Dinoflagellates are single celled organisms that reflect the ecological conditions in modern oceans and lakes. Their earliest undisputed fossil record suggests that dinoflagellates originated from the Middle Triassic ...Dinoflagellates are single celled organisms that reflect the ecological conditions in modern oceans and lakes. Their earliest undisputed fossil record suggests that dinoflagellates originated from the Middle Triassic (c. 240 Ma ago). However, the presence of molecular biomarkers (dinosterane, 4α-methyl-24-ethylcholestane and tria-romatic dinosteroids) in rock extracts and coccoid dinoflagellate fossils from the upper Sinian to Cambrian of the Tarim basin confirms the hypothesis that dinoflagellates have an ancient origin, and predate the oldest undisputed dinoflagellate fossils at least by 300 Ma, as early as the late Sinian-Cambrian.展开更多
The genus Operculina,a large symbiont-bearing benthic foraminifer,is characterized by high morphological variability showing thick involute to intermediate semi-involute to flat evolute tests.Different morphotypes are...The genus Operculina,a large symbiont-bearing benthic foraminifer,is characterized by high morphological variability showing thick involute to intermediate semi-involute to flat evolute tests.Different morphotypes are either considered as ecophenotypes or distinct species.In order to test the hypothesis of ecophenotypes versus different species,a single cell high throughput sequencing approach was applied to assess the interspecific diversity of Operculina.This results in two groups of ribotypes,one corresponding to Operculina ammonoides/Operculina discoidalis,the other containing Operculina complanata/Operculina elegans.These groups can also be separated morphologically.Therefore,O.complanata and O.elegans represent a single species and the latter can be regarded as a junior synonym of O.complanata.Operculina ammonoides and O.discoidalis also form a single species,which makes the latter a junior synonym of O.ammonoides.Because generic differences in Operculina species are manifested in morphology and molecular genetics,the genus Neoassilina with the designated species Neoassilina ammonoides is installed.Additional analysis of ribosomal SSU rDNA data of eight recent nummulitid genera confirms the obtained high troughput sequencing results and further shows that Palaeonummulites venosus builds a clade with O.complanata that branches at the base of other Nummulitidae containing Planostegina,Planoperculina,Cycloclypeus,Heterostegina,Operculinella and Neoassilina.展开更多
The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZ...The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZC/MZCs） consist of brecciated carbonate and low-temperature calcium-hydro-silicate rocks,which include unusual high- and ultra-high-temperature low-pressure（HT-LP） meta-morphic mineral assemblages.The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm.of Cretaceous（Maastrichtian） age.In this paper we present detailed geographic, geomorphologic,structural and geological data from the MZCs of the South Levant,which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm.,because MZC late Oligocene-late Pleistocene deposits occur within or unconformable i.e.,with stratigraphic hiatus,overlap both the late Cretaceous and,in places,Neogene stratigraphic units.We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene-late Pleistocene time. This model explains（i） the presence of dikes and tube-like bodies,which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons;（ii） mineral assemblages of sanidinite facies metamorphism;（iii） multi-stage character of HT-LP pyrometamorphism;and （iv） multi-stage low-temperature hydrothermal alteration.High temperatures（up to 1500℃） mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes.Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault.Our model may significantly change the prospects for oil-and-gas deposits in the region.展开更多
Background:Gap models are individual-based models for forests.They simulate dynamic multispecies assemblages over multiple tree-generations and predict forest responses to altered environmental conditions.Their develo...Background:Gap models are individual-based models for forests.They simulate dynamic multispecies assemblages over multiple tree-generations and predict forest responses to altered environmental conditions.Their development emphases designation of the significant biological and ecological processes at appropriate time/space scales.Conceptually,they are with consistent with A.G.Tansley’s original definition of"the ecosystem".Results:An example microscale application inspects feedbacks among terrestrial vegetation change,air-quality changes from the vegetation’s release of volatile organic compounds(VOC),and climate change effects on ecosystem production of VOC’s.Gap models can allocate canopy photosynthate to the individual trees whose leaves form the vertical leaf-area profiles.VOC release depends strongly on leaf physiology by species of these trees.Leaf-level VOC emissions increase with climate-warming.Species composition change lowers the abundance of VOC-emitting taxa.In interactions among ecosystem functions and biosphere/atmosphere exchanges,community composition responses can outweigh physiological responses.This contradicts previous studies that emphasize the warming-induced impacts on leaf function.As a mesoscale example,the changes in climate(warming)on forests including pest-insect dynamics demonstrates changes on the both the tree and the insect populations.This is but one of many cases that involve using a gap model to simulate changes in spatial units typical of sampling plots and scaling these to landscape and regional levels.As this is the typical application scale for gap models,other examples are identified.The insect/climatechange can be scaled to regional consequences by simulating survey plots across a continental or subcontinental zone.Forest inventories at these scales are often conducted using independent survey plots distributed across a region.Model construction that mimics this sample design avoids the difficulties in modelling spatial interactions,but we also discuss simulation at these scales with contagion effects.Conclusions:At the global-scale,successful simulations to date have used functional types of plants,rather than tree species.In a final application,the fine-scale predictions of a gap model are compared with data from micrometeorological eddy-covariance towers and then scaled-up to produce maps of global patterns of evapotranspiration,net primary production,gross primary production and respiration.New active-remote-sensing instruments provide opportunities to test these global predictions.展开更多
Production of voluminous igneous arc rocks,high-pressure/low-temperature(HP/LT) metamafic rocks,westward relative migration of the Klamath Mountains province,and U-Pb ages of deposition,sediment sources,and spatial lo...Production of voluminous igneous arc rocks,high-pressure/low-temperature(HP/LT) metamafic rocks,westward relative migration of the Klamath Mountains province,and U-Pb ages of deposition,sediment sources,and spatial locations of Jurassic and younger,detrital zirconbearing clastic rocks constrain geologic development of the northern California continental edge as follows:(1) At~ 175 Ma,transpressive plate underflow began to generate an Andean-type Klamath-Sierran arc along the margin.(2)Oceanic crustal rocks were metamorphosed under HP/LT conditions in an inboard,east-inclined subduction zone from~ 170-155 Ma.Except for the Red Ant blueschists,such Ethologies remained stored at depth;most HP/LT mafic tectonic blocks returned surfaceward only during mid- and Late Cretaceous time,chiefly entrained in circulating,buoyant Franciscan mud-matrix melange.(3) By ~ 165 Ma and continuing to ~ 150-140 Ma,erosion supplied volcanogenic debris to proximal Mariposa-Galice ± Myrtle overlap strata.(4) At ~ 140,immediately prior to the onset of paired Franciscan and Great Valley Group(GVG) +Hornbrook deposition,the Klamath salient was deformed and displaced ~ 100-150 km westward relative to the Sierran arc,stranding pre-existing oceanic crust on the south as the Coast Range Ophiolite(CRO).(5) After the end-ofJurassic seaward step-out of the Farallon-North American convergent plate junction,terrigineous debris began to be deposited in the outboard Franciscan trench and intervening Great Valley forearc.(6) Voluminous sedimentation and accretion of Franciscan Eastern + Central belts and GVG detritus took place during paroxysmal igneous activity and rapid,nearly orthogonal plate convergence at^125-80 Ma.(7) Sierran arc volcanism-plutonism ceased by^80 Ma in northern California,signaling a transition to shallow,nearly subhorizontal eastward plate underflow attending Laramide orogeny far to the east.(8) Presently exposed Paleogenelower Miocene Franciscan Coastal Belt sedimentary strata were deposited in a tectonic realm unaffected by HP/LT subduction.(9) Grenville-age detrital zircons are absent from the post-120 Ma Franciscan section.(10) Judging from petrofacies and zircon U-Pb data,the Franciscan Eastern Belt contains debris derived principally from the Sierra Nevada and Klamath ranges;detritus from the Idaho Batholith as well as Sierra Nevada Batholith may be present in some Central Belt sandstones,whereas clasts from the Idaho Batholith,Challis volcanics,and Cascade Range appear in progressively younger Paleogene-lower Miocene Coastal Belt sediments.(11) Gradual NW dextral offset of the Franciscan trench deposits of as much as^1,600 km may have occurred relative to the native GVG forearc and basement terranes of the American Southwest.展开更多
Highly oriented pyrolytic graphites are irradiated with 40.5-Me V and 67.7-Me V ^112Sn-ions in a wide range of fluences： 1×10^11 ions/cm^2–1×10^14ions/cm^2. Raman spectra in the region between 1200 cm^-1 a...Highly oriented pyrolytic graphites are irradiated with 40.5-Me V and 67.7-Me V ^112Sn-ions in a wide range of fluences： 1×10^11 ions/cm^2–1×10^14ions/cm^2. Raman spectra in the region between 1200 cm^-1 and 3500cm^-1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-Me V Sn-ions than that observed for 67.7-Me V Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ～ 3-cm^-1frequency shift toward lower wavenumber for the D band and ～ 6-cm^-1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1×10^14 ions/cm^2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover,the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.展开更多
Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of...Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of observations using leaf level gas exchange, chlorophyll fluorescence and remotely sensed reflectance measurements of vegetation experiencing chronic exposure to volcanic gas emissions;to develop techniques for monitoring the relative health of vegetation along the edge of an acute vegetative kill zone of a natural disaster and potential preeruption vegetation physiology. Experiments were conducted along an elevation gradient that corresponds to the SO2 gradient on vegetation along the south flank of Volcán Turrialba, Costa Rica. This study site is a natural environment with high volcanic degassing activity with significant SO2 emissions (n/d-0.281 ppm). Corresponding to an SO2 gradient, a substantial increase in CO2 concentration of (430-517 ppm) was identified. We further show the physiological interactions of SO2 and CO2 have on vegetation along the kill zone of this natural disaster can be assessed by examining the SO2/CO2 ratios. The physiological indices tested and relationships among measurements emphasized in this research will add to the assessment of the impact atmospheric volcanic gas emissions have on the physiology of surrounding vegetation as well as advance the capability of remotely sensed environmental stress in natural settings.展开更多
In this paper,the Multi-Temporal Interferometric Synthetic Aperture Radar(MT-InSAR)technology is adopted to monitor the Line of Sight(LOS)displacement of Fushun West Opencast Coal Mine(FWOCM)and its surrounding areas ...In this paper,the Multi-Temporal Interferometric Synthetic Aperture Radar(MT-InSAR)technology is adopted to monitor the Line of Sight(LOS)displacement of Fushun West Opencast Coal Mine(FWOCM)and its surrounding areas in northeast China using Sentinel-1 Synthetic Aperture Radar(SAR)images acquired from 2018 to 2022.The spatial-temporal evolution of urban subsidence and the south-slope landslide are both analyzed in detail.Comparison with ground measurements and cross-correlation analysis via cross wavelet transform with monthly precipitation data are also conducted,to analyze the influence factors of displacements in FWOCM.The monitoring results show that a subsidence basin appeared in the urban area near the eastern part of the north slope in 2018,with settlement center located at the intersection of E3000 and fault F1.The Qian Tai Shan(QTS)landslide on the south slope,which experienced rapid sliding during 2014 to 2016,presents seasonal deceleration and acceleration with precipitation,with the maximum displacement in vicinity of the Liushan paleochannel.The results of this paper have fully taken in account for the complications of large topographic relief,geological conditions,spatial distribution and temporal evolution characteristics of surface displacements in opencast mining area.The wide range and long time series dynamic monitoring of opencast mine are of great significance to ensure mine safety production and geological disaster prevention in the investigated mining area.展开更多
The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the ...The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while,after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.展开更多
The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for t...The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.展开更多
Using a minitype and stress-type test device for similar material simulation of coal-mining subsidence, the relation between tectonic stress and coal-mining subsidence was successfully simulated, furthermore, the test...Using a minitype and stress-type test device for similar material simulation of coal-mining subsidence, the relation between tectonic stress and coal-mining subsidence was successfully simulated, furthermore, the test period of similar material simulation was obviously shortened and the test process was more dexterous and convenient. To do simi-lar material simulation with the minitype and stress-type test device was feasible and high-efficient. Bringing two models with the same geological and mining conditions to bear lateral compressive stress and tensile stress respectively and simulating the process of underground mining, the test results indicate that: under the compressive stress, the col-lapse of the coal roof occurs belatedly and the damaged range in cover of coal seam is smaller, therefore the movement and deformation of the cover and its damage to the ground geological environment are not evident; whereas under tensile stress, the situation is contrary to which mentioned above. A conclusion was obtained from the test that the ground environment hazards in coal mining areas were controlled by the regional geo-logical tectonic stress field.展开更多
This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural condi...This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural conditions. Diurnal changes of leaf-level gas exchange (carbon assimilation rate (A), stomatal conductance (gs), transpiration rate (E)), chlorophyll fluorescence and canopy-scale remote sensing were measured on top crown of valley oak (Quercus lobata) in the foothills of central California, USA. The results indicated Q. lobata experienced saturating irradiance (PAR), which induced photoinhibition indicated by a decrease in the quantum efficiency of photosystem II (r2 = 0.648 with Fv ′/Fm′ and r2 = 0.73 with FPSII) and open reaction centers (qP;r2 = 0.699). The excess absorbed quantum energy was dissipated as heat through the Xanthophyll cycle and other processes (photorespiration and the water-water cycle) rather than energy emission as steady state chlorophyll fluorescence (Fs). An increase in leaf temperature caused by the activity of Xanthophyll cycle was correlated to a decrease in Fs (r2 = 0.381) and an increase in evaporative cooling through E (r2 = 0.800) and water use efficiency (WUE;r2 = 0.872).展开更多
Non-Darcian flow has been well documented for fractured media, while the potential non-Darcian flow and its driven factors in field-scale discrete fracture networks (DFNs) remain obscure. This study conducts Monte Car...Non-Darcian flow has been well documented for fractured media, while the potential non-Darcian flow and its driven factors in field-scale discrete fracture networks (DFNs) remain obscure. This study conducts Monte Carlo simulations of water flow through DFNs to identify non-Darcian flow and non-Fickian pressure propagation in field-scale DFNs, by adjusting fracture density, matrix hydraulic conductivity, and the general hydraulic gradient. Numerical simulations and analyses show that interactions of the fracture architecture with the hydraulic gradient affect non-Darcian flow in DFNs, by generating and adjusting complex pathways for water. The fracture density affects significantly the propagation of hydraulic head/pressure in the DFN, likely due to fracture connectivity and flow channeling. The non-Darcian flow pattern may not be directly correlated to the non-Fickian pressure propagation process in the regional-scale DFNs, because they refer to different states of water flow and their controlling factors may not be the same. Findings of this study improve our understanding of the nature of flow in DFNs.展开更多
Zircon SHRIMP dating from Qaidamshan granite shows that the granite age is 446 Ma, similar to that of eclogite in the UHP belt. We think that both granite and eclogite may be formed at different stages during tectonic...Zircon SHRIMP dating from Qaidamshan granite shows that the granite age is 446 Ma, similar to that of eclogite in the UHP belt. We think that both granite and eclogite may be formed at different stages during tectonic evolution of this area. Together with other studies we suggested that the collision of ocean and continent plates may occur at the early Caledonian in this area, forming the eclogite, and the collision of continent and continent plates at the late Caledonian, forming the Qaidanishan granite with the zircon SHRIMP age of 446 Ma.展开更多
Dinosteranes and 4-methyl-24-ethylcholestanes are usually to be thought of as biomarkers for dinoflagellates, and 24-norcholestanes and C28 steranes for diatom. Therefore, the highest concentrations of these compounds...Dinosteranes and 4-methyl-24-ethylcholestanes are usually to be thought of as biomarkers for dinoflagellates, and 24-norcholestanes and C28 steranes for diatom. Therefore, the highest concentrations of these compounds are typically found in strata deposited since the beginning of the Mesozoic. However these compounds appeared widely and abundantly in extracts from organic-rich sediments in the Sinian and Cambrian of the Tarim Basin. This suggests that some of the planktonic algae such as dinoflagellates and diatoms have an earlier origin than the Mesozoic. Some of the remarkable algal fossils observed in the Cambrian, in both well He 4 and the outcrop section of Xiao-Er-Bulak, Tarim Basin, provide possible biological evidence for this kind of inference.展开更多
Relatively high abundance of C<sub>31</sub> steranes has been identified from cretaceous source rocks and crude oils in the Songliao Basin, China. C<sub>31</sub> steranes which occur as ten iso...Relatively high abundance of C<sub>31</sub> steranes has been identified from cretaceous source rocks and crude oils in the Songliao Basin, China. C<sub>31</sub> steranes which occur as ten isomers were tentatively identified as 4, 22, 23, 24-tetrametyhlcholestane based on their retention time and mass spectrum.They bear a lower thermal stability and occur as important components in the immature oils of Chaochang region because they have three-methyl groups in their side chain. The relatively high abundance of C<sub>31</sub> steranes in the samples can indicate the source input of some special algae in the brackish and saline environment. Therefore they can be used as very useful biomarkers for organic facies analysis and oil correlation. Their biological source perhaps related to the dinoflagellate such as G. foliaceum and P. foliaceum. The gorgostanol are considered as possible precursors for the putative C<sub>31</sub>4methyl sterane which formed in the stage of diagenesis.展开更多
As a promising candidate material for hydrogen storage, ammonia borane(NH3BH3) has attracted significant interest in recent years due to its remarkably high hydrogen content. Subjecting this material to high pressure ...As a promising candidate material for hydrogen storage, ammonia borane(NH3BH3) has attracted significant interest in recent years due to its remarkably high hydrogen content. Subjecting this material to high pressure not only enables the formation of novel phases and compounds with exotic properties, but also improves our basic understanding of material's behavior at different levels of atomic and molecular interactions. This review focuses on the perspective of high-pressure chemical hydrogen storage related to NH3BH3-based materials. Four main aspects are discussed: the structures and bonding of NH3BH3 over a wide pressure–temperature space, thermolysis of NH3BH3 at high pressure, the formation of a novel high-pressure H-rich compound as a result of storage of additional molecular H2 in NH3BH3, and the potential rehydrogenation of the thermally decomposed NH3BH3 under the extreme of pressure.展开更多
文摘Dinoflagellates are single celled organisms that reflect the ecological conditions in modern oceans and lakes. Their earliest undisputed fossil record suggests that dinoflagellates originated from the Middle Triassic (c. 240 Ma ago). However, the presence of molecular biomarkers (dinosterane, 4α-methyl-24-ethylcholestane and tria-romatic dinosteroids) in rock extracts and coccoid dinoflagellate fossils from the upper Sinian to Cambrian of the Tarim basin confirms the hypothesis that dinoflagellates have an ancient origin, and predate the oldest undisputed dinoflagellate fossils at least by 300 Ma, as early as the late Sinian-Cambrian.
基金supported by Israel Science Foundation(No.1267/21)to Sigal Abramovichthe Swiss National Science Foundation(No.31003A_179125)to Jan PawlowskiOpen Access funding provided by University of Geneva。
文摘The genus Operculina,a large symbiont-bearing benthic foraminifer,is characterized by high morphological variability showing thick involute to intermediate semi-involute to flat evolute tests.Different morphotypes are either considered as ecophenotypes or distinct species.In order to test the hypothesis of ecophenotypes versus different species,a single cell high throughput sequencing approach was applied to assess the interspecific diversity of Operculina.This results in two groups of ribotypes,one corresponding to Operculina ammonoides/Operculina discoidalis,the other containing Operculina complanata/Operculina elegans.These groups can also be separated morphologically.Therefore,O.complanata and O.elegans represent a single species and the latter can be regarded as a junior synonym of O.complanata.Operculina ammonoides and O.discoidalis also form a single species,which makes the latter a junior synonym of O.ammonoides.Because generic differences in Operculina species are manifested in morphology and molecular genetics,the genus Neoassilina with the designated species Neoassilina ammonoides is installed.Additional analysis of ribosomal SSU rDNA data of eight recent nummulitid genera confirms the obtained high troughput sequencing results and further shows that Palaeonummulites venosus builds a clade with O.complanata that branches at the base of other Nummulitidae containing Planostegina,Planoperculina,Cycloclypeus,Heterostegina,Operculinella and Neoassilina.
基金Dr.Ella Sokol is acknowledged for joint collaboration while studying metamorphic mineralogy of MSCz.Contribution to IGCP Project #592 sponsored by UNESCOIUGSIn memory of Prof.R.Shagam (Beer-Sheva University),recently passed away,who encouraged our model and supported our researchfulfilled in the frame of Science project of Institute of Geology and Mineralogy,Siberian Branch,Russian Academy of Sciences
文摘The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZC/MZCs） consist of brecciated carbonate and low-temperature calcium-hydro-silicate rocks,which include unusual high- and ultra-high-temperature low-pressure（HT-LP） meta-morphic mineral assemblages.The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm.of Cretaceous（Maastrichtian） age.In this paper we present detailed geographic, geomorphologic,structural and geological data from the MZCs of the South Levant,which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm.,because MZC late Oligocene-late Pleistocene deposits occur within or unconformable i.e.,with stratigraphic hiatus,overlap both the late Cretaceous and,in places,Neogene stratigraphic units.We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene-late Pleistocene time. This model explains（i） the presence of dikes and tube-like bodies,which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons;（ii） mineral assemblages of sanidinite facies metamorphism;（iii） multi-stage character of HT-LP pyrometamorphism;and （iv） multi-stage low-temperature hydrothermal alteration.High temperatures（up to 1500℃） mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes.Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault.Our model may significantly change the prospects for oil-and-gas deposits in the region.
基金funded by the USA NASA grant NNH16ZDA001N-ESUSPIUSA NASA grant WBS:509496.02.08.09.66+5 种基金USA NASA ABoVE grant NNX17AE44GUSA DoD SERDP grant RC18-1183USA NASA grant(IDS-80NSSC17K0110)USA NSF grant(AGS-1837891)USA NSF-ATMO 1837891USA NSF Hydrologic Sciences grant 1561473。
文摘Background:Gap models are individual-based models for forests.They simulate dynamic multispecies assemblages over multiple tree-generations and predict forest responses to altered environmental conditions.Their development emphases designation of the significant biological and ecological processes at appropriate time/space scales.Conceptually,they are with consistent with A.G.Tansley’s original definition of"the ecosystem".Results:An example microscale application inspects feedbacks among terrestrial vegetation change,air-quality changes from the vegetation’s release of volatile organic compounds(VOC),and climate change effects on ecosystem production of VOC’s.Gap models can allocate canopy photosynthate to the individual trees whose leaves form the vertical leaf-area profiles.VOC release depends strongly on leaf physiology by species of these trees.Leaf-level VOC emissions increase with climate-warming.Species composition change lowers the abundance of VOC-emitting taxa.In interactions among ecosystem functions and biosphere/atmosphere exchanges,community composition responses can outweigh physiological responses.This contradicts previous studies that emphasize the warming-induced impacts on leaf function.As a mesoscale example,the changes in climate(warming)on forests including pest-insect dynamics demonstrates changes on the both the tree and the insect populations.This is but one of many cases that involve using a gap model to simulate changes in spatial units typical of sampling plots and scaling these to landscape and regional levels.As this is the typical application scale for gap models,other examples are identified.The insect/climatechange can be scaled to regional consequences by simulating survey plots across a continental or subcontinental zone.Forest inventories at these scales are often conducted using independent survey plots distributed across a region.Model construction that mimics this sample design avoids the difficulties in modelling spatial interactions,but we also discuss simulation at these scales with contagion effects.Conclusions:At the global-scale,successful simulations to date have used functional types of plants,rather than tree species.In a final application,the fine-scale predictions of a gap model are compared with data from micrometeorological eddy-covariance towers and then scaled-up to produce maps of global patterns of evapotranspiration,net primary production,gross primary production and respiration.New active-remote-sensing instruments provide opportunities to test these global predictions.
基金The National Science Foundation provided additional aid through grant NSF EAR 0948676 to Marty Grove
文摘Production of voluminous igneous arc rocks,high-pressure/low-temperature(HP/LT) metamafic rocks,westward relative migration of the Klamath Mountains province,and U-Pb ages of deposition,sediment sources,and spatial locations of Jurassic and younger,detrital zirconbearing clastic rocks constrain geologic development of the northern California continental edge as follows:(1) At~ 175 Ma,transpressive plate underflow began to generate an Andean-type Klamath-Sierran arc along the margin.(2)Oceanic crustal rocks were metamorphosed under HP/LT conditions in an inboard,east-inclined subduction zone from~ 170-155 Ma.Except for the Red Ant blueschists,such Ethologies remained stored at depth;most HP/LT mafic tectonic blocks returned surfaceward only during mid- and Late Cretaceous time,chiefly entrained in circulating,buoyant Franciscan mud-matrix melange.(3) By ~ 165 Ma and continuing to ~ 150-140 Ma,erosion supplied volcanogenic debris to proximal Mariposa-Galice ± Myrtle overlap strata.(4) At ~ 140,immediately prior to the onset of paired Franciscan and Great Valley Group(GVG) +Hornbrook deposition,the Klamath salient was deformed and displaced ~ 100-150 km westward relative to the Sierran arc,stranding pre-existing oceanic crust on the south as the Coast Range Ophiolite(CRO).(5) After the end-ofJurassic seaward step-out of the Farallon-North American convergent plate junction,terrigineous debris began to be deposited in the outboard Franciscan trench and intervening Great Valley forearc.(6) Voluminous sedimentation and accretion of Franciscan Eastern + Central belts and GVG detritus took place during paroxysmal igneous activity and rapid,nearly orthogonal plate convergence at^125-80 Ma.(7) Sierran arc volcanism-plutonism ceased by^80 Ma in northern California,signaling a transition to shallow,nearly subhorizontal eastward plate underflow attending Laramide orogeny far to the east.(8) Presently exposed Paleogenelower Miocene Franciscan Coastal Belt sedimentary strata were deposited in a tectonic realm unaffected by HP/LT subduction.(9) Grenville-age detrital zircons are absent from the post-120 Ma Franciscan section.(10) Judging from petrofacies and zircon U-Pb data,the Franciscan Eastern Belt contains debris derived principally from the Sierra Nevada and Klamath ranges;detritus from the Idaho Batholith as well as Sierra Nevada Batholith may be present in some Central Belt sandstones,whereas clasts from the Idaho Batholith,Challis volcanics,and Cascade Range appear in progressively younger Paleogene-lower Miocene Coastal Belt sediments.(11) Gradual NW dextral offset of the Franciscan trench deposits of as much as^1,600 km may have occurred relative to the native GVG forearc and basement terranes of the American Southwest.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11179003,10975164,10805062,and 11005134)
文摘Highly oriented pyrolytic graphites are irradiated with 40.5-Me V and 67.7-Me V ^112Sn-ions in a wide range of fluences： 1×10^11 ions/cm^2–1×10^14ions/cm^2. Raman spectra in the region between 1200 cm^-1 and 3500cm^-1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-Me V Sn-ions than that observed for 67.7-Me V Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ～ 3-cm^-1frequency shift toward lower wavenumber for the D band and ～ 6-cm^-1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1×10^14 ions/cm^2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover,the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.
文摘Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of observations using leaf level gas exchange, chlorophyll fluorescence and remotely sensed reflectance measurements of vegetation experiencing chronic exposure to volcanic gas emissions;to develop techniques for monitoring the relative health of vegetation along the edge of an acute vegetative kill zone of a natural disaster and potential preeruption vegetation physiology. Experiments were conducted along an elevation gradient that corresponds to the SO2 gradient on vegetation along the south flank of Volcán Turrialba, Costa Rica. This study site is a natural environment with high volcanic degassing activity with significant SO2 emissions (n/d-0.281 ppm). Corresponding to an SO2 gradient, a substantial increase in CO2 concentration of (430-517 ppm) was identified. We further show the physiological interactions of SO2 and CO2 have on vegetation along the kill zone of this natural disaster can be assessed by examining the SO2/CO2 ratios. The physiological indices tested and relationships among measurements emphasized in this research will add to the assessment of the impact atmospheric volcanic gas emissions have on the physiology of surrounding vegetation as well as advance the capability of remotely sensed environmental stress in natural settings.
基金supported by the Natural Science Foundation of China[grant number 42071453]the geological hazard investigation project of Liaoning Province[grant number 2022020700179]the Fund of National Key Laboratory of Science and Technology on Remote Sensing Information and imagery Analysis,Beijing Research Institute of Uranium Geology[grant number 6142A01210407].
文摘In this paper,the Multi-Temporal Interferometric Synthetic Aperture Radar(MT-InSAR)technology is adopted to monitor the Line of Sight(LOS)displacement of Fushun West Opencast Coal Mine(FWOCM)and its surrounding areas in northeast China using Sentinel-1 Synthetic Aperture Radar(SAR)images acquired from 2018 to 2022.The spatial-temporal evolution of urban subsidence and the south-slope landslide are both analyzed in detail.Comparison with ground measurements and cross-correlation analysis via cross wavelet transform with monthly precipitation data are also conducted,to analyze the influence factors of displacements in FWOCM.The monitoring results show that a subsidence basin appeared in the urban area near the eastern part of the north slope in 2018,with settlement center located at the intersection of E3000 and fault F1.The Qian Tai Shan(QTS)landslide on the south slope,which experienced rapid sliding during 2014 to 2016,presents seasonal deceleration and acceleration with precipitation,with the maximum displacement in vicinity of the Liushan paleochannel.The results of this paper have fully taken in account for the complications of large topographic relief,geological conditions,spatial distribution and temporal evolution characteristics of surface displacements in opencast mining area.The wide range and long time series dynamic monitoring of opencast mine are of great significance to ensure mine safety production and geological disaster prevention in the investigated mining area.
基金supported by the European Union (CC-Water S project, SEE/A/022/2.1/X)by the Ministero dell'Istruzione, dell'Università e della Ricerca (PRIN2008TL25YL)
文摘The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while,after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.
文摘The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.
基金Supported by the National Natural Science Foundation of China(40472104)
文摘Using a minitype and stress-type test device for similar material simulation of coal-mining subsidence, the relation between tectonic stress and coal-mining subsidence was successfully simulated, furthermore, the test period of similar material simulation was obviously shortened and the test process was more dexterous and convenient. To do simi-lar material simulation with the minitype and stress-type test device was feasible and high-efficient. Bringing two models with the same geological and mining conditions to bear lateral compressive stress and tensile stress respectively and simulating the process of underground mining, the test results indicate that: under the compressive stress, the col-lapse of the coal roof occurs belatedly and the damaged range in cover of coal seam is smaller, therefore the movement and deformation of the cover and its damage to the ground geological environment are not evident; whereas under tensile stress, the situation is contrary to which mentioned above. A conclusion was obtained from the test that the ground environment hazards in coal mining areas were controlled by the regional geo-logical tectonic stress field.
文摘This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural conditions. Diurnal changes of leaf-level gas exchange (carbon assimilation rate (A), stomatal conductance (gs), transpiration rate (E)), chlorophyll fluorescence and canopy-scale remote sensing were measured on top crown of valley oak (Quercus lobata) in the foothills of central California, USA. The results indicated Q. lobata experienced saturating irradiance (PAR), which induced photoinhibition indicated by a decrease in the quantum efficiency of photosystem II (r2 = 0.648 with Fv ′/Fm′ and r2 = 0.73 with FPSII) and open reaction centers (qP;r2 = 0.699). The excess absorbed quantum energy was dissipated as heat through the Xanthophyll cycle and other processes (photorespiration and the water-water cycle) rather than energy emission as steady state chlorophyll fluorescence (Fs). An increase in leaf temperature caused by the activity of Xanthophyll cycle was correlated to a decrease in Fs (r2 = 0.381) and an increase in evaporative cooling through E (r2 = 0.800) and water use efficiency (WUE;r2 = 0.872).
文摘Non-Darcian flow has been well documented for fractured media, while the potential non-Darcian flow and its driven factors in field-scale discrete fracture networks (DFNs) remain obscure. This study conducts Monte Carlo simulations of water flow through DFNs to identify non-Darcian flow and non-Fickian pressure propagation in field-scale DFNs, by adjusting fracture density, matrix hydraulic conductivity, and the general hydraulic gradient. Numerical simulations and analyses show that interactions of the fracture architecture with the hydraulic gradient affect non-Darcian flow in DFNs, by generating and adjusting complex pathways for water. The fracture density affects significantly the propagation of hydraulic head/pressure in the DFN, likely due to fracture connectivity and flow channeling. The non-Darcian flow pattern may not be directly correlated to the non-Fickian pressure propagation process in the regional-scale DFNs, because they refer to different states of water flow and their controlling factors may not be the same. Findings of this study improve our understanding of the nature of flow in DFNs.
文摘Zircon SHRIMP dating from Qaidamshan granite shows that the granite age is 446 Ma, similar to that of eclogite in the UHP belt. We think that both granite and eclogite may be formed at different stages during tectonic evolution of this area. Together with other studies we suggested that the collision of ocean and continent plates may occur at the early Caledonian in this area, forming the eclogite, and the collision of continent and continent plates at the late Caledonian, forming the Qaidanishan granite with the zircon SHRIMP age of 446 Ma.
文摘Dinosteranes and 4-methyl-24-ethylcholestanes are usually to be thought of as biomarkers for dinoflagellates, and 24-norcholestanes and C28 steranes for diatom. Therefore, the highest concentrations of these compounds are typically found in strata deposited since the beginning of the Mesozoic. However these compounds appeared widely and abundantly in extracts from organic-rich sediments in the Sinian and Cambrian of the Tarim Basin. This suggests that some of the planktonic algae such as dinoflagellates and diatoms have an earlier origin than the Mesozoic. Some of the remarkable algal fossils observed in the Cambrian, in both well He 4 and the outcrop section of Xiao-Er-Bulak, Tarim Basin, provide possible biological evidence for this kind of inference.
文摘Relatively high abundance of C<sub>31</sub> steranes has been identified from cretaceous source rocks and crude oils in the Songliao Basin, China. C<sub>31</sub> steranes which occur as ten isomers were tentatively identified as 4, 22, 23, 24-tetrametyhlcholestane based on their retention time and mass spectrum.They bear a lower thermal stability and occur as important components in the immature oils of Chaochang region because they have three-methyl groups in their side chain. The relatively high abundance of C<sub>31</sub> steranes in the samples can indicate the source input of some special algae in the brackish and saline environment. Therefore they can be used as very useful biomarkers for organic facies analysis and oil correlation. Their biological source perhaps related to the dinoflagellate such as G. foliaceum and P. foliaceum. The gorgostanol are considered as possible precursors for the putative C<sub>31</sub>4methyl sterane which formed in the stage of diagenesis.
基金supported by United States Department of Energy through the Stanford Institute for Materials and Energy Science(DE-AC02-76SF00515)
文摘As a promising candidate material for hydrogen storage, ammonia borane(NH3BH3) has attracted significant interest in recent years due to its remarkably high hydrogen content. Subjecting this material to high pressure not only enables the formation of novel phases and compounds with exotic properties, but also improves our basic understanding of material's behavior at different levels of atomic and molecular interactions. This review focuses on the perspective of high-pressure chemical hydrogen storage related to NH3BH3-based materials. Four main aspects are discussed: the structures and bonding of NH3BH3 over a wide pressure–temperature space, thermolysis of NH3BH3 at high pressure, the formation of a novel high-pressure H-rich compound as a result of storage of additional molecular H2 in NH3BH3, and the potential rehydrogenation of the thermally decomposed NH3BH3 under the extreme of pressure.
