1998 Vol. 16, No. 1
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Display Method:
1998, 16(1): 1-7.
Abstract:
Oceanographic studies more than 30 years revealed the existence of internal tides and internal waves indeep-water , however , internal-tide deposits were not recognized and studied systematically in the stratigraphcrecord until Gao Zhenzhong and K. A. Eriksson studied Ordovician deep-water sediments in the central Ap-palachians of the USA in the early 1990s. The term of internal-tide deposits was introduced for the first timein their paper. Two facies were recognized in the Ordovician of the Fincastle area，Appalachians:(1) bidirec-tional cross-laminated very fine grained sandstone facies，and (2)unidirectional cross-bedded and cross-lami-mated medium-to fine-grained sandstone fades. Recently, internal-tide deposits were first found in the Upper Ordovician in the Tonglu area, ZhejiangProvince，which are similar to that found in Appalachians in some sedimentary characteristics but also havesome marked difference from that in Appalachians. During the late age of Late Ordovician the Tonglu areawas located on the southeastern slope of a deep-water basin. The internal-tide deposits described in this paperwere found within the Upper Ordovician Yankou Formation，which consists of a succession of thin alternatelayers of sandstones and mudstones. This set of thin alternate layers displayed clear rhythmicity and could beclassified into many sequences from fine-grained to coarse-grained，and to fine-grained again upwards. Eachsequence consists of more than ten or tens of couplets of sandstones and mudstones with 0. 2-1 m in thick-ness and could be refered to as a symmetrically graded couplet sequence. This kind of internal-tide depositswith this sequence could be called as a rhythemic thin alternate layer facies of sandstone and mudstone,whichformed in deep-water slope environment and should probably be the product of internal tide sedimentation.Palaeoslope dipping towards northwest and southeast ward and northwest ward sedimentary structures indi-cate that the internal tide currents flew mainly alternatively up and down on the slope. Based on the study,theinteranl-tide deposits were inferred to be formed in open slope where there was a longer relative static period(the period of slack water)during tidal current reversals,so mud-size materials could deposit and form muddybeds. The formation of each couplet of sandstone and mudstone might be the result of diurnal or semidiurnaltide. But the formation of symmetrically graded couplet sequence might be the result of periodical change ofspring tide and neap tide.
Oceanographic studies more than 30 years revealed the existence of internal tides and internal waves indeep-water , however , internal-tide deposits were not recognized and studied systematically in the stratigraphcrecord until Gao Zhenzhong and K. A. Eriksson studied Ordovician deep-water sediments in the central Ap-palachians of the USA in the early 1990s. The term of internal-tide deposits was introduced for the first timein their paper. Two facies were recognized in the Ordovician of the Fincastle area，Appalachians:(1) bidirec-tional cross-laminated very fine grained sandstone facies，and (2)unidirectional cross-bedded and cross-lami-mated medium-to fine-grained sandstone fades. Recently, internal-tide deposits were first found in the Upper Ordovician in the Tonglu area, ZhejiangProvince，which are similar to that found in Appalachians in some sedimentary characteristics but also havesome marked difference from that in Appalachians. During the late age of Late Ordovician the Tonglu areawas located on the southeastern slope of a deep-water basin. The internal-tide deposits described in this paperwere found within the Upper Ordovician Yankou Formation，which consists of a succession of thin alternatelayers of sandstones and mudstones. This set of thin alternate layers displayed clear rhythmicity and could beclassified into many sequences from fine-grained to coarse-grained，and to fine-grained again upwards. Eachsequence consists of more than ten or tens of couplets of sandstones and mudstones with 0. 2-1 m in thick-ness and could be refered to as a symmetrically graded couplet sequence. This kind of internal-tide depositswith this sequence could be called as a rhythemic thin alternate layer facies of sandstone and mudstone,whichformed in deep-water slope environment and should probably be the product of internal tide sedimentation.Palaeoslope dipping towards northwest and southeast ward and northwest ward sedimentary structures indi-cate that the internal tide currents flew mainly alternatively up and down on the slope. Based on the study,theinteranl-tide deposits were inferred to be formed in open slope where there was a longer relative static period(the period of slack water)during tidal current reversals,so mud-size materials could deposit and form muddybeds. The formation of each couplet of sandstone and mudstone might be the result of diurnal or semidiurnaltide. But the formation of symmetrically graded couplet sequence might be the result of periodical change ofspring tide and neap tide.
1998, 16(1): 15-21.
Abstract:
Widely exposed in the northern belt of West Qingling Mountains,the Shujiaba Formation (Devonian) isa set of extremely thick terrigenous clastic rock measures. Two sharply different viewpoints on the paleogeog-raphy environment of the formation still exist,i. e. shallow sea and deep sea facies. This paper placed emphasison the 43 ichnogenera discovered by the authors to discuss the paleoenvironment information provided bythem. The description and plates of the 43 trace fossils of the Shujiaba Fm. have been reported openly,and theyare: Acanthorhaphe，Arthrophus，Belorha phe，Bostricoph yton，Buthotrephis，Chondrites，Cochilichnus，Cos-morhaphe, Dictyodora，Fucusopsis, Glockeria，Gordia，Granularia，Helicolithus，Helminthoida，Helminthopsis，Lennea，Lophoctenium，Megagra pton，Neonereites，Nereites，Paleohelminthoida，Paleod ict yon，Planolites，Pro-topaleodicyon，Protovirgularia，Rhabdoglyphus，Rhabdoichnus，Rusoph ycus(?)，Saerichnites，Sagittichnus，Scolicia，Skolithos，S pirophycus，S pirorha phe，Sguamodictyon，Subphyllochorda，Sublorenzinia，Subularia，Ta phrhelminthoida , Ta phrhelmintho psis , T uberculichnus , Urohelminthaida. Some cognition was reached according to the study on the trace fossil groups mentioned above，that is，1)Classified in terms of trace facies,only a few ichnogenera existing in the near source turbidite of trace groupin the Shujiaba Fm. belonged to the Skolithos trace facies,but a majority of trace fossil ichnogenera belongedto the Nereites facies. They were preserved on the interface between Section Tc and Te in the thin-beddedturbidite formed in the distal area of turbidity current. According to the researches at home and abroad，itcould be seen that it is the unique feature of th trace fossil assemblage in vertical distribution in turbidite mea-sures or flysch facies that the trace facies of deep and shallow water co-exist in a single depositional profile，just like the Shujiaba Fm. 2)Classified according to the morphology，the already discovered trace fossils were predominated by thecurved , spiral, regular snakelike and netlike species. Nowadays，these complex and regular geometrical patternshave already become the important sign to distinguish the deep water trace fossils. 3 ) According to the ethological classif ication，the 43 ichnogeriera bassically，belonged to the feeding trailand trail. And the latter was generally in the leading role. This kind of trace fossils was mainly distributed atthe bottom of tranquil water body in abyssal-byssal areas. 4 ) Classified according to the distribution characteristics of water depth，the trace fossil of the ShujiabaFm. was predominated by the deep water members，of which the water depth distribution ranges from thedistal one to the byssal trough one. From the discussion above，it could be seen that the trace group in the Shujiaba Fm. was formed in abathyalbyssal environment related to turbidity current , and the largest water depth in deposition period couldsometimes exceed 2000m.
Widely exposed in the northern belt of West Qingling Mountains,the Shujiaba Formation (Devonian) isa set of extremely thick terrigenous clastic rock measures. Two sharply different viewpoints on the paleogeog-raphy environment of the formation still exist,i. e. shallow sea and deep sea facies. This paper placed emphasison the 43 ichnogenera discovered by the authors to discuss the paleoenvironment information provided bythem. The description and plates of the 43 trace fossils of the Shujiaba Fm. have been reported openly,and theyare: Acanthorhaphe，Arthrophus，Belorha phe，Bostricoph yton，Buthotrephis，Chondrites，Cochilichnus，Cos-morhaphe, Dictyodora，Fucusopsis, Glockeria，Gordia，Granularia，Helicolithus，Helminthoida，Helminthopsis，Lennea，Lophoctenium，Megagra pton，Neonereites，Nereites，Paleohelminthoida，Paleod ict yon，Planolites，Pro-topaleodicyon，Protovirgularia，Rhabdoglyphus，Rhabdoichnus，Rusoph ycus(?)，Saerichnites，Sagittichnus，Scolicia，Skolithos，S pirophycus，S pirorha phe，Sguamodictyon，Subphyllochorda，Sublorenzinia，Subularia，Ta phrhelminthoida , Ta phrhelmintho psis , T uberculichnus , Urohelminthaida. Some cognition was reached according to the study on the trace fossil groups mentioned above，that is，1)Classified in terms of trace facies,only a few ichnogenera existing in the near source turbidite of trace groupin the Shujiaba Fm. belonged to the Skolithos trace facies,but a majority of trace fossil ichnogenera belongedto the Nereites facies. They were preserved on the interface between Section Tc and Te in the thin-beddedturbidite formed in the distal area of turbidity current. According to the researches at home and abroad，itcould be seen that it is the unique feature of th trace fossil assemblage in vertical distribution in turbidite mea-sures or flysch facies that the trace facies of deep and shallow water co-exist in a single depositional profile，just like the Shujiaba Fm. 2)Classified according to the morphology，the already discovered trace fossils were predominated by thecurved , spiral, regular snakelike and netlike species. Nowadays，these complex and regular geometrical patternshave already become the important sign to distinguish the deep water trace fossils. 3 ) According to the ethological classif ication，the 43 ichnogeriera bassically，belonged to the feeding trailand trail. And the latter was generally in the leading role. This kind of trace fossils was mainly distributed atthe bottom of tranquil water body in abyssal-byssal areas. 4 ) Classified according to the distribution characteristics of water depth，the trace fossil of the ShujiabaFm. was predominated by the deep water members，of which the water depth distribution ranges from thedistal one to the byssal trough one. From the discussion above，it could be seen that the trace group in the Shujiaba Fm. was formed in abathyalbyssal environment related to turbidity current , and the largest water depth in deposition period couldsometimes exceed 2000m.
1998, 16(1): 27-33.
Abstract:
From the view of reservoir sedimentology,this paper analyzed the formation of braided river sandbodiesin the Zhangjiakou region,identified three-order bounding surfaces and six types of lithofacies，and discussedthe influence of sedimentation and diagenesis on reservoir properties. It was concluded that sedimentation is adominant factor controlling reservoir properties, and the influence of diagenesis on reservoir properties is af-fected by sedimentation. Middle grain size and mud content have great influence on reservoir properties. theinfluence of cements on porosity is greater than that on permeability. It was also showed that there is a closerelationship between lithofacies and reservoir properties,lithofacies formed in high energy environment usuallyare good reservoirs. The control of bounding surface on reservoirs lies in the following:the first order bound-ing surface controls the geometry and extension of sandbodies, the second one controls the heterogeneity ofsandbodies,and the third one controls the distribution of favorable reservoirs. Finally,a 1-D and a 2-D geolog-ical reservoir models were established,these models would be instructive for oil production.
From the view of reservoir sedimentology,this paper analyzed the formation of braided river sandbodiesin the Zhangjiakou region,identified three-order bounding surfaces and six types of lithofacies，and discussedthe influence of sedimentation and diagenesis on reservoir properties. It was concluded that sedimentation is adominant factor controlling reservoir properties, and the influence of diagenesis on reservoir properties is af-fected by sedimentation. Middle grain size and mud content have great influence on reservoir properties. theinfluence of cements on porosity is greater than that on permeability. It was also showed that there is a closerelationship between lithofacies and reservoir properties,lithofacies formed in high energy environment usuallyare good reservoirs. The control of bounding surface on reservoirs lies in the following:the first order bound-ing surface controls the geometry and extension of sandbodies, the second one controls the heterogeneity ofsandbodies,and the third one controls the distribution of favorable reservoirs. Finally,a 1-D and a 2-D geolog-ical reservoir models were established,these models would be instructive for oil production.
1998, 16(1): 40-44.
Abstract:
We found a vast area of modern and paleo-sand dunes and desertifized grassland in the source area ofYellow River on the northeastern Qinghai-Xizang (Tibet) Plateau. Remote sensing，geomorphological , sedi-mentological and chronological analyses have demonstrated that these sand dunes are locally formed semi-ma-tured dunes characterized by coarse and moderately sorted grains and a majority of semi-matured aeoliansands. They are formed mainly in four periods, i. e.，the late penultimate glacial，last glacial maximun，coldepisodes of the Holocene , and present day. The distribution of sand dunes and the aeolian maturity of sandsincrease significantly with time，suggesting an intensified air circulation，with which tremendous dusts weretransported to loess deposition areas on the eastern front of the Qinghai-Xizang Plateau and its adjacentdownwind area.
We found a vast area of modern and paleo-sand dunes and desertifized grassland in the source area ofYellow River on the northeastern Qinghai-Xizang (Tibet) Plateau. Remote sensing，geomorphological , sedi-mentological and chronological analyses have demonstrated that these sand dunes are locally formed semi-ma-tured dunes characterized by coarse and moderately sorted grains and a majority of semi-matured aeoliansands. They are formed mainly in four periods, i. e.，the late penultimate glacial，last glacial maximun，coldepisodes of the Holocene , and present day. The distribution of sand dunes and the aeolian maturity of sandsincrease significantly with time，suggesting an intensified air circulation，with which tremendous dusts weretransported to loess deposition areas on the eastern front of the Qinghai-Xizang Plateau and its adjacentdownwind area.
1998, 16(1): 50-57.
Abstract:
Source rock evaluation is the basis of oil and gastion) and the efficiency of a source rock can be nowresource assessment. The quality,the nature(or attribu-evaluated by studying hydrocarbon expulsion process of the source rock during its geohistory. This paper，applying the basinmodeling and uncertainty analysis methods,studied the effect and the relative contribution of thirteen majorgeological factors to source rock evaluation , and discussed the probability distribution of the source rock quali-ty evaluation index(SRIQ),source rock nature evaluation index(SRIN) and source rock efficiency evaluationindex(SRIE) under the effects of these major geological factors.
Source rock evaluation is the basis of oil and gastion) and the efficiency of a source rock can be nowresource assessment. The quality,the nature(or attribu-evaluated by studying hydrocarbon expulsion process of the source rock during its geohistory. This paper，applying the basinmodeling and uncertainty analysis methods,studied the effect and the relative contribution of thirteen majorgeological factors to source rock evaluation , and discussed the probability distribution of the source rock quali-ty evaluation index(SRIQ),source rock nature evaluation index(SRIN) and source rock efficiency evaluationindex(SRIE) under the effects of these major geological factors.
1998, 16(1): 64-69.
Abstract:
The Jurassic System is one of the rare oil-bearing horizons with both marine and nonmarine petroleumsources discovered in Tarim Basin up to now. Abundant hydrocarbon source,high porosity and permeability，good muddy caprocks and various kinds of traps constitute beneficial conditions to form the Jurassic oil pools.There are 2 types of petroleum accumulation,i. e. ,Kuche-type and Tabei-type which were formed during Hi-malayan orogeny. Petroleum distribution could be divided into 5 zones including thrust-fold zone，foredeepzone，slope zone，tensional foreland uplift zone and drapping anticline zone. And petroleum occurrence wascontrolled by faults and unconformities which are the secondary migration of petrleum. As a target bed，theJurassic systems distributed in the northern slope of the Tabei uplift,thrust-fold zone of the Kuche depressionand the Yingjisu sag are the favourable exploration area.
The Jurassic System is one of the rare oil-bearing horizons with both marine and nonmarine petroleumsources discovered in Tarim Basin up to now. Abundant hydrocarbon source,high porosity and permeability，good muddy caprocks and various kinds of traps constitute beneficial conditions to form the Jurassic oil pools.There are 2 types of petroleum accumulation,i. e. ,Kuche-type and Tabei-type which were formed during Hi-malayan orogeny. Petroleum distribution could be divided into 5 zones including thrust-fold zone，foredeepzone，slope zone，tensional foreland uplift zone and drapping anticline zone. And petroleum occurrence wascontrolled by faults and unconformities which are the secondary migration of petrleum. As a target bed，theJurassic systems distributed in the northern slope of the Tabei uplift,thrust-fold zone of the Kuche depressionand the Yingjisu sag are the favourable exploration area.
1998, 16(1): 76-80.
Abstract:
Based upon the theory of fractal geometry，fractal dimensions of fault systems in the area east to theDaqing placanticline, Songliao Basin，were calculated using the box-counting approach to the reflecting T2T3and T4horizon and the studied area was divided into eight zones with different oil and gas distribution fea-tures. From the analysis of fractal behaviours on different sub一systems of faults in the studied area，it wasfound that the zone with high fault fractal dimensions is in good correspondence with the distribution of gasaccumulation from deep source rocks. This suggested that faults are main paths for gas migration from deepsource rocks. It was also concluded that the fratcal dimension of an fault system is an important parameter toquantitatively characterize the nature of migration and distribution of gas from deep source rocks.
Based upon the theory of fractal geometry，fractal dimensions of fault systems in the area east to theDaqing placanticline, Songliao Basin，were calculated using the box-counting approach to the reflecting T2T3and T4horizon and the studied area was divided into eight zones with different oil and gas distribution fea-tures. From the analysis of fractal behaviours on different sub一systems of faults in the studied area，it wasfound that the zone with high fault fractal dimensions is in good correspondence with the distribution of gasaccumulation from deep source rocks. This suggested that faults are main paths for gas migration from deepsource rocks. It was also concluded that the fratcal dimension of an fault system is an important parameter toquantitatively characterize the nature of migration and distribution of gas from deep source rocks.
1998, 16(1): 87-91.
Abstract:
The evaluation of hydrocarbon resources is nowadays based on the elemental unit of hydrocarbon-bearinggeological bodies within structural units instead of on the structural unit itself. The discrimination of sourcerock bodies requires three-dimensional treatment of geological,geochemical and geophysical data. Based on thedata of cores, logging curves，paleontologic fossils geochemical parameters and seismograms, the present pa-per,taking the Niuzhuang subdepression as an example,described the geometric shape of low-mature and ma-ture source rocks in the upper submember of the Shasi section;moreover,the paper discussed the mutual rela-tionship of them both in genesis and evolution.
The evaluation of hydrocarbon resources is nowadays based on the elemental unit of hydrocarbon-bearinggeological bodies within structural units instead of on the structural unit itself. The discrimination of sourcerock bodies requires three-dimensional treatment of geological,geochemical and geophysical data. Based on thedata of cores, logging curves，paleontologic fossils geochemical parameters and seismograms, the present pa-per,taking the Niuzhuang subdepression as an example,described the geometric shape of low-mature and ma-ture source rocks in the upper submember of the Shasi section;moreover,the paper discussed the mutual rela-tionship of them both in genesis and evolution.
1998, 16(1): 103-106.
Abstract:
Utilizing a vacuum-electric-magnetic breaker system to crush the salt deposit sample and extract the liq-uid and gaseous inclusion in the salt deposit. the result shows that the crushing proportion has a relationshipwith the amount of sample，numbers of strike and the content of water in the salt deposit sample.
Utilizing a vacuum-electric-magnetic breaker system to crush the salt deposit sample and extract the liq-uid and gaseous inclusion in the salt deposit. the result shows that the crushing proportion has a relationshipwith the amount of sample，numbers of strike and the content of water in the salt deposit sample.
1998, 16(1): 112-119.
Abstract:
Comparison and discussion were carried out with various methods,using vitrinite reflectance(VR) to re-construct paleotemperature of sedimentary basins. It was perceived that the Easy Ro algorithm is the most ac-curate method for prediction of VR and then for paleotemperature throughout the range of organic maturitynormally encountered. The Easy Ro model was cased to restore paleotemperature gradients(PG) of four sedi-mentary basins in the eastern and western China,respectively. It was indicated that the eastern basins charac-teristic of continental rift basin had higher paleotemperature gradients in the Mesozoic-Cenozoic Era thanthose characteristic of foreland basin in the western China. The eastern basins had more than 4. 0℃/ 100m ofPG from the Late Mesozoic to Early Cenozoic Era，but lower than 3. 0-2. 5℃/100m in the western basinsof China during the same period. Three of the four basins concerned,Liaohe Basin,subei Basin in the east andsantanghu Basin in the west, had a decreasing evolution in PG in Late Mesozoic, whileQaidarn Basin under-went an increasing evolution in PG,from 2. 5℃/100m to nowadays 3. 0℃/100m. The success of PG recon-structions for four basins suggested that the Easy Ra algorithm is suitable to PG reconstruction of various tec-tonically different basins.
Comparison and discussion were carried out with various methods,using vitrinite reflectance(VR) to re-construct paleotemperature of sedimentary basins. It was perceived that the Easy Ro algorithm is the most ac-curate method for prediction of VR and then for paleotemperature throughout the range of organic maturitynormally encountered. The Easy Ro model was cased to restore paleotemperature gradients(PG) of four sedi-mentary basins in the eastern and western China,respectively. It was indicated that the eastern basins charac-teristic of continental rift basin had higher paleotemperature gradients in the Mesozoic-Cenozoic Era thanthose characteristic of foreland basin in the western China. The eastern basins had more than 4. 0℃/ 100m ofPG from the Late Mesozoic to Early Cenozoic Era，but lower than 3. 0-2. 5℃/100m in the western basinsof China during the same period. Three of the four basins concerned,Liaohe Basin,subei Basin in the east andsantanghu Basin in the west, had a decreasing evolution in PG in Late Mesozoic, whileQaidarn Basin under-went an increasing evolution in PG,from 2. 5℃/100m to nowadays 3. 0℃/100m. The success of PG recon-structions for four basins suggested that the Easy Ra algorithm is suitable to PG reconstruction of various tec-tonically different basins.
1998, 16(1): 126-131.
Abstract:
The Tertiary in the Aerjin Slope in Caidam Basin is characterized by strong carbonate recrystallization，weak compaction, weak quartz overgrowth and enrichment of the early-stage carbonate. The carbonate ce-ment,influenced by the salinity to some degree,is mainly inorganic with few relation to biogas. In muds clayassemblage is illite-illite/montmorillonite-chlorite. With the increase of depth the relative content of illite fluc-tuates and that of chlorite decreases. The illite may be terrestrial origin.
The Tertiary in the Aerjin Slope in Caidam Basin is characterized by strong carbonate recrystallization，weak compaction, weak quartz overgrowth and enrichment of the early-stage carbonate. The carbonate ce-ment,influenced by the salinity to some degree,is mainly inorganic with few relation to biogas. In muds clayassemblage is illite-illite/montmorillonite-chlorite. With the increase of depth the relative content of illite fluc-tuates and that of chlorite decreases. The illite may be terrestrial origin.
1998, 16(1): 137-139.
Abstract:
Quantitative analysis of minerals in reservoir rocks is the basis to determine sedimentary and diageneticfacies,and is one of the key factors to reservoir protection during the process of drilling，well一completion andoil production. On the basis of investigating the traditional segregation of clay minerals and its defects;a multi-ple grain size segregation method was put forward，which ensured the qualitative and qantitative determina-tion of clay minerals in reservoir rocks.
Quantitative analysis of minerals in reservoir rocks is the basis to determine sedimentary and diageneticfacies,and is one of the key factors to reservoir protection during the process of drilling，well一completion andoil production. On the basis of investigating the traditional segregation of clay minerals and its defects;a multi-ple grain size segregation method was put forward，which ensured the qualitative and qantitative determina-tion of clay minerals in reservoir rocks.
1998, 16(1): 146-151.
Abstract:
The loess accumulation rates of Liujiapo, Luochuan，Xifeng,Baoji,Jiuzhoutai and Dadunling sections onthe loess plateau were systematically studied in this paper. It was found that the loess accumulation rates have increased step by step from past to present,and decreased from NW to SE in thesame fashion,besides the variation from glacial to interglacial epoches. There were several periods of extremelyhigh rates of the loess accumulation during Quaternary，which are coincided with the uplift events of theQinghai一Tibetan Plateau. At about 0. 7 MaBP，the winter monsoon had a remarkable change both in winddirection and intensity. Since then，the intensity of winter monsoon has become stronger and stronger,whilethe direction of winter monsoon has changed to northwest. This paper proved that the loess accumulation ratecan beconsidered as one of the best indices to indicate the winter monsoon variations of the Loess Plateau.
The loess accumulation rates of Liujiapo, Luochuan，Xifeng,Baoji,Jiuzhoutai and Dadunling sections onthe loess plateau were systematically studied in this paper. It was found that the loess accumulation rates have increased step by step from past to present,and decreased from NW to SE in thesame fashion,besides the variation from glacial to interglacial epoches. There were several periods of extremelyhigh rates of the loess accumulation during Quaternary，which are coincided with the uplift events of theQinghai一Tibetan Plateau. At about 0. 7 MaBP，the winter monsoon had a remarkable change both in winddirection and intensity. Since then，the intensity of winter monsoon has become stronger and stronger,whilethe direction of winter monsoon has changed to northwest. This paper proved that the loess accumulation ratecan beconsidered as one of the best indices to indicate the winter monsoon variations of the Loess Plateau.
1998, 16(1): 8-14.
Abstract:
The subsiding mechanism,basin shape and other features of the continental fault lacustrine basin are dif-ferent from those of other sedimentary basins，which results in the difference of the interior constitution ofsedimentary sequence and the feature of sequence boundary. The sequence stratigraphy model from the pas-sive continental-margin cannot be directly applied to the basin,althouth the basic principle of sequence stratig-raphy is still applicable.This paper analysed the sedimentary sequence of the lacustrine transgressive and la-custrine regressive cycle (T-R cycle)from the lacustrine basin of Dongpu，and showed that the sequence iscomposed of the lower lacustrine trangressive system trace (LTST) and upper lacustrine regressive systemtrace(LRST). The reservoir sandbodies of various genetic types were well developed in LTST. The high fre-quency T-R cyclical sequences superimposing on the tectonic sedimentary cycle lacked the Type I sequenceboundary because of the steep margin of the fault basin and the little change of lake level Main factors control-ling the development of the T-R cycle are the episodic movement of structure(fault)and the higher frequenceT-R cycle is related to Milankovitch climate cycle.
The subsiding mechanism,basin shape and other features of the continental fault lacustrine basin are dif-ferent from those of other sedimentary basins，which results in the difference of the interior constitution ofsedimentary sequence and the feature of sequence boundary. The sequence stratigraphy model from the pas-sive continental-margin cannot be directly applied to the basin,althouth the basic principle of sequence stratig-raphy is still applicable.This paper analysed the sedimentary sequence of the lacustrine transgressive and la-custrine regressive cycle (T-R cycle)from the lacustrine basin of Dongpu，and showed that the sequence iscomposed of the lower lacustrine trangressive system trace (LTST) and upper lacustrine regressive systemtrace(LRST). The reservoir sandbodies of various genetic types were well developed in LTST. The high fre-quency T-R cyclical sequences superimposing on the tectonic sedimentary cycle lacked the Type I sequenceboundary because of the steep margin of the fault basin and the little change of lake level Main factors control-ling the development of the T-R cycle are the episodic movement of structure(fault)and the higher frequenceT-R cycle is related to Milankovitch climate cycle.
1998, 16(1): 22-26.
Abstract:
Transgression has been routinely regarded as to be rapidly accomplished，relatively simple in successionand commonly characteristic of deposit. Study on trace fossils and sedimentary features of Tataertage Forma-tion indicated that transgressive systems tracts possess their own unique complexities and can be grouped intothree main subdivisions:(1)the first group of fades is produced by the process of transgressive erosion includ-ing transgressive lags with Glossifungites ichnofacies;(2) the second one corresponds to those sediments de-posited while relative sea level is rising slowly or related to the stillstand cycle during an overall transgression，including foreshore and shoreface sandstones as well as mudstones with Skolithos ichnofacies and proximalCrzcziana ichnofacies(3)the last one reflects the rapid rising of relative sea level including offshore mudstoneswith distal Cruziana ichnofacies.
Transgression has been routinely regarded as to be rapidly accomplished，relatively simple in successionand commonly characteristic of deposit. Study on trace fossils and sedimentary features of Tataertage Forma-tion indicated that transgressive systems tracts possess their own unique complexities and can be grouped intothree main subdivisions:(1)the first group of fades is produced by the process of transgressive erosion includ-ing transgressive lags with Glossifungites ichnofacies;(2) the second one corresponds to those sediments de-posited while relative sea level is rising slowly or related to the stillstand cycle during an overall transgression，including foreshore and shoreface sandstones as well as mudstones with Skolithos ichnofacies and proximalCrzcziana ichnofacies(3)the last one reflects the rapid rising of relative sea level including offshore mudstoneswith distal Cruziana ichnofacies.
1998, 16(1): 34-39.
Abstract:
There are multipatterns in the Yongding River and they transfer from the braided to meandering,then toan abranched channel along the flow direction. The braided stream segment can be subdivided into two types:One is a high slope braided river which is distributed in the fluvial fan，water escaping,gravitational sliding,water flow dragging,ripple gliding,bioturbation,wave action and slump-ing,and can be divided into seven types according to their origins. Those formed by water escaping and waterflow dragging are the most common and typical ones among them. On surfaces of the deformed beddings of water escaping type，there are usually many nipple-like and do-ral fin-like projectings which may sometimes have a hole for water escaping in the center of each projecting，and the deformed beddings may have abrupt contact with their neighbor beddings. Deformed beddings of wa-ter flow dragging type usually possess five characteristics as follows: (1)the overlying sedments and sedimentary structures of them,such as clay boulder or sand-sized grainsin massive and parallel beddings，regressive sand waves，climbing-ripple laminations, are all formed by waterflow of high velocity. (2)the axial planes of fold curve-like deformed beddings are often randomly oriented,al-though they may sometimes dip toward the upper reach. (3)usually,they show abrupt contact with overlyingbeddings and gradual or abrupt contact with underlying beddings of them according to extent of deformation.(4)most of them are deformed severely and show very complicated appearences such as the cabbage-like onesand the bag-like or tube-like ones. (5)they are steadily widespread and sometimes may be well-stratified andgraded.
There are multipatterns in the Yongding River and they transfer from the braided to meandering,then toan abranched channel along the flow direction. The braided stream segment can be subdivided into two types:One is a high slope braided river which is distributed in the fluvial fan，water escaping,gravitational sliding,water flow dragging,ripple gliding,bioturbation,wave action and slump-ing,and can be divided into seven types according to their origins. Those formed by water escaping and waterflow dragging are the most common and typical ones among them. On surfaces of the deformed beddings of water escaping type，there are usually many nipple-like and do-ral fin-like projectings which may sometimes have a hole for water escaping in the center of each projecting，and the deformed beddings may have abrupt contact with their neighbor beddings. Deformed beddings of wa-ter flow dragging type usually possess five characteristics as follows: (1)the overlying sedments and sedimentary structures of them,such as clay boulder or sand-sized grainsin massive and parallel beddings，regressive sand waves，climbing-ripple laminations, are all formed by waterflow of high velocity. (2)the axial planes of fold curve-like deformed beddings are often randomly oriented,al-though they may sometimes dip toward the upper reach. (3)usually,they show abrupt contact with overlyingbeddings and gradual or abrupt contact with underlying beddings of them according to extent of deformation.(4)most of them are deformed severely and show very complicated appearences such as the cabbage-like onesand the bag-like or tube-like ones. (5)they are steadily widespread and sometimes may be well-stratified andgraded.
1998, 16(1): 45-49.
Abstract:
Deformed beddings of differentsizes areoften observed in the Yellow River Delta. They are formed bywater escaping,gravitational sliding,water flow dragging,ripple gliding,bioturbation,wave action and slump-ing,and can be divided into seven types according to their origins. Those formed by water escaping and waterflow dragging are the most common and typical ones among them. On surfaces of the deformed beddings of water escaping type，there are usually many nipple-like and do-ral fin-like projectings which may sometimes have a hole for water escaping in the center of each projecting，and the deformed beddings may have abrupt contact with their neighbor beddings. Deformed beddings of wa-ter flow dragging type usually possess five characteristics as follows: (1)the overlying sedments and sedimentary structures of them,such as clay boulder or sand-sized grainsin massive and parallel beddings，regressive sand waves，climbing-ripple laminations, are all formed by waterflow of high velocity. (2)the axial planes of fold curve-like deformed beddings are often randomly oriented,al-though they may sometimes dip toward the upper reach. (3)usually,they show abrupt contact with overlyingbeddings and gradual or abrupt contact with underlying beddings of them according to extent of deformation.(4)most of them are deformed severely and show very complicated appearences such as the cabbage-like onesand the bag-like or tube-like ones. (5)they are steadily widespread and sometimes may be well-stratified andgraded.
Deformed beddings of differentsizes areoften observed in the Yellow River Delta. They are formed bywater escaping,gravitational sliding,water flow dragging,ripple gliding,bioturbation,wave action and slump-ing,and can be divided into seven types according to their origins. Those formed by water escaping and waterflow dragging are the most common and typical ones among them. On surfaces of the deformed beddings of water escaping type，there are usually many nipple-like and do-ral fin-like projectings which may sometimes have a hole for water escaping in the center of each projecting，and the deformed beddings may have abrupt contact with their neighbor beddings. Deformed beddings of wa-ter flow dragging type usually possess five characteristics as follows: (1)the overlying sedments and sedimentary structures of them,such as clay boulder or sand-sized grainsin massive and parallel beddings，regressive sand waves，climbing-ripple laminations, are all formed by waterflow of high velocity. (2)the axial planes of fold curve-like deformed beddings are often randomly oriented,al-though they may sometimes dip toward the upper reach. (3)usually,they show abrupt contact with overlyingbeddings and gradual or abrupt contact with underlying beddings of them according to extent of deformation.(4)most of them are deformed severely and show very complicated appearences such as the cabbage-like onesand the bag-like or tube-like ones. (5)they are steadily widespread and sometimes may be well-stratified andgraded.
1998, 16(1): 58-63.
Abstract:
Bsaed on the studies of structures of formation pressure and the characteristics of natural gas in TarimBasin,the paperl shows that there are several independent natural gas migration and accumulation systems inthe eastern part of Tarim Basin. There are no hydrodynamic connections between the systems and the charac-teristics of natural gas is different in different systems. The migration of natural gas was restricted within thelimit of individual system,and the lateral migration across the systems was very difficult. As a result,the nat-ural gas generated in a system could only accumulate within the same system,and this is very important to theoccurrence and evaluation of natural gas in the basin. According to different geological conditions in differentsystems , three kinds of migration and accumulation models have been developped.
Bsaed on the studies of structures of formation pressure and the characteristics of natural gas in TarimBasin,the paperl shows that there are several independent natural gas migration and accumulation systems inthe eastern part of Tarim Basin. There are no hydrodynamic connections between the systems and the charac-teristics of natural gas is different in different systems. The migration of natural gas was restricted within thelimit of individual system,and the lateral migration across the systems was very difficult. As a result,the nat-ural gas generated in a system could only accumulate within the same system,and this is very important to theoccurrence and evaluation of natural gas in the basin. According to different geological conditions in differentsystems , three kinds of migration and accumulation models have been developped.
1998, 16(1): 70-75.
Abstract:
Fan deltaic depositional systems are well developed in rift basins,and usually consist of fan delta plain as-sociation, fan delta-front association and prodelta association. Nine genetic facies can be distinguished in fandeltaic depositional systems. Controlled by sediment flux rate, available accommodation expansion rate andbasin-bounded fault,fan deltaic depositional system style can be generally divided into five types ,i. e. degrad-ing,aggrading,prograding,steep slope and slow slope fan deltas. The braided distributary channel sand-bodiesdeveloped in fan delta plains and their related subaqueous distributary mouth bar and flood gravity currentsand-bodies deposited in fan delta-front zones are high quality reservoirs. Oil exploration results have shownthat principal oil reservoirs are distributed dominantly in fan delta-front zones and interdistributary bays,andsome reservoirs are developed in fan delta plain areas. Influenced by burial-depth and diagenesis,principal oil-bearing beds in different areas and different horizons are different because of the various relationships betweenphysical properties and lithologies. Therefore,the relationship of depositional system distribution to oil and gasaccumulation can be applied to search for residual oil-bearing beds and to predict prospect areas.
Fan deltaic depositional systems are well developed in rift basins,and usually consist of fan delta plain as-sociation, fan delta-front association and prodelta association. Nine genetic facies can be distinguished in fandeltaic depositional systems. Controlled by sediment flux rate, available accommodation expansion rate andbasin-bounded fault,fan deltaic depositional system style can be generally divided into five types ,i. e. degrad-ing,aggrading,prograding,steep slope and slow slope fan deltas. The braided distributary channel sand-bodiesdeveloped in fan delta plains and their related subaqueous distributary mouth bar and flood gravity currentsand-bodies deposited in fan delta-front zones are high quality reservoirs. Oil exploration results have shownthat principal oil reservoirs are distributed dominantly in fan delta-front zones and interdistributary bays,andsome reservoirs are developed in fan delta plain areas. Influenced by burial-depth and diagenesis,principal oil-bearing beds in different areas and different horizons are different because of the various relationships betweenphysical properties and lithologies. Therefore,the relationship of depositional system distribution to oil and gasaccumulation can be applied to search for residual oil-bearing beds and to predict prospect areas.
1998, 16(1): 81-86.
Abstract:
Based on the periodic analysis for the typical wells of Tarim Basin with the method of wave analysis，theperiod of 100 Ma was obviously seen. Since Cambrian，there are four complete periods and each of them iscomposed of two half-periods of positive phase and negative phase. Tertiary is the positive phase of the fifthperiod. All of the processes of deposition and erosion，and entrapment cycles are controlled by the 100 Ma pe-riod. The controlling effects of the period for the process of deposition and erosion are confirmed by that thepositive and negative phases are corresponding to the depositional and erosional ages, respectively. The con-trolling effects of the period for petroleum system are known by that the petroleum system of the Early Paleo-zoic is made up of the first periodic wave，the petroleum systems from the Late Paleozoic to the Mesozoic con-sisted of the second to fourth periodic waves, and the petroleum system of Cenozoic is made up of the positivephase of the fifth period.
Based on the periodic analysis for the typical wells of Tarim Basin with the method of wave analysis，theperiod of 100 Ma was obviously seen. Since Cambrian，there are four complete periods and each of them iscomposed of two half-periods of positive phase and negative phase. Tertiary is the positive phase of the fifthperiod. All of the processes of deposition and erosion，and entrapment cycles are controlled by the 100 Ma pe-riod. The controlling effects of the period for the process of deposition and erosion are confirmed by that thepositive and negative phases are corresponding to the depositional and erosional ages, respectively. The con-trolling effects of the period for petroleum system are known by that the petroleum system of the Early Paleo-zoic is made up of the first periodic wave，the petroleum systems from the Late Paleozoic to the Mesozoic con-sisted of the second to fourth periodic waves, and the petroleum system of Cenozoic is made up of the positivephase of the fifth period.
1998, 16(1): 98-102.
Abstract:
Hydrous pyrolysis experiment was carried out using Carboniferous bright brown coal(R°=0. 56%)nearShengli Oil-field , East China to evaluate the hydrocarbon generation potential of coal. The coal sample is vitri-nite-rich ( 74. 5%)and liptinite-poor ( 8. 8%)with inertinite of 16. 7%.Much of vitrinite in the sample con-sists of hydrogen-rich desmocollinite. The hydrous pyrolysis was performed at 200℃，230℃，260 ℃，290 ℃，320℃and 350`℃for 72 hours，respectively. Both total pyrolysates and expelled oil increased with temperaturebefore reaching their maximum yields at 320'C (R°=1. 18%)，and decreased afterwards. The gaseous prod-ucts increased sharply at 3200℃(R°=1. 18%)and tended to increasing evenly at their peak yield point of350'℃(R°=1. 53%).The results show that the coal has a higher hydrocarbon generation potential and expul-sion effeciency. It is proposed that the hydrocarbon potential of coals depends not only on their organic mat-ters but also on their depositional environments. Reducing conditions are favorable depositional environmentfor oil-prone coal. The fractures and cleats are beneficial to the expulsion of the oil from coal.
Hydrous pyrolysis experiment was carried out using Carboniferous bright brown coal(R°=0. 56%)nearShengli Oil-field , East China to evaluate the hydrocarbon generation potential of coal. The coal sample is vitri-nite-rich ( 74. 5%)and liptinite-poor ( 8. 8%)with inertinite of 16. 7%.Much of vitrinite in the sample con-sists of hydrogen-rich desmocollinite. The hydrous pyrolysis was performed at 200℃，230℃，260 ℃，290 ℃，320℃and 350`℃for 72 hours，respectively. Both total pyrolysates and expelled oil increased with temperaturebefore reaching their maximum yields at 320'C (R°=1. 18%)，and decreased afterwards. The gaseous prod-ucts increased sharply at 3200℃(R°=1. 18%)and tended to increasing evenly at their peak yield point of350'℃(R°=1. 53%).The results show that the coal has a higher hydrocarbon generation potential and expul-sion effeciency. It is proposed that the hydrocarbon potential of coals depends not only on their organic mat-ters but also on their depositional environments. Reducing conditions are favorable depositional environmentfor oil-prone coal. The fractures and cleats are beneficial to the expulsion of the oil from coal.
1998, 16(1): 107-111.
Abstract:
Discussed the principal features of the strontium isotope composition in oceanic carbonates and the sulfurisotope composition (pyrites)in the black shale,as well as the significance of the palao-oceanic geology in theMiddle Cretaceous in the South Tibet, as follows. 1. The 87Sr/8Sr ratio in the oceanic carbonate was about 0. 708 4-0. 709 0. Strontium originated fromthe crust amounted to 28%一3000.The influence inputted from the continental materials in the studied areawas greater than that in the other areas. The 87Sr/86Sr value in the volcanic lava was 0. 709 5,and higher thanthe average value of the synchronous basalt. The strontium,originated from the crust,in the volcanic lave ac-counted for 65.2 X 10-6 , amounting to 34%in the total. A large number of the crust origin materials was as-similated in the forming process of the volcanic lava. 2. The sulfur isotope composition (pyrites) in the black shale was 27%-31. 6%.The sulfur originatedfrom the synchronous seawater sulfate,and the pyrite was the diagenetic product in the middle— late diage-nesis. The δ34S (pyrites)，formed in the different time and environment, was very different. The sulfur iso-topes could reflect the environment evolution process in the diagenesis.
Discussed the principal features of the strontium isotope composition in oceanic carbonates and the sulfurisotope composition (pyrites)in the black shale,as well as the significance of the palao-oceanic geology in theMiddle Cretaceous in the South Tibet, as follows. 1. The 87Sr/8Sr ratio in the oceanic carbonate was about 0. 708 4-0. 709 0. Strontium originated fromthe crust amounted to 28%一3000.The influence inputted from the continental materials in the studied areawas greater than that in the other areas. The 87Sr/86Sr value in the volcanic lava was 0. 709 5,and higher thanthe average value of the synchronous basalt. The strontium,originated from the crust,in the volcanic lave ac-counted for 65.2 X 10-6 , amounting to 34%in the total. A large number of the crust origin materials was as-similated in the forming process of the volcanic lava. 2. The sulfur isotope composition (pyrites) in the black shale was 27%-31. 6%.The sulfur originatedfrom the synchronous seawater sulfate,and the pyrite was the diagenetic product in the middle— late diage-nesis. The δ34S (pyrites)，formed in the different time and environment, was very different. The sulfur iso-topes could reflect the environment evolution process in the diagenesis.
1998, 16(1): 120-125.
Abstract:
Sedimentational/syngenetic(SS),diagenetic(DG) and post-diagenetic(PD) carbonate minerals in the im-mature oil source rocks of the upper part of the Shasi member in Dongying Depression were identified undermicroscope and analyzed by EPMA(electronic probe micro-analysis). Three composition change patterns wereproposed as follows:(1) The Mg/Ca atomic ratio deceases from 0. 9 in the SS carbonate to 0. O1 in the DGone;(2)the Mg/Ca ratio keeps high values in the SS and DG ones，but it becomes very low in the PS ones;and(3) the ratio increase largely from the SS carbonate to the DG ones. According to the relationship betweensalinity of pore-fluids and the Mg/Ca ratio of carbonates,the above patterns were considered as the result ofdifferent environmental evolution histories from the SS to DG，then to PS stages. The salinity of diageneticpore-fluid was. proved very high in the center of the depression,which was believed to have been favorable. tothe generation of immature oil in the area. In addition,the research methods in this paper might be useful forsimilar studies in other areas.
Sedimentational/syngenetic(SS),diagenetic(DG) and post-diagenetic(PD) carbonate minerals in the im-mature oil source rocks of the upper part of the Shasi member in Dongying Depression were identified undermicroscope and analyzed by EPMA(electronic probe micro-analysis). Three composition change patterns wereproposed as follows:(1) The Mg/Ca atomic ratio deceases from 0. 9 in the SS carbonate to 0. O1 in the DGone;(2)the Mg/Ca ratio keeps high values in the SS and DG ones，but it becomes very low in the PS ones;and(3) the ratio increase largely from the SS carbonate to the DG ones. According to the relationship betweensalinity of pore-fluids and the Mg/Ca ratio of carbonates,the above patterns were considered as the result ofdifferent environmental evolution histories from the SS to DG，then to PS stages. The salinity of diageneticpore-fluid was. proved very high in the center of the depression,which was believed to have been favorable. tothe generation of immature oil in the area. In addition,the research methods in this paper might be useful forsimilar studies in other areas.
1998, 16(1): 132-136.
Abstract:
Diagenetic facies refers to a rock body which is characteristic of diagenetic fabric. The main purpose ofdiagenetic facies study is to make it clear the evolution of diagenetic envirenment by studying epigenetic diver-sion of unstable particles in deposition under different diagenetic conditions. In this paper，four basic types ofdiagenetic facies were identified in the reef facies system by studying diagenetic characters of the Late Permi-an reef in Cili，Hunan Province. They were the sea floor diagenetic facies，fresh-saline water diagenetic fa-ties，deep-buried diagenetic facies and fresh-water diagenetic facies. Some of the facies can be subdivided fur-ther
Diagenetic facies refers to a rock body which is characteristic of diagenetic fabric. The main purpose ofdiagenetic facies study is to make it clear the evolution of diagenetic envirenment by studying epigenetic diver-sion of unstable particles in deposition under different diagenetic conditions. In this paper，four basic types ofdiagenetic facies were identified in the reef facies system by studying diagenetic characters of the Late Permi-an reef in Cili，Hunan Province. They were the sea floor diagenetic facies，fresh-saline water diagenetic fa-ties，deep-buried diagenetic facies and fresh-water diagenetic facies. Some of the facies can be subdivided fur-ther
1998, 16(1): 140-145.
Abstract:
TheJiaolai basin is a Late Mesozoic fault basin anud has an extensive outcroping coerae elastic system is its narthasst border. Based.the minutefiled macroexamination indoor macroexamination and gold-conbeat test on the trsc an the casxx daatic naennbar a the utudy area,thedeposits and established thdr sedimentary eequenceb acrd types of ssome typical dspositional associations in the diffrrent.it was suggested that different dspositional hydrodynamic candition is the main reason causingthe complicated icated chasrge texture in a xonglomerate bed By comparing domestic and aborad information,thispaper poinred out that the clatatec rnembar forms in a dry. prcaumal quickly-accumulattedsubaerial slludiel fan environment ,and it also probed into the gold-bearing behaviour of this member.
TheJiaolai basin is a Late Mesozoic fault basin anud has an extensive outcroping coerae elastic system is its narthasst border. Based.the minutefiled macroexamination indoor macroexamination and gold-conbeat test on the trsc an the casxx daatic naennbar a the utudy area,thedeposits and established thdr sedimentary eequenceb acrd types of ssome typical dspositional associations in the diffrrent.it was suggested that different dspositional hydrodynamic candition is the main reason causingthe complicated icated chasrge texture in a xonglomerate bed By comparing domestic and aborad information,thispaper poinred out that the clatatec rnembar forms in a dry. prcaumal quickly-accumulattedsubaerial slludiel fan environment ,and it also probed into the gold-bearing behaviour of this member.
1998, 16(1): 152-156.
Abstract:
Gurbantonggut Desert is the second largest desert in China. It forms in an arid area far away from seasand oceans ,and does not be affected by monsoon. Under the influence of the regional topography and west-ern air current，a particular regional climatic environment forms. This paper mainly discusses the granularcomposition of surface sand in the different types of sand deserts (moving sand desert and fixed sand desert)in Gurbantonggut Desert，and the interrelation between sand granularity and heat transmission in sand layerand sand moisture content. The results of field observation and sample analysis show that heat transmissionand moisture movement in sand layer as well as evaporation from sand surface of the different types of thedesert are directly related to sand granular composition. Moreover,sand granular composition plays an impor-tant role in sensible heat and latent heat of sand surface and feedback of the desert to climate. Meanwhile，sand granularity and change process of water and heat transmission directly influence the survival rate andgrowth of plants in the desert ,and have an important effect on desert climate and environment.
Gurbantonggut Desert is the second largest desert in China. It forms in an arid area far away from seasand oceans ,and does not be affected by monsoon. Under the influence of the regional topography and west-ern air current，a particular regional climatic environment forms. This paper mainly discusses the granularcomposition of surface sand in the different types of sand deserts (moving sand desert and fixed sand desert)in Gurbantonggut Desert，and the interrelation between sand granularity and heat transmission in sand layerand sand moisture content. The results of field observation and sample analysis show that heat transmissionand moisture movement in sand layer as well as evaporation from sand surface of the different types of thedesert are directly related to sand granular composition. Moreover,sand granular composition plays an impor-tant role in sensible heat and latent heat of sand surface and feedback of the desert to climate. Meanwhile，sand granularity and change process of water and heat transmission directly influence the survival rate andgrowth of plants in the desert ,and have an important effect on desert climate and environment.
