Publications

Scientific Publications Referencing
Elemental Scientific Lasers’ NWR Systems

Multiple search fields may be used to refine results. Most recent publications appear first.

1...

Multiplex quantitative imaging of human myocardial infarction by mass spectrometry-immunohistochemistry

Year: 2018
Products: NWR213;New Wave;
Authors: Aljakna, A;Lauer, E;Lenglet, S;Grabherr, S;Fracasso, T;Augsburger, M;Sabatasso, S;Thomas, A;
Journal: Int. J. Legal Med.

Simultaneous assessment of a panel of protein markers is becoming essential in order to enhance biomarker research and improve diagnostics. Specifically, postmortem diagnostics of early myocardial ischemia in sudden cardiac death cases could benefit from a multiplex marker assessment in the same tissue section. Current analytical antibody-based techniques (immunohistochemistry and immunofluorescence) limit multiplex analysis usually to not more than three antibodies. In this study, mass spectrometry-immunohistochemistry (MS-IHC) was performed by combining laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with rare-metal-isotope-tagged antibodies as a technique for multiplex analysis of human postmortem myocardial tissue samples. Tissue sections with myocardial infarction were simultaneously analyzed for seven primary, rare-metal-isotope-tagged antibodies (troponin T, myoglobin, fibronectin, C5b-9, unphosphorylated connexin 43, VEGF-B, and JunB). Comparison between the MS-IHC approach and chromogenic IHC showed similar patterns in ionic and optical images. In addition, absolute quantification was performed by MS-IHC, providing a proportional relationship between the signal intensity and the local marker concentration in tissue sections. These data demonstrated that LA-ICP-MS combined with rare-metal-isotope-tagged antibodies is an efficient strategy for simultaneous testing of multiple markers and allows not only visualization of molecules within the tissue but also quantification of the signal. Such imaging approach has a great potential in both diagnostics and pathology-related research.

Petrogenesis of Early Cretaceous dioritic dikes in the Shanyang-Zhashui area, South Qinling, central China: Evidence for partial melting of thickened lower continental crust

Year: 2018
Products: UP213;New Wave;
Authors: Chen, L;Yan, Z;Wang, Z;Wang, K;
Journal: Journal of Asian Earth Sciences

The dioritic dikes distributed in the Shanyang-Zhashui area of the South Qinling region play an important role in understanding the deep magmatic processes and tectonic evolution during the orogenic process. The zircon UPb ages of the dioritic dikes indicate that they were emplaced at ∼144 Ma and therefore postdate the dikes that formed in the intracontinental orogenic background after the continental collision between the North China Block (NCB) and the South China Block (SCB). The dioritic dikes have SiO2 contents of 56.86-64.93 wt%; K2O contents of 1.65-3.21 wt%; low MgO (1.50-2.66 wt%), Y (14.4-25.5 ppm) and heavy rare earth element (HREE) contents; low Mg# values (39.9-49); high Sr contents (528-4833 ppm); and high Sr/Y ratios (32.8-189). They exhibit highly fractionated REE and flat HREE patterns, strong enrichment in large ion lithophile elements (LILEs; e.g., Rb, Ba, and U) and depletion in high field strength elements (HFSEs) (e.g., Nb), as well as positive Sr and negative Ti anomalies. Furthermore, these dioritic dikes exhibit (87Sr/86Sr)i ratios ranging from 0.7048 to 0.7083, εNd(t) values ranging from −3.3 to −1.4, and εHf(t) values ranging from −4.1 to 1.6. The geochemical patterns of the dioritic dikes indicate that they possess adakitic characteristics. Moreover, the low MgO contents, Mg# values, Ni contents, Th/Ce ratios, and SrNdHf isotopic features all indicate that these dioritic dikes were generated by the partial melting of thickened mafic lower crust. The high La/Yb and Sr/Y ratios, low Y and Yb contents, absence of significant Eu anomalies, flat HREE patterns, and low Nb/Ta ratios of these rocks suggest that the adakitic melts were derived from the melting of garnet-bearing amphibolite. The geochronologic, elemental and isotopic evidence suggests that the dioritic dikes may have formed in a locally extensional environment within an overall N-S compressional setting or during the transition from compressional to extensional environments in the Early Cretaceous. This process resulted in the upwelling of the asthenospheric or lithospheric mantle, causing partial melting of the mafic lower crust and forming the adakitic dioritic melts.

Detrital zircon and igneous protolith ages of high-grade metamorphic rocks in the Highland and Wanni Complexes, Sri Lanka: Their geochronological correlation with southern India and East Antarctica

Year: 2018
Products: UP213;New Wave;New Wave Research;
Authors: Kitano, I;Osanai, Y;Nakano, N;Adachi, T;Fitzsimons, I;
Journal: Journal of Asian Earth Sciences

The high-grade metamorphic rocks of Sri Lanka place valuable constraints on the assembly of central parts of the Gondwana supercontinent. They are subdivided into the Wanni Complex (WC), Highland Complex (HC) and Vijayan Complex (VC), but their correlation with neighbouring Gondwana terranes is hindered by a poor understanding of the contact between the HC and WC. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of remnant zircon cores from 45 high-grade metamorphic rocks in Sri Lanka reveals two domains with different age characteristics that correlate with the HC and WC and which help constrain the location of the boundary between them. The HC is dominated by detrital zircon ages of ca. 3500-1500 Ma from garnet-biotite gneiss, garnet-cordierite-biotite gneiss, some samples of garnet-orthopyroxene-biotite gneiss and siliceous gneiss (interpreted as paragneisses) and igneous protolith ages of ca. 2000-1800 Ma from garnet-hornblende-biotite gneiss, other samples of garnet-orthopyroxene-biotite gneiss, garnet-two-pyroxene granulite, two-pyroxene granulite and charnockite (interpreted as orthogneisses). In contrast, the WC is dominated by detrital zircon ages of ca. 1100-700 Ma from paragneisses and igneous protolith ages of ca. 1100-800 Ma from orthogneisses. This clearly suggests the HC and WC have different origins, but some of our results and previous data indicate their spatial distribution does not correspond exactly to the unit boundary proposed in earlier studies using Nd model ages. Detrital zircon and igneous protolith ages in the HC suggest that sedimentary protoliths were eroded from local 2000-1800 Ma igneous rocks and an older Paleoproterozoic to Archean craton. In contrast, the WC sedimentary protoliths were mainly eroded from local late Mesoproterozoic to Neoproterozoic igneous rocks with very minor components from an older 2500-1500 Ma craton, and in the case of the WC precursor sediments there was possibly additional detritus derived from early to middle Neoproterozoic metamorphic rocks. The relic zircon core ages in the HC are comparable with those of the Trivandrum Block and Nagercoil Block of southern India. In contrast, those ages in the WC match the Achankovil Shear Zone and Southern Madurai Block of southern India. These comparisons are also supported by Th/U ratios of detrital zircon cores from paragneisses (Th/U ratios of >0.10 for the former and not only >0.10 but also ≤0.10 for the latter). Comparisons with the Lützow-Holm Complex of East Antarctica indicate that the geochronological characteristics of the HC and WC broadly match those of the Skallen Group, and the Ongul and Okuiwa Groups, respectively.

Provenance of a Permian accretionary complex (Nishiki Group) of the Akiyoshi Belt in Southwest Japan and Paleogeographic implications

Year: 2018
Products: NWR213;ESI;
Authors: Zhang, X;Takeuchi, M;Ohkawa, M;Matsuzawa, N;
Journal: Journal of Asian Earth Sciences

The Akiyoshi Belt in the Inner Zone of Southwest Japan is made up of a Permian accretionary complex, the main component of which is the Late Permian Nishiki Group that mainly consists of sandstone, mudstone, felsic tuff and a minor amount of chert and conglomerate. We employ multiple methods, which includes sandstone petrography, detrital garnet composition and detrital zircon U-Pb dating to investigate the likely sources of these terrigenous deposits and to reconstruct the paleogeographic link between the proto-Japan and the East Asian continent. The highly immature Late Permian sandstones are interpreted to derive from multi-type source rocks that include felsic igneous rocks, basalts, sedimentary rocks and low to medium-grade metamorphic rocks in proximal locations. The detrital zircon U-Pb results show that all samples contain a dominant Early to Late Permian zircon population (294-254 Ma) and these zircons are interpreted to be derived from an active volcanic arc, which was most likely caused by subduction of the Paleo-Pacific plate beneath the South China Block. We found that spessartine-rich almandine garnets and almandine garnets dominated assemblages in the lower unit changed to grossular-andradite garnets dominated assemblage in the upper unit, which was caused by a progressive uplifting and denudation of the Permian volcanic arc.

Multiple crust reworking in the French Armorican Variscan belt: implication for the genesis of uranium-fertile leucogranites

Year: 2018
Products: NWR193UC;ESI;
Authors: Ballouard, C;Poujol, M;Zeh, A;
Journal: Int J Earth Sci (Geol Rundsch)

Muscovite peraluminous granites (MPGs) form by partial melting of the continental crust and can be related to metalliferous deposits such as tin, tungsten, and uranium (U). Metal enrichment in MPGs commonly results from fractional crystallization, but the metal contents of the source play a major role for their fertility. Between ca. 320 and 300 Ma (Late Carboniferous), the French Armorican Variscan belt was intruded by numerous U-fertile MPGs that contain inherited zircon grains with a wide range of ages from Archean-to-Carboniferous. U-Pb and Hf isotopic data of zircon grains from Brioverian-to-Carboniferous sediments, Cambrian-to-Early Carboniferous granitoids, and Late Carboniferous MPGs indicate that the crust of the Armorican Massif is made up by detritus mainly derived from the West African craton (3500-1600 Ma; TDM = 3.8-2.3 Ga), Grenvillian belt (1200-900 Ma; TDM = 2.7-1.2 Ga), and Avalonian-Cadomian belt (800-550 Ma; TDM = 2.5-0.8 Ga) and that the crust was affected by magmatic events at 510-470 Ma (TDM = 1.6-0.6 Ga), 410-330 Ma (TDM = 1.6-1 Ga), and 320-300 Ma. Furthermore, they reveal that the Late Carboniferous MPGs were mainly formed by partial melting of Brioverian sediments with Cambro-Ordovician and Devonian-Carboniferous granitoids, which are all genetically linked with each other and characterized by Th/U < 4. The new data suggest that the U-fertile MPGs result from multiple reworking of U-rich Brioverian sediments, deposited ca. 550 Ma ago on the northern margin of Gondwana, and partially molten during several Paleozoic events, causing a successive increase in U content in the middle-upper crust. 

Species- and habitat-specific otolith chemistry patterns inform riverine fisheries management

Year: 2018
Products: UP213;New Wave;New Wave Research;
Authors: Radigan, W;Carlson, A;Kientz, J;Chipps, S;Fincel, M;Graeb, B;
Journal: River Res Applic

Geology and hydrology are drivers of water chemistry and thus important considerations for fish otolith chemistry research. However, other factors such as species and habitat identity may have predictive ability, enabling selection of appropriate elemental signatures prior to costly, perhaps unnecessary water/age‐0 fish sampling. The goal of this study was to develop a predictive methodology for using species and habitat identity to design efficient otolith chemistry studies. Duplicate water samples and age‐0 fish were collected from 61 sites in 4 Missouri River reservoirs for walleye Sander vitreus and one impoundment (Lake Sharpe, South Dakota) for other fishes (bluegill Lepomis macrochirus, black crappie Pomoxis nigromaculatus, gizzard shad Dorosoma cepedianum, largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, white bass Morone chrysops, white crappie P. annularis, and yellow perch Perca flavescens). Water chemistry (barium:calcium [Ba:Ca], strontium:calcium [Sr:Ca]) was temporally stable, spatially variable, and highly correlated with otolith chemistry for all species except yellow perch. Classification accuracies based on bivariate Ba:Ca and Sr:Ca signatures were high (84% across species) yet varied between floodplain and main‐channel habitats in a species‐specific manner. Thus, to maximize the reliability of otolith chemistry, researchers can use species classifications presented herein to inform habitat selection (e.g., study reservoir‐oriented species such as white bass in main‐ channel environments) and habitat‐based classifications to inform species selection (e.g., focus floodplain studies on littoral species such as largemouth bass). Overall, species and habitat identity are important considerations for efficient, effective otolith chemistry studies that inform and advance fisheries and aquatic resource management.

Otolith chemistry as a fisheries management tool after flooding: The case of Missouri River gizzard shad

Year: 2018
Products: New Wave;New Wave Research;
Authors: Radigan, W;Carlson, A;Fincel, M;Graeb, B;
Journal: River Res Applic

Reduced river-floodplain connectivity can decrease fisheries production and cause ecological and socioeconomic consequences. In 2011, the largest flood on record in the Missouri River since 1898 nearly eliminated connectivity between an embayment (Hipple Lake) and Lake Sharpe, impeding movement of walleye (Sander vitreus) and a forage fish, gizzard shad (Dorosoma cepedianum). Thus, we used otolith chemistry to quantify Hipple Lake's natal contribution to Lake Sharpe's gizzard shad population and forecast effects of connectivity loss on the reservoir's socioeconomically important walleye fishery. Fish were classified to natal habitats with 79-89% accuracy, with most gizzard shad (64%) hatching in floodplain habitats (i.e., embayments, tributaries, canals, and stilling basins). Hipple Lake contributed 12% of gizzard shad to Lake Sharpe, more than a tributary (4%) and embayment (0%) but less than a canal (27%) and stilling basin (21%). Hipple Lake (178 acres) covers 0.31% of Lake Sharpe (56,884 acres), so its natal contribution is 38 times what would be expected if contribution was linearly related to area. Sediment and water management to maintain connectivity between Lake Sharpe and Hipple Lake and other floodplain habitats is important for continued gizzard shad production and prey supply for the walleye fishery. Otolith chemistry facilitates assessment of gizzard shad natal contributions in different habitats, serving as a fisheries management tool to inform floodplain habitat protection and rehabilitation after floods.

Ascent of migmatites of a high-temperature metamorphic complex due to buoyancy beneath a volcanic arc: a mid-Cretaceous example from the eastern margin of Eurasia

Year: 2018
Products: NWR193;ESI;
Authors: Miyazaki, K;Ikeda, T;Matsuura, H;Danhara, T;Iwano, H;Hirata, T;
Journal: International Geology Review

Mixtures of melt and residue in a high-T metamorphic complex have a lower density and viscosity than the surrounding host crust, and the mixtures should ascend due to buoyancy. The mixtures are recognized as migmatites in the high-T metamorphic complex. To confirm ascent of migmatites, we conducted numerical simulations of ascent of a model migmatite (buoyant viscous fluid). The numerical simulations show that the model migmatite could rise to shallow levels of a model crust so long as it is continuously produced at the bottom of the model crust. Otherwise it ceases to rise at depth due to loss of buoyancy by cooling. The numerical simulations also show that the model migmatite experiences vertical thinning during the ascent. The ascent mechanism proposed in this paper requires the continuous production of partially melted rocks at the base of the crust, which is provided by a continuous input of energy into the crust from the mantle. Given that high-T metamorphic complexes are associated with igneous activity beneath a volcanic arc, the igneous activity reflects the energy input into the lower crust from the mantle. A high-grade part (migmatites) of a high-T metamorphic complex in the Omuta district of northern Kyushu, southwest Japan, experienced thinning during ascent. Large amount of igneous rocks, such as plutonic and volcanic rocks, are also distributed in northern Kyushu. Zircon U-Pb ages of igneous rocks from northern Kyushu reveal that igneous activity continued from 115 to 93 Ma, and that peak igneous activity at 110-100 Ma was synchronous with the ascent of migmatites of the high-T metamorphic complex in northern Kyushu. Therefore, the numerical simulations may provide an appropriate model of the ascent of migmatites of the high-T metamorphic complex beneath a volcanic arc, at the eastern margin of Eurasia in the mid-Cretaceous.

Late Paleocene-early Eocene granitoids in the Jiamusi Massif, NE China: Zircon U-Pb ages, geochemistry, and tectonic implications

Year: 2018
Products: UP213;New Wave;
Authors: Li, P;Liu, Z;Li, S;Zhao, Q;Shi, Q;Li, C;Yang, X;
Journal: International Geology Review

Northeast (NE) China is characterized by large areas of Mesozoic and Paleozoic granitoids, whereas Cenozoic granitoids are scarce. This paper reports LA-ICP-MS zircon U-Pb ages and whole-rock geochemical data for late Paleocene-early Eocene granitoids from the Jiamusi Massif, NE China, in order to determine their petrogenesis and tectonic implications. Geochronological data indicate that the granodiorite and dioritic porphyry from the Wudingshan pluton formed at 51.5 ± 0.3 Ma and 56.3 ± 0.8 Ma, respectively. The biotite-quartz diorite, biotite granodiorite, and dioritic porphyry have high SiO2 (68.38-70.06 wt.%), Al2O3 (15.34-15.79 wt.%), and Na2O (3.96-4.49 wt.%) contents, low MgO contents (1.10-1.26 wt.%), A/CNK ratios of 0.99-1.11, and are classified as medium- to high-K calc-alkaline and weakly peraluminous I-type granitoids. They are enriched in LREEs and LILEs, and depleted in HFSEs, with Nb/Ta ratios of 10.4-15.0. Moreover, they have negative Nb-Ta-Ti anomalies, indicating that they were derived from continental crust. Combining with the previously published isotopic data and regional geological results, we suggest that the late Paleocene-early Eocene granitoids (56-52 Ma) were probably derived from partial melting of juvenile lower crust, and formed in an active continental margin setting, possibly related to subduction slab rollback of the Paleo-Pacific Plate.

Sedimentary characteristics and provenance of the basal conglomerate of the Late Jurassic-Early Cretaceous Jiaolai Basin, eastern China and their implications for the uplift of the Sulu Orogenic Belt

Year: 2018
Products: UP213;New Wave;
Authors: Zhang, P;Kuang, H;Liu, Y;Meng, Z;Peng, N;Xu, H;
Journal: International Geology Review

The basal conglomerates (‘Linsishan Conglomerate’, LC, herein) are exposed discontinuously along the northern part of the Sulu Orogenic Belt (SOB) and the southern part of the Jiaobei Terrane. Studying these conglomerates can offer key constrains for the formation age of the Jiaolai Basin and improve our understanding of the uplift and erosional histories of the SOB and Jiaobei Terrane, which are still in great controversy. In Huangyadi section, the LC is characterized as debris-flow deposits, channel deposits, and sheet-flow deposits. However, in Shanjiao section, the LC is changed to sheet-flow and sieve deposits, as well as debris-flow and channel deposits. These deposit characteristics indicate an unstable tectonic setting during initial opening stage of the basin. Based on the data of conglomerate component, palaeocurrent, and debris zircons ages, it can be inferred that the sediments in the Laiyang region were sourced from the Jiaobei Terrane and Northern Sulu Orogenic Belt (NSOB), and the sediments in the Zhucheng and Wulian regions were derived from the Jiaobei Terrane and the Southern Sulu Orogenic Belt (SSOB). Besides, the sediments in the Haiyang and Jimo regions were provided by the NSOB and SSOB, respectively. The significant SHRIMP U-Pb ages of a tuff developing in the LC has been obtained, indicating that 149 ± 2.5 Ma is the oldest age constraint for the Jiaolai Basin. In addition, our result shows that the Latest Jurassic (ca. 149 Ma) may be a critical time; before this time, the Jiaobei Terrane and the SOB experienced a rapid uplift with minimal uplift velocity (~0.9 km/Ma); since then, the Orogen began to collapse and a series of basins formed rapidly in its core, which indicate the tectonic stress regime of the Dabie-Sulu Orogen varied from compressional stress to tensile stress.

Assembly and dispersal history of continental blocks within the Altun-Qilian-North Qaidam mountain belt, NW China

Year: 2018
Products: UP213;New Wave;
Authors: Fu, C;Yan, Z;Guo, X;Niu, M;Cao, B;Wu, Q;Li, X;Wang, Z;
Journal: International Geology Review

The continental arc and intraplate magmatic rocks occur widely within the Altun-Qilian-North Qaidam (AQNQ) region of NW China and play a key role in reconstructing the assembly and dispersal history of micro-continental blocks within a complex orogenic system. In the South Qilian belt, amphibolites from the Hualong Complex can be subdivided into four types based on their lithologies, ages, and tectonic affinities. Type I is characterized by garnet and Proterozoic detrital zircons, indicating a metasedimentary origin. Type II and IV amphibolites are tholeiitic and calc-alkaline, respectively, and characterized by enrichment in LREES, Th, U, and Ba, accompanied by depletion in Nb and Ta, indicating a continental arc setting on an active continental margin. Type III is alkaline with ocean island basalt affinity and considered to have intraplate, rift-related origins. SHRIMP U-Pb dating and previous studies suggest that type II, III, and IV amphiboltes are formed at 1126 Ma, 882 Ma, and 470 Ma, respectively, which corresponds to 1126-895 Ma continental arc magmatism, 882-580 Ma rifted-related magmatism, and 522-440 Ma continental arc magmatism within the AQNQ. The three episodes of magmatism further demonstrate the processes of assembly and breakup of the Proterozoic supercontinent Rodinia and reassembly of the Altun-Qilian-North Qaidam orogenic belt.

Cretaceous A-type volcanic-intrusive rocks and simultaneous mafic rocks along the Gan-Hang Tectonic Belt, Southeast China: petrogenesis and implications for the transition of crust-mantle interaction

Year: 2018
Products: NWR213;
Authors: Wang, H;Chen, P;Wang, K;Ling, H;Wu, J;Tang, J;Zhao, Y;
Journal: International Geology Review

Abundant evidence points to the Cretaceous crust-mantle interaction and plate subduction in the Gan-Hang Tectonic Belt (GHTB), southeastern China, but the evolutionary process remains poorly constrained. Here we conduct a comprehensive study on Daqiaowu granitic porphyry and diabase dikes in the eastern GHTB, in conjunction with previous studies on simultaneous felsic and mafic rocks along the GHTB, to demonstrate their petrogenesis and geodynamic evolutionary process. The Daqiaowu granitic porphyry (125 Ma), as well as the coeval granitic rocks, exhibits high zircon saturation temperatures, alkalis, 104 *Ga/Al ratios, and Zr + Nb + Ce + Y contents, concluding a distinctive belt of the Early Cretaceous (~137- 125 Ma) A-type volcanic-intrusive rocks in the GHTB. Their εNd(t) and zircon εHf(t) values gradually increased through time from approximately −9.0 to −1.0 and −10.0 to +4.0, respectively, implying increasing contribution of mantle-derived components to their formation, and hence progressively intensified crust-mantle interaction in an intra-arc rift environment (a geodynamic transition stage from continental arc to back-arc) during the Early Cretaceous. This plausibility is further supported by the Early Cretaceous Daqiaowu diabase dikes and coeval mafic rocks which exhibit arc-like magmatic signatures and were derived from mantle wedge. In contrast, the Late Cretaceous mafic rocks show ocean island basaltlike geochemical characteristics, reflecting a depleted asthenosphere mantle source. This discrepancy of mantle sources concludes that the geodynamic setting in the GHTB may have basically transferred to back-arc regime in the Late Cretaceous. Thus, the Cretaceous geodynamic evolutionary process in the GHTB can be defined as the Early Cretaceous gradually intensified crust-mantle interaction in a geodynamic transition stage (from continental arc to back-arc extension) and the Late Cretaceous back-arc extensional setting.

Petrogenesis and tectonic implications of Triassic A-type granites in southeastern China: insights from zircon U-Pb-Hf isotopic and whole-rock geochemical compositions of the Luoguyan and Guiyantou granites in northwestern Fujian Province

Year: 2018
Products: New Wave Research;
Authors: Gao, W;Wang, Z;Li, L;Tan, Y;
Journal: International Geology Review

Triassic A-type granites in eastern South China Block (SCB) are abundant in the Wuyi-Yunkai tectonic domain and provide an important opportunity to explore the early Mesozoic evolution of continental crust of the SE part of the SCB. We carried out U-Pb zircon dating, Lu-Hf isotope analyses of zircon, and whole-rock geochemical analyses for two granitic plutons, the Guiyantou (GYT) and Luoguyan (LGY) granites, from northwestern Fujian Province. LA-ICP-MS U-Pb zircon analyses yielded ages of 232 ± 4 to 231 ± 7 Ma and 221 ± 5 Ma (Middle-Late Triassic) for the GYT and LGY granites. These two granites belong to metaluminous to weakly peraluminous high K calc-alkaline A-type granite that are enriched in K, Al, light rare earth element and Rb, Th, U, and Pb, and depleted in Nb, Ta, P, and Ti. Their rare earth element patterns are highly fractionated with (La/Yb)N ratios of 2-21 and strong negative Eu anomalies (Eu/Eu* = 0.02-0.31). In situ Hf isotopic analysis of zircon from the GYT and LGY granites yielded εHf(t) values ranging from -11.5 to -1.1, with corresponding two-stage Hf model ages from 1.98 to 1.33 Ga, from which it is inferred that the GYT and LGY magmas formed by partial melting of Proterozoic metasedimentary rock in the Cathaysia block. The two granites were emplaced at 232 and 221 Ma and together with Triassic A-type granites in coastal region of the SCB, which is in agreement with an extensional tectonic setting in the Middle-Late Triassic. We suggest that the Middle-Late Triassic A-type granites in eastern SCB were probably formed in an intracontinental, post-orogenic extensional regime that collision was between the SCB and an ‘unknown block’ or the eastern extension of Indochina block.

Obsidian economy on the Cauria Plateau (South Corsica, Middle Neolithic): New evidence from Renaghju and I Stantari

Year: 2018
Products: NWR213;
Authors: Orange, M;Le Bourdonnec, F;D'Anna, A;Tramoni, P;Lugliè, C;Bellot-Gurlet, L;Scheffers, A;Marchesi, H;Guendon, J;Joannes-Boyau, R;
Journal: Quaternary International

This paper aims to study and compare the obsidian economies of Renaghju and I Stantari, two neighbouring Neolithic sites located on the Cauria plateau (south-western Corsica). The occupation phase 3 of Renaghju and phase 1 of I Stantari, both attributed to the Middle Neolithic (fifth millennium BC), have provided respectively 112 and 99 obsidian artefacts. With the aim of completing our rather lacunary knowledge of the obsidian consumption behaviours in place in Corsica during this period, the entire assemblages have been geochemically characterised virtually non-destructively using LA-ICP-MS at SOLARIS (Southern Cross University [SCU]). Our analyses revealed that, while the obsidian raw materials were exclusively sourced from the Monte Arci complex in Sardinia (SA, SB2, and SC sub-types only), rather different consumption patterns are observed for the two sites despite their comparable nature (megalithic sites) and geographical proximity (400 m apart). These differences in obsidian consumption on adjacent sites could be explained by their divergent functions (ceremonial site [Renaghju] vs. ceremonial locus and large settlement [I Stantari]), or eventually point towards the need for a readjustment of the chronological attribution of the I Stantari phase 1 occupation level.

Identifying stock structuring in the sandeel, Ammodytes marinus , from otolith microchemistry

Year: 2018
Products: NWR213;New Wave;
Authors: Wright, P;Régnier, T;Gibb, F;Augley, J;Devalla, S;
Journal: Fisheries Research

Identifying the scale of population processes is important for sustainable fisheries management. In the North Sea, the lesser sandeel, Ammodytes marinus, is now managed as seven stocks delineated on the basis of biophysical model predictions of the limited scale of larval mixing. This study used otolith chemistry to evaluate whether the stock units defined from these predictions actually reflect the degree of isolation of early life stages. Elemental composition near the core, settlement check and summer opaque zone were examined using laser ablation-inductively coupled plasma mass spectrometry in young of the year, sampled across 8 grounds within three of the main fished stocks in 2011. There were significant spatial differences in otolith chemistry enabling post-settled juveniles to be discriminated among stock areas and even between some grounds. Clustering of near core chemistry pointed to four natal sources, with dominant clusters in each of the three stocks studied and one unique to the Central Western North Sea (sandeel assessment area 4). Moreover, near core chemistry was similar to that of post-settled juveniles at the stock area level. Consistency in the scaling of early life mixing predicted by biophysical models and otolith chemistry supports the present stock units used in assessments.

New insights into the metallogeny of MVT Zn-Pb deposits: A case study from the Nayongzhi in South China, using field data, fluid compositions, and in situ S-Pb isotopes

Year: 2018
Products: UPfemto 266;ESI;
Authors: Zhou, J;Wang, X;Wilde, S;Luo, K;Huang, Z;Wu, T;Jin, Z;
Journal: American Mineralogist

The newly discovered Nayongzhi Zn-Pb deposit (>20 Mt ores at 1.11-15.65 wt% Zn and 0.59-0.97 wt% Pb) in NW Guizhou province, South China, is hosted by late Ediacaran and early Cambrian carbonate rocks. The ore body is structurally controlled by a kilometer-scale reverse fault-anticline system and occurs as stratiform, lentiform, or steeply dipping vein structures. Its geological feature is comparable to that of the Mississippi Valley-type (MVT) Zn-Pb deposits. δ34S values (+11.8 to +33.0‰) of sulfide minerals determined by NanoSIMS have a larger range than those determined by conventional bulk analysis (δ34S = +18.12 to +24.79‰). This suggests that S isotopes determined by in situ analysis can reflect the nature of fractionation involved in mineralization. Furthermore, cores of sulfide crystals have higher δ34S values (+26.1 to +33.0‰) than their rims (+11.8 to +24.5‰). This implies a mixture of multiple S reservoirs or a Rayleigh fractionation of S isotopes occurred during ore formation process. Additionally, both S isotopic compositions determined by in situ and bulk analyses reflect the enrichment of 34S in hydrothermal fluid (δ34Sfluid > +11.8‰), a typical characteristic of marine sulfate-derived S. Such S isotopic signatures also show that thermochemical sulfate reduction (TSR) is the dominant mechanism for the incorporation of S2− from SO2−4. Pb isotopic ratios of galena obtained by femtosecond LA-MC-ICPMS plot in the field that overlaps with the Pb evolution curve of upper crust contributed to the orogeny and the field of modern lower crust, and can be compared to the Proterozoic metamorphic rocks. The means that the majority of Pb metal is sourced from the basement rocks. Although δ13C values (-4.1 to +0.5‰) of calcite separates and corresponding fluids are similar to both fresh limestone (-1.7 to +1.3‰) and typical marine carbonate rocks, the δ18O values (+12.4 to +14.1‰) are significantly lower than both limestone (+24.1 to +25.5‰) and marine carbonate rocks. Such C-O isotopic characteristics suggest that the source of C is ore-hosting carbonate rocks, whereas O has a mixed source of metamorphic fluids and carbonate rocks resulting from water/rock (W/R) interaction. This study demonstrates that (1) fluid mixing caused rapid sulfide precipitation, resulting in significant fractionation of S isotopes; and (2) both the W/R interaction and CO2 degassing controlled local carbonate cyclic process of dissolution → re-crystallization, which provided metastable physical and chemical conditions for giant sulfide mineralization. These two processes are crucial in forming MVT deposits.

Textural and mineral chemical evidence for the cumulate origin and evolution of high-titanium basalt fragment 71597

Year: 2018
Products: UP213;
Authors: Donohue, P;Neal, C;
Journal: American Mineralogist

Basalt fragment 71597 is the sole high-titanium mare basalt showing evidence for olivine accumulation during formation. The petrogenesis of this unique sample was investigated using quantitative textural analysis and major- and trace-element mineral geochemistry. Crystal size distribution analysis identified two size populations of olivine, which we separate into cumulate and matrix olivine. The spatial distribution of olivine also supports clustering of olivine crystals, likely during accumulation. Observed mineral chemistry was consistent with an origin through olivine accumulation, although where this occurred cannot be discerned (e.g., in ponded melts at the base of or in the lunar crust, or within a thick high-Ti basalt flow). Attempts to place 71597 within a geochemical group were inconclusive both using subtraction of cumulate olivine from bulk composition, and by modal recombination of major phases. However, equilibrium liquid compositions of augite and plagioclase are determined to be consistent with an origin by fractionation from the Type B2 chemical suite of Apollo 17 high-Ti basalts. This method of classification has potential for placing other Type U (“Unclassified”) basalts into chemical suites.

Leesite, K(H2O)2[(UO2)4O2(OH)5]·3H2O, a new K-bearing schoepite-family mineral from the Jomac mine, San Juan County, Utah, U.S.A.

Year: 2018
Products: UP213;New Wave;New Wave Research;
Authors: Olds, T;Plášil, J;Kampf, A;Spano, T;Haynes, P;Carlson, S;Burns, P;Simonetti, A;Mills, O;
Journal: American Mineralogist

Leesite (IMA2016-064), K(H2O)2[(UO2)4O2(OH)5]·3H2O, is a new uranyl-oxide hydroxyl-hydrate found underground in the Jomac mine, Brown’s Rim, White Canyon mining district, San Juan County, Utah. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses provided the empirical formula K0.67Na0.004Ca0.012U4O20H15.31, based on 4 U and 20 O apfu. Sheets in the crystal structure of leesite adopt the fourmarierite anion topology, and so belong to the schoepite family of related structures that differ in the interlayer composition and arrangement, and charge of the sheet. Leesite may form as one of the principal components of “gummite” mixtures formed during the alteration of uraninite, and the unit cell of leesite resembles the previously described, but poorly understood mineral, paraschoepite. Uptake of dangerous radionuclides (90Sr, 135Cs, 137Cs, 237Np, 238Pu) into the structure of leesite and other members of the family has important implications for the safe disposal of nuclear waste.

The giant inoceramid Platyceramus platinus as a high-resolution paleoclimate archive for the Late Cretaceous of the Western Interior Seaway

Year: 2018
Products: NWR193;ESI;
Authors: Walliser, E;Mertz-Kraus, R;Schöne, B;
Journal: Cretaceous Research

Platyceramus platinus was a giant inoceramid bivalve that inhabited the outer shelf environments of the Western Interior Seaway (WIS) in North America. With axial heights typically exceeding 1 m, the shells of this species potentially serve as a unique high-resolution geochemical proxy archive for Late Cretaceous paleoclimate. Here we present the first sclerochronological investigation of P. platinus shells to evaluate the usefulness of this species as an archive of short-term (e.g., seasonal to inter-annual) paleoenvironmental variability. We analyzed the growth patterns, the stable oxygen (δ18O) and carbon (δ13C) isotope values of well-preserved P. platinus shell fragments from the Santonian Niobrara Formation at Monument Rocks (Kansas, USA), a National Natural Landmark. A series of diagenetic tests, including cathodoluminescence (CL), scanning electron microscopy (SEM), and geochemical (LA-ICP-MS) analysis, confirmed the good state of preservation of the material. Shell microgrowth patterns suggested lunar daily (circalunidian) growth and that P. platinus grew nearly uninterruptedly throughout the year. Assuming a δ18Ow value of −3.45 ± 0.26‰, reconstructions based on shell δ18O data suggest average seasonal temperature variations between 12.5 ± 3.0 and 25.5 ± 1.1 °C and a mean annual temperature of 17.0 ± 4.1 °C for the outer shelf environment of the WIS. Repeated sudden negative δ13C shifts of up to 2.00‰ and Mn-rich shell growth bands (Mn/Ca ratios up to 90.21 μmol/mol) suggest that P. platinus filter-fed on suspended organic detritus which sank from the upper water column during episodic events. The availability of large amounts of suspended food, however, slowed shell accretion rates of P. platinus. This shell growth behavior combined with the positive δ13C values (0.03-3.96‰) possibly indicate a chemosymbiotic lifestyle that allowed P. platinus to survive under oxygen-depleted conditions at the seafloor.

U-Pb Ages and Lu-Hf Isotopes of Detrital Zircons from Sedimentary Units across the Mid-Neoproterozoic Unconformity in the Western Jiangnan Orogen of South China and Their Tectonic Implications

Year: 2018
Products: UP213;New Wave;
Authors: Su, H;Jiang, S;Mao, J;Zhang, D;Wu, X;Qin, H;
Journal: The Journal of Geology

The Jiangnan Orogen, located at the southeastern margin of the Yangtze Block, South China, records the complete history of assembly and evolution between the Yangtze and Cathaysia blocks. Neoproterozoic sedimentary sequences are widespread in the Jiangnan Orogen, with a regional angular unconformity separating the Sibao and Danzhou groups. U-Pb geochronology and Lu-Hf isotope analyses were carried out on detrital zircons across this unconformity and also the associated granites in the western Jiangnan Orogen in this study. Our new results, combined with previous data, indicate that the Sibao and Danzhou groups were deposited at 860-832 and 803-764 Ma, respectively. Thus, this unconformity was constrained to be 832-803 Ma. Detrital zircons from the Sibao and Danzhou groups have generally similar age populations, with three major peaks at 2000-1550, 1000-880, and 850-830 (760) Ma and one minor at 2600-2400 Ma. The most important generation of juvenile crust appears to have occurred at 2600-2400 Ma. Both recycling of ancient crustal materials and addition of juvenile mantle components took place in the time intervals of 2000-1550 and 1000-880 Ma. Detrital zircons in the age population of 850-830 (760) Ma were probably derived from proximal magmatic rocks in the western Jiangnan Orogen, reflecting fast erosion of newly formed igneous rocks. The Sibao and equivalents were deformed and intruded by granites posterior to the deposition of the Sibao and equivalent sequences after 832 Ma but before deposition of the Danzhou and equivalent units before 803 Ma. The pre-Danzhou deformation marked a collision along the southeast margin of the Yangtze Craton. The regional angular unconformity sealed the Jiangnan Orogeny, and thus the collision between the Yangtze and Cathaysia blocks was during 832-803 Ma. The Danzhou and equivalent units unconformably overlying the Sibao Group record the onset of rifting along the southeastern Yangtze margin beginning around 803 Ma.

The anomaly of glass beads and glass beadmaking waste at Jiuxianglan, Taiwan

Year: 2018
Products: UP213;New Wave;
Authors: Wang, K;Iizuka, Y;Hsieh, Y;Lee, K;Chen, K;Wang, C;Jackson, C;
Journal: Archaeol Anthropol Sci

Glass beads and beadmaking waste have been excavated at the Iron Age site of Jiuxianglan (ca. third century BC–eighth century AD) in southeastern Taiwan. It was suggested that this site may be a production and exchange centre of glass beads in Iron Age Taiwan. This paper presents the analysis of 44 samples, to explore the relationship between glass beads and waste and the nature of bead production at Jiuxianglan. The analysis combines data on style, chemical composition, microstructure and distribution of glass beads and waste. The results do not show a compositional or structural match between the glass beads and glass waste, suggesting that the glass beads may not have been produced at this site.

U-Pb and Hf isotope analysis of detrital zircons from Devonian-Permian strata of Kotel’ny Island (New Siberian Islands, Russian Eastern Arctic): Insights into the Middle-Late Paleozoic evolution of the Arctic

Year: 2018
Products: UP213;New Wave;
Authors: Ershova, V;Prokopiev, A;Andersen, T;Khudoley, A;Kullerud, K;Thomsen, T;
Journal: Journal of Geodynamics

U-Pb and Lu-Hf isotope analyses of detrital zircons collected from the Devonian-Permian strata of Kotel’ny Island (New Siberian Islands, Eastern Russian Arctic) provide vital information about provenance areas and history of the poorly studied Paleozoic basement of the Laptev and East Siberian shelves. Based on detrital zircon signatures, our study reveals that the studied succession can be divided into two distinct groups: Devonian-Lower Carboniferous and uppermost Carboniferous-Permian. U-Pb and Lu-Hf isotope signatures of detrital zircons from the Devonian-Lower Carboniferous deposits correspond to well-known Precambrian-Early Paleozoic magmatic and metamorphic events within the northern part of Baltica, indicative of a peri-Baltican affinity of the New Siberian Islands during this time. A lack of zircon ages close to the depositional age of the formation, along with a mature composition of the sandstones, suggest that the Devonian-Lower Carboniferous succession formed as a result of extensive sediment reworking from a distal provenance. By contrast, uppermost Carboniferous-Permian sandstones have an immature composition, with numerous young detrital zircons close to the age of sedimentation and Hf signatures typical of a continental arc environment. We therefore suggest that the provenance for these younger deposits was located within a coeval orogeny and based on previous studies, we conclude that these deposits were sourced from the north-western part of the Uralian Orogen.

Birth of an ocean in the Red Sea: Oceanic-type basaltic melt intrusions precede continental rupture

Year: 2018
Products: New Wave;New Wave Research;
Authors: Ligi, M;Bonatti, E;Bosworth, W;Cai, Y;Cipriani, A;Palmiotto, C;Ronca, S;Seyler, M;
Journal: Gondwana Research

The role of magmatism in continental rupture at the birth of a new ocean is poorly understood. Continental rupture can take place with voluminous volcanism, as in the southern Red Sea, or in a relatively non-volcanic mode, as in the northern Red Sea. We report geophysical, geochemical and geochronological evidence suggesting that continental rupture in the northern Red Sea is preceded by MORB-type basaltic melt intrusions that cooled at depth forming gabbros at progressively shallower crustal levels as rifting progressed towards continental separation. One of these gabbros yielded an 40Ar/39Ar age of 25 ± 6 Ma, suggesting intrusion during early rifting. A magma chamber we detected 3.5 km below Thetis Deep, an axial segment of initial oceanic crust accretion, represents the final stage in this progression. Oceanic crust accretion in the Red Sea rift starts first at depth before continental rupture and initiation of sea floor spreading.

Pore structure, wettability and tracer migration in four leading shale formations in the Middle Yangtze Platform, China

Year: 2018
Products: UP213;New Wave;
Authors: Yang, R;Hu, Q;He, S;Hao, F;Guo, X;Yi, J;He, X;
Journal: Marine and Petroleum Geology

Deposited in different sedimentary settings, four leading shale formations (Late Ordovician Wufeng, Early Silurian Longmaxi, Late Permian Dalong, and Early Jurassic Dongyuemiao Shales) are currently the most promising zones for shale gas development in the Middle Yangtze Platform of South China. Based on complementary tests [low pressure gas physisorption, mercury injection capillary pressure (MICP), contact angle measurement, fluid imbibition into initially dry shale, and tracer diffusion into initially fluid-saturated shale followed by tracer mapping with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)], this work investigates their pore structure (both geometry and connectivity) and wettability characteristics, as well as the coupled effects of these characteristics on fluid flow and tracer migration.

Zircon U-Pb age, Trace Element, and Hf Isotopic Compositions of Nordmarkite in the Lizhuang Rare Earth Element Deposit in the Western Margin of the Yangtze Block

Year: 2018
Products: UP213;New Wave;
Authors: ZHOU, J;TAN, H;GONG, D;ZHU, Z;LUO, L;
Journal: Acta Geologica Sinica - English Edition

The Mianning-Dechang (MD) rare earth element (REE) belt, located in the northern Kangdian axis (KDA) in the western margin of the Yangtze platform, is one of the most economically significant REE mineral belts in China. REE mineralization is associated with Himalayan carbonatite-alkaline complexes. The Lizhuang nordmarkite occurred in the northern part of the MD REE belt. The majority of zircons from the Lizhuang nordmarkite are characterized by pronounced positive Ce yet slightly negative Eu anomalies and high U/Yb. Moreover, all zircons have stable Hf isotopic compositions with initial 176Hf/177Hf ratios ranging from 0.282739 to 0.282808 and an average value of 0.282773. The negative Lu/Hf and positive εHf(t) range from −0.98 to −0.94 (average value of −0.96) and from −0.56 to 1.89 (the majority is positive, with an average of 0.66), respectively. These characteristics indicate that the rock is derived from an enriched mantle and subducted material. LA‐ICP‐MS analysis of the zircons from the intrusion yields a weighted mean 206Pb/238U age of 28.57±0.61Ma. During this period, the tectonic activity in the KDA is not plate subduction but an intraplate tectonic exhibiting fold-thrust and strike-slip behaviors in the western marginal zone of the Yangtze platform (WMYB). We suggest the possibility of an existing eastward old slab subduction under WMYB combined with a regional tectonic evolution. The Lizhuang nordmarkite may be derived from an enriched mantle beneath the western part of the Yangtze craton, which originated from the remelting of the Tethys subducting slab, because of the Himalayan strike-slip that formed a special type of REE deposit called strike-slip‐type REE deposits.

Two Types of Granites in the Western Yangtze Block and Their Implications for Regional Tectonic Evolution: Constraints from Geochemistry and Isotopic Data

Year: 2018
Products: ESI;
Authors: MABI, A;YANG, Z;ZHANG, M;WEN, D;LI, Y;LIU, X;
Journal: Acta Geologica Sinica - English Edition

In the western Yangtze Block, widespread Mesoproterozoic to Neoproterozoic rocks are the key to understanding the Precambrian tectonic‐magmatic evolution of the region. However, their petrogenesis and tectonic setting are still controversial. In this paper, zircon U‐Pb ages, Sm‐Nd isotopic and whole‐rock geochemical data are reported from selected fresh samples in the southern Dechang county, southwestern China, in order to constrain their emplacement age and magma source, as well as their petrogenesis and tectonic setting. They are mainly composed of biotite monzogranite, monzonitic granite, biotite granodiorites, and quartz diorite. Two ages of 1055 ± 43 Ma and 837.6 ± 3.8 Ma were obtained through zircon U‐Pb dating by LA‐ICP‐MS and LA‐MC‐ICP‐MS, respectively. According to their major element compositions, the Grenville‐age granites are peraluminous calc‐alkaline series calcic S‐type granite. In contrast, the mid‐Neoproterozoic granites are metaluminous calc‐alkaline series alkalic I‐type granite. Furthermore, the S‐type granites are enriched in LREEs relative to HREEs with (La/Yb)N ratios of 3.85-18.56 and underwent major fractionation with strongly negative Eu anomalies (Eu/Eu* = 0.38-0.66). In the MORB‐normalized trace element variation diagram, all the samples are enriched in Ce and large ion lithophile elements such as Rb, Th, and K, and depleted in high field strength elements such as Nb, and Ti, with negative Sr and Ti anomalies. The I‐type granites are enriched in LREEs with slight negative Eu anomalies (Eu/Eu* = 0.83-0.93). They are characterized by the enrichment of highly incompatible elements (such as K, Rb, Ba, Th) and LREEs, relative to MORB. Neodymium isotopic data show that the S‐type granites display 143Nd/144Nd values of 0.51241-0.51256, and have εNd (t = 1055 Ma) values of (−3.29) to (−3.81). Calculated tDM ages yield values from 1.87 to 1.91 Ga with the tDM.2stg ages of 1.86 to 1.9 Ga. The I‐type granites have 143Nd/144Nd ratios between 0.51192 and 0.51195, corresponding to initial εNd (t = 837 Ma) values of 1.22 to 5.63. Calculated tDM ages yield values from 1.0 to 1.38 Ga and the tDM.2stg ages yield values from 0.99 to 1.06 Ga. The S‐type granites are distinguished as syn‐collision granite, whereas the I‐type granites were formed as arc magmas according to the Rb‐(Yb+Ta) and R1‐R2 tectonic discrimination diagrams. To conclude, there are two types of spatially associated granite, the Mesoproterozoic S‐type granite which were derived from re‐melting of upper crustal mudstone and/or clastics and resulted from the convergence of two continental plates, and the mid‐Neoproterozoic I‐type granite which formed in continental arc and resulted from mantle‐derived magma mixed crust material, in the western Yangtze Block. Furthermore, we suggest that collision between the Yangtze and Cathaysia blocks occurred at about 1055 Ma, and caused the S‐type granite. The I‐type granite related to the subduction of oceanic lithosphere eastward underneath the Yangtze Block in the mid‐Neoproterozoic.

The Pico do Itapeva Formation: A record of gravitational flow deposits in an Ediacaran intracontinental basin, southern Brasília Orogen, SE Brazil

Year: 2018
Products: UP213;New Wave;
Authors: Caputo Neto, V;Ribeiro, A;Nepomuceno, F;Dussin, I;Trouw, R;
Journal: Journal of South American Earth Sciences

The Pico do Itapeva Formation is a key metasedimentary unit to the understanding of the extensional events that occurred between the late stage of the southern Brasília Orogen collision and the main collision in the central Ribeira Orogen. The formation crops out in a 20 km long NE-trending narrow belt in the Mantiqueira mountain range in eastern São Paulo State, Brazil. It is located in the interference zone of the southern Brasília and the central Ribeira orogens and records deformation and greenschist facies metamorphism (biotite zone) related to the Brasiliano orogeny. The Pico do Itapeva Formation rests unconformably on a metaigneous substratum of the Socorro-Guaxupé Nappe/Embu Terrane and, on the southern side, is truncated by a steep SE-dipping dextral reverse shear zone. It consists of a coarsening- and thickening-upward succession, with minimum thickness of 800 m, composed of lutite, arkose and conglomerate. These rocks constitute three distinct lithofacies associations: LAI- arkose, arkose-lutite composite beds, lutite and fine conglomerate beds; LAII- arkose, pebbly arkose and scarce lutite and; LAIII- conglomerate and pebbly arkose. Most of the beds are massive; graded beds, dish and convolute structures occur locally. Bed thickness varies from thin to very thick and amalgamated bodies constitute up to 30m thick strata. Three mappable units at scale 1:20,000 were recognized based on different proportions of the three lithofacies associations. The deposits are interpreted as the record of mass flows and associated processes in a fan delta setting developed in an intermontane rift basin. U-Pb LA-ICP-MS detrital zircon ages suggest the maximum depositional age at ca. 611 Ma and the basin evolution is interpreted in the range between 611 and 580 Ma during an inter-orogenic stage between the Brasília and Ribeira orogenies.

Stratigraphic and geochronological characterization of the Mato Verde group, Central Espinhaço (Brazil): An Eocalymmian rifting record in the western domain of the Congo-São Francisco paleocontinent

Year: 2018
Products: UP213;New Wave;New Wave Research;
Authors: Costa, A;Danderfer, A;Lana, C;
Journal: Journal of South American Earth Sciences

The Mato Verde Group comprises an important volcano-sedimentary record occurring in the eastern Congo-São Francisco paleocontinent along the western border of the Central Espinhaço. This succession is interpreted as a basin rift related to one of the stages of basin formation in the Espinhaço aulacogen at the northern end of the Araçuaí Orogen. The stratigraphic architecture and U-Pb data from the volcano-sedimentary succession, as well from the overlying succession, provide new insight into the evolution of Mato Verde rifting. The sedimentary pattern of this succession is interpreted as the basin infilling of an intracontinental rift that was compartmentalized in two half-grabens. The basal succession defined as the Panelas Formation contains entirely siliciclastic sedimentation, such as alluvial fan, delta fan and minor fluvial and lacustrine facies associations. Detrital zircon grains extracted from basal conglomerates show mainly Archean and Paleoproterozoic ages. The upper sequence is represented by the Riacho Seco Formation, which consists of volcanic lava beds and volcaniclastic rocks. At the top of the succession, a lapilli tuff is dated at 1586 ± 15 Ma, which is interpreted as the final age of the rift phase. The Vereda da Cruz Formation occurs in stratigraphic discontinuity above the Mato Verde succession and comprises exclusively aeolian sedimentation. The youngest grain defines a maximum sedimentation age of 1616 ± 30 Ma. This basin stage is interpreted as due to a thermal subsidence process that is related to Mato Verde rifting. The equivalent unit to the Mato Verde Group is only found in the Northern Espinhaço and is represented by the Pajeú Group. The basin-fill patterns and Calymmian ages suggest a direct link with the second rifting event within the São Francisco paleocontinent, which was responsible for the development of the Espinhaço basin.

Petrogenesis of the Mairupt microgranite: A witness of an Uppermost Silurian magmatism in the Rocroi Inlier, Ardenne Allochton

Year: 2018
Products: NWR193UC;ESI;
Authors: Cobert, C;Baele, J;Boulvais, P;Poujol, M;Decrée, S;
Journal: Comptes Rendus Geoscience

Magmatism in the Rocroi inlier (Ardenne Allochton, southeastern Avalonia during eo-Hercynian times) consists of a swarm of bimodal dykes (diabase and/or microgranite) emplaced in Middle to Upper Cambrian siliciclastics (Revin Group). Felsic volcanites interbedded within the Upper Silurian/Lower Devonian transgressive strata on the eastern edge of the inlier were interpreted as belonging to the same magmatic event. This was subsequently invalidated by zircon U-Pb dating of the Mairupt and Grande Commune magmatic rocks, which yielded an Upper Devonian age. Here we report a reevaluation of the age of the Mairupt microgranite based on LA-ICP-MS in situ U-Pb zircon geochronology, which yields a concordant age of 420.5 ± 2.9 Ma (Late Silurian/Early Devonian). This new dating restores the consistency between the different magmatic occurrences in the Rocroi inlier. The geochemical and petrographical data furthermore indicate a major crustal contribution, which fits well within the context of crust thinning of the Ardenne margin (southeastern Avalonia) in the transtensional Rheno-Hercynian back-arc basin.

Petrogenesis and geochronology of Mishao peraluminous I-type granites, Shalair valley area, NE Iraq

Year: 2018
Products: NWR213;Electro Scientific Industries;
Authors: Abdulzahra, I;Hadi, A;Asahara, Y;Azizi, H;Yamamoto, K;
Journal: Chemie der Erde

The Shalair area, which is located in northeastern Iraq, is considered to be part of the northern Sanandaj-Sirjan Zone (SaSZ) and contains several granitoid bodies. One of these bodies, the Mishao porphyritic-granite (MG), was crystallized at 111.6 ± 2.4 Ma, based on its zircon U-Pb age. Its geochemical characteristics suggest that the MG rocks are calc-alkaline, peraluminous, I-type granites with microgranular mafic enclaves. They are enriched in SiO2, Na2O, Al2O3 and Zr and depleted in MgO, Fe2O3, Nb and Ti; in contrast, the enclave sample records lower SiO2 content and higher contents of MgO and Fe2O3. These rocks show an enrichment of LREE relative to HREE, and pronounced negative Eu anomalies implying feldspar fractionation. The isotopic and geochemical characteristics of the MG samples suggest that these rocks are evolved through fractional crystallization. In the La/Nb-Nb diagram and Sm/Nd ratios, the MG rocks and the enclave samples exhibit strong evidence for crustal contamination. The MG rocks record high initial 87Sr/86Sr (0.70625-0.70740) and low 143Nd/144Nd(i) (0.51235-0.51274) ratios. These Sr-Nd isotopic data, combined with the presence of high Th/U and Rb/Sr ratios and significant depletions of Nb, Ta and Ti, show a relation of these bodies to an active continental margin regime. Based on the age and geochemical data of the MG, this study presents new information about the occurrence of Middle Cretaceous magmatic activities, which are related to the active continental margins in the SaSZ that run parallel to the Zagros Fold-Thrust Belt.


1...