The absence of humic vitrinite complicates the determination of thermal maturity in pre-Devonian sediments.Lower Paleozoic shales contain structured zooclasts,solid bitumen,and vitrinite-like materials,and their refle...The absence of humic vitrinite complicates the determination of thermal maturity in pre-Devonian sediments.Lower Paleozoic shales contain structured zooclasts,solid bitumen,and vitrinite-like materials,and their reflectances have been found to be valid maturity proxies.Yet there remains much controversy as to the degree of evolution of reflectances.The current work aims to investigate the reflectance of dispersed organic matter(DOM),as well as their transformation degree and organic pore development.To this end,this study evaluated an Upper Ordovician zooclasts-bearing shale and a Middle Jurassic coal sample via anhydrous-pyrolysis to compare differences in the maturation pathways between marine-derived DOM and terrigenous vitrinite.These two original samples were cut into small blocks and placed in an identical vacuum stainless vessel simultaneously.The pyrolysis was carried out at isothermal temperatures ranging from 250 to 550℃ for 48 h.The morphologic and reflectance changes of DOM in pyrolysis residues were studied and compared with previous pyrolysis results.Adopting the combined use of optical reflectance and scanning electron microscope(SEM)techniques,the study shows that DOM in the shale components consists of solid bitumen(SB),bituminite,chitinozoans,a few graptolites,vitrinite-like particles(VLP),alginate and liptodetrinite.The reflectance sequence,from high to low,is zooclasts,VLP and SB.Their reflectances gradually increases as the pyrolysis temperature rises,although the rate of growth is slower than that of co-heating coal vitrinite.Notably,zooclasts yield significantly higher reflectance values than those of VLP and SB at each pyrolysis temperature.However,the VLP undergoes two distinct phases in reflectance development,despite gradual morphology changes similar to vitrinite.Based on evidence of the optical texture and organic pore evolution,we argue that a fair amount of VLP in studied Upper Ordovician shale does not consist of graptolite-type fragments.Consequently,the VLPRo serves as a reliable indicator for assessing organic matter maturity in Ordovician shales with a reflectance value of less than 2.0%.This investigation enhances scholarly understandings of marine-derived DOM evolution issues,providing clearer correlations among reflectances of different DOM and reducing uncertainties in thermal maturity determination.展开更多
A technique for real-time synchronous integration of radar and raingauge measurements based on the concept of the quasi same-rain-volume sampling（QSVS） is presented.Because of the temporal and spatial discrepancies ...A technique for real-time synchronous integration of radar and raingauge measurements based on the concept of the quasi same-rain-volume sampling（QSVS） is presented.Because of the temporal and spatial discrepancies and resolution differences,the integration of radar measurements with raingauge observations has long been a difficult task.Observations indicate that there exists a correlation that conforms to the power law between hourly accumulated raingauge measurement（Q_G） and detected radar echo（Z_（OH）） over the raingauge.On the basis of this,a concept of the QSVS and five direct correspondent formulas of radar and raingauge samples are built up,aiming to eliminate the temporal and spatial discrepancies.A convenient and practical sampling method—the time integral vertical synchronous sampling（TIVS） is proposed and the Z_（OH）—Q_G relationship is studied.It is significant that under the fixed exponent,the coefficient A_B or A_M varies flexibly in accordance with the temporal and spatial variability of natural precipitation,having the function of synchronously integrating the Z—R conversion and the gauge adjustment into a single equation,and thus the precipitation estimation errors caused by detecting resolution differences between radar and raingauge can be obviously mitigated.The real-time synchronous integration technique using the Z_（OH）—Q_G relationship to estimate the ground hourly rainfall accumulation is called the radar-gauge synchronous integration method（RASIM）.The experiments of two cases show that the accuracy of estimated surface hourly rainfall accumulation within 230 km is about 90%,and the average relative error for the point estimation over the whole process is about 20%. Through the detailed analysis of the applicability of TIVS in three environmental fields with various wind drifts,the physical essence of TIVS is explored：it is an approximate QSVS.By analyzing the data pairs of radar and raingauge,an effective quality-control procedure is established,which can greatly improve the stability and rationarity of the Z_（OH）—Q_G relationship.The forecasting product of hourly rainfall accumulation derived from the RASIM has been put into operation.It is demonstrated that the RASIM plays an important role in the quantitative monitoring and forecasting of short-term torrential rainfall.展开更多
基金supported by National Natural Science Foundation of China(Nos.42202172,U24B6001,41830424)the Fundamental Research Funds for the Central Universities,CHD(300102274202).
文摘The absence of humic vitrinite complicates the determination of thermal maturity in pre-Devonian sediments.Lower Paleozoic shales contain structured zooclasts,solid bitumen,and vitrinite-like materials,and their reflectances have been found to be valid maturity proxies.Yet there remains much controversy as to the degree of evolution of reflectances.The current work aims to investigate the reflectance of dispersed organic matter(DOM),as well as their transformation degree and organic pore development.To this end,this study evaluated an Upper Ordovician zooclasts-bearing shale and a Middle Jurassic coal sample via anhydrous-pyrolysis to compare differences in the maturation pathways between marine-derived DOM and terrigenous vitrinite.These two original samples were cut into small blocks and placed in an identical vacuum stainless vessel simultaneously.The pyrolysis was carried out at isothermal temperatures ranging from 250 to 550℃ for 48 h.The morphologic and reflectance changes of DOM in pyrolysis residues were studied and compared with previous pyrolysis results.Adopting the combined use of optical reflectance and scanning electron microscope(SEM)techniques,the study shows that DOM in the shale components consists of solid bitumen(SB),bituminite,chitinozoans,a few graptolites,vitrinite-like particles(VLP),alginate and liptodetrinite.The reflectance sequence,from high to low,is zooclasts,VLP and SB.Their reflectances gradually increases as the pyrolysis temperature rises,although the rate of growth is slower than that of co-heating coal vitrinite.Notably,zooclasts yield significantly higher reflectance values than those of VLP and SB at each pyrolysis temperature.However,the VLP undergoes two distinct phases in reflectance development,despite gradual morphology changes similar to vitrinite.Based on evidence of the optical texture and organic pore evolution,we argue that a fair amount of VLP in studied Upper Ordovician shale does not consist of graptolite-type fragments.Consequently,the VLPRo serves as a reliable indicator for assessing organic matter maturity in Ordovician shales with a reflectance value of less than 2.0%.This investigation enhances scholarly understandings of marine-derived DOM evolution issues,providing clearer correlations among reflectances of different DOM and reducing uncertainties in thermal maturity determination.
基金Supported by the Hubei Provincial Key Technology R&D Program(2004AA306B01)the Hubei Provincial International Cooperative Project(2005CA012)
文摘A technique for real-time synchronous integration of radar and raingauge measurements based on the concept of the quasi same-rain-volume sampling（QSVS） is presented.Because of the temporal and spatial discrepancies and resolution differences,the integration of radar measurements with raingauge observations has long been a difficult task.Observations indicate that there exists a correlation that conforms to the power law between hourly accumulated raingauge measurement（Q_G） and detected radar echo（Z_（OH）） over the raingauge.On the basis of this,a concept of the QSVS and five direct correspondent formulas of radar and raingauge samples are built up,aiming to eliminate the temporal and spatial discrepancies.A convenient and practical sampling method—the time integral vertical synchronous sampling（TIVS） is proposed and the Z_（OH）—Q_G relationship is studied.It is significant that under the fixed exponent,the coefficient A_B or A_M varies flexibly in accordance with the temporal and spatial variability of natural precipitation,having the function of synchronously integrating the Z—R conversion and the gauge adjustment into a single equation,and thus the precipitation estimation errors caused by detecting resolution differences between radar and raingauge can be obviously mitigated.The real-time synchronous integration technique using the Z_（OH）—Q_G relationship to estimate the ground hourly rainfall accumulation is called the radar-gauge synchronous integration method（RASIM）.The experiments of two cases show that the accuracy of estimated surface hourly rainfall accumulation within 230 km is about 90%,and the average relative error for the point estimation over the whole process is about 20%. Through the detailed analysis of the applicability of TIVS in three environmental fields with various wind drifts,the physical essence of TIVS is explored：it is an approximate QSVS.By analyzing the data pairs of radar and raingauge,an effective quality-control procedure is established,which can greatly improve the stability and rationarity of the Z_（OH）—Q_G relationship.The forecasting product of hourly rainfall accumulation derived from the RASIM has been put into operation.It is demonstrated that the RASIM plays an important role in the quantitative monitoring and forecasting of short-term torrential rainfall.
