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Open Journal of Geology 2024年第6期14卷 655-670页

作者： Gbele Ouattara Baco Traore Ziandjêdé Hervé Siagné Aboubacar Denon Souleymane Sangare Marc Ephrem Allialy Laboratoire des Sciences Gographiques du Gnie Civil et des Gosciences Institut National Polytechnique Flix HOUPHOUT-BOIGNY (INP-HB) Yamoussoukro Cte dIvoire EUREKAGEO Sarl Consulting Mining Company Bamako Republic of Mali Unit de Formation et de Recherche des Sciences de la Terre et des Ressources Minires (UFR-STRM) University of Cocody Abidjan Cte dIvoire

Post-Neoproterozoic dolerites from the Kéniéba region (Western Mali) are often associated with kimberlites. The rarity of kimberlite outcrops led to the study of doleritic rocks, spatially associated with them. The petrographic and lithogeochemical study showed that the dolerites of the Kéniéba kimberlitic fields are of tholeiitic nature and of the E-MORB (Enriched-Mid Ocean Ridge Basalt) type. This reflects an enrichment over time, compared to the Birimian dolerites of the volcano-sedimentary greenstone belt of Toumodi, in central C?te d’Ivoire. Furthermore, these dolerites are enriched in SiO2, TiO2, Zr and poor in Fe2O3, MgO. These dolerites would have formed in a late to post-orogenic intracontinental context during the breakup of Gondwana. Structurally, Kéniéba dolerites are often associated with kimberlite pipes, fractures and large deep structures identified using aeromagnetic images. Taking into account the fact that kimberlites do not outcrop in the Kéniéba region, the geochemical study coupled with the interpretation of aeromagnetic data proved to be very useful for the search for pipes.

关键词： Dolerites Kimberlitic Fields petrology Structures Kéniéba Mali

Organic geochemistry and petrology of source rocks from the Banqiao Sag, Bohai Bay Basin, China: Implications for petroleum exploration

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Petroleum Science 2022年第4期19卷 1505-1515页

作者： Xiang-Bai Liu Guang-Di Liu Wen-Ya Jiang Ze-Zhang Song Na Wang State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China College of Geosciences China University of PetroleumBeijing102249China Exploration and Development Research Institute Dagang Oilfield CompanyPetroChinaTianjin300280China

The organic geochemistry and petrology of source rocks determine the hydrocarbon generation potential of the Banqiao Sag. In this study, organic geochemistry and petrology were used to determine the abundance of organic matter(OM), OM type, OM maturity, and sedimentary environments of the source rocks, collected from Cenozoic Shahejie Formation, Banqiao Sag, Bohai Bay Basin, China. Vitrinite and liptinite are the main maceral composition of the source rocks, and range from 18% to 81% and from 2% to82% on a mineral matter free(MMF) basis, respectively. The values of vitrinite reflectance(Ro)(0.36%-1.20%) and the Tmaxvalues(397-486.C) show that the thermal maturity range from low mature to peak-maturity. The abundance of OM varies between 0.22% and 4.37%, suggesting that the source rocks of the Shahejie(Es) Formation are mainly fair to good source rocks. The Rock-Eval pyrolysis results show that the source rocks have good petroleum generation potential. The amount of free hydrocarbons(S_1)and hydrocarbons generated from pyrolysis(S_(2)) range within 0.01-3.70 mg/g, and 0.04-29.17 mg/g. The hydrogen index(HI) varies between 18.18 and 741.13 mg HC/g TOC, with most of the samples appearing to be mainly Type II kerogen, and thereby exhibiting the ability to generate both oil and gas. The ratios of Pr/Ph, the cross plot of Pr/nC_(17)-Ph/nC_(18), the cross plot of C_(29)/C_(27)-Pr/Ph, and ternary of dibenzothiophene, dibenzofuran, and fluorene, indicate that the Shahejie Formation deposited in suboxic and weak reducing environments. The main biological source is from advanced plants. The maceral composition and rock pyrolysis data indicate the kerogen type is a humic type or mixed sapropelic-humic type. The source rocks of the Shahejie(Es) Formation occur in the oil window, and the abundant organic richness,humic kerogen demonstrate that these rocks are effective oil and gas source rocks. The mudstone rocks in the Shahejie Formation are the main source of oil and gas and represent the main exploration target for the Banq

关键词： Lacustrine source rocks petrology Biomarkers Depositional environment Banqiao Sag

Meso-Archean to Mid-Paleozoic Granitoids in Oulad Dlim Massif(the Pericratonic Terrane of the Reguibat Shield,West African Craton,Morocco):petrology,Geochemistry,Geochronology and Geological Implications

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Journal of Earth Science 2022年第5期33卷 1152-1165页

作者： Haissen Faouziya Montero Pilar Molina Jose Francisco Lodeiro Francisco Mouttaqi Abdellah Chaib Mustapha Bea Fernando LGAGE Département de GéologieFacultédes Sciences Ben M’sikHassan II University of CasablancaB.P.5366MaarifCasablancaMaroc Department of Mineralogy and petrology University of GranadaCampus FuentenuevaGranada18002Spain Office National des Hydrocarbures et des Mines 5 Avenue Moulay HassanRabatMaroc

The Oulad Dlim Massif,adjacent to the Reguibat Shield in South Morocco was considered up to now as part of the Variscan belt(Mauritanides)with a polyphase geologic history and a complex geodynamic evolution implicating oceans closures and accretion of exotic terranes(Avalonian and Meguman)during the Variscan-Alleghanian orogeny.The use of modern technology to characterize the petrology,the geochemistry and the geochronology of the lithological units forming this region,combined to field surveys has led to an updated geological architecture and different geological history.The Oulad Dlim Massif is mainly a deformed Archean terrane,as recorded by its eastern and western sectors,dominated in its central part by a bimodal felsic-mafic magmatism forming the Ediacaran sector.The study of these magmatic complexes supports strongly the intracontinental origin of this bimodal magmatism vs.the oceanic origin published before in literature.The exploration of this massif conducted also to the identification of a Silurian-Devonian sector in the western part.Therefore,up to date,different magmatic events lasting from the Meso-Archean to the Cretaceous are recorded in the Oulad Dlim Massif rocks,among them different generations of granitoids are reported.New data on granitoids from the Ediacaran sector are presented in this paper.This recent data demonstrates that Oulad Dlim Massif has been affected by the main Ediacaran–Cambrian extensional event widely documented in other structural domains of Morocco and other parts of North Gondwana.Additionally,the study of the Silurian-Devonian sector rocks highlighted the presence of a Caledonian tectonic event challenging the ideas about the paleogeography of this part of northwestern Africa and its geological evolution during the Paleozoic.However,despite the significant contribution of this extensive survey and the abundance of data on the Oulad Dlim Massif,more studies are required to reconstruct the puzzle at plate tectonic scale.

关键词： Archean Ediacaran bimodal magmatism extension intracontinental rifting Caledonian tectonic event petrology geochemistry

Genesis and tectonic setting of Early Jurassic granitic rocks in Huashan Town,Xingcheng,western Liaoning

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Global Geology 2024年第1期27卷 1-19页

作者： ZHAO Junfeng LI Weimin LIU Tongjun GAO Jinhui College of Earth Sciences Jilin UniversityChangchun 130061China Key Laboratory of Mineral Resources Evaluation in Northeast Asia Ministry of Natural ResourcesChangchun 130026China

There are a large number of Mesozoic intrusive and volcanic rocks in western Liaoning of China,which is an ideal place to study the Mesozoic Paleo-Pacific subduction processes,and lithospheric destruc-tion of North China Craton.Detailed petrographic,zircon U-Pb dating and geochemical studies of the Early Jurassic granites in Huashan pluton,Xingcheng,western Liaoning,indicate that the Early Jurassic granites were formed at 184-174 Ma,mainly composed of syenite and monzogranite.The geochemical characteristics show high contents of SiO_(2),Al_(2)O_(3)and Na_(2)O+K_(2)O,low contents of Fe_(2)O_(3)and MgO,enrichment in LREEs and LILEs,and depletion in HREEs and HFSEs,and have a high content of Sr and low contents of Y and Yb,with weak negative Eu anomalies and slightly negative anomalies of Ce,indicating that they are a set of intermediate-acidic adakitic granites in high-K calc-alkaline series.All the facts significantly suggest that the Early Jurassic adakitic granites were formed at the active continental margin in the context of Paleo-Pacific plate subduction.

关键词： geochemistry petrology adakite North China Craton western Liaoning

petrology and Sr-Nd isotope systematics of the Ahobil kimberlite(Pipe-16)from the Wajrakarur field, Eastern Dharwar craton, southern India

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Geoscience Frontiers 2019年第3期10卷 1167-1186页

作者： Abhinay Sharma Alok Kumar Praveer Pankaj Dinesh Pandit Ramananda Chakrabarti N.V.Chalapathi Rao EPMA and SEM Laboratories Department of Geology Banaras Hindu University Centre for Earth Sciences Indian Institute of Science

Detailed mineralogical, bulk-rock geochemical and Sr-Nd isotopic data for the recently discovered Ahobil kimberlite(Pipe-16) from the Wajrakarur kimberlite field(WKF), Eastern Dharwar craton(EDC),southern India, are presented. Two generations of compositionally distinct olivine, Ti-poor phlogopite showing orangeitic evolutionary trends, spinel displaying magmatic trend-1, abundant perovskite, Tirich hydrogarnet, calcite and serpentine are the various mineral constituents. On the basis of(i) liquidus mineral composition,(ii) bulk-rock chemistry, and(iii) Sr-Nd isotopic composition, we show that Ahobil kimberlite shares several characteristic features of archetypal kimberlites than orangeites and lamproites. Geochemical modelling indicate Ahobil kimberlite magma derivation from small-degree melting of a carbonated peridotite source having higher Gd/Yb and lower La/Sm in contrast to those of orangeites from the Eastern Dharwar and Bastar cratons of Indian shield. The T_(Dm) Nd model age(～2.0 Ga) of the Ahobil kimberlite is(i) significantly older than those(1.5～1.3 Ga) reported for Wajrakarur and Narayanpet kimberlites of EDC,(ii) indistinguishable from those of the Mesoproterozoic EDC lamproites,and(iii) strikingly coincides with the timing of the amalgamation of the Columbia supercontinent. High bulk-rock Fe-Ti contents and wide variation in oxygen fugacity fO_2, as inferred from perovskite oxybarometry, suggest non-prospective nature of the Ahobil kimberlite for diamond.

关键词： petrology Isotopes Kimberlite Wajrakarur Dharwar craton India

petrology and geochemistry of mafic and ultramafic cumulate rocks from the eastern part of the Sabzevar ophiolite(NE Iran): Implications for their petrogenesis and tectonic setting

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Geoscience Frontiers 2020年第6期11卷 2347-2364页

作者： Fatemeh Rahmani Mohamad Ali Mackizadeh Moussa Noghreyan Claudio Marchesi Carlos J.Garrido Department of Geology Faculty of SciencesUniversity of IsfahanP.O.Box:81746-73441IsfahanIran Instituto Andaluz de Ciencias de La Tierra(IACT) CSIC-Universidad de GranadaAvenida de Las Palmeras 418100ArmillaGranadaSpain Departamento de Mineralogía y Petrología Facultad de CienciasUniversidad de GranadaAvenida Fuentenueva s/n18002GranadaSpain

The Late Cretaceous Sabzevar ophiolite represents one of the largest and most complete fragments of Tethyan oceanic lithosphere in the NE Iran.It is mainly composed of serpentinized mantle peridotites slices;nonetheless,minor tectonic slices of all crustal sequence constituents are observed in this ophiolite.The crustal sequence contains a well-developed ultramafic and mafic cumulates section,comprising plagioclase-bearing wehrlite,olivine clinopyroxenite,olivine gabbronorite,gabbronorite,amphibole gabbronorite and quartz gabbronorite with adcumulate,mesocumulate,heteradcumulate and orthocumulate textures.The crystallization order for these rocks is olivine±chromian spinel→clinopyroxene→plagioclase→orthopyroxene→amphibole.The presence of primary magmatic amphiboles in the cumulate rocks shows that the parent magma evolved under hydrous conditions.Geochemically,the studied rock units are characterized by low TiO2(0.18-0.57 wt.%),P2 O5(<0.05 wt.%),K2 O(0.01-0.51 wt.%)and total alkali contents(0.12-3.04 wt.%).They indicate fractionated trends in the chondrite-normalized rare earth element(REE)plots and multi-element diagrams(spider diagrams).The general trend of the spider diagrams exhibit slight enrichment in large ion lithophile elements(LILEs)relative to high field strength elements(HFSEs)and positive anomalies in Sr,Pb and Eu and negative anomalies in Zr and Nb relative to the adjacent elements.The REE plots of these rocks display increasing trend from La to Sm,positive Eu anomaly(Eu/Eu*=1.06-1.54)and an almost flat pattern from medium REE(MREE)to heavy REE(HREE)region[(Gd/Yb)N=1-1.17].Moreover,clinopyroxenes from the cumulate rocks have low REE contents and show marked depletion in light REE(LREE)compared to MREE and HREE[(La/Sm)N=0.10-0.27 and(La/Yb)N=0.08-0.22].The composition of calculated melts in equilibrium with the clinopyroxenes from less evolved cumulate samples are closely similar to island arc tholeiitic(IAT)magmas.Modal mineralogy,geochemical features and REE modeling indicate that Sabzevar cumulate

关键词： petrology Geochemistry Cumulate rocks Sabzevar ophiolite Supra-subduction zone Iran

petrology and phase equilibrium modeling of sapphirine ＋ quartz assemblage from the Napier Complex, East Antarctica: Diagnostic evidence for Neoarchean ultrahigh-temperature metamorphism

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Geoscience Frontiers 2013年第6期4卷 655-666页

作者： Hisako Shimizu Toshiaki Tsunogae M.Santosh Graduate School of Life and Environmental Sciences University of Tsukuba Department of Geology University of Johannesburg China University of Geosciences (Beijing) Division of Interdisciplinary Science Faculty of ScienceKochi University

A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine ＋ quartz assemblage from two localities （Tonagh Island （TI） and Priestley Peak （PP）） in the Napier Complex,East Antarctica,provides unequivocal evidence for extreme crustal metamorphism possibly associated with the collisional orogeny during Neoarchean.The reaction microstructures associated with sapphirine ＋ quartz vary among the samples,probably suggesting different tectonic conditions during the metamorphic evolution.Sapphirine and quartz in TI sample were probably in equilibrium at the peak stage,but now separated by corona of Grt ＋ Sil ＋ Opx suggesting near isobaric cooling after the peak metamorphism,whereas the Spr ＋ Qtz ＋ Sil ＋ Crd ＋ Spl assemblage replaces garnet in PP sample suggesting post-peak decompression.The application of mineral equilibrium modeling in NCKFMASHTO system demonstrated that Spr ＋ Qtz stability is lowered down to 930 ℃ due to small Fe3＋ contents in the rocks （mole Fe2O3/（FeO ＋ Fe2O3） =0.02）.The TI sample yields a peak p-T range of 950-1100 ℃ and 7.5-11 kbar,followed by cooling toward a retrograde stage of 800-950 ℃ and 8-10 kbar,possibly along a counterclockwise p-T path.In contrast,the peak condition of the PP sample shows 1000-1050 ℃ and ＞12 kbar,which was followed by the formation ofSpr ＋ Qtz corona around garnet at 930-970 ℃ and 6.7-7.7 kbar,suggesting decompression possibly along a clockwise p-T trajectory.Such contrasting p-T paths are consistent with a recent model on the structural framework of the Napier Complex that correlates the two areas to different crustal blocks.The different p-T paths obtained from the two localities might reflect the difference in the tectonic framework of these rocks within a complex Neoarchean subduction/collision belt.

关键词： Ultrahigh-temperature granulite petrology Pseudosection modeling Napier complex Antarctica

petrology of Garnet Amphibolites from the Hualong Group: Implications for Metamorphic Evolution of the Qilian Orogen, NW China

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Journal of Earth Science 2018年第5期29卷 1102-1115页

作者： Yilong Li Limin Zhao Zhuoyang Li Biji Luo Jianping Zheng Fraukje M.Brouwer School of Earth Sciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Geology & Geochemistry Group Department of Earth Sciences VU Amsterdam

The Qilian Orogen marks the junction of the North China, South China and Tarim cratons. The mechanism of continental growth during the formation of the orogen remains unclear. Based on detailed fieldwork, we present a systematic study of petrography, mineral chemistry and phase equilibria of garnet amphibolites from the Hualong Group, which represents the Precambrian basement in the southern accretionary belt of the Qilian Orogen. The garnet amphibolites mainly consist of amphibole, plagioclase, garnet and quartz, with minor pyroxene, biotite and ilmenite. A peak stage of upper amphibolite facies to low-temperature granulite facies metamorphism and retrograde metamorphism in the amphibolite facies affected the samples. Garnet has a homogeneous composition of Alm66-71Grs14-17Prp9_12Sps3-s, amphibole is ferro-hornblende, biotite belongs to the ferro-biotite species and pyroxene is dominated by orthopyroxene with few clinopyroxene. Pseudosection modeling of the garnet amphibolite samples indicates clockwise P-T paths. The samples witness peak metamorphism at conditions of -4.9-6.3 kbar and -755-820 ℃ in the upper amphibolite facies to low- temperature granulite facies, and retrograde cooling and decompression at conditions of-2.5-3.1 kbar and -325-545 ℃. It is inferred that peak metamorphism with high temperature and low pressure occurred at ca. 450 Ma during northward subduction of the South Qilian oceanic crust beneath the central Qilian Block. When continental collision occurred between the central Qilian and the Qaidam blocks, the Hualong Block was aecreted onto the South Qilian accretionary complex and experienced amphibolite facies retrograde metamorphism at ca. 440 Ma.

关键词： Qilian Orogen Hualong Group garnet amphibolite petrology metamorphic P-T path PerpleX.

petrology and Geochemical Features of Crystalline Rocks in Ora-Ekiti,Southwestern Nigeria

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Advances in Geological and Geotechnical Engineering Research 2023年第2期5卷 24-37页

作者： O.A.OlaOlorun O.O.Akinola A.O.Oyinloye Department of Geology Ekiti State UniversityP.M.B.5363Ado-EkitiNigeria

This research investigates and reports on the petrology and geochemical characteristics of crystalline basement rocks in Ora-Ekiti,Southwestern Nigeria.Exhaustive geological investigation reveals migmatite,banded gneiss,granite gneiss and biotite gneiss underlie the area.In reducing order of abundance,petrographic examination reveals that migmatite contains quartz,muscovite and opaque minerals.Banded geniuses contain quartz,biotite,plagioclase,and opaque minerals.Granite geniuses contain quartz,plagioclase,biotite,microcline and opaque;while biotite geniuses contain biotite,plagioclase,opaque minerals,and quartz.Silica contents in migmatite(69.50%-72.66%;ca.71.23%),banded gneiss(71.66%-77.1%;ca.75.23%),biotite gneiss(72.32%-76.18%;ca.73.83%)and granite gneiss(69.82%-73.15%;ca.71.95%)indicate the rocks are siliceous.High alumina contents in migmatite(12.18%),banded gneiss(10.28%),biotite gneiss(11.46%)and granite gneiss(9.97%)are comparable to similar rocks in the basement complex.All the rocks show Ba,Sr and Rb enrichment.Harker diagrams of Al_(2)O_(3)versus SiO_(2)and CaO versus SiO_(2)show negative trends while Na_(2)O versus SiO_(2),K_(2)O versus SiO_(2)and TiO_(2)versus SiO_(2)plots showed positive trends.This variation probably depicts extensive crystal fractionation in the magmatic systems that produced the rocks prior to metamorphism or partial melting of the precursor rock.SiO_(2)versus(Na_(2)O+K_(2)O)classifies the rocks as granite to granodiorite.The rocks are high K-calc-alkaline and calc-alkalic on SiO_(2)-K_(2)O plot.This shows the rocks are potassic meaning that they are formed from a potassium-rich source.The plot of Al_(2)O_(3)/(Na_(2)O+K_(2)O)versus Al_(2)O_(3)/(CaO+Na_(2)O+K_(2)O)reveals the crystalline rocks are orogenic and originated from granitoid with meta luminous affinity.The rocks consist of gneisses of no economic minerals,but the petrology reveals them as common rocks typical of metamorphic terrains and geochemical features of the rocks reveal they are felsic and of granitic compo

关键词： Ora-Ekiti Crystalline basement rocks petrology Metaluminous affinity

petrology, physicochemical and thermal analyses of selected cretaceous coals from the Benue Trough Basin in Nigeria

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International Journal of Coal Science & Technology 2020年第1期7卷 26-42页

作者： S.A.Akinyemi O.F.Adebayo B.B.Nyakuma A.K.Adegoke O.A.Aturamu O.A.OlaOlorun A.Adetunji J.C.Hower M.M.Hood A.Jauro Department of Geology Ekiti State University.P.M.B 5363Ado EkitiEkiti StateNigeria School of Chemical and Energy Engineering Universiti Teknologi MalaysiaSkudaiMalaysia Department of Geology Obafemi Awolowo UniversityP.M.BOB.lie IfeOsun StateNigeria Centre for Applied Energy Research University of KentuckyKentuckyUSA National Centre for Petroleum Research and Development(NCPRD) Abubakar Tafawa Balewa UniversityBauchiNigeria

Abundant coal resources that were previously neglected due to a crude oil boom need revitalisation and integration into the national electricity mix to address the energy demands of the Nigerian population.Selected coal samples from the Benue Trough sedimentary basin in Nigeria were examined by various techniques,including proximate and ultimate analyses,organic petrography,Fourier transform infrared ray spectroscopy,and thermogravimetric analysis.Based on vitrinite reflectance,the Lafia-Obi(OLB),Garin Maiganga(GMG),Imiegba(IMG),and Okaba(OKB)coals are classified as subbituminous,while the Lamja1(LMJ1),Lamja2(LMJ2)and Chikila(CHK)coals are high volatile B bituminous.The Enugu(ENG)coal is on the boundary between subbituminous and high volatile C bituminous.Organic petrographic results indicate vitrinite and fusinite contents steadily increase from the Lower Benue Trough coals to the Upper Benue Trough coals,while semifusinite and total mineral contents follow a reverse pattern.Thermal decomposition occurred in three stages,i.e.,drying,devolatilization,and coke formation above 700°C;and the coal reactivity follows the following order,ENG>IMG>IGH>CHK>LMJ>OKB>GMG>LFB.The higher temperatures(above 900°C)are required to decompose the coals for efficient energy recovery.The LMJ1,LMJ2,OLB,CHK,GMG,and OKB coals can be exploited for electricity power generation.However,the Imeagha and Enugu coals are best suitable for both cement and power generation.

关键词： petrology Thermal analysis Cretaceous coal Benue Trough Nigeria