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Mineralogical Evidence for Regional Metamorphism Overprinted by Contact Metamorphism

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Acta Geologica sinica(English Edition) 2012年第1期86卷 48-64页

作者： Mahboobeh JAMsHIDI BADR Fariborz MAsOUDI alan s.collins Ali sORBI Department of Geology Payam Noor University Department of Geology Shahid Beheshi University Tectonics Resources and Exportation(TRaX)School of Earth and Environmental SciencesUniversity of Adelaide Department of sciences Karaj BranchIslamic Azad University

The soursat metamorphic complex （sMC） in northwestern Iran is part of the sanandaj- sirjan metamorphic belt. The complex is composed of different metamorphic and plutonic rocks, but is dominated by metapelites composed of garnet, staurolite, kyanite, fibrolite, cordierite, and andalusite. Porphyroblasts in schists have the same fabric, and three stages of schistosity are present. The internal schistosity （sn） inclusion trails are also offset by conjugate sets of extensional schistosity （sn＋l） and a second （sn＋2） that crenulates （sn＋l）. Polyphase metamorphisms are present in the complex. Garnet, staurolite, kyanite, and fibrolite assemblage preserves conditions during the M1 metamorphic event. This assemblage yields a P-t estimate of 645±11℃ and 6.5±0.5 kbar. Other samples of the central part of sMC contain cordierite and andalusite （M2） overgrowth that yields a P- t estimate of 532±33℃ and 2.1±1.1 kbar.

关键词： metamorphism north-west Iran sanandaj-sirjan zone soursat metamorphic complex.

Evolving provenance in the Proterozoic Pranhita-Godavari Basin,India

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Geoscience Frontiers 2015年第3期6卷 453-463页

作者： Udeni Amarasinghe Asru Chaudhuri alan s.collins Gautam Deb sarbani Patranabis-Deb Centre for Tectonics Resources and Exploration(TRaX)School of Earth and Environmental SciencesThe University of Adelaide Department of Geology Presidency College Geological studies Unit(GsU) Indian Statistical Institute

The Pranhita-Godavari Basin in central eastern India is one of the Proterozoic ＂Purana＂ basins of cratonic India. New geochronology demonstrates that it has a vast depositional history of repeated basin reactivation from the Palaeoproterozoic to the Mesozoic. U-Pb laser ablation inductively coupled plasma mass spectrometry dating of detrital zircons from two samples of the somanpalli Group--a member of the oldest sedimentary cycle in the valley--constrains its depositional age to - 1620 Ma and demonstrates a tripartite age provenance with peaks at - 3500 Ma, - 2480 Ma and - 1620 Ma, with minor age peaks in the Eoarchaean （ - 3.8 Ga） and at - 2750 Ma. These ages are consistent with palaeocurrent data suggesting a southerly source from the Krishna Province and Enderby Land in East Antarctica. The similarity in the maximum depositional age with previously published autbigenic glauconite ages suggest that the origin of the Pranhita-Godvari Graben originated as a rift that formed at a high angle to the coeval evolving late Meosproterozoic Krishna Province as Enderby Land collided with the Dharwar craton of India. In contrast, detrital zircons from the Cycle III sullavai Group red sandstones yielded a maximum depositional age of 970 - 20 Ma and had age peaks of -2550 Ma, -1600 Ma and then a number of Mesoproterozoic detrital zircons terminating in three analyses at - 970 Ma. The provenance of these is again consistent with a southerly source from the Eastern Ghats Orogen and Antarctica. Later cycles of deposition include the overlying Albaka/Usur Formations and finally the late Palaeozoic to Mesozoic Gondwana supergroup.

关键词： LA-icpms U-Pb zircon geochronology Godavari Purana Gondwana

Tracking the Cretaceous transcontinental Ceduna River through Australia:The hafnium isotope record of detrital zircons from offshore southern Australia

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Geoscience Frontiers 2016年第2期7卷 237-244页

作者： Jarred Lloyd alan s.collins Justin L.Payne stijn Glorie simon Holford Anthony J.Reid Centre for Tectonics Resources and Exploration(TRaX)Department of Earth SciencesThe University of Adelaide Centre for Tectonics Resources and Exploration(TRaX)School of Built and Natural EnvironmentsThe University of South Australia Centre for Tectonics Resources and Exploration(TRaX)Australian School of PetroleumThe University of Adelaide Geological survey of south Australia Department of State DevelopmentGovernment of South Australia

The middle-upper Cretaceous Ceduna River system traversed continental Australia from the NE coast to the centre of the southern coast. At its mouth, it formed a vast delta system that is similar in scale to the Niger delta of West Africa. The delta system is composed of two main lobes that represent different phases of delta construction. A recent hypothesis has challenged the traditional idea that both lobes of the delta were derived from a transcontinental river system by suggesting that the upper lobe （santonian -Maastrichtian） is instead derived from a restricted catchment within southern Australia. Hf isotopic data presented here fingerprint the original source of the upper delta lobe zircons to NE Australia, with data comparing well with similar U-Pb and Lu-Hf isotopic data from the Lachlan Orogen, the New England Orogen, the eastern Musgraves Province and the northern Flinders Ranges. These data do not preclude a model where the lobe is derived from recycled Eromanga Basin sediments during a phase of late Cretaceous inland Australian uplift, but when coupled with reconnaissance low-temperature thermochronometry from the region of the Ceduna River course indicating widespread Triassic-Jurassic exhumation, and comparisons with detrital zircon data from the Winton Formation upstream of any proposed uplift, we suggest that both lobes of the Ceduna Delta are likely to be derived from a transcontinental Ceduna River.

关键词： Detrital zircon Hf U-Pb Ceduna sub-basin Bight basin Australia

Prograde and retrograde growth of monazite in migmatites:An example from the Nagercoil Block,southern India

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Geoscience Frontiers 2015年第3期6卷 373-387页

作者： Tim E.Johnson Chris Clark Richard J.M.Taylor M.santosh alan s.collins Department of Applied Geology The Institute for Geoscience Research(TIGeR)Curtin University school of the Earth sciences and Resources China University of Geosciences(Beijing) Tectonics Resources and Exploration(TRaX)Department of Earth SciencesUniversity of Adelaide

Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure-temperature-time （P-T-t） evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagioclase, magnetite, ilmenite, spinel and melt is consistent with peak metamorphic pressures of 6-8 kbar and temperatures in excess of 900 ℃. subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 ℃. sHRIMP U-Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palae- oproterozoic crystallisation ages. New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation, and the minimum age of the metamorphic peak, to around 560 Ma. The data suggest two stages of monazite growth. The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite. Relatively REE-depleted rims, which have a pronounced negative europium anomaly, grew during melt crystallisation along the retrograde path at around 535 Ma. Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer, supporting a long-lived high-grade metamorphic history. The metamorphic conditions, timing and duration of the implied clockwise P-T-t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent.

关键词： Monazire Migmatite Zircon Geochronology Phase equilibria modelling Gondwana

An apatite U-Pb thermal history map for the northern Gawler Craton,south Australia

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Geoscience Frontiers 2018年第5期9卷 1293-1308页

作者： James W.Hall stijn Glorie Anthony J.Reid samuel C.Boone alan s.collins ANDrew Gleadow Tectonics Resources and Exploration (TRaX) Department of Earth Sciences University of Adelaide Geological survey of south Australia Department of State Development school of Earth sciences The University of Melbourne

Apatite U-Pb thermochronology was applied to granitoid basement samples across the northern Gawler Craton to unravel the Proterozoic, post-orogenic, cooling history and to examine the role of major fault zones during cooling. Our observations indicate that cooling following the ~2500 Ma sleaford Orogeny and ~1700 Ma Kimban Orogeny is restricted to the Christie and Wilgena Domains of the central northern Gawler Craton. The northern Gawler Craton mainly records post-Hiltaba Event(~1590 Ma) U-Pb cooling ages. Cooling following the ~1560 Ma Kararan Orogeny is preserved within the Coober Pedy Ridge,Nawa Domain and along major shear zones within the south-western Fowler Domain. The Nawa Domain samples preserve U-Pb cooling ages that are >150 Ma younger than the samples within the Coober Pedy Ridge and Fowler Domain, indicating that later(~1300 Ma) fault movement within the Nawa Domain facilitated cooling of these samples, caused by arc collision in the Madura Province of eastern Western Australia. When compared to^(40)Ar/^(39) Ar from muscovite, biotite and hornblende, our new apatite U-Pb ages correlate well, particularly in regions of higher data density. Our data also preserve a progressive younging of U-Pb ages from the nucleus of the craton to the periphery with a stark contrast in U-Pb ages across major structures such as the Karari shear Zone and the southern Overthrust, which indicates the timing of reactivation of these major crustal structures. Although this interpolation was based solely on thermochronological data and did not take into account structural or other geological data, these maps are consistent with the structural architecture of the Gawler Craton and reveal the thermal footprint of known tectonic and magmatic events in the Gawler Craton.

关键词： Apatite UePb Gawler Craton Karari shear Zone Thermochronology Hiltaba event

Late syn-to post-collisional magmatism in Madagascar:The genesis of the Ambalavao and Maevarano suites

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Geoscience Frontiers 2019年第6期10卷 2063-2084页

作者： Donnelly B.Archibald alan s.collins John D.Foden Justin L.Payne Peter Holden Théodore Razakamanana Department of Earth sciences St.Francis Xavier UniversityPhysical Sciences Complex5009 Chapel SquareAntigonishNSB2G 2W5Canada Centre for Tectonics Resources and Exploration(TRaX)Department of Earth SciencesThe University of AdelaideAdelaide 5005SAAustralia Centre for Tectonics Resources and Exploration(TRaX)School of Built and Natural EnvironmentsUniversity of South AustraliaMawson LakesSA5001Australia Research school of Earth sciences The Australian National UniversityCanberraACT2601Australia Departement des sciences de la Terre Universitede ToliaraToliara601Madagascar

The East African Orogen involves a collage of Proterozoic microcontinents and arc terranes that became wedged between older cratonic blocks during the assembly of *** Ediacaran-Cambrian Ambalavao and Maevarano suites in Madagascar were emplaced during the waning orogenic stages and consist of weakly deformed to undeformed plutonic rocks and dykes of mainly porphyritic granite but also gabbro,diorite and charnockite.U-Pb geochronological data date emplacement of the Ambalavao suite to between ca.580 Ma and 540 Ma and the Maevarano suite to between ca.537 Ma and522 *** and trace element concentrations are consistent with emplacement in a syn-to postcollisional tectonic setting as A-type(anorogenic) ***(δ^(18)O of 5.27‰-7.45‰) and hafnium(ε(Hf)(t) of-27.8 to-12.3) isotopic data from plutons in the Itremo and Antananarivo Domains are consistent with incorporation of an ancient crustal *** primitive δ^(18)O(5.27‰-5.32‰) andε(Hf)(t)(+0.0 to+0.2) isotopic values recorded in samples collected from the Ikalamavony Domain demonstrate the isotopic variation of basement sources present in the Malagasy *** Hf isotopic composition of Malagasy zircon are unlike more juvenile Ediacaran-Cambrian zircon sou rces elsewhere in the East African Orogen and,as such,Madagascar represents a distinct and identifiable detrital zircon source region in Phanerozoic sedimentary provenance *** together,these data indicate that high-T crustal anatexis,crustal assimilation and interaction of crustal material with mantle-derived melts were the processes operating during magma *** magmatism was coeval with polyphase deformation throughout Madagascar during the amalgamation of Gondwana and magmatism is interpreted to reflect lithospheric delamination of an extensive orogenic plateau.

关键词： Madagascar geology East African orogen Zircon geochronology Zircon oxygen and hafnium isotopes Post-collisional magmatism

Neoproterozoic tectonic geography of the south-east Congo Craton in Zambia as deduced from the age and composition of detrital zircons

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Geoscience Frontiers 2019年第6期10卷 2045-2061页

作者： Brandon L.Alessio alan s.collins Peter siegfried stijn Glorie Bert De Waele Justin Payne Donnelly B.Archibald Centre for Tectonics Resources and Exploration(TRaX)Dept of Earth SciencesThe University of AdelaideAdelaideSouth Australia 5005Australia GeoAfrica Prospecting services cc ErosNamibia sRK Consulting 1/10 Richardson StWest PerthWestern Australia 6005Australia Curtin University of Technology Kent StBentleyWestern Australia 6102Australia Centre for Tectonics Resources and Exploration(TRaX)School of Built and Natural EnvironmentsUniversity of South AustraliaAdelaideSouth Australia 5000Australia st.Francis Xavier University Physical Sciences Complex5009 Chapel SquareAntigonishNova Scotia B2G 2W5Canada

The southern Irumide Belt(sIB)is an orogenic belt consisting of a number of lithologically varied Mesoproterozoic and Neoproterozoic terranes that were thrust upon each *** belt lies along the southwest margin of the Archaean to Proterozoic Congo Craton,and bears a Neoproterozoic tectonothermal overprint relating to the Neoproterozoic-Cambrian collision between the Congo and Kalahari *** preserves a record of about 500 million years of plate interaction along this part of the Congo *** zircon samples from the sIB were analysed for U-Pb and Lu-Hf isotopes,as well as trace element *** data are used to constrain sediment-source relationships between sIB terranes and other Gondwanan terranes such as the local Congo Craton and Irumide belt and wider afield to Madagascar(Azania)and *** correlations are then used to interpret the Mesoproterozoic to Neoproterozoic affinity of the rocks and evolution of the *** zircon samples from the Chewore-Rufunsa and Kacholola(previously referred to as Luangwa-Nyimba)terranes of the sIB yield zircon U-Pb age populations and evolvedε(Hf)(t)values that are similar to the Muva supergroup found throughout eastern Zambia,primarily correlating with Ubendian-Usagaran(ca.2.05-1.80 Ga)phase magmatism and a cryptic basement terrane that has been suggested to underlie the Bangweulu Block and Irumide *** data suggest that the sIB was depositionally connected to the Congo Craton throughout the *** more eastern Nyimba-sinda terrane of the sIB(previously referred to as Petauke-sinda terrane)records detrital zircon ages andε(Hf)(t)values that correlate with ca.1.1-1.0 Ga magmatism exposed elsewhere in the sIB and Irumide *** ascribe this difference in age populations to the polyphase development of the province,where the sedimentary and volcanic rocks of the Nyimba-sinda terrane accumulated in extensional basins that developed in the *** deposition wou

关键词： Detrital zircon geochronology Tectonics Hafnium isotopes Zambia southern irumide belt Irumide belt

Efficiently adding mode multiplexing for cost-effective,high-capacity fiber links

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Advanced Photonics 2024年第1期6卷 8-9页

作者： alan E.Willner Huibin Zhou University of southern California Los AngelesCaliforniaUnited States

For decades,a powerful approach to adding data capacity in an optical communication link has been to multiplex independent data-carrying channels and transmit them simultaneously along a fiber.^(1)For example,wavelength-division-multiplexing(WDM)was a key technology in the 1990s and early 2000s to dramatically increase aggregate capacity in a fiber by multiplexing beams of different wavelengths.^(2)For the past roughly 15 years,there has been great promise that space-division-multiplexing(sDM)may bring similar capacity enhancements to optical fiber communications.^(1–3)

关键词： fiber multiplexing adding

Recognition and tectonic implications of an extensive Neoproterozoic volcano-sedimentary rift basin along the southwestern margin of the Tarim Craton, northwestern China

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Recognition and tectonic implications of an extensive Neopro...