The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitiv...The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.展开更多
In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea a...In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea as research objects. The chronostratigraphic framework of the DLW3101 core and elemental strata of the DLW3101 core and the DLW3102 core since MIS5 are established by analyzing oxygen isotope, calcium carbonate content, and X-Ray Fluorescence(XRF) scanning elements. On the basis of the information obtained by analyzing the sedimentary structure and chemical elements in the landslide deposition, we found that the DLW3102 core shows four layers of submarine landslides, and each landslide layer is characterized by high Si, K, Ti, and Fe contents, thereby indicating terrigenous clastic sources. L1(2.15–2.44 m) occurred in MIS2, which is a slump sedimentary layer with a small sliding distance and scale. L2(15.48–16.00 m) occurred in MIS5 and is a debris flow-deposited layer with a scale and sliding distance that are greater than those of L1. L3(19.00–20.90 m) occurred in MIS5; its upper part(19.00–20.00 m) is a debris flow-deposited layer, and its lower part(20.00–20.90 m) is a sliding deposition layer. The landslide scale of L3 is large. L4(22.93–24.27 m) occurred in MIS5; its upper part(22.93–23.50 m) is a turbid sedimentary layer, and its lower part(23.50–24.27m) is a slump sedimentary layer. The landslide scale of L4 is large.展开更多
Si, Ti, Al, Fe, Mn, Ca, Mg, K, Na, P and Sr, Ba, Rb, Ga, V, Zr, Cr, Ni, Co, Cu, Zn, Pb,Nb, Y, Th, La in the core S01 were analyzed and the pattems of their enrichment are discussed.Enrichment of Na, Fe, Mn, Ba, Cu ele...Si, Ti, Al, Fe, Mn, Ca, Mg, K, Na, P and Sr, Ba, Rb, Ga, V, Zr, Cr, Ni, Co, Cu, Zn, Pb,Nb, Y, Th, La in the core S01 were analyzed and the pattems of their enrichment are discussed.Enrichment of Na, Fe, Mn, Ba, Cu elements in the core indicates volcanic material are an importantsoarce of the sediments in the area. The enrichment frequently varying with the deposition processshows bottom volcanism is frequent in the area and that the studied area is a margin basin with distinctoceanic characteristics. The abnormal enrichment of Mn at the layers(0-15 cm and 665-670 cm) of the core could beclosely related to and so, indicate, the wide deposition hiatus that have occurred in the West PacificOcean and adjacent margin seas since Late Pleistocene.展开更多
The well SK-I in the Songliao Basin is the first scientific borehole targeting the continental Cretaceous strata in China. Oval concretions, thin laminae and beds of dolostone are found intercalated within mudstone an...The well SK-I in the Songliao Basin is the first scientific borehole targeting the continental Cretaceous strata in China. Oval concretions, thin laminae and beds of dolostone are found intercalated within mudstone and organic-rich black shale in the Nenjiang Formation of Campanian age. Low ordered ferruginous dolomite is composed of euhedral--subhedral rhombs with cloudy nucleus and light rims formed during the diagenesis, which are typical features of replacement. The heavy carbon isotopes （δ13CPDB -- 1.16-16.0） are results of both the fermentation of organic matter by microbes and degassing of carbon dioxide during the period of diagenesis, and the presence of light oxygen isotopes （δ18OPDB- 18.53--5.1） is a characteristic feature of fresh water influence which means the carbonate may have been altered by ground water or rainwater in the late diagenesis. Marine water incursions into the nor- mally lacustrine basin have been proved by both the salinity of Z value and the occurrence of foraminifera in the same strata where dolomite occurs. Pyrite framboids observed by SEM are usually enclosed in the dolomite crystals or in the mudstones, supporting the sulfate reducing bacteria （SRB）. The formation of both dolomite and pyrite are associated with marine water incursions, which not only supply magnesium ion for dolomite, but also result in limited carbonate precipitation in the basin. The presence of pyrite framboids indicates the development of an anoxic environment associated with salinity stratification in the lake. The dolomite in the Nenjiang Formation is the results of marine water incursions, diagenetic replacement of calcareous carbonate and sulfate reducing bacteria （SRB）.展开更多
ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced on April 26, 2010 that it has been chosen by China Mobile to deliver its IMS core network in key Chinese prov...ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced on April 26, 2010 that it has been chosen by China Mobile to deliver its IMS core network in key Chinese provinces. The China Mobile＇ s commercial IMS network will boast 1.4 million lines when it is completed in three months. According to the comprehensive evaluation process by China Mobile, ZTE was ranked among the tier one IMS supplier group for the project this time.展开更多
Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low
Full enjoyment of human rights, a lofty ideal pursued by the human race for a long time, is what the people of contemporary China have spared no ef- forts to attain. The Chinese people were virtually denied human figh...Full enjoyment of human rights, a lofty ideal pursued by the human race for a long time, is what the people of contemporary China have spared no ef- forts to attain. The Chinese people were virtually denied human fights when the ＂three large mountains＂-- imperialism, feudalism and the bureaucratic bour- geoisie - oppressed them. To achieve national liberation, independence, de- mocracy, freedom and human fights, the unyielding Chinese people fought protracted struggles for which they made huge sacrifices.展开更多
Both evolution of the Asian monsoon system and the Cenozoic global cooling are thought to be closely linked to the Himalayan—Tibetan orogen. The South China Sea (SCS) with its high sedimentation rates of carbonate\|r...Both evolution of the Asian monsoon system and the Cenozoic global cooling are thought to be closely linked to the Himalayan—Tibetan orogen. The South China Sea (SCS) with its high sedimentation rates of carbonate\|rich hemipelagic sediments offers a unique opportunity to study the variability of the East Asian monsoon, the erosion and weathering of tectonic orogens as well as its possible impact on global and regional climate.Leg 184, the first deep\|sea drilling leg to the seas off China, cored 17 holes at 6 sites in the northern and southern parts of the SCS and recovered 5463m of sediment. The drilling of hemipelagic sediments was exceptionally successful, with core recovery averaging 83%～101%. The 32Ma sequence of deep\|sea sediments recovered during Leg 184 covers almost the entire environmental history of the SCS since its opening. The abnormally high sediment accumulation rates in the Oligocene section are correlative with the incipient sea floor spreading. The bathyal nature of the Oligocenefauna implies that rifting occurred in the Eocene or earlier. Faunal changesfrom the early to late Oligocene are indicative of basin deepening, a trend thatis even more evident in the Miocene section. Sediment deformation, abruptlithologic changes, and a hiatus occur near the Oligocene/Miocene boundary,representing one of the most significant events in the tectonic andenvironmental history of the SCS.展开更多
基金supported by funding from the National Natural Science Foundation of China (grant no. 41904061)China Postdoctoral Science Foundation (grant no. 2018M640742)
文摘The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.
基金supported by the National Natural Science Foundation of China (No. 41506071)the NSFCShandong Joint Fund for Marine Science Research Centers (No. U1606401)the National Program on Global Change and Air-Sea Interaction (No. GASI-GEO-GE-0503)
文摘In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea as research objects. The chronostratigraphic framework of the DLW3101 core and elemental strata of the DLW3101 core and the DLW3102 core since MIS5 are established by analyzing oxygen isotope, calcium carbonate content, and X-Ray Fluorescence(XRF) scanning elements. On the basis of the information obtained by analyzing the sedimentary structure and chemical elements in the landslide deposition, we found that the DLW3102 core shows four layers of submarine landslides, and each landslide layer is characterized by high Si, K, Ti, and Fe contents, thereby indicating terrigenous clastic sources. L1(2.15–2.44 m) occurred in MIS2, which is a slump sedimentary layer with a small sliding distance and scale. L2(15.48–16.00 m) occurred in MIS5 and is a debris flow-deposited layer with a scale and sliding distance that are greater than those of L1. L3(19.00–20.90 m) occurred in MIS5; its upper part(19.00–20.00 m) is a debris flow-deposited layer, and its lower part(20.00–20.90 m) is a sliding deposition layer. The landslide scale of L3 is large. L4(22.93–24.27 m) occurred in MIS5; its upper part(22.93–23.50 m) is a turbid sedimentary layer, and its lower part(23.50–24.27m) is a slump sedimentary layer. The landslide scale of L4 is large.
文摘Si, Ti, Al, Fe, Mn, Ca, Mg, K, Na, P and Sr, Ba, Rb, Ga, V, Zr, Cr, Ni, Co, Cu, Zn, Pb,Nb, Y, Th, La in the core S01 were analyzed and the pattems of their enrichment are discussed.Enrichment of Na, Fe, Mn, Ba, Cu elements in the core indicates volcanic material are an importantsoarce of the sediments in the area. The enrichment frequently varying with the deposition processshows bottom volcanism is frequent in the area and that the studied area is a margin basin with distinctoceanic characteristics. The abnormal enrichment of Mn at the layers(0-15 cm and 665-670 cm) of the core could beclosely related to and so, indicate, the wide deposition hiatus that have occurred in the West PacificOcean and adjacent margin seas since Late Pleistocene.
基金supported by the National Key Program for Basic Research 973 Project(Grant No. 2006CB701406)of Chinathe Opening Research Program of the National Laboratory of Mineral Materials,China University of Geosciences,Beijing(No.07A007)
文摘The well SK-I in the Songliao Basin is the first scientific borehole targeting the continental Cretaceous strata in China. Oval concretions, thin laminae and beds of dolostone are found intercalated within mudstone and organic-rich black shale in the Nenjiang Formation of Campanian age. Low ordered ferruginous dolomite is composed of euhedral--subhedral rhombs with cloudy nucleus and light rims formed during the diagenesis, which are typical features of replacement. The heavy carbon isotopes （δ13CPDB -- 1.16-16.0） are results of both the fermentation of organic matter by microbes and degassing of carbon dioxide during the period of diagenesis, and the presence of light oxygen isotopes （δ18OPDB- 18.53--5.1） is a characteristic feature of fresh water influence which means the carbonate may have been altered by ground water or rainwater in the late diagenesis. Marine water incursions into the nor- mally lacustrine basin have been proved by both the salinity of Z value and the occurrence of foraminifera in the same strata where dolomite occurs. Pyrite framboids observed by SEM are usually enclosed in the dolomite crystals or in the mudstones, supporting the sulfate reducing bacteria （SRB）. The formation of both dolomite and pyrite are associated with marine water incursions, which not only supply magnesium ion for dolomite, but also result in limited carbonate precipitation in the basin. The presence of pyrite framboids indicates the development of an anoxic environment associated with salinity stratification in the lake. The dolomite in the Nenjiang Formation is the results of marine water incursions, diagenetic replacement of calcareous carbonate and sulfate reducing bacteria （SRB）.
文摘ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced on April 26, 2010 that it has been chosen by China Mobile to deliver its IMS core network in key Chinese provinces. The China Mobile＇ s commercial IMS network will boast 1.4 million lines when it is completed in three months. According to the comprehensive evaluation process by China Mobile, ZTE was ranked among the tier one IMS supplier group for the project this time.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41002060, 41272274)the Foundation of Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant to QS Fan)
文摘Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low
文摘Full enjoyment of human rights, a lofty ideal pursued by the human race for a long time, is what the people of contemporary China have spared no ef- forts to attain. The Chinese people were virtually denied human fights when the ＂three large mountains＂-- imperialism, feudalism and the bureaucratic bour- geoisie - oppressed them. To achieve national liberation, independence, de- mocracy, freedom and human fights, the unyielding Chinese people fought protracted struggles for which they made huge sacrifices.
文摘Both evolution of the Asian monsoon system and the Cenozoic global cooling are thought to be closely linked to the Himalayan—Tibetan orogen. The South China Sea (SCS) with its high sedimentation rates of carbonate\|rich hemipelagic sediments offers a unique opportunity to study the variability of the East Asian monsoon, the erosion and weathering of tectonic orogens as well as its possible impact on global and regional climate.Leg 184, the first deep\|sea drilling leg to the seas off China, cored 17 holes at 6 sites in the northern and southern parts of the SCS and recovered 5463m of sediment. The drilling of hemipelagic sediments was exceptionally successful, with core recovery averaging 83%～101%. The 32Ma sequence of deep\|sea sediments recovered during Leg 184 covers almost the entire environmental history of the SCS since its opening. The abnormally high sediment accumulation rates in the Oligocene section are correlative with the incipient sea floor spreading. The bathyal nature of the Oligocenefauna implies that rifting occurred in the Eocene or earlier. Faunal changesfrom the early to late Oligocene are indicative of basin deepening, a trend thatis even more evident in the Miocene section. Sediment deformation, abruptlithologic changes, and a hiatus occur near the Oligocene/Miocene boundary,representing one of the most significant events in the tectonic andenvironmental history of the SCS.
