Based on comprehensive analysis of tectonic and fault evolution, core, well logging, seismic, drilling, and production data, the reservoir space characteristic, distribution, origin of fault-karst carbonate reservoir ...Based on comprehensive analysis of tectonic and fault evolution, core, well logging, seismic, drilling, and production data, the reservoir space characteristic, distribution, origin of fault-karst carbonate reservoir in Yueman block of South Tahe area, Halahatang oilfield, Tarim Basin, were studied systematically. And the regular pattern of hydrocarbon accumulation and enrichment was analyzed systematically based on development practice of the reservoirs. The results show that fault-karst carbonate reservoirs are distributed in the form of "body by body" discontinuously, heterogeneously and irregularly, which are controlled by the development of faults. Three formation models of fault-karst carbonate reservoirs, namely, the models controlled by the main deep-large fault, the secondary fault and the secondary internal fault, are built. The hydrocarbon accumulation and enrichment of fault-karst carbonate reservoirs is controlled by the spatiotemporal matching relation between hydrocarbon generation period and fault activity, and the size and segmentation of fault. The study results can effectively guide the well deployment and help the efficient development of fault-karst carbonate reservoirs of South Tahe area, Halahatang oilfield.展开更多
The lower Cambrian Niutitang Formation hydrocarbon source rocks at the Dingshan- Lintanchang structure in the southeast Sichuan Basin were of medium-good quality with two excellent hydrocarbon-generating centers devel...The lower Cambrian Niutitang Formation hydrocarbon source rocks at the Dingshan- Lintanchang structure in the southeast Sichuan Basin were of medium-good quality with two excellent hydrocarbon-generating centers developed in the periphery areas, with a possibility of forming a medium to large-sized oil-gas field. Good reservoir rocks were the upper Sinian （Dengying Formation） dolomites. The mudstone in the lower Cambrian Niutitang Formation with a good sealing capacity was the cap rock. The widely occurring bitumen in the Dengying Formation indicates that a paleo oil pool was once formed in the study area. The first stage of paleo oil pool formation was maturation of the lower Cambrian source rocks during the late Ordovician. Hydrocarbon generation from the lower Cambrian source rocks stopped due to the Devonian-Carboniferous uplifting. The lower Cambrian source rocks then restarted generation of large quantities of hydrocarbons after deposition of the middle Permian sediments. This was the second stage of the paleo oil pool formation. The oil in the paleo oil pool began to crack during the late Triassic and a paleo gas pool was formed. This paleo gas pool was destroyed during the Yanshan-Himalayan folding, uplifting and denudation. Bitumen can be widely seen in the Dengying Formation in wells and outcrops in the Sichuan Basin and its periphery areas. This provides strong evidence that the Dengying Formation in the Sichuan Basin and its periphery areas was once an ultra-large structural-lithologic oil-gas field, which was damaged during the Yanshan-Himalayan period.展开更多
The depth is important for ore finding in Jiaodong gold deposit. However, many geologists are still discussing how to confirm the depth for the tectonic and metallogenesis formation. The authors of this paper propose ...The depth is important for ore finding in Jiaodong gold deposit. However, many geologists are still discussing how to confirm the depth for the tectonic and metallogenesis formation. The authors of this paper propose a new method-the correction of metallogenic depth via its structure to calculate the depth. This method, based on the crust rock in a solid stress state, emphasizes the elastic pattern rather than the static fluid pattern. In addition, this method is more appropriate to the actual situation in the crust than the method of weight/special weight. The authors of this paper illustrating, with the Jiaodong gold deposit as an example, the metallogenic depth correction via structure conclude that the depth of the most deposits, lower than 4-6 km, is often 2.5 km. Therefore, the authors suggest that there exists a second enrichment belt and that ore resources are more potential at the belt of Jiaodong area. These results have been demonstrated by years of exploration.展开更多
The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58elements including Au from 746 sediment samples at 736 sampling sites,corresponding to a sampling density of about one si...The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58elements including Au from 746 sediment samples at 736 sampling sites,corresponding to a sampling density of about one site per 1000 km2.Under strict quality control using field duplicates,certified reference materials,and analytical replicate samples,the Au was determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS).The detection limit of Au was 0.20×10^(-9).The 95%range(2.5%–97.5%)of Au concentrations was from 0.24×10^(-9) to 1.36×10^(-9),and the median value was 0.40×10^(-9).The most noticeable Au distribution patterns shown on the map are mainly located between Lusaka and Ndola(Lufilian Arc Belt).In addition,several high Au value areas occurred in Mansa,Muyombe,Chipata,and Livingstone.The spatial distribution patterns of Au in tectonic units,drainage basins,and geomorphological landscapes could be related to the Lufilian Arc Belt and Bangweulu Block.The Au concentrations show metallogenic belts between Muyombe and Mbala areas,between Mansa and Ndola areas,and between Lusaka and Kasempa areas.展开更多
It has been suggested that eclogites in the Dabie orogenic be lt are exhumation products, which had subducted into the deep-seated mantle and undergone ultra-high pressure metamorphism during the Triassic. But no dire...It has been suggested that eclogites in the Dabie orogenic be lt are exhumation products, which had subducted into the deep-seated mantle and undergone ultra-high pressure metamorphism during the Triassic. But no direct evidence supports this process except the calculated p-T conditions from mineral thermobarometers. The Late Cretaceous basalts studied in the prese nt paper, however, have provided some geochemical evidence for crust-mantle int eraction in the area. These basalts are distributed in Mesozoic faulted basins i n central and southern Dabie orogenic belt. Since little obvious contamination f rom continental crust and differentiation-crystallization were observed, it is suggested, based on a study of trace elements, that the basalts are alkaline and resultant from batch partial melting of the regional mantle rocks, and share th e same or similar geochemical features with respect to their magma source. In th e spider diagram normalized by the primitive mantle, trace element geochemistry data show that their mantle sources are enriched in certain elements concentrate d in the continental crust, such as Pb, K, Rb and Ba, and slightly depleted in s ome HFSE such as Hf, P and Nb. Pb-Sr-Nd isotopic compositions further suggest the mantle is the mixture of depleted mantle and enriched one . T his interaction can explain the trace element characteristics of basaltic magmas , i.e., the enrichment of Pb and the depletion of Hf, P and Nb in basalts can be interpreted by the blending of the eclogites in DOB (enriched in Pb and deplete d in Hf, P and Nd) with the East China depleted mantle (As compared to the primi tive mantle, it is neither enriched in Pb nor depleted in Hf, P and Nb). It is a lso indicated that the eclogites in the Dabie orogenic belt were surely derived from the exhumation materials, which had delaminated into the deep-seated mantl e. Moreover, the process subsequently resulted in compositional variation of the mantle (especially in trace elements and isotopes), as revealed by the late man tle-derived basalts in the Dabie orogenic belt.展开更多
基金Supported by the China National Sicence and Technology Project(2016ZX05004)
文摘Based on comprehensive analysis of tectonic and fault evolution, core, well logging, seismic, drilling, and production data, the reservoir space characteristic, distribution, origin of fault-karst carbonate reservoir in Yueman block of South Tahe area, Halahatang oilfield, Tarim Basin, were studied systematically. And the regular pattern of hydrocarbon accumulation and enrichment was analyzed systematically based on development practice of the reservoirs. The results show that fault-karst carbonate reservoirs are distributed in the form of "body by body" discontinuously, heterogeneously and irregularly, which are controlled by the development of faults. Three formation models of fault-karst carbonate reservoirs, namely, the models controlled by the main deep-large fault, the secondary fault and the secondary internal fault, are built. The hydrocarbon accumulation and enrichment of fault-karst carbonate reservoirs is controlled by the spatiotemporal matching relation between hydrocarbon generation period and fault activity, and the size and segmentation of fault. The study results can effectively guide the well deployment and help the efficient development of fault-karst carbonate reservoirs of South Tahe area, Halahatang oilfield.
基金supported by the National Basic Research Program of China (No. 2005CB422106)
文摘The lower Cambrian Niutitang Formation hydrocarbon source rocks at the Dingshan- Lintanchang structure in the southeast Sichuan Basin were of medium-good quality with two excellent hydrocarbon-generating centers developed in the periphery areas, with a possibility of forming a medium to large-sized oil-gas field. Good reservoir rocks were the upper Sinian （Dengying Formation） dolomites. The mudstone in the lower Cambrian Niutitang Formation with a good sealing capacity was the cap rock. The widely occurring bitumen in the Dengying Formation indicates that a paleo oil pool was once formed in the study area. The first stage of paleo oil pool formation was maturation of the lower Cambrian source rocks during the late Ordovician. Hydrocarbon generation from the lower Cambrian source rocks stopped due to the Devonian-Carboniferous uplifting. The lower Cambrian source rocks then restarted generation of large quantities of hydrocarbons after deposition of the middle Permian sediments. This was the second stage of the paleo oil pool formation. The oil in the paleo oil pool began to crack during the late Triassic and a paleo gas pool was formed. This paleo gas pool was destroyed during the Yanshan-Himalayan folding, uplifting and denudation. Bitumen can be widely seen in the Dengying Formation in wells and outcrops in the Sichuan Basin and its periphery areas. This provides strong evidence that the Dengying Formation in the Sichuan Basin and its periphery areas was once an ultra-large structural-lithologic oil-gas field, which was damaged during the Yanshan-Himalayan period.
文摘The depth is important for ore finding in Jiaodong gold deposit. However, many geologists are still discussing how to confirm the depth for the tectonic and metallogenesis formation. The authors of this paper propose a new method-the correction of metallogenic depth via its structure to calculate the depth. This method, based on the crust rock in a solid stress state, emphasizes the elastic pattern rather than the static fluid pattern. In addition, this method is more appropriate to the actual situation in the crust than the method of weight/special weight. The authors of this paper illustrating, with the Jiaodong gold deposit as an example, the metallogenic depth correction via structure conclude that the depth of the most deposits, lower than 4-6 km, is often 2.5 km. Therefore, the authors suggest that there exists a second enrichment belt and that ore resources are more potential at the belt of Jiaodong area. These results have been demonstrated by years of exploration.
基金financially supported by the Sino-Zambian Cooperation in Geological and Geochemical Mapping(2012–2015)the China-Aid Airborne Geophysical Survey and Geochemical and Geological Mapping Technical Cooperation Project(2015–2019)the geological investigation project of the China Geological Survey(DD20201150,DD20201148,DD20190439)。
文摘The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58elements including Au from 746 sediment samples at 736 sampling sites,corresponding to a sampling density of about one site per 1000 km2.Under strict quality control using field duplicates,certified reference materials,and analytical replicate samples,the Au was determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS).The detection limit of Au was 0.20×10^(-9).The 95%range(2.5%–97.5%)of Au concentrations was from 0.24×10^(-9) to 1.36×10^(-9),and the median value was 0.40×10^(-9).The most noticeable Au distribution patterns shown on the map are mainly located between Lusaka and Ndola(Lufilian Arc Belt).In addition,several high Au value areas occurred in Mansa,Muyombe,Chipata,and Livingstone.The spatial distribution patterns of Au in tectonic units,drainage basins,and geomorphological landscapes could be related to the Lufilian Arc Belt and Bangweulu Block.The Au concentrations show metallogenic belts between Muyombe and Mbala areas,between Mansa and Ndola areas,and between Lusaka and Kasempa areas.
文摘It has been suggested that eclogites in the Dabie orogenic be lt are exhumation products, which had subducted into the deep-seated mantle and undergone ultra-high pressure metamorphism during the Triassic. But no direct evidence supports this process except the calculated p-T conditions from mineral thermobarometers. The Late Cretaceous basalts studied in the prese nt paper, however, have provided some geochemical evidence for crust-mantle int eraction in the area. These basalts are distributed in Mesozoic faulted basins i n central and southern Dabie orogenic belt. Since little obvious contamination f rom continental crust and differentiation-crystallization were observed, it is suggested, based on a study of trace elements, that the basalts are alkaline and resultant from batch partial melting of the regional mantle rocks, and share th e same or similar geochemical features with respect to their magma source. In th e spider diagram normalized by the primitive mantle, trace element geochemistry data show that their mantle sources are enriched in certain elements concentrate d in the continental crust, such as Pb, K, Rb and Ba, and slightly depleted in s ome HFSE such as Hf, P and Nb. Pb-Sr-Nd isotopic compositions further suggest the mantle is the mixture of depleted mantle and enriched one . T his interaction can explain the trace element characteristics of basaltic magmas , i.e., the enrichment of Pb and the depletion of Hf, P and Nb in basalts can be interpreted by the blending of the eclogites in DOB (enriched in Pb and deplete d in Hf, P and Nd) with the East China depleted mantle (As compared to the primi tive mantle, it is neither enriched in Pb nor depleted in Hf, P and Nb). It is a lso indicated that the eclogites in the Dabie orogenic belt were surely derived from the exhumation materials, which had delaminated into the deep-seated mantl e. Moreover, the process subsequently resulted in compositional variation of the mantle (especially in trace elements and isotopes), as revealed by the late man tle-derived basalts in the Dabie orogenic belt.
