Petrogenesis of Late Triassic high-Mg diorites and associated granitoids with implications for Paleo-Tethys evolution in the northeast Tibetan Plateau

2019 ◽  
Vol 132 (5-6) ◽  
pp. 955-976
Author(s):  
Jun Tan ◽  
Jun-Hao Wei ◽  
Shao-Qing Zhao ◽  
Yan-Jun Li ◽  
Yan Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Chemical Exchange ◽  
Magma Mixing ◽  
Late Triassic ◽  
Mafic Enclave ◽  
Compositional Evolution ◽  
Inductively Coupled ◽  
Tethys Ocean

Abstract Recent research on Paleo-Tethys tectonics has identified a huge late Paleozoic to Mesozoic igneous belt that extends more than 2500 km in the northeast Tibetan Plateau. However, the magma genesis and evolution in this belt remains a subject of considerable debate. This paper presents a combination of zircon U-Pb ages, mineral compositions, major and trace element concentrations, and Sr-Nd-Hf isotopic data for the plutons across the Zhiduo arc belt that marks the site connecting different tectonic-magmatic units. The studied rocks from one quartz diorite, two granodiorite plutons, and their mafic enclaves define a continuous compositional evolution varying from high- to medium-K calc-alkaline gabbroic diorite to granodiorite. Laser ablation–inductively coupled plasma–mass spectroscopy U-Pb analyses of zircons from these three plutonic suites and one mafic enclave yield Late Triassic ages of 222–217 Ma, establishing that the mafic and felsic magmas were nearly coeval. All these rocks are featured by zoned hornblende and plagioclase with Mg- and Ca-rich mantles or oscillatory change in compositions. They exhibit high and variable MgO (up to 4.88–5.66 wt%), Cr, and Ni contents except that one granitoid pluton (Dangjiangrong) possesses high Co (up to 145.0 ppm). They are characterized by subduction-type trace element patterns, with prominent positive Rb, Th, Pb, and K anomalies and negative Ba, Nb, P, and Ti. Together with continuous and heterogeneous Sr-, Nd-, and zircon Hf-isotopic compositions, it suggests that these Late Triassic high-Mg diorites and associated granitoids were generated through magma mixing and fractional crystallization accompanied by chemical exchange. Taking into account the magmatic record from nearby regions, we suggest that double-sided subduction and rollback of the subducting Paleo-Tethys oceanic slab is the main mechanism to generate geochemically-varied magmatism in the northeast Tibetan Plateau, and eventually close the Paleo-Tethys Ocean during much of the Late Triassic.

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

2020 ◽  
Vol 177 (5) ◽  
pp. 997-1012 ◽  
Author(s):  
Dongfang Song ◽  
Wenjiao Xiao ◽  
Brian F. Windley ◽  
Chunming Han
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Late Triassic ◽  
Primitive Mantle ◽  
Early Triassic ◽  
Accretionary Complex ◽  
Content Type ◽  
Inductively Coupled ◽  
Supplementary Material ◽  
Spider Diagrams

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

Provenance of basaltic tephra from Vatnajökull subglacial volcanoes, Iceland, as determined by major- and trace-element analyses

The Holocene ◽  
2011 ◽  
Vol 21 (7) ◽  
pp. 1037-1048 ◽  
Author(s):  
Bergrún Arna Óladóttir ◽  
Olgeir Sigmarsson ◽  
Gudrún Larsen ◽  
Jean-Luc Devidal
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Major Element ◽  
Element Composition ◽  
Major Element Composition ◽  
Volcanic System ◽  
The Holocene ◽  
Inductively Coupled ◽  
Ice Cap ◽  
The North

The Holocene eruption history of subglacial volcanoes in Iceland is largely recorded by their tephra deposits. The numerous basaltic tephra offer the possibility to make the tephrochronology in the North Atlantic area more detailed and, therefore, more useful as a tool not only in volcanology but also in environmental and archaeological studies. The source of a tephra is established by mapping its distribution or inferred via compositional fingerprinting, mainly based on major-element analyses. In order to improve the provenance determinations for basaltic tephra produced at Grímsvötn, Bárdarbunga and Kverkfjöll volcanic systems in Iceland, 921 samples from soil profiles around the Vatnajökull ice-cap were analysed for major-element concentrations by electron probe microanalysis. These samples are shown to represent 747 primary tephra units. The tephra erupted within each of these volcanic system has similar chemical characteristics. The major-element results fall into three distinctive compositional groups, all of which show regular decrease of MgO with increasing K2O concentrations. The new analyses presented here considerably improve the compositional distinction between products of the three volcanic systems. Nevertheless, slight overlap of the compositional groups for each system still remains. In situ trace-element analyses by laser-ablation-inductively-coupled-plasma-mass-spectrometry were applied for better provenance identification for those tephra having similar major-element composition. Three trace-element ratios, Rb/Y, La/Yb and Sr/Th, proved particularly useful. Significantly higher La/Yb distinguishes the Grímsvötn basalts from those of Bárdarbunga and Rb/Y values differentiate the basalts of Grímsvötn and Kverkfjöll. Additionally, the products of Bárdarbunga, Grímsvötn and Kverkfjöll form distinct compositional fields on a Sr/Th versus Th plot. Taken together, the combined use of major- and trace-element analyses in delineating the provenance of basaltic tephra having similar major-element composition significantly improves the Holocene tephra record as well as the potential for correlations with tephra from outside Iceland.

Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil

2010 ◽  
Vol 74 (4) ◽  
pp. 645-658 ◽  
Author(s):  
F. C. J. Vilalva ◽  
S. R. F. Vlach
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Alkali Feldspar ◽  
Trace Element Composition ◽  
Inductively Coupled ◽  
Coupled Substitution ◽  
Plasma Mass Spectrometry ◽  
Compositional Variations ◽  
End Members ◽  
South Brazil

AbstractTurkestanite, a rare Th- and REE-bearing cyclosilicate in the ekanite–steacyite group was found in evolved peralkaline granitesfrom the Morro Redondo Complex, south Brazil. It occurswith quartz, alkali feldspar and an unnamed Y-bearing silicate. Electron microprobe analysis indicates relatively homogeneous compositions with maximum ThO2, Na2O and K2O contentsof 22.4%, 2.93% and 3.15 wt.%, respectively, and significant REE2O3 abundances(5.21 to 11.04 wt.%). The REE patterns show enrichment of LREE over HREE, a strong negative Eu anomaly and positive Ce anomaly, the latter in the most transformed crystals. Laser ablation inductively coupled plasma mass spectrometry trace element patterns display considerable depletions in Nb, Zr, Hf, Ti and Li relative to whole-rock sample compositions. Observed compositional variations suggest the influence of coupled substitution mechanisms involving steacyite, a Na-dominant analogue of turkestanite, iraqite, a REE-bearing end-member in the ekanite–steacyite group, ekanite and some theoretical end-members. Turkestanite crystals were interpreted as having precipitated during post-magmatic stages in the presence of residual HFSE-rich fluidscarrying Ca, the circulation of which wasenhanced by deformational events.

Trace Element Geochemistry and Mineral Inclusions Constraints on the Petrogenesis of a Marble–Hosted Ruby Deposit in Yunnan Province, China

2021 ◽  
Author(s):  
Wenqing Huang ◽  
Pei Ni ◽  
Ting Shui ◽  
Junyi Pan ◽  
Mingsen Fan ◽  
...  
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Yunnan Province ◽  
Geographic Origin ◽  
Source Rocks ◽  
Trace Element Geochemistry ◽  
Mineral Inclusion ◽  
Element Geochemistry ◽  
Inductively Coupled ◽  
Mineral Inclusions

Abstract Primary rubies in the Ailao Shan of Yunnan Province, China, are found in three layers of marble. However, the origin and source rocks of placer rubies in the Yuanjiang area remains unclear. Trace element geochemistry and inclusion mineralogy within these materials can provide information on their petrogenesis and original source. Zircon, rutile, mica group minerals, titanite, and apatite group minerals were the main solid inclusions identified within the placer Yuanjiang rubies, along with other mineral inclusions such as pyrite, pyrrhotite, plagioclase group minerals, and scapolite group minerals. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) measurements showed that the placer rubies are characterized by average values of Mg (31 ppmw), Ti (97 ppmw), V (77 ppmw), Cr (3326 ppmw), Fe (71 ppmw), and Ga (66ppmw). A trace-element oxide diagram, Fe values (<350 ppmw), and the mineral inclusion assemblage suggest marble sources for the placer ruby. Therefore, the Yuanjiang rubies (both primary and placer) are metamorphic, and this fits well with the observations that skarn and related minerals are mostly absent in this deposit. Yuanjiang rubies can be readily separated from the high-iron rubies of different geological types by their Fe content (<1000 ppmw). The discriminators Mg, Ga, Cr, V, Fe, and Ti have potential in separating Yuanjiang rubies from some other marble-hosted deposits, such as Snezhnoe. Nevertheless, geographic origin determination remains a challenge when considering the similarities in compositional features between the Yuanjiang rubies and rubies from some other marble-hosted deposits worldwide (e.g., Luc Yen). The presence of kaolinite group minerals and clusters of euhedral, prismatic zircon crystals in ruby suggest a Yuanjiang origin.

scholarly journals Using trace elements to identify the geographic origin of migratory bats

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10082
Author(s):  
Jamin G. Wieringa ◽  
Juliet Nagel ◽  
David M. Nelson ◽  
Bryan C. Carstens ◽  
H. Lisle Gibbs
Keyword(s):  
Trace Elements ◽  
Wind Energy ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Geographic Origin ◽  
Lasiurus Borealis ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Trace Element Profiles ◽  
Geographic Sources

The expansion of the wind energy industry has had benefits in terms of increased renewable energy production but has also led to increased mortality of migratory bats due to interactions with wind turbines. A key question that could guide bat-related management activities is identifying the geographic origin of bats killed at wind-energy facilities. Generating this information requires developing new methods for identifying the geographic sources of individual bats. Here we explore the viability of assigning geographic origin using trace element analyses of fur to infer the summer molting location of eastern red bats (Lasiurus borealis). Our approach is based on the idea that the concentration of trace elements in bat fur is related through the food chain to the amount of trace elements present in the soil, which varies across large geographic scales. Specifically, we used inductively coupled plasma–mass spectrometry to determine the concentration of fourteen trace elements in fur of 126 known-origin eastern red bats to generate a basemap for assignment throughout the range of this species in eastern North America. We then compared this map to publicly available soil trace element concentrations for the U.S. and Canada, used a probabilistic framework to generate likelihood-of-origin maps for each bat, and assessed how well trace element profiles predicted the origins of these individuals. Overall, our results suggest that trace elements allow successful assignment of individual bats 80% of the time while reducing probable locations in half. Our study supports the use of trace elements to identify the geographic origin of eastern red and perhaps other migratory bats, particularly when combined with data from other biomarkers such as genetic and stable isotope data.

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