaris. Also the analysis of fossil pollen of successive layers of soil for both regions resulted in findings of fossil pollen of the species Chenopodiaceae by 51.2%, in Mendes, while, 7% in the Avaris. This is strong evidence of the existence conditions of salt in Mendes than Avaris archaeological sites.
文摘Groundwater is the water located beneath the earth's surface in the soil pore spaces and in the fractures of rock formations. As one of the most important natural resources, groundwater is associated with the environment, public health, welfare, and long-term economic growth, which affects the daily activities of human beings. In modern urban areas, the primary contaminants of groundwater are artificial products, such as gasoline and diesel. To protect this important water resource, a series of efforts have been exerted, including enforcement and remedial actions. Each year, the TGPC (Texas Groundwater Protection Committee) in US publishes a "Joint Groundwater Monitoring and Contamination Report" to describe historic and new contamination cases in each county, which is an important data source for the design of prevention strategies. In this paper, a DDM (data dependent modeling) approach is proposed to predict county-level NCC (new contamination cases). A case study with contamination information from Harris County in Texas was conducted to illustrate the modeling and prediction process with promising results. The one-step prediction error is 1.5%, while the two-step error is 12.1%. The established model can be used at the county-level, state-level, and even at the country-level. Besides, the prediction results could be a reference during decision-making processes.
基金funded by the"Experimental Exploration of Active Faults in Urban Areas(20041138)"project of the National Development and Reform Commission of China
文摘This paper reviews the history and progress of research on active tectonics in China and overseas.By giving a brief introduction on the history of active tectonic research in China and other countries,the paper sums up the process and development of quantitative investigation of active tectonics since the 1980s.The focus is on the main efforts and progress made in China on certain aspects of research,such as basic surveys and applied investigation of active tectonics,the study of theories related to regional active tectonics and their kinematics and geodynamics,surveys on coupling relations between deep and shallow structures,active fault surveys and prospecting and seismic hazard assessment in urban areas,as well as the efforts made using Quaternary geochronology.Furthermore,the paper looks back on Chinese quantitative investigation of active tectonics in China and sums up cognitions derived from studies on the determination of several basic and measurable parameters of active tectonics.These parameters include the length of fault and fault segmentation,coseismic slip and cumulative slip,fault slip rate,the sequence of paleoearthquake events and the time elapsed since the most recent event.At the same time,efforts and progress made in China on assessing the long-term seismic potential for active faults and evaluating the risk from potential active fault movement have been reviewed by summarizing research on developing theories,models,methods and the application of time-dependent seismic potential to probabilistic assessment,magnitude estimation for potential earthquakes on active faults,and the forecast of potential risk caused by active fault movement.Finally,in consideration of the realities and problems in the research of active tectonics in China,the authors put forward several suggestions for issues worthy of more attention for further investigation in the future.
基金sponsored by the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant Nos.CUG090102&CUG150612)National Natural Science Foundation of China(Grant Nos.41672074&41502067).
文摘The thermal history of the Jiaodong region and adjacent provinces (Shandong and northem Jiangsu) have been extensively studied, particularly by apatite fission track (AFT) dating. However, the AFT ages from surface outcrops range broadly and do not show an apparent relationship between age and elevation. This work provides a multiple low temperature thermochronological dataset including zircon and apatite (U-Th)/He ages (ZHe and AHe), and AFT ages from a 1000-m-deep borehole at the Jiaojia goldfield in the northwest of Jiaodong Peninsula. ZHe, AFT and AHe ages range from -100-70, -85-50 and -65-50 Ma, respectively. These data conform to the principles of age vs. closure temperature and age vs. elevation and thus can be employed to estimate the exhumation history. Based on the density histogram of fission track length calculation, thermal history modeling, and previously published AFT ages from the Chinese Continental Science Drill program, this work concludes that compared to the AFT ages from surface outcrops, the low temperature thermochronological ages from the boreholes show a better relationship between age, elevation and closure temperature, and the age becomes younger with increasing depth. In addition, the exhumation history in the Jiaodong and adjacent areas can be divided into two distinct stages: a short, rapid tectonic exhumation (-100-95 Ma) and a long, slow exhumation since 95 Ma. The rate and amount of tectonic exhumation since 95 Ma are inferred as -30 m Ma-1 and -3 km, respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41330206 & 41702051)the National Key Research and Development Project (Grant No. 2016YFC0600403)the China Postdoctoral Science Foundation (Grant Nos. 2017T100204 & 2017M611314)
文摘This paper presents a review on the rock associations, geochemistry, and spatial distribution of Mesozoic-Paleogene igneous rocks in Northeast Asia. The record of magmatism is used to evaluate the spatial-temporal extent and influence of multiple tectonic regimes during the Mesozoic, as well as the onset and history of Paleo-Pacific slab subduction beneath Eurasian continent. Mesozoic-Paleogene magmatism at the continental margin of Northeast Asia can be subdivided into nine stages that took place in the Early-Middle Triassic, Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, Late Cretaceous, and Paleogene, respectively. The Triassic magmatism is mainly composed of adakitic rocks,bimodal rocks, alkaline igneous rocks, and A-type granites and rhyolites that formed in syn-collisional to post-collisional extensional settings related to the final closure of the Paleo-Asian Ocean. However, Triassic calc-alkaline igneous rocks in the Erguna-Xing'an massifs were associated with the southward subduction of the Mongol-Okhotsk oceanic slab. A passive continental margin setting existed in Northeast Asia during the Triassic. Early Jurassic calc-alkaline igneous rocks have a geochemical affinity to arc-like magmatism, whereas coeval intracontinental magmatism is composed of bimodal igneous rocks and A-type granites. Spatial variations in the potassium contents of Early Jurassic igneous rocks from the continental margin to intracontinental region, together with the presence of an Early Jurassic accretionary complex, reveal that the onset of the PaleoPacific slab subduction beneath Eurasian continent occurred in the Early Jurassic. Middle Jurassic to early Early Cretaceous magmatism did not take place at the continental margin of Northeast Asia. This observation, combined with the occurrence of low-altitude biological assemblages and the age population of detrital zircons in an Early Cretaceous accretionary complex,indicates that a strike-slip tectonic regime existed between the continental margin and Paleo-Pacific slab during the Middle Jurassic to early Early Cretaceous. The widespread occurrence of late Early Cretaceous calc-alkaline igneous rocks, I-type granites, and adakitic rocks suggests low-angle subduction of the Paleo-Pacific slab beneath Eurasian continent at this time. The eastward narrowing of the distribution of igneous rocks from the Late Cretaceous to Paleogene, and the change from an intracontinental to continental margin setting, suggest the eastward movement of Eurasian continent and rollback of the PaleoPacific slab at this time.
文摘Chinese scientists make history by editing humangenes with new technologyIs it possible for humans to wall off a branch of knowledge that is deemed too dangerous,risky or formidable to pursue?That is what James Burke,the science historian,asked in his 1985 documentary series,
基金supported by the National Natural Science Foundation of China(Grant Nos.41472186&91414301)the National Key Basic Research Program of China(Grant No.2016YFC0600102)
文摘The NE-to NNE-striking Tan-Lu Fault Zone(TLFZ) is the largest fault zone in East China, and a typical representative for the circum-Pacific tectonics. Its late Mesozoic evolution resulted from subduction of the Paleo-Pacific Plate,and can be used for indication to the subduction history. The TLFZ reactivated at the end of Middle Jurassic since its origination in Middle Triassic. This phase of sinistral motion can only be recognized along the eastern edge of the Dabie-Sulu orogenis,and indicates initiation of the Paleo-Pacific(Izanagi) Plate subduction beneath the East China continent. After the Late Jurassic standstill, the fault zone experienced intense sinistral faulting again at the beginning of Early Cretaceous under N-S compression that resulted from the NNW-ward, low-angle, high-speed subduction of the Izanagi Plate. It turned into normal faulting in the rest of Early Cretaceous, which was simultaneous with the peak destruction of the North China Craton caused by backarc extension that resulted from rollback of the subducting Izanagi Plate. The TLFZ was subjected to sinistral, transpressive displacement again at the end of Early Cretaceous. This shortening event led to termination of the North China Craton destruction. The fault zone suffered local normal faulting in Late Cretaceous due to the far-field, weak backarc extension. The late Mesozoic evolution of the TLFZ show repeated alternation between the transpressive strike-slip motion and normal faulting. Each of the sinistral faulting event took place in a relatively short period whereas every normal faulting event lasted in a longer period, which are related to the subduction way and history of the Paleo-Pacific Plates.