Spider Diagrams Research Articles

Assessing the digital health transformation with the SCIROCCO Exchange tool in Puglia Region

Abstract Have we progressed integrated care in Europe? The EU Health Programme funded project, SCIROCCO Exchange addresses this question by providing online self-assessment tool for integrated care. Among the project partners, Puglia Region and the Strategic Regional Agency for Health and Social Care (AReSS), assessed the integrated care maturity level of the six Puglia' Local Health Authorities. The SCIROCCO Exchange project provides a 12-dimensions online tool for European regions to assess their maturity in the provision of integrated care, including identification of strengths, weaknesses and areas for improvement. The methodology provides the following steps: 1) selection of key stakeholders participating in the assessment; 2) conducting the individual assessments; 3) building the consensus among the involved stakeholders. The outcomes of the assessment were captured in the form of spider diagrams, highlighting Puglia' strengths and weaknesses in integrated care. The research has provided a multi-dimensional representation of the integrated care maturity level of the Puglia' Local Health Authorities. With reference to the SCIROCCO Exchange tool dimensions, major strengths include: Digital Infrastructure; Population Approach; Process Co-ordination; and Citizen Empowerment. Among the areas for improvement: Finance & Funding; Removal of Inhibitors; and Evaluation Methods were identified. The experience of using the SCIROCCO Exchange Tool have demonstrated benefits and added value of the Tool in guiding involved stakeholders towards the implementation of integrated care in Puglia and in stimulating multi-stakeholders discussions and participants' engagement. The assessment results will be used to orient an Action Plan to facilitate much more effective and tailored knowledge transfer process and provide better digital care services in Puglia.

Provenance and paleo-weathering of Paleoproterozoic siliciclastic sedimentary rocks of Bijawar Group, Sonrai Basin, Uttar Pradesh, India: using a geochemical approach

Shales and sandstones of the Paleoproterozoic Bijawar Group (India) have been studied to decipher their paleo-weathering conditions and provenance based on geochemistry. Shale samples are composed of k-feldspars, mica, quartz, and fine iron-oxides, whereas sandstones are composed of quartz and k-feldspars. The predominant positive correlation of K2O vs TiO2, Na2O vs Al2O3, and K2O vs Al2O3 indicates that the elements are associated with detrital phases. Trace elements Sc, Rb, Ba,Th, Y, and Zr show a strong positive correlation with Al2O3 and K2O which indicates that the absolute abundances of these elements are controlled mainly by illite. A negative correlation of trace elements Ni, Cu, Co with Al2O3, and K2O represents their presence in iron oxides like magnetite, ilmenite, and hematite. Multi-element Post-Archaean Australian Average Shale (PAAS) normalized spider diagrams show enrichment of V, Pb, Zr, Y, Hf, Th, Rb, and depletion of Ni, Sr, Ba, Nb, U. The depletion of Sr indicates the least enrichment of plagioclase and the same is also supported by negative Eu-anomaly of the samples, though weak. The chondrite normalized rare earth element (REE) plots show a slightly light-REE (LREE) enriched and flat heavy-REE (HREE) pattern with weak negative Eu anomaly. The overall, high values of LaN/SmN (avg. 10.49), CeN/YbN (avg.0.37), LaN/YbN (avg. 34.28) and low values of GdN/YbN (avg. 1.82) and TiO2 (0.27–1.82, average 0.92 < PAAS) in most of the samples, show a relationship with the felsic source rocks. The index of compositional variability (ICV) of the samples is < 0.84 which indicates no enrichment of primary minerals. The chemical index of alteration (CIA) of present samples varies from 48.60 to 81.69, indicating low to moderate intensity of chemical weathering of the source. The plot between SiO2 and Al2O3 + K2O + Na2O depicts that majority of the samples belong to the environment from humid to semi-humid and have attained a high chemical maturity. The high SiO2/Al2O3 values (1.36–20.79) in studied samples indicate relatively high sediment maturity due to the extreme sorting of sediments in a stable cratonic regime. A stable cratonic regime, with a low upliftment rate that has allowed strong chemical weathering of protoliths, is further indicated by low CaO, Na2O, and Sr contents of the studied samples. The overall geochemical characteristics of the present samples—high SiO2, Al2O3 and K2O and low TiO2, MgO, Na2O, and CaO contents—suggest a felsic provenance. The felsic nature of the source rocks is also supported by the trace element ratios like (La/Lu)N (7.72–76.89), La/Sc (1.50–7.40), La/Co (0.39–11.48), Th/Co (0.80–15.90), and Cr/Th (0.08–5.10). Since the Bijawar Group is sited over the Bundelkhand Granite Gneiss Complex (BGGC), it is, therefore, plausible that the main source components of Bijawar Group siliciclastic rocks are the BGGC felsic rocks.

Measuring sustainability of urban mobility: A pilot study of Asian cities

Sustainability of urban mobility has emerged as an important global, regional and local question. This paper presents the results of a pilot study conducted for the assessment of urban mobility in four Asian cities. The ten urban transport indicators set and the sustainable urban transport index (SUTI) are used to measure sustainability of urban mobility. Primary and secondary urban transport data from four Asian cities Greater Jakarta, Kathmandu, Hanoi and Colombo were collected and analyzed using the SUTI methodology and tool to produce assessment reports. The results of assessment are displayed visually in a spider diagram. This enables policy makers to comprehend state of all 10 urban mobility indicators in a city at a glance and discuss interventions and strategies required to improve the score of indicators with low value and improve overall sustainability of urban mobility. The findings and results supported policy makers in city authorities to identify policy gaps and prioritize policy measures to improve urban mobility. The study also confirmed the usefulness the SUTI data collection guideline to collect standardize data and Excel based SUTI tool to analyze data and measure sustainability of urban mobility in a city as well as to make comparison among peer cities.

Petrology and geochemistry of the Lattan Mountain magmatic rocks in the Sanandaj–Sirjan Zone, west of Iran

Igneous rocks are distributed in the Lattan Mountain area, the center part of Sanandaj–Sirjan Zone, west Iran. Based on the mineralogy and geochemical composition, these are subvolcanic, volcanic, and plutonic rocks. It includes basalts, andesitic basalt, and andesite, with porphyritic to microlithic porphyry and vitrophyric textures as well as dolerite, diorite, gabbro, and microdiorite with a varied granular, microgranular, intersertal, and intergranular textures. The chemical compositions indicated to calc-alkaline to transitional nature, enrichment in LIL elements (Rb, Ba, Th, U, and Pb), and depletion in Ti and Zr, as it is evident in spider diagrams normalized to a primitive mantle. In addition, samples have enrichments of LREE relative to HREE. The Rb-Sr whole-rock isochron of these magmatic rocks shows an age of 152 ± 14 Ma (late Jurassic). The initial 87Sr/86Sr (0.7047 to 0.7051) and 143Nd/144Nd ratios range from (0.512534 to 0.512710) and eNdt = − 0.1 to + 2.2 that indicated to BSE composition. Our results suggest that the magmas for the magmatic rocks were derived from metasomatized enriched MORB-like sources. These rocks were formed in an island arc setting during subduction and closure of the Neotethys oceanic lithosphere beneath the Iran microplate about 152 Ma.

Carbonate Deposits of Eastern Sarmatia (Early Precambrian Ignateevo Formation, Kursk Block): Sedimentation Conditions and Paleocontinental Correlations

The Neoarchean–Early Paleoproterozoic section of the Eastern Sarmatia Kursk Block contains different formations: terrigenous-carbonate (Ignateevo Formation), terrigenous (Stoilo Formation), and banded iron (Korobki Formation). The Kursk Block sequences have obvious similarities to the coeval terrigenous-carbonaceous-ferriferous formations of the Kaapvaal and Pilbara cratons. The Ignateevo Formation dolomites are correlated with the Campbellrand–Malmani and Wittenoom–Carawine carbonate platforms. Carbonate rocks of all three cratons are silicified and show no evidence of clastic contamination. They are characterized by low Sr concentrations and are enriched in Fe and Mn. The REE distribution in carbonate rocks is characteristic of Neoarchean marine sediments: flat profiles on spider diagrams, positive La anomalies, absence of Ce anomaly, and increased Y/Ho ratios relative to the chondrite value. The values of δ13C (0.3–0.9‰ PDB) and δ18O (–10.1 to –13.0‰ PDB) in the Ignateevo Formation dolomites fall within the range of the Late Archean and Early Paleoproterozoic marine carbonate sediments. The 87Sr/86Sr ratio in the Ignateevo Formation dolomites (0.7101–0.7195) is higher than that in the Neoarchean marine carbonates, which implies either isolation of the paleobasin or disturbance of the Rb–Sr isotope systems during metamorphism. The Ignateevo Formation dolomites and calc-silicate rocks (intensively silicified dolomites) are closest in their isotope-geochemical characteristics to shallow-water dolomites of the Campbellrand–Malmani Platform (South Africa). Probably, the Ignateevo Formation dolomites and partly the formations composing the Campbellrand–Malmani Platform formed in the most isolated part of the paleobasin, which facilitated to their complete dolomitization and partial silicification.

New horizons in quantitative compositional mapping – Analytical conditions and data reduction using XMapTools

Quantitative compositional mapping is a key technique for imaging solids and, therefore, for trying to understand compositional zoning systematics in a broad range of geological materials. Compositional mapping requires an adapted analytical method for efficient data collection, a post-processing calibration stage to obtain elemental concentration values, and specific computer tools for exploring and visualising the data. In this contribution, we describe optimal analytical conditions, possible physical limitations and data reduction strategies for compositional maps of major, minor and trace elements obtained by electron probe microanalysis (EPMA) and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Data reduction is performed using the computer software XMapTools, which incorporates a large variety of options and tools for data processing, data calibration and data visualisation based on single and multi-channel maps or via binary, ternary and spider diagrams.

Geochemistry and genesis of igneous rocks and skarn of Shahrak iron ore (Northeast of Kurdistan)

Shahrak iron deposit is located at the north of Sheikh-Besharat village, northwest of the city Hassan-Abad Yasukand, Kurdistan province. The study area includes igneous rocks, skarn zone, metamorphic zone (marble), and iron ore. Igneous rocks exposed in the district include calc-alkaline volcanic rocks with the dominant composition of rhyolite, andesite, dacite, trachyandesite, volcanoclastic (tuff) and intrusive rocks of diorite and granodiorite type, and carbonate rocks of Qom Formation (Miocene). Based on field studies, petrography of volcanic rocks and the skarn zone and Fe ore mineralography in the area, it can be said that iron mineralization and skarn formation occur adjacent to the igneous masses. The skarn index minerals are evidence of this event. The spider diagram patterns of rare earth elements of the Shahrak deposit samples normalized to the chondrite indicate more enrichment in light rare earth elements (LREE) than heavy rare earth elements (HREE). Positive Eu and negative Ce anomalies are characteristic of hydrothermal iron ore deposits. The different pattern of trace elements in the igneous rocks and the ore indicates their various geneses. The less important role of low salinity non-magmatic fluids in ore formation is concluded by chemical analysis results.

Amphibole and whole-rock geochemistry of early Late Jurassic diorites, Central Tibet: Implications for petrogenesis and geodynamic processes

Arc magmas are generated by complex geological processes in subduction settings. Due to the complexity of source materials and geological processes, the genesis of arc magmatic rocks can be difficult to disentangle. Here, we report on diorites from the Kenama area of the middle-eastern part of the Bangong–Nujiang suture zone in central Tibet. New SIMS and LA–ICP–MS zircon UPb dating for three diorite samples indicates that they crystallized during the early Late Jurassic (ca. 161 Ma). The diorites can be divided into two groups based on whole-rock major element compositions and mineralogical characteristics: Group I diorites with relatively low SiO2 (47.6–53.4 wt%), and high MgO (4.97–9.10 wt%) and amphibole contents (50–54 vol%); and Group II diorites with slightly higher SiO2 (56.9–59.5 wt%), and low MgO (2.9–3.8 wt%) and amphibole contents (25–30 vol%). The Group I diorites exhibit relative enrichment in light rare earth element (LREE) ((La/Yb)N = 5.7–10.5) with slightly negative Eu anomalies, and are characterized by enrichment of large ion lithophile elements (LILEs; K, Rb, Ba, Th, and U), the depletion of high field strength elements (HFSEs; Nb, Ta, Zr, Hf, and Ti). The Group I diorites have relatively high initial 87Sr/86Sr ratios (0.7073–0.7094), variably negative εNd(t) values(−10.3 to −5.9), negative zircon εHf(t) values (−14.8 to–4.4), and slightly elevated δ18O values (6.5‰–7.3‰). The Group II diorites show similar trace element characteristics to Group I. They also have high initial 87Sr/86Sr ratios (0.7083–0.7087), uniformly negative εNd(t) values (−9.5 to −9.0), negative zircon εHf(t) values (−10.3 to −4.2), and elevated δ18O values (6.6‰–7.5‰). Amphiboles from Group I and Group II diorites have low Al2O3 contents (3.6–9.9 wt% and 5.6–8.5 wt%, respectively), and formed at similar P–T conditions (751–871 °C and 69–226 MPa and 745–832 °C and 77–162 MPa, respectively). On primitive mantle-normalized spider diagrams, these low-Al amphibole grains have slightly convex upward REE patterns with distinctly negative anomalies in Pb, Sr, Eu, Zr, Hf, and Ti, suggesting that amphiboles from both groups crystallized from the similar arc magmas after plagioclase and magnetite crystallization. These mineralogical, geochemical and isotopic characteristics suggest that both groups of Kenama diorites probably originated from an enriched lithospheric mantle metasomatized by subducted oceanic sediment-derived melts. Their parental magmas may have similar geochemical characteristics and underwent varying degrees of accumulation and fractional crystallization. The Group I diorites were likely generated by accumulation of amphibole and fractional crystallization of olivine, clinopyroxene, and plagioclase from mafic magmas, and the Group II diorites were formed by the fractional crystallization of clinopyroxene and plagioclase from mafic magmas that were geochemically similar to the Group I diorites. In combination with regional geology, in particular adjacent ophiolites, high-magnesian andesitic rocks and Cretaceous sedimentary rocks, we conclude that all of the Kenama diorites were probably generated in an early Late Jurassic arc setting related to the subduction of the Bangong–Nujiang Tethys oceanic lithosphere.

Carboniferous to Early Triassic magmatism and accretion in Alxa (NW China): implications for accretionary orogenesis of the southern Altaids

Alxa occupies a crucial position between the Tianshan–Beishan orogen to the west and the Solonker suture to the east and is important in our understanding of the accretionary orogenesis of the southern Altaids. To unravel the tectonic history of the Alxa region, we undertook an integrated study of the field geology, geochemistry and geochronology of magmatic rocks and an accretionary complex. Six granites and one rhyolite from the Zhusileng–Hangwula arc show a peraluminous, high-K calc-alkaline composition and one gabbro is tholeiitic. They show patterns rich in incompatible elements and negative Nb–Ta anomalies on primitive mantle-normalized trace element spider diagrams. Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating reveals 348–329 and 267–250 Ma magmatic events. These data indicate that the Zhusileng–Hangwula arc was a Japan-type island arc from the late Paleozoic to Early Triassic. The Engger Us mélange comprises pillow basalts with a normal-type mid-ocean ridge basalt composition, tuffs, cherts, siliceous mudstones, limestones and turbidites, which are tectonically juxtaposed by a block-in-matrix structure. This mélange is interpreted as a Carboniferous–Permian accretionary complex. These new data, combined with previous studies, confirm that the Palaeo-Asian Ocean subducted bidirectionally in the Alxa region in the Carboniferous–Early Triassic. A consistent divergent subduction system existed from Alxa to Solonker before the terminal closure of the Palaeo-Asian Ocean in the Mid- to Late Triassic. Supplementary material: Major and trace element data and zircon U-Pb age results of all the samples are available at: https://doi.org/10.6084/m9.figshare.c.4962230

Discovery and identification of clay-sized tuffaceous rocks in Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, China

This study for the first time demonstrates that some of the so-called clay-sized mudstones observed by the naked eye, such as clay-sized black mudstones and clay-sized oil shales, which are rich in black organic matter (including oil and asphaltene), in the Chang 73 Submember of the Upper Triassic Yanchang Formation in the Ordos Basin of China are actually clay-sized tuffaceous rocks (including tuff, sedimentary tuff and tuffaceous sedimentary rock) with high hydrocarbon generation capacities. Thus, these rocks can be defined as clay-sized tuffaceous source rocks. Identification of this lithology has important theoretical and practical significance for the exploration and development of shale oil in the Chang 7 Member. Through the macroscopic observation of drill cores and outcrop profiles, microscopic observation of electron probe thin sections and whole-rock inorganic geochemical analysis (including major, trace and rare earth elements), this work demonstrates that the organic matter-rich clay-sized tuffaceous rocks, especially clay-sized tuffs, have the following characteristics. First, the clay-sized tuffaceous rocks with little black organic matter are mainly greyish white, yellowish brown and purplish grey, and mixed colors occur in areas with strong bentonite lithification. Second, the clay-sized tuffaceous rocks have experienced strong devitrification and recrystallization, forming abundant flaky aluminosilicate minerals with directional arrangement. In thin sections under a polarizing microscope, the interference colors generally show regular alternation between the lowest interference color of first-order yellow and the highest interference color of second-order blue-green. Third, the rock samples plot in the igneous rock field in the TiO2-SiO2 cross-plot and exhibit similar trace element and rare earth element patterns on spider diagrams, indicating that the samples are derived from the same source. The results prove that clay-sized tuffaceous rocks may be widespread in the Chang 73 Submember of the Upper Triassic Yanchang Formation in the Ordos Basin, China.

PETROGRAFIA, GEOQUÍMICA E GEOCRONOLOGIA DAS ROCHAS GRANÍTICAS DA OROGENIA SAN IGNÁCIO (BOLÍVIA)

Esta contribuição visa caracterizar os granitos do Proterozóico de San Ignacio orogenia, ocidental da Bolívia, descrevendo sua composição química e isótopos de U-Pb e Sm / Nd para identificar fontes e processos de formação desyas rochas. Os resultados de granitoides químicos e isotópicos de Cachuela, Motacusal e Talcoso, apresentam idade U / Pb em zircão entre 1307 e 1333 Ma, sugerindo uma época importante de geração de granitoides no pré-Cambriano boliviano. Química (granitos de tipo A) e isótopos de Nd (εNd (1330) entre -0,77 e -3,86) aqui relatados para o pré-Cambriano boliviano indica que o evento San Ignacio, é representado por um arco magmático com participação de crosta continental previamente formada, representando um importante período colional no craton Amazônico da Amazônia.

Petrogenesis and geodynamic implications of Early Cretaceous highly fractionated leucogranites in the northern Lanping–Simao terrane, Eastern Tibetan Plateau

A felsic intrusion in the Guaguazi Cu mining district in the northern Lanping–Simao terrane, Eastern Tibetan Plateau was revealed through drill holes and is composed of highly fractionated leucogranites. In this paper, we report zircon U–Pb ages and whole-rock compositions to constrain the petrogenesis and geodynamic setting of this intrusion. Zircon grains separated from two leucogranite samples have identical U–Pb ages of 123.9 ± 2.0 Ma and 123.6 ± 1.9 Ma, indicating that the crystallization age of the intrusion is Early Cretaceous (ca. 124 Ma). Leucogranites from the intrusion have SiO2 contents from 74.3 to 77.6 wt% with differentiation index values of 96.3–97.6, indicative of highly fractionated nature. They are weakly peraluminous (A/CNK = 1.01–1.10) and have light REE enrichment ((La/Yb)N = 5.4–8.5) and negative Eu anomalies (Eu/Eu* = 0.26–0.45). The primitive-mantle-normalized spider diagram indicates strong enrichment in large-ion lithophile elements (Rb, Th, U, K, and Pb) relative to high-field-strength elements (Nb, Ta, P, and Ti). The high initial 87Sr/86Sr ratios (0.7070–0.7094) and negative εNd(t) values (−8.18 to −7.20) and TDM2 ages of 1.58–1.51 Ga of the rocks, suggest that their source was predominantly Mesoproterozoic lower continental crust with insignificant mantle contribution. High initial 207Pb/204Pb (15.74–15.75) and 206Pb/204Pb (18.51–18.63) ratios further confirm their crustal source and highly evolved nature. Considering the petrogenetic similarity of Early Cretaceous granitoids in the Guaguazi area and the Gaoligong tectonic belt, we propose that the eastern Bangong–Nujiang Tethyan Ocean was closed at least no later than the Early Cretaceous, and that the Guaguazi granitic intrusion formed in a crustal thickening setting in response to the Lhasa–Qiangtang collision.

Petrogenesis of late Cenozoic basalts from Dalinor, Inner Mongolia: Implications for lateral mantle heterogeneity in eastern China

We present major element, trace element and Sr-Nd-Pb-Hf isotopic compositions of the late Cenozoic basaltic rocks from Dalinor, Inner Mongolia, on the west of the Greater Hinggan Mountain Range in Northeast Asia, and discuss the origin of mantle source heterogeneity beneath Northeast Asia. The early-stage volcanoes (EV) from Dalinor produced predominantly quartz tholeiitic and olivine tholeiitic basalts whereas the late-stage volcanoes (LV) produced alkali basalts. Variations in the degree of partial melting and in fractionation crystallization could explain most of the changes in major and trace element compositions within individual groups. Trace element ratios and Sr-Nd-Pb-Hf isotope ratios between the EV and LV groups indicate a heterogeneous mantle source. The EV group is characterized by an ocean island basalt (OIB)-like spider diagram and positive anomalies of Sr, Ba and K, moderately LREE-enriched pattern ((La/Yb)N = 5.7–8.2), high Ba/Nb (10.2–16.5), and negative correlation between Dy/Yb and SiO2. Two thirds of the EV samples have low Nb/U (<37). The source rock for the EV lavas was amphibole-bearing metasomatized lithospheric mantle. The LV lavas have high TiO2 content (2.57–3.65 wt%), high Nb/U (42.4–58.8) and Indian-MORB-like SrNd isotopic compositions, indicating their asthenospheric origin. The Sr-Nd-Pb isotopic compositions of the Dalinor lava overlap those of the Southeast China basalts, and are consistent with source mixing between a depleted mantle component (DM) and an enriched mantle EM2 component. The western part of the trans-Greater Hinggan Mountain Range mantle source profile has a DM + EM2 signature, whereas the eastern part of the profile has a DM + EM1 signature. This lateral mantle source heterogeneity cannot be explained by the stagnant Pacific slab in the mantle transition zone. Instead, we propose that the EM2 component originated from the descending slab during a slab avalanche in the lower mantle near the westernmost leading edge of stagnant slab, before finally residing in the lithospheric mantle.

Geochemistry of volcanic flows of Nakora area of Malani igneous suite, Northwestern India: Constraints on magmatic evolution and petrogenesis

The geochemical characteristics of volcanic flows of Nakora area of Malani Igneous Suite have been determined to understand their magmatic evolution and petro-genetic aspects. Geochemically, they are high in silica, total alkalis, high field strength elements (HFSE), low ion lithophile elements (LILE), rare metals and rare earth elements; represent A-type affinity with potential mineralization associations. Here, we carried out average geochemical data bank of representative samples of 44 individual lava flows of isolated hill-locks. The relative enrichment of trace elements and negative anomalies of Sr, Eu, P and Ti in the multi-element spider diagrams suggests that the emplacement of the lava flows was controlled by complex magmatic processes i.e. fractional crystallization, partial melting, magma mixing, crustal contamination and assimilation. Moreover, NRCmagma provides new geochemical approaches to understand geodynamic evolution of MIS and emplaced in plume related extensional geodynamic settings in NW Indian shield.&#x0D; Keywords: Geochemistry; Volcanic flows; Nakora; Malani Igneous Suite; Rajasthan; Rodina

Petrogenesis of the Middle Jurassic andesitic dikes in the giant Dexing porphyry copper ore field, South China: Implications for mineralization

The giant Dexing porphyry copper ore field, containing 9.7 Mt copper, is the largest porphyry copper system in South China. The petrogenesis of andesitic dikes in the Dexing ore field and their genetic link with porphyry mineralization remain unclear. This paper presents LA-ICP-MS zircon U-Pb dating, elemental and Sr-Nd-Hf isotopic data of the andesitic dikes in the Dexing porphyry copper ore field. The Dexing andesitic dikes were emplaced during the Middle Jurassic at ca. 166 Ma. The Dexing andesitic dikes have relative high MgO contents and Mg# ratios but low TiO2 contents. They also have obvious Nb, Ta and Ti depletion in the primitive mantle normalized spider diagrams. The geochemical affinity of arc magma and low Ti contents indicate that the magma source is probably lithosphere mantle modified by subduction process. A non-arc setting during the Middle Jurassic is inferred due to the absence of typical arc rocks and the presence of rifting-related magmatic rocks in the interior of South China. The non-arc setting implies that the Neoproterozoic Jiangnan Orogen was likely responsible for the arc geochemical features. The concentration of copper in the andesitic dikes is not high, supporting that remelting of the metal-rich Neoproterozoic juvenile lower continental crust instead of the mantle is the critical factor for the giant porphyry style mineralization. The mantle derived mafic magma may play a key role for providing significant heat for remelting of the metal-rich lower continental crust via underplating into the crust-mantle boundary.

Evolution of Late Cretaceous to Palaeogene basalt–andesite–dacite–rhyolite volcanic suites along the northern margin of the Ladakh magmatic arc, NW Himalaya, India

This paper describes a comprehensive geochemical study of basalt–andesite–dacite–rhyolite volcanic association in the Khardung volcanic suite along the northern margin of the Ladakh magmatic arc. This volcanic association is outcropped mainly in the segment of the further north of the Khardung village to Khalsar delineating from the Ladakh magmatic arc by ~2 km thick porphyritic sill. The closed association of basalt–andesite–dacite–rhyolite volcanic within a volcanic suite suggests that these rocks may be genetically inter-related and might have derived from the same parental magma source. Felsic lavas (dacite–rhyolite) show SiO2 range from 64.75 to 79.11 wt.%, while intermediate lavas (basaltic andesite–andesite) ranges from 50.80 to 51.81 wt.% with mafic lavas (basalt) span from 53.39 to 62.05 wt.%. These volcanic suites show enrichment in LIL elements (Rb, Ba, Th, U, and Pb) and depletion in Nb, P, and Ti, which can be evident in spider diagrams with pronounced to mild Eu negative anomalies in REE patterns. Previous reports on zircon U–Pb ages of the Khardung volcanics range between 60 and 69.7 Ma confirm an upper bound eruption age of this volcanic suite as pre-collision continental arc magmas. Hence, the results of geochemical modelling suggest that the Khardung mafic–intermediate-felsic lavas were generated from the melting of 1–4% spinel and garnet-bearing lherzolite sources. The generated parental magmas were modified by crustal materials during the magma ascent along with fractional crystallization and were metasomatized by slab-derived fluids released from the subducting Neo-Tethyan oceanic crust during the Late Cretaceous to Palaeogene in the northern margin of the Ladakh magmatic arc.

Evidence for multiple sources for inorganic components in the Tucheng coal deposit, western Guizhou, China and the lack of critical-elements

Terrigenous materials from sediment-source regions are important controls on the types and concentrations of inorganic components in coal. The Kangdian Upland (dominated by the Emeishan basalts) is the dominant terrigenous supplier for most of the Late Permian coals, as well as for their associated host rocks (roof and floor strata) in southwestern China. The high volatile bituminous coals (Nos. 3 and 6 coals) are the two major minable coal seams in the Tucheng coal deposit in southwestern China. Unlike most Late Permian coals in this region that are characterized by elevated concentrations of the element assemblage Sc-V-Cr-Co-Ni-Cu-Zn-Se, these two coals are not enriched in this assemblage although Se is slightly concentrated.The mineralogical (e.g., relatively abundant quartz and mixed-layer illite/smectite) and elemental distribution patterns (e.g., spider diagrams of rare earth elements, discrimination diagrams of Al2O3-TiO2 and Zr/TiO2-Nb/Y, and elemental assemblages) indicate that the inorganic components in the two coal seams were mainly derived from unidentified volcanic arc and/or distal orogens, while the clastic components in the roof and floor strata of the two coal seams were mainly supplied by the high-Ti Emeishan basalts. The two partings in the two coal seams, identified as tonsteins, were probably derived from the final (rejuvenated) activity of the Emeishan plume. Critical elements in the two coals and associated non-coal horizons (partings, roof and floor strata) are economically unpromising, indicating that prospecting for Late Permian coal-hosted critical metal ore deposits in the vicinity of the Emeishan plume in southwestern China, should not be focused on coals with inorganic components derived mostly from distal volcanic arcs and orogens and high-Ti Emeishan basalts, and a minor contribution of volcanic ashes resulting from the final rejuvenated activity of the Emeishan plume.

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

The Late Cretaceous Sabzevar ophiolite represents one of the largest and most complete fragments of Tethyan oceanic lithosphere in the NE Iran. It is mainly composed of serpentinized mantle peridotites slices; nonetheless, minor tectonic slices of all crustal sequence constituents are observed in this ophiolite. The crustal sequence contains a well-developed ultramafic and mafic cumulates section, comprising plagioclase-bearing wehrlite, olivine clinopyroxenite, olivine gabbronorite, gabbronorite, amphibole gabbronorite and quartz gabbronorite with adcumulate, mesocumulate, heteradcumulate and orthocumulate textures. The crystallization order for these rocks is olivine ​± ​chromian spinel → clinopyroxene → plagioclase → orthopyroxene → amphibole. The presence of primary magmatic amphiboles in the cumulate rocks shows that the parent magma evolved under hydrous conditions. Geochemically, the studied rock units are characterized by low TiO2 (0.18–0.57 ​wt.%), P2O5 (<0.05 ​wt.%), K2O (0.01–0.51 ​wt.%) and total alkali contents (0.12–3.04 ​wt.%). They indicate fractionated trends in the chondrite-normalized rare earth element (REE) plots and multi-element diagrams (spider diagrams). The general trend of the spider diagrams exhibit slight enrichment in large ion lithophile elements (LILEs) relative to high field strength elements (HFSEs) and positive anomalies in Sr, Pb and Eu and negative anomalies in Zr and Nb relative to the adjacent elements. The REE plots of these rocks display increasing trend from La to Sm, positive Eu anomaly (Eu/Eu∗ ​= ​1.06–1.54) and an almost flat pattern from medium REE (MREE) to heavy REE (HREE) region [(Gd/Yb)N ​= ​1–1.17]. Moreover, clinopyroxenes from the cumulate rocks have low REE contents and show marked depletion in light REE (LREE) compared to MREE and HREE [(La/Sm)N ​= ​0.10–0.27 and (La/Yb)N ​= ​0.08–0.22]. The composition of calculated melts in equilibrium with the clinopyroxenes from less evolved cumulate samples are closely similar to island arc tholeiitic (IAT) magmas. Modal mineralogy, geochemical features and REE modeling indicate that Sabzevar cumulate rocks were formed by crystal accumulation from a hydrous depleted basaltic melt with IAT affinity. This melt has been produced by moderate to high degree (~15%) of partial melting a depleted mantle source, which partially underwent metasomatic enrichment from subducted slab components in an intra-oceanic arc setting.

Late Neoproterozoic mafic sills in the Suizhou area of the South Qinling block: constraints for the tectonic evolution of the northern margin of the Yangtze craton

ABSTRACT Late Neoproterozoic gabbroic-diabasic sills are widely distributed in the eastern part of the South Qinling block. Here, a comprehensive geochronological and geochemical study of these mafic sills has been conducted. LA-ICP-MS zircon U-Pb results indicate that the gabbroic-diabasic sills were formed at 632 ± 2 Ma. The sills consist mainly of tholeiitic basaltic rocks with relatively low TiO2 contents (0.81–1.07 wt.%) and high Fe2O3 T/MgO ratios. These rocks display relatively flat to moderate light rare earth elements (LREE) enrichment patterns and positive Eu anomalies (Eu/Eu* = 1.15–1.41). On the primitive mantle normalized spider diagram, the samples show E-MORB-like geochemical features. All of the studied samples display similar Sm-Nd isotopic compositions with negative εNd (t) values ranging from −6.2 to −5.5. Most clinopyroxenes from the mafic sills have relatively low Al/Ti ratios similar to those of typical rift-related cumulates. Therefore, Whole-rock and mineral geochemical features of the studied samples suggest that the mafic sills might have been derived from partial melting of a metasomatised subcontinental lithospheric mantle source in a continental rift setting. It can be advocated that the break-up of the Rodinia supercontinent in the northern part of the Yangtze craton might have been a long-lasting process. By comparison of the coherent Neoproterozoic magmatic events in the northern Yangtze craton and the Tarim block, it can be suggested that the Yangtze craton might have been adjacent to the Tarim block in the reconstruction model of the Rodinia supercontinent.

Late Triassic back-arc spreading and initial opening of the Neo-Tethyan Ocean in the northern margin of Gondwana: Evidences from Late Triassic BABB-type basalts in the Tethyan Himalaya, Southern Tibet

The tectonic evolution of the Neo-Tethyan oceanic plate between the Indian Plate and the Lhasa Terrane is a key issue for the evolution of Gondwana and formation of the Tibetan Plateau. In this paper we report on the geochemistry, SrNd isotope compositions, and zircon UPb dating of Late Triassic basalts from the Nieru Formation (T3n) in the Kampa region, southern Tibet. The basalts have relatively low contents of MgO, TiO2, and total alkalis (K2O + Na2O), and they have affinities to tholeiitic basalt. They exhibit weakly fractionated rare earth element (REE) patterns with slight depletions in LREEs and slightly negative Eu anomalies on a chondrite-normalized diagram. On a primitive-mantle-normalized spider diagram, they are characterized by slight enrichments in large ion lithophile elements (LILEs) and relatively flat patterns of high field strength elements (HFSEs), except for depletions in Ba, Nb, Ta, and Ti. Their initial 87Sr/86Sr ratios vary from 0.718133 to 0.738977 and εNd(t) values are relatively depleted (4.09–5.22), similar to mid-ocean ridge basalts in the Yarlung Zangbo ophiolite. We propose the T3n basalts were derived from a shallow and depleted mantle source by relatively high-degree partial melting in the spinel stability field. They underwent slight crustal contamination as well as the fractional crystallization of clinopyroxene. The T3n basalts are similar to typical back-arc basin basalts (BABB) such as the Okinawa BABB. This indicates an extensional back-arc-basin setting along the northern margin of Gondwana during the Late Triassic. The initial opening of the Neo-Tethyan Ocean was related to the southwards subduction of the Paleo-Tethyan oceanic plate and back-arc-basin spreading during the Late Triassic. Magmatic activity along the passive continental margin records key information on continental break-up and incipient ocean development.