检索结果-南通市图书馆

Mineralogy and whole-rock geochemistry of the Oligocene Barail Group of rocks of Belt of Schuppen,Northeast India:Implications for tectono-provenance and paleo-weathering

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第5期43卷 904-932页

作者： Manash Pratim Gogoi Yunpeng Dong Pradip Borgohain Devojit Bezbaruah Arvind Pandey Yadav Krishna Gogoi Garima Konwar Gautam Raj Bawri Bubul Bharali department of Petroleum Technology Dibrugarh UniversityAssam 786004India department of geology Northwest UniversityXi’an 710069China department of Applied geology Dibrugarh UniversityAssam 786004India department of Statistics Central University of RajasthanAjmer 305817India department of geology Mizoram UniversityAizawlMizoram 796004India department of geology Pachhunga University CollegeAizawlMizoram 796001India

The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal *** river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail *** purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental *** sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical *** sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:11.58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.18),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc *** conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.14),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71),and Th/U(6.03),which were further additionally supported by C-Value(1.01),PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).

关键词： Belt of Schuppen Barail Group Sandstone Petrography Geochemistry Provenance Tectonic setting

Platform Evolution in an Oligo-Miocene Back-arc Basin:An Example from the Central Iran Basin

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第1期98卷 185-206页

作者： Masoud SHARIFI-YAZDI Amirhossein ENAYATI Jamal SALEHI AGHDAM Mohammad BAHREHVAR Seyed Mustafa REZAEI department of geology Faculty of Earth SciencesGeography and AstronomyUniversity of Vienna1090 Vienna.Austria geology and Geophysics department Tehran Energy Consultants(TEC Co.)TehranIran School of geology College of ScienceUniversity of TehranTehranIran department of geology Tarbiat Modares UniversityTehranIran

The Qom Formation is the most important hydrocarbon reservoir target in Central *** Qom platform developed in a back-arc basin during the Oligo-Miocene due to the closing of the Tethyan *** formation consists of a variety of carbonate and non-carbonate facies deposited on a platform ranging from supratidal to basin.A combination of tectonic and eustatic events led to some lateral and vertical facies variations in the study *** third-order depositional sequences and related surfaces were identified regarding vertical facies changes in the studied sections of this Oligo-Miocene *** to all results and data,this succession was initially deposited during the Chattian upon a distally steepened ramp of siliciclastic-carbonate composition,including the Bouma ***,from the late Chattian to the Aquitanian,the platform changed into a homoclinal carbonate ramp with a gentle *** respect to tectonic activity,this phase was a calm period during the deposition of the Qom ***,a drowned carbonate platform and a rimmed shelf emerged during the Burdigalian,terminated by the continental deposits of the Upper Red *** all geological characteristics,three main tectono-eustatic evolutionary phases have been recognized in the Qom back-arcbasin.

关键词： carbonate ramp depositional facies submarine fan eustasy basement faults back-arc basin

Basin Analysis and Paleogeography of the Zagros Foreland Basin during the Maastrichtian, High Zagros Basin, Iran

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第5期35卷 1527-1545页

作者： Hossein Ghanbarloo Amrollah Safari department of geology University of Isfahan

A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin. Based on the study of more than 1 000 rock samples, nine carbonate microfacies and three terrigenous facies were identified. The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin. Three(Gandom Kar area), two(Ardal area), seven(Gardbishe area), five(Shirmard area), two(Kuh-e-Kamaneh area), three(Kuh-e-Balghar area), and six(Murak area) of depositional sequences(3rd order) were identified. The thickness of the lowstand systems tract(LST) due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian. During the Middle Maastrichtian, the shallow and deep marine deposits were formed during the transgressive systems tract(TST) and highstand systems tract(HST) in this basin and the rate of subsidence in the center of this basin(Gardbishe area) is higher than in other areas and the platform was drowned in this area. The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin(except the south part) during the Late Maastrichtian. Paleogeographical studies on the Zagros Basin during the Late Campanian-Maastrichtian showed the following results: shallow marine environments were developed in the southeast of this basin, and the turbidite, delta, and fluvial environments in the northwest were developed more than in other areas.

关键词： Maastrichtian deposits local fault depositional sequences Neotethys Basin Inception Foreland Basin Late Cretaceous basin analysis paleogeography

Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield:A review

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第3期43卷 588-622页

作者： Abdel-Aal MAbdel-Karim Mohamed MHamdy Adel A.Surour geology department Faculty of ScienceZagazig UniversityZagazig 44519Egypt geology department Faculty of ScienceTanta UniversityTanta 31527Egypt department of Geological Sciences Faculty of ScienceNew Galala City 43511Egypt geology department Faculty of ScienceCairo UniversityGiza 12613Egypt

Neoproterozoic island arc assemblage of the Arabian–Nubian Shield(ANS)in the Eastern Desert(ED)of Egypt comprises juvenile suites of metavolcanics(MV),large amounts of meta-sedimentary rocks(MS),and voluminous metagabbros-diorites(MGD)and syn-tectonic intrusions of older granitoids(OG).We report here the updates of these four rock units in terms of classification,distribution,chemical characteristics,geodynamic evolution,metamorphism,and *** addition,we discuss these integrated data to elucidate a reasonable and reliable model for crustal evolution in the *** main features of these rock units indicate their relation to each other and the geodynamic environment dominated by early immature oceanic island arcs to primitive continental *** information of the island arc metavolcanic and plutonic rocks(gabbros,diorites,tonalites,and granodiorites)furnish evidence of the genetic *** include proximity and a coeval nature in the field;all protolith magmas are subalkaline in nature following calc-alkaline series with minor tholeiitic affinities;common geochemical signature of the arc rocks and subduction-related magmatism;their similar enrichment in LREEs;and similar major element compositions with mafic melts derived from metasomatized mantle *** volcano-sedimentary and the OG rocks underwent multiphase deformation events whereas the MGD complexes deformed *** on the magmatic,sedimentological,and metamorphic evolutions constrained by geochronological data as well as the progressive evolutionary trend from extensional to compressional regimes,a possible gradual decrease in the subducted slab dip angle is the most infl uential in any geodynamic model for arc assemblage in the ED of Egypt.

关键词： Island arc assemblage Magmatism Crustal growth Neoproterozoic Arabian–Nubian Shield Eastern Desert Egypt

Petrologic evolution of the Gysian ophiolitic serpentinites,NW Iran

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第5期43卷 996-1011页

作者： Monir Modjarrad Donna L.Whitney Hadi Omrani department of geology Faculty of SciencesUrmia UniversityUrmiaIran department of Earth and Environmental Sciences University of MinnesotaMinneapolisMNUSA department of geology Faculty of SciencesGolestan UniversityGorgānIran

The Gysian ophiolite of NW Iran is located at the intersection of the ophiolite belts of SE Turkey,NE Iraq,and Iran,and provides the opportunity to investigate the preserved subduction and obduction history of an important tectonic site that has not previously been *** serpentinized peridotites of the Gysian ophiolite contain the assemblagelizardite+chrysotile+spinel/Mg-spinelwith relict clinopyroxene(diopside)and very rare relict orthopyroxene and *** compositions of clinopyroxenes and spinels are more consistent with the formation of the inferred protolithharzburgitesinafore-arcorsupra-subduction zone instead of an abyssal *** Gysian ophiolite is a remnant of the Neo-Tethyan arc-ophiolitic system and records shallow subduction(<50 km,indicated by the absence of antigorite)in the Late Cretaceous to Paleocene beforeobductionalongthrustfaultsoverthecontinental *** review the spatial trends of the metamorphic grade of the Neo-Tethyan ophiolites in this region and provide detailed information about the petrology and mineral chemistry of the Gysian ophiolite.

关键词： Ophiolite Neo-Tethyan Gysian Serpentinite Iran

Mineralogy and geochemistry of trachytic rocks from the Lichi Volcanics, Eastern Himalaya: insights into the Kerguelen mantle plume activity in the Eastern Himalayan Region

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第1期43卷 180-197页

作者： Pallabi Basumatary Deepshikha Borah Hiredya Chauhan Tribujjal Prakash Bibhuti Gogoi department of geology Cotton UniversityGuwahatiAssam 781001India Wadia Institute of Himalayan geology DehradunUttarakhand 248001India

The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics(~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic rocks from the Lichi volcanics, which are exposed in the Ranga valley, along the Kimin-Yazali road section in the Eastern Himalayan Region, Northeast India. The trachytes occur in close association with sandstones of the Gondwana Group of rocks and are characterised based on field, petrographical, and geochemical *** fine-grained trachytes are composed of alkali feldspar, biotite, plagioclase, sodic-amphibole, apatite, illmenite, and titanite. The REE profiles of the evolved trachytic rocks(higher SiO_(2)content) display fractionated trends. The fractionation of accessory mineral phases, like apatite and titanite, was possibly responsible for the strongly fractionated REE patterns of the evolved *** trachytic rocks demonstrate high apatite saturation temperatures of 988 ± 14 ℃(1σ, n = 8). The Aluminium Saturation Index(< 1.1) and binary discrimination diagrams of these peralkaline trachytes define their affinity with A-type granitoids. Elemental ratios like Y/Nb, Nb/U,and Ce/Pb signify that the Lichi trachytes are differentiated products of mantle-derived ocean island basalts. Trace elemental discrimination diagrams Th/Yb versus Nb/Yb, Y versus Nb, and Y + Nb versus Rb reflect a within-plate tectonic regime for the trachytes. From the results presented in this work, we infer that the development of rifting events during the breakup of eastern Gondwana due to the onset of Kerguelen plume activity further led to underplating of basic magma in lower crustal levels. These parental basaltic magmas underwent fractionation processes forming differentiated trachyandesites and *** into consideration the similarities recorded between the Lichi volcanics and Abor volcanics, this study supports the idea that Kerguelen plume ac

关键词： Peralkaline trachytes Trachyandesites A-type granitoids Apatite saturation temperature Abor volcanics Eastern Gondwana

Structural geology and Chronology of Shear Zones along the Shangdan Suture in Qinling Orogenic Belt,China:Implications for Late Mesozoic Intra-Continental Deformation of East Asia

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第2期35卷 376-393页

作者： Falak Sheir Wei Li Le Zhang Basil Alabowsh Liuqing Jiang Li Liang Sainan Gao Shair Baz Umar Ashraf State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an710069China Institute of geology University of PunjabLahore45590Pakistan

The Shangdan suture zone(SDZ)in the Qinling orogenic belt(QOB)is a key to understanding the East Asia tectonic *** SDZ gives information about convergent processes between the North China Block(NCB)and South China Block(SCB).In the Late Mesozoic,several shear zones evolved along the SDZ boundary that helps us comprehend the collisional deformation between the NCB and SCB,which was neglected in previous *** shear zones play an essential role in the tectonic evolution of the East Asia *** study focuses on the deformation and geochronology of two shear zones distributed along the SDZ,identified in the Shaliangzi and Maanqiao *** shear sense indicators and kinematic vorticity numbers(0.54–0.90)suggest these shear zones have sinistral shear and sub-simple shear deformation *** quartz’s dynamic recrystallization and c-axis fabric analysis in the Maanqiao shear zone(MSZ)revealed that the MSZ experienced deformation under green-schist facies conditions at∼400–500℃.The Shaliangzi shear zone deformed under amphibolite facies at∼500–700℃.The^(40)Ar/^(39)Ar(muscovite-biotite)dating of samples provided a plateau age of 121–123 *** with previously published data,our results concluded that QOB was dominated by compressional tectonics during the Late Early ***,we suggested that the Siberian Block moved back to the south and Lhasa-Qiantang-Indochina Block to the north,which promoted intra-continental compressional tectonics.

关键词： Qinling orogenic belt Shangdan suture zone shear zone Late Mesozoic intra-continental deformation East Asia tectonics

Kink-band Kinematic Analysis and its Implications for Late-stage Deformation in the Internal Parts of the Zagros Collision(Sanandaj–Sirjan Zone) in West Iran

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第4期98卷 921-935页

作者： Maryam HEYDARI Mahdi BEHYARI department of geology Faculty of SciencesUrmia University57153165 UrmiaIran

In the internal parts of the Zagros collision zone, several deformation phases have been superimposed. The early deformation phase caused the development of a penetrative foliation. The late-stage deformation phase was preferentially accommodated within shear zones and caused the generation of shear bands, implying a non-coaxial component of deformation, the end of this stage deformation was marked by the development of kink-bands. In the vicinity of Zagros suture zone, the kink angle increased from 40° to 60°, and the kink-bands was converted to chevron folds. In this region, the external(α) and internal(β) angular ratio is α/β ≠ 1 and kink angle increased, and deformation occurred with 10% to 30% volume loss. Farther from the suture zone in the east, α/β = 1;and total volume was constant or increased by 5% to 10%. Kink-bands kinematic analysis in the study area revealed this structures were sensitive to deformation conditions and components such that, with decreasing distance to the Zagros suture zone, shearing and rotation increased, a high kinematic vorticity dominated, and volume loss occurred during deformation.

关键词： kink-band shear zone strain vorticity Zagros Iran

The nature and movement of thrusts in the eastern Iranian orogen:Sechengi Area on the northern border of Lut and Sistan

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第9期21卷 3157-3171页

作者： Shahriar KESHTGAR Mahmoud Reza HEYHAT Sasan BAGHERI Ebrahim GHOLAMI Seyed Naser RAISOSSADAT department of geology Faculty of ScienceUniversity of BirjandBirjand ***Iran department of geology Faculty of ScienceUniversity of Sistan and BaluchestanZahedan 98167-45845Iran

The eastern Iranian range,known as the Sistan suture zone in the past,has recently been identified as the Sistan *** Paleogene orogeny is located between the Lut and Afghan *** structural analysis shows that most of the thrusts dip towards the NW so that the Permo-Triassic sediments and Jurassic micro-diorites of the Lut Block overthrusted over the younger *** studies show that the tectonic vergence was from the NW to the SE of the Sechengi area in the NW part of Sistan *** recognized three deformation phases in eastern *** first N-S deformation event(D1)resulted in the formation of tight E-W folds(F1)and associated cleavages(S1).The second E-W deformation event(D2),which occurred in the late Paleogene led to the bending of older structures,including the axial plane of the first-generation folds giving them a new northwest direction(F2).Additionally,the ramp of the first-phase thrusts(striking E-W)was reactivated,acquiring a new NNW orientation and exhibiting SSE tectonic *** third deformation event(D3)resulted in the formation of NNE and WNW conjugate faults in eastern *** consecutive deformation events perpendicular to each other are inconsistent with the models of simple linear orogen presented for eastern Iran(*** of eastern Iran continental crust and subsequence linear collision)and seem more consistent with the buckling orogeny(Orocline).

关键词： Thrust Tectonic vergence Orocline Buckling Sechengi Eastern Iranian ranges.