E. Ameh, M. S. Kolawole, S. O. Idakwo, C. Ameh, Ebo GabrielImeokparia
Soil samples were collected randomly but uniformly distributed around Itakpe iron-ore mines in both dry and wet seasons. Surface soils were collected from 0cm to 10cm using stainless steel augers and located using Global Positioning System (GPS). Soil samples were air-dried, sieved through 500um mesh and 1.0g digested, evaporated and analysed using Atomic Absorption Spectrometer (AAS).Five (5) geo-environmental indices were used to quantitatively evaluate the degree of soil contamination due to iron ore mining. The anthropogenic factor (AF) for both seasons revealed that all heavy metals have greater than 50% AF except for Cd in the dry season. The geo accumulation index (Igeo) for both seasons showed background concentration to unpolluted for Cu and Zn while Fe, Ni, Cdand Pb recorded moderately to very highly polluted. The pollution index (Eri), showed tiny hazard level for all the heavy metals in dry season and in wet season, Cd and Ni recorded strong hazard level while tiny hazard level were observed for Cu and Pb. The ecological pollution index for the area is strong (RI=323.25). Dry and wet season enrichment factor (EF) revealed background concentration for all the heavy metals except Fe with EF> 40 (extremely high enrichment). While contamination factor (CF) was very high for Fe in both seasons, Cu and Ni recorded considerable to very high contamination in dry season. The wet season also revealed considerable contamination for Ni and Cd; moderate to considerable contamination for Cu, Zn and Pb. The sites in both seasons have experienced various degrees of deterioration but more significant in wet season. Based on these indices, the soils around Itakpe iron-ore area has suffered significant degrees of contaminations with respect to Fe, Ni, Cd and Pb.
{"title":"Distributional Coefficients and Enrichment Studies of Potentially Toxic Heavy Metals in Soils Around Itakpe Iron-Ore Mine, North Central Nigeria","authors":"E. Ameh, M. S. Kolawole, S. O. Idakwo, C. Ameh, Ebo GabrielImeokparia","doi":"10.5539/ESR.V6N1P85","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P85","url":null,"abstract":"Soil samples were collected randomly but uniformly distributed around Itakpe iron-ore mines in both dry and wet seasons. Surface soils were collected from 0cm to 10cm using stainless steel augers and located using Global Positioning System (GPS). Soil samples were air-dried, sieved through 500um mesh and 1.0g digested, evaporated and analysed using Atomic Absorption Spectrometer (AAS).Five (5) geo-environmental indices were used to quantitatively evaluate the degree of soil contamination due to iron ore mining. The anthropogenic factor (AF) for both seasons revealed that all heavy metals have greater than 50% AF except for Cd in the dry season. The geo accumulation index (Igeo) for both seasons showed background concentration to unpolluted for Cu and Zn while Fe, Ni, Cdand Pb recorded moderately to very highly polluted. The pollution index (Eri), showed tiny hazard level for all the heavy metals in dry season and in wet season, Cd and Ni recorded strong hazard level while tiny hazard level were observed for Cu and Pb. The ecological pollution index for the area is strong (RI=323.25). Dry and wet season enrichment factor (EF) revealed background concentration for all the heavy metals except Fe with EF> 40 (extremely high enrichment). While contamination factor (CF) was very high for Fe in both seasons, Cu and Ni recorded considerable to very high contamination in dry season. The wet season also revealed considerable contamination for Ni and Cd; moderate to considerable contamination for Cu, Zn and Pb. The sites in both seasons have experienced various degrees of deterioration but more significant in wet season. Based on these indices, the soils around Itakpe iron-ore area has suffered significant degrees of contaminations with respect to Fe, Ni, Cd and Pb.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"9 1","pages":"85"},"PeriodicalIF":0.0,"publicationDate":"2016-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84149903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lifei Zou, Yang Yang, Xuyang Zhang, Ruixue Li, Q. Miao
Huayuan lead-zinc ore field in Zhangjiajie of western Hunan, is a large-sized, and the ore bodies algal limestones the margin of the shallow platform in the lower part of the Early Cambrian Qingxudong Formation. The authors expounded the ore-hosting lithology, sedimentary environment and petrographic evolution of Huayuan lead-zinc ore field. According to the metallogenic characteristics of the Huayuan lead-zinc ore field, the formation and evolution of the ore field is divided into the First construction (geological processes), the secondary construction (lithofacies characteristics) and the third-level construction (basic rock unit).
{"title":"Analysis on the Construction of Huayuan MVT Lead - Zinc Ore Field in Zhangjiajie of the Western Hunan, China","authors":"Lifei Zou, Yang Yang, Xuyang Zhang, Ruixue Li, Q. Miao","doi":"10.5539/ESR.V6N1P79","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P79","url":null,"abstract":"Huayuan lead-zinc ore field in Zhangjiajie of western Hunan, is a large-sized, and the ore bodies algal limestones the margin of the shallow platform in the lower part of the Early Cambrian Qingxudong Formation. The authors expounded the ore-hosting lithology, sedimentary environment and petrographic evolution of Huayuan lead-zinc ore field. According to the metallogenic characteristics of the Huayuan lead-zinc ore field, the formation and evolution of the ore field is divided into the First construction (geological processes), the secondary construction (lithofacies characteristics) and the third-level construction (basic rock unit).","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"53 1","pages":"79"},"PeriodicalIF":0.0,"publicationDate":"2016-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75960851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Trace and Rare Earth Elements (REEs) data are used to constrain the geochemical evolution of the amphibolites from Ifewara in the Ife-Ilesha schist belt of southwestern Nigeria. The amphibolites can be grouped into banded and sheared amphibolites. Major element data show SiO2 (48.34%), Fe2O3 (11.03-17.88%), MgO (5.76-9.90%), CaO (7.76-18.6%) and TiO2 (0.44-1.77%) contents which are similar to amphibolites in other schist belts in Nigeria. The Al2O3 (2.85-15.55%) content is varied, with the higher values suggesting alkali basalt protolith. Trace and rare earth elements composition reveal Sr (160-1077ppm), Rb (0.5-22.9ppm), Ni (4.7-10.2ppm), Co (12.2-50.9 ppm) and Cr (2-7ppm). Chondrite-normalized REE patterns show that the banded amphibolites have HREE depletion and both negative and positive Eu anomalies while the sheared variety showed slight LREE enrichment with no apparent Eu anomaly. The study amphibolites plot in the Mid Oceanic Ridge Basalts (MORB) and within plate basalt fields on the Zr/Y vs Zr discriminatory diagrams. They are further classified as volcanic arc basalt and E-type MORB on the Th- Hf/3- Ta and the Zr-Nb-Y diagrams. The amphibolites precursor is considered a tholeiitic suite that suffered crustal contamination, during emplacement in a rifted crust.
{"title":"Geochemical Characteristics and Tectonic Setting of Amphibolites in Ifewara Area, Ife-Ilesha Schist Belt, Southwestern Nigeria","authors":"A. Bolarinwa, A. A. Adepoju","doi":"10.5539/ESR.V6N1P43","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P43","url":null,"abstract":"Trace and Rare Earth Elements (REEs) data are used to constrain the geochemical evolution of the amphibolites from Ifewara in the Ife-Ilesha schist belt of southwestern Nigeria. The amphibolites can be grouped into banded and sheared amphibolites. Major element data show SiO2 (48.34%), Fe2O3 (11.03-17.88%), MgO (5.76-9.90%), CaO (7.76-18.6%) and TiO2 (0.44-1.77%) contents which are similar to amphibolites in other schist belts in Nigeria. The Al2O3 (2.85-15.55%) content is varied, with the higher values suggesting alkali basalt protolith. Trace and rare earth elements composition reveal Sr (160-1077ppm), Rb (0.5-22.9ppm), Ni (4.7-10.2ppm), Co (12.2-50.9 ppm) and Cr (2-7ppm). Chondrite-normalized REE patterns show that the banded amphibolites have HREE depletion and both negative and positive Eu anomalies while the sheared variety showed slight LREE enrichment with no apparent Eu anomaly. The study amphibolites plot in the Mid Oceanic Ridge Basalts (MORB) and within plate basalt fields on the Zr/Y vs Zr discriminatory diagrams. They are further classified as volcanic arc basalt and E-type MORB on the Th- Hf/3- Ta and the Zr-Nb-Y diagrams. The amphibolites precursor is considered a tholeiitic suite that suffered crustal contamination, during emplacement in a rifted crust.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"10 1","pages":"43"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84578769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seismic full waveform inversion seeks to make use of the full information based on full wave field modeling to extract quantitative information from seismograms. Its serious nonlinearity and high dependence on initial velocity model often results in unsatisfactory inversion results in paleo-karsts carbonate reservoir characterized by strong heterogeneity. The paper presents an improved strategy of multi-scale inversion to establish velocity field model of waveform tomography. the forward wave equation algorithm was derived in frequency domain, and then the Matrix formalism for the iterative inverse methods is derived by gradient methods to speed up calculation and to avoid convergence to local minimum value. After massive amount of frequencies tests, the appropriate bandwidth are extracted, and the velocity field calculated at low frequency is used as the input of the high frequency. After the iteration, the accurate velocity field is inverted. Finally, frequency domain wave equation full waveform inversion in mathematical and physical models is conducted in order to verify the inverse program. The method of selecting the inverse frequencies is proved to be effective.
{"title":"Frequency Domain Wave Equation Inversion and Its Application on the Heterogeneous Reservoir Model Data","authors":"Zhiyuan Tang","doi":"10.5539/ESR.V6N1P55","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P55","url":null,"abstract":"Seismic full waveform inversion seeks to make use of the full information based on full wave field modeling to extract quantitative information from seismograms. Its serious nonlinearity and high dependence on initial velocity model often results in unsatisfactory inversion results in paleo-karsts carbonate reservoir characterized by strong heterogeneity. The paper presents an improved strategy of multi-scale inversion to establish velocity field model of waveform tomography. the forward wave equation algorithm was derived in frequency domain, and then the Matrix formalism for the iterative inverse methods is derived by gradient methods to speed up calculation and to avoid convergence to local minimum value. After massive amount of frequencies tests, the appropriate bandwidth are extracted, and the velocity field calculated at low frequency is used as the input of the high frequency. After the iteration, the accurate velocity field is inverted. Finally, frequency domain wave equation full waveform inversion in mathematical and physical models is conducted in order to verify the inverse program. The method of selecting the inverse frequencies is proved to be effective.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"19 1","pages":"55"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86224361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metallic ores of economic values often occur within profiles above basement rocks in tropical regions due to weathering and secondary enrichment. This study is carried out to determine the geochemistry and appraise the potential for metallic ore enrichment in the weathered profiles over Syenite and Younger Granite in Pankshin area. Top-soil, laterite and rock samples are collected from two lateritic profiles above Syenite and Younger Granite. The syenite rock is composed of alkali feldspars (perthite), nepheline, clinopyroxene, with minor amount of orthopyroxene, hornblende, plagioclase and few quartz grains, indicating oversaturation. The Younger Granite contains plagioclase feldspars, microcline, quartz, biotite, hornblende and reibeckite. Quartz (61.0%), kaolinite (32.0%) and microcline (7.0%) are the dominant minerals in the X-ray diffraction (XRD) of the decomposed rocks. The Chemical Index of Alteration (CIA) of both rocks is generally >90. There are enhancements of V, Sc, Zr and TiO2 in the Syenite profile and Fe2O3, Zr, V and TiO2 in the Younger Granite profile as reflected in the Accumulation Factor (AF), loss and gain of elements (K), though the values were too low for ore mineralization except for iron and titanium in the Younger Granite profile.
{"title":"Geochemistry of Weathered Profiles over Syenite and Younger Granite in Pankshin Area, North Central Nigeria","authors":"A. Bolarinwa, A. J. Adeola","doi":"10.5539/ESR.V6N1P63","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P63","url":null,"abstract":"Metallic ores of economic values often occur within profiles above basement rocks in tropical regions due to weathering and secondary enrichment. This study is carried out to determine the geochemistry and appraise the potential for metallic ore enrichment in the weathered profiles over Syenite and Younger Granite in Pankshin area. Top-soil, laterite and rock samples are collected from two lateritic profiles above Syenite and Younger Granite. The syenite rock is composed of alkali feldspars (perthite), nepheline, clinopyroxene, with minor amount of orthopyroxene, hornblende, plagioclase and few quartz grains, indicating oversaturation. The Younger Granite contains plagioclase feldspars, microcline, quartz, biotite, hornblende and reibeckite. Quartz (61.0%), kaolinite (32.0%) and microcline (7.0%) are the dominant minerals in the X-ray diffraction (XRD) of the decomposed rocks. The Chemical Index of Alteration (CIA) of both rocks is generally >90. There are enhancements of V, Sc, Zr and TiO2 in the Syenite profile and Fe2O3, Zr, V and TiO2 in the Younger Granite profile as reflected in the Accumulation Factor (AF), loss and gain of elements (K), though the values were too low for ore mineralization except for iron and titanium in the Younger Granite profile.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"89 1","pages":"63"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76182101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The early and mid 20th century was a time of great interest in the rise of agriculture and its role in the evolution of civilizations societies in particular environments. Late 20th century efforts to reconstruct the nature and history of prehistoric farming societies in the northern lowlands of South America ranged from expansive hypotheses to regional case studies using archaeobotanical technologies then available. Since 2000, a large number of regional studies using expanded and refined methods have produced broadly interesting results. Approaches from the fields of geography and earth sciences are being recruited increasingly. The resulting empirical evidence does shed light on aspects of the history of human use of some plants but, as always, has raised more questions than it solved. Many of the problems interpreting the processual and evolutionary significance of these findings are methodological ones. This article reviews what seem to be the most important methodological and interpretive issues of this area of research for the tropical lowlands (up to c. 1500 m a.s.l) of northern South America.
{"title":"Method and Theory of Early Farming: The Orinoco and Caribbean Coasts of South America","authors":"A. Roosevelt","doi":"10.5539/ESR.V6N1P1","DOIUrl":"https://doi.org/10.5539/ESR.V6N1P1","url":null,"abstract":"The early and mid 20th century was a time of great interest in the rise of agriculture and its role in the evolution of civilizations societies in particular environments. Late 20th century efforts to reconstruct the nature and history of prehistoric farming societies in the northern lowlands of South America ranged from expansive hypotheses to regional case studies using archaeobotanical technologies then available. Since 2000, a large number of regional studies using expanded and refined methods have produced broadly interesting results. Approaches from the fields of geography and earth sciences are being recruited increasingly. The resulting empirical evidence does shed light on aspects of the history of human use of some plants but, as always, has raised more questions than it solved. Many of the problems interpreting the processual and evolutionary significance of these findings are methodological ones. This article reviews what seem to be the most important methodological and interpretive issues of this area of research for the tropical lowlands (up to c. 1500 m a.s.l) of northern South America.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"1 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2016-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84403356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The potential for conventional and/or unconventional hydrocarbon exploration requires the presence of organic-rich, thermally mature rock units containing oil or gas-prone kerogen. Thick black, organic rich shale intervals are well exposed along roadside cuts and river banks at several localities in the eastern part of the Mamfe Basin. Earlier described as anoxic lake bottom deposits, these fine grained rocks constitute the probable pod of active source rock in this basin and belonging to the middle stratigraphic unit of the three that make up the basin’s sedimentary fill. Samples collected from representative outcrop sections (Etoko mile 21, Bachuo Ntai, and Satom Bridge) in the study area were subjected to geochemical analytic techniques; Total Organic Carbon (TOC), Rock-Eval Pyrolysis and Vitrinite reflectance (%Ro) values were calculated. TOC data obtained range from 1.06% to 16.10% indicating good to excellent hydrocarbon generative potentials, Rock-Eval Pyrolysis data plotted along Kerogen Types I, II and III with oil and gas generative potentials. 4 out of 9 samples fall within the oil window from the calculated %Ro while temperatures corresponding to the peak of kerogen pyrolysis (Tmax) and Production Index (PI) for the 9 samples range from 398oC to 463oC indicating that the organic matter (OM) are immature to post mature.The black shale unit of this part of the basin therefore contains very high amounts of good to excellent quality of thermally matured organic matter which can produce and expel oil and gas respectively.
{"title":"Hydrocarbon Source Rock Potential of the Lacustrine Black Shale Unit, Mamfe Basin, Cameroon, West Africa","authors":"Njoh Olivier Anoh, Njie Sarah Mesanga","doi":"10.5539/ESR.V5N2P217","DOIUrl":"https://doi.org/10.5539/ESR.V5N2P217","url":null,"abstract":"The potential for conventional and/or unconventional hydrocarbon exploration requires the presence of organic-rich, thermally mature rock units containing oil or gas-prone kerogen. Thick black, organic rich shale intervals are well exposed along roadside cuts and river banks at several localities in the eastern part of the Mamfe Basin. Earlier described as anoxic lake bottom deposits, these fine grained rocks constitute the probable pod of active source rock in this basin and belonging to the middle stratigraphic unit of the three that make up the basin’s sedimentary fill. Samples collected from representative outcrop sections (Etoko mile 21, Bachuo Ntai, and Satom Bridge) in the study area were subjected to geochemical analytic techniques; Total Organic Carbon (TOC), Rock-Eval Pyrolysis and Vitrinite reflectance (%Ro) values were calculated. TOC data obtained range from 1.06% to 16.10% indicating good to excellent hydrocarbon generative potentials, Rock-Eval Pyrolysis data plotted along Kerogen Types I, II and III with oil and gas generative potentials. 4 out of 9 samples fall within the oil window from the calculated %Ro while temperatures corresponding to the peak of kerogen pyrolysis (Tmax) and Production Index (PI) for the 9 samples range from 398oC to 463oC indicating that the organic matter (OM) are immature to post mature.The black shale unit of this part of the basin therefore contains very high amounts of good to excellent quality of thermally matured organic matter which can produce and expel oil and gas respectively.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"12 1","pages":"217"},"PeriodicalIF":0.0,"publicationDate":"2016-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90446237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acidic volcanic rocks of Shetang-Boyang area are located in the western Qinling orogenic belt, consist of rhyolite and granite porphyry. They are comparable in the chemical composition, enriched in Si, alkali, Al and a little bit of Mg, Ca and Ti. The contents of HFSE (Zr, Hf) and LILE (Rb, Th, U) are high, however, the content of Ba, Sr, Ti, P have obviously depleted and there are obvious negative Eu anomalies (Eu/Eu*=0.06-0.13). These geochemical characteristics are revealed that these volcanic rocks have an A 1 type affinity. Geochemical data combined with regional studies, show that these volcanic rocks were formed in a continental extension setting and the western Qinling orogenic belt in 211Ma has been in the tectonic setting of post-collisional extension.
{"title":"Geochemical Characteristics and Tectonic Significance of the Acidic Volcanic Rocks from the Shetang-Boyang Area, Western Qinling Orogenic Belt, China","authors":"A. Ma, Hao Guan, Lifei Zou, Lanlan Sun","doi":"10.5539/ESR.V5N2P209","DOIUrl":"https://doi.org/10.5539/ESR.V5N2P209","url":null,"abstract":"Acidic volcanic rocks of Shetang-Boyang area are located in the western Qinling orogenic belt, consist of rhyolite and granite porphyry. They are comparable in the chemical composition, enriched in Si, alkali, Al and a little bit of Mg, Ca and Ti. The contents of HFSE (Zr, Hf) and LILE (Rb, Th, U) are high, however, the content of Ba, Sr, Ti, P have obviously depleted and there are obvious negative Eu anomalies (Eu/Eu*=0.06-0.13). These geochemical characteristics are revealed that these volcanic rocks have an A 1 type affinity. Geochemical data combined with regional studies, show that these volcanic rocks were formed in a continental extension setting and the western Qinling orogenic belt in 211Ma has been in the tectonic setting of post-collisional extension.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"21 1","pages":"209"},"PeriodicalIF":0.0,"publicationDate":"2016-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88332698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuanyin Zhang, Zandong Sun, Zhijun Jin, N. Dong, Yequan Chen, Xi-wu Liu
For the modeling of complex reservoirs with strong heterogeneity, for instance the deeply buried paleokarst reservoirs in the Tarim Basin, the traditional method by lateral interpolation and extrapolation of measured logs between well locations with the guiding of interpreted seismic horizons is driven by distance and often leads to non-geologic solutions, while the past improvements via adding seismic velocities or attributes information are still not accurate due to the resolution limitation or AVO (amplitude versus offset) effects contamination. In this paper, we present an amplitude-based modeling method by utilizing the heterogeneous information from seismic data to guide the geological model construction, based on the inverted pure P-wave data which have removed the AVO effects. The proposed method is applied in the impedance inversion of the paleokarst carbonate reservoirs in the Tarim Basin, where the reservoirs are characterized by substantial heterogeneity. Both the constructed Low frequency model (LFM) and the inverted impedance results of proposed method are more correlative with drilling data than that of traditional method. This method is more beneficial for strong heterogeneous reservoirs description especially in well insufficient or absent areas, suggested by the comparisons with traditional methods in the ZG8 area.
{"title":"An Amplitude-Based Modeling Method and its Application on the Impedance Inversion in Heterogeneous Paleokarst Carbonate Reservoirs","authors":"Yuanyin Zhang, Zandong Sun, Zhijun Jin, N. Dong, Yequan Chen, Xi-wu Liu","doi":"10.5539/ESR.V5N2P199","DOIUrl":"https://doi.org/10.5539/ESR.V5N2P199","url":null,"abstract":"For the modeling of complex reservoirs with strong heterogeneity, for instance the deeply buried paleokarst reservoirs in the Tarim Basin, the traditional method by lateral interpolation and extrapolation of measured logs between well locations with the guiding of interpreted seismic horizons is driven by distance and often leads to non-geologic solutions, while the past improvements via adding seismic velocities or attributes information are still not accurate due to the resolution limitation or AVO (amplitude versus offset) effects contamination. In this paper, we present an amplitude-based modeling method by utilizing the heterogeneous information from seismic data to guide the geological model construction, based on the inverted pure P-wave data which have removed the AVO effects. The proposed method is applied in the impedance inversion of the paleokarst carbonate reservoirs in the Tarim Basin, where the reservoirs are characterized by substantial heterogeneity. Both the constructed Low frequency model (LFM) and the inverted impedance results of proposed method are more correlative with drilling data than that of traditional method. This method is more beneficial for strong heterogeneous reservoirs description especially in well insufficient or absent areas, suggested by the comparisons with traditional methods in the ZG8 area.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"141 3 1","pages":"199"},"PeriodicalIF":0.0,"publicationDate":"2016-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76183966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Kepezhinskas, Glenn M.D. Eriksen, N. Kepezhinskas
Geology of the Norwegian Lapland is dominated by diverse Archean crystalline basement complexes superimposed with Proterozoic greenstone belts. Isotopic dating of detrital zircons from basement gneisses in the Kirkenes area establishes presence of Early Archean (3.69 Ga) crustal component as well as three major episodes of crustal growth at 3.2 Ga, 2.7-2.9 Ga and 2.5 Ga. Precambrian terranes are intruded by ultramafic-mafic dikes and sills that range in composition from komatiites and ultramafic-mafic lamprophyres to high-Mg basalts and low-Ti subalkaline basalts. Geochemical characteristics of these rocks fall into three principal groups: 1) enriched compositions with high Nd, Nb, Hf, Zr and Th concentrations and elevated La/Th and Nb/Th coupled with low La/Nb, Ba/Nb and U/Nb ratios; 2) compositions depleted in Th, Hf and Nb together with low LREE/HFSE (such as La/Nb) and LILE/HFSE (such as Ba/Nb and U/Nb) ratios; 3) transitional group clearly identified by marked depletions in Ti, Nb and Ta contents coupled with enrichment in Th and U and other large-ion lithophile elements (LILE). These geochemical characteristics are interpreted within the framework of two principal source models: 1) derivation of parental ultramafic-mafic melts from multiple mantle sources (depleted to enriched) inherited from Archaean lithospheric tectonics and 2) a single primitive mantle source which underwent several depletion and enrichment episodes, at least partially associated with subduction zone processes. Subduction modification of depleted lithospheric mantle was assisted by accretion of subducted sediment to depleted mantle source at Archean, Proterozoic or Early Paleozoic convergent margin. Alkaline ultramafic rocks such as lamprophyres and mica picrites display geochemical characteristics supportive of their origin within stability field of diamond in a deep mantle beneath Norwegian Arctic margin which, together with other lithospheric characteristics, suggests its high potential for hosting economic diamond mineralization.
{"title":"Geochemistry of Ultramafic to Mafic Rocks in the Norwegian Lapland: Inferences on Mantle Sources and Implications for Diamond Exploration","authors":"P. Kepezhinskas, Glenn M.D. Eriksen, N. Kepezhinskas","doi":"10.5539/ESR.V5N2P148","DOIUrl":"https://doi.org/10.5539/ESR.V5N2P148","url":null,"abstract":"Geology of the Norwegian Lapland is dominated by diverse Archean crystalline basement complexes superimposed with Proterozoic greenstone belts. Isotopic dating of detrital zircons from basement gneisses in the Kirkenes area establishes presence of Early Archean (3.69 Ga) crustal component as well as three major episodes of crustal growth at 3.2 Ga, 2.7-2.9 Ga and 2.5 Ga. Precambrian terranes are intruded by ultramafic-mafic dikes and sills that range in composition from komatiites and ultramafic-mafic lamprophyres to high-Mg basalts and low-Ti subalkaline basalts. Geochemical characteristics of these rocks fall into three principal groups: 1) enriched compositions with high Nd, Nb, Hf, Zr and Th concentrations and elevated La/Th and Nb/Th coupled with low La/Nb, Ba/Nb and U/Nb ratios; 2) compositions depleted in Th, Hf and Nb together with low LREE/HFSE (such as La/Nb) and LILE/HFSE (such as Ba/Nb and U/Nb) ratios; 3) transitional group clearly identified by marked depletions in Ti, Nb and Ta contents coupled with enrichment in Th and U and other large-ion lithophile elements (LILE). These geochemical characteristics are interpreted within the framework of two principal source models: 1) derivation of parental ultramafic-mafic melts from multiple mantle sources (depleted to enriched) inherited from Archaean lithospheric tectonics and 2) a single primitive mantle source which underwent several depletion and enrichment episodes, at least partially associated with subduction zone processes. Subduction modification of depleted lithospheric mantle was assisted by accretion of subducted sediment to depleted mantle source at Archean, Proterozoic or Early Paleozoic convergent margin. Alkaline ultramafic rocks such as lamprophyres and mica picrites display geochemical characteristics supportive of their origin within stability field of diamond in a deep mantle beneath Norwegian Arctic margin which, together with other lithospheric characteristics, suggests its high potential for hosting economic diamond mineralization.","PeriodicalId":11486,"journal":{"name":"Earth Science Research","volume":"38 1","pages":"148"},"PeriodicalIF":0.0,"publicationDate":"2016-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84908170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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