scholarly journals Recognition of Late Triassic Cu-Mo Mineralization in the Northern Yidun Arc (S.E. Tibetan Plateau): Implications for Regional Exploration

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 765 ◽  
Author(s):  
Zhen-Dong Tian ◽  
Cheng-Biao Leng ◽  
Xing-Chun Zhang ◽  
Li-Min Zhou ◽  
Yan-Wen Tang
Keyword(s):  
Tibetan Plateau ◽  
Late Triassic ◽  
Geodynamic Setting ◽  
Type I ◽  
Type Ii ◽  
Host Granite ◽  
Icp Ms ◽  
Tethys Ocean ◽  
Metallogenic Age ◽  
Yidun Arc

The Yidun arc, located in the southeastern Tibetan Plateau, was formed by the westward subduction of the Ganze-Litang Paleo-Tethys ocean in Late Triassic. It is well-known for the formation of numerous Mesozoic porphyry-skarn Cu-Mo-(Au) deposits in the arc. To date, more than 20 Cu-Mo-(Au) deposits (>10 million tonnes Cu resources) have been discovered in the southern Eastern Yidun arc. However, few Cu-Mo deposits have been discovered in the northern Eastern Yidun arc. In recent years, some Cu-Mo deposits or occurrence are successively discovered in the northern Eastern Yidun arc, but their ore-forming ages are not well constrained. It remains unclear whether such Cu-Mo mineralization formed by similar metallogenic event and geodynamic setting as the Cu-Mo-(Au) mineralization in the south. In order to determine the metallogenic age and shed light on potential links between Cu-Mo mineralization and regional magmatic events, we present molybdenite Re-Os and zircon U-Pb ages to constrain the timing of two types of Cu-Mo mineralization in the northern Eastern Yidun arc (type I and type II). Molybdenite ICP-MS Re-Os dating results show that type I mineralization was formed at 217.7 ± 3.6 Ma, which is highly consistent with the formation ages of the host granite (218.1 ± 1.5 Ma, 2σ, n = 15, MSWD = 0.92) and aplite dyke (217.3 ± 1.3 Ma, 2σ, n = 16, MSWD = 0.50) within error. While the type II mineralization has a relatively younger formation age of 211.8 ± 4.7 Ma than the host granite (217.1 ± 1.5 Ma, 2σ, n = 14, MSWD = 0.96) and type I Cu-Mo mineralization. These data indicate that the Cu-Mo mineralization in the northern Eastern Yidun arc was temporally and spatially related to the Late Triassic magmatism in the region. Rhenium (Re) concentrations in the molybdenite from type I mineralization, ranging from 12.77 to 111.1 ppm (typically > 100 ppm), indicate that the ore-forming metals were derived mainly from a mantle source. However, Re contents in molybdenite from the type II mineralization, ranging from 7.983 to 10.40 ppm, indicate that the ore-forming metals were derived from a mixed mantle and crustal source with a predominantly crustal component. This study confirms that the northern Eastern Yidun arc exists Late Triassic Cu-Mo metallogenesis, and thus much attention should be paid on this region to find more Late Triassic Cu-Mo resources.

scholarly journals Lithological-geochemical types of deposits of Cretaceous-Paleogene flysch of the Ukrainian Carpathians and conditions of their formaition

2019 ◽  
Vol 4 (181) ◽  
pp. 116-133
Author(s):  
Ihor POPP ◽  
Petro MOROZ ◽  
Mykhailo SHAPOVALOV
Keyword(s):  
Organic Matter ◽  
Petroleum Hydrocarbons ◽  
Oxygen Deficit ◽  
Type I ◽  
Type Ii ◽  
Huge Amount ◽  
Siliceous Rocks ◽  
Anoxic Events ◽  
Tethys Ocean ◽  
Geochemical Investigation

The results of lithological, mineralogical and geochemical investigation of Cretaceous-Paleogene flysch deposits of the Ukrainian Carpathians are cited here. There are three main lithological-geochemical types of these deposits which differ in the composition of rock-forming ingredients of biogenic origin (SiO2 biog, CaCO3, Corg): grey limestone-clayey-terrigenous (type-I), non-carbonate or low-carbonate-clayey-terrigenous (type-II), and black carbonate-silica-terrigenous-clayey (type-III). The deposits of the first type are attributed to alkaline-oxic (oxic-calcitic), the second – to acid and low-alcaline oxic (oxic with redeposited glauconite), the third – to reducing (siderite, dolomite or ferrodolomite and low-reducing calcitic) and strong by reducing (primary-sulfidic or hydrogen sulfidic) mineralogical-geochemical facies. The forming of the Barremian-Albian (Shypot suite; Spas suite) and Oligocene (Menilite suite; Dusynska suite) organic-rich sediments in the Ukrainian Carpathians we associate with the phase of oceanic anoxic events OAE-1 and OAE-4 in the Carpathian segment of the Tethys, where anoxic reducing environments favoured to fossilization of huge amount of the dispersed organic matter. The structural-fabric features and composition of separate lithological types of silicites and diagenetic concretions of the Lower Cretaceous and Oligocene of the Ukrainian Carpathians show that their sedimentogenesis and diagenesis took place in conditions of strong oxygen deficit. The studied siliceous rocks can be considered as indicators of the anoxic events in the Carpathian segment of Tethys ocean. It is shown, that alcaline-reducting environments which was the most favourable for the diagenetic transformation of sedimentary organic matter in to petroleum hydrocarbons, prevailed in the organic-rich deposits of Oligocene age.

scholarly journals Supplemental Material: Multiple sources and magmatic evolution of the Late Triassic Daocheng batholith in the Yidun Terrane: Implications for evolution of the Paleo-Tethys Ocean in the eastern Tibetan Plateau

2021 ◽  
Author(s):  
Pengsheng Dong ◽  
Guochen Dong
Keyword(s):  
Trace Elements ◽  
Geochemical Modeling ◽  
Major And Trace Elements ◽  
Late Triassic ◽  
Magmatic Evolution ◽  
Eastern Tibetan Plateau ◽  
Isotopic Data ◽  
Multiple Sources ◽  
Icp Ms ◽  
Tethys Ocean

Table S1: Mineral association of samples from the Daocheng batholith; Table S2: LA-ICP-MS U-Pb isotopic data for zircons from the Daocheng batholith; Table S3: Hf isotopic data for zircons from the Daocheng batholith; Table S4: Trace elements data for zircons from the Daocheng batholith; Table S5: Major and trace elements data for the Daocheng batholith; Table S6: Whole-rock Sr-Nd isotopic data of the Daocheng batholith; Table S7: Representative microprobe analyses of amphibole from the Daocheng batholith; Table S8: Partition coefficient for minerals used in geochemical modeling.

scholarly journals Multiple sources and magmatic evolution of the Late Triassic Daocheng batholith in the Yidun Terrane: Implications for evolution of the Paleo-Tethys Ocean in the eastern Tibetan Plateau

2021 ◽  
Author(s):  
Pengsheng Dong ◽  
Guochen Dong ◽  
M. Santosh ◽  
Xuanxue Mo ◽  
Peng Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Chemical Diffusion ◽  
Late Triassic ◽  
Eastern Tibetan Plateau ◽  
Multiple Sources ◽  
Nd Isotopes ◽  
Fine Grained ◽  
Tethys Ocean ◽  
T Values ◽  
Lower Crustal

Granitoids with diverse composition and tectonic settings provide important tools for exploring crustal evolution and regional geodynamic history. Here we present an integrated study using petrological, mineralogical, zircon U-Pb geochronological, whole-rock geochemical, and isotopic data on the Late Triassic Daocheng batholith in the Yidun Terrane with a view to understanding the petrogenesis of a compositionally diverse batholith and its implications for the evolution of the Paleo-Tethys Ocean in the eastern Tibetan Plateau. The different lithological units of the batholith, including granodiorite, monzogranite, and quartz diorite, with abundant mafic microgranular enclaves in the granodiorite (MME I) and monzogranite (MME II), show identical crystallization ages of 218−215 Ma. The mineral assemblage and chemical composition of the granodiorite are identical to those of tonalitic-granodioritic melts generated under water-unsaturated conditions. The insignificant Eu anomalies and low magmatic temperatures indicate hydrous melting in the source. The relatively narrow range of whole-rock chemical and Sr-Nd isotopes, as well as the zircon trace element and Hf isotopic compositions of the granodiorite, suggest a homogeneous crustal source for the magma. Our modeling suggests that the rock was produced by 20−50% of lower crustal melting. The Daocheng monzogranites display more evolved compositions and larger variations in Sr-Nd-Hf isotopes than the granodiorite, which are attributed to assimilation and the fractional crystallization process. This is evidenced by the presence of metasedimentary enclave and inherited zircon grains with Neoproterozoic and Paleozoic ages, a non-cotectic trend in composition, and the trend shown by the modeling of initial 87Sr/86Sr ratios and Sr. The quartz diorites and MMEs showing composition similar to that of andesitic primary magma have high zircon εHf(t) values and are characterized by enrichment in LILEs and depletion of HFSEs. They were derived from the partial melting of lithospheric mantle that had been metasomatized by slab melts and fluids. The MMEs in both rocks display typical igneous texture and higher rare earth element (REE) and incompatible element concentrations than their host granites. The presence of fine-grained margins, acicular apatite, and plagioclase megacrysts suggests a magma mingling process. The overgrowth of amphibole around the pyroxene, quartz ocelli rimmed by biotite, and oscillatory zones of plagioclase are all indicative of chemical diffusion. Their enriched Sr-Nd isotopes imply isotopic equilibrium with the host granites. Based on a comparison with the coeval subduction-related magmatism, we propose that subduction and subsequent rollback of the Paleo-Tethys (Garzê-Litang Ocean) oceanic slab was the possible mechanism that triggered the diverse Triassic magmatism within the eastern Tibetan Plateau.

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.

scholarly journals A Study on Beryl in the Cuonadong Be-W-Sn Polymetallic Deposit, Longzi County, Tibet, China

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 777
Author(s):  
Jia-Qi Shen ◽  
Zhi-Kang Hu ◽  
Shi-Yuan Cui ◽  
Yu-Fei Zhang ◽  
En-Qi Li ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Metal Content ◽  
Near Infrared ◽  
Type I ◽  
Type Ii ◽  
Chemical Analyses ◽  
Inductively Coupled ◽  
Polymetallic Deposit ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

Recently, aquamarine was discovered in the Cuonadong Be-W-Sn Polymetallic Deposit, Longzi County, Tibet. Longzi aquamarine is being extracted and is expected to be available over the next decade. This study provides a full set of data through standard gemmological properties, including scenes, color characteristics and advanced spectroscopic and chemical analyses, including micro ultraviolet–visible–near-infrared (UV–Vis–NIR), Raman and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The main inclusions in Longzi aquamarine are gas–liquid inclusions and a great number of quartz inclusions. The content of type I H2O is greater than that of type II H2O because of the low-alkali metal content, and “tetrahedral” substitutions and “octahedral” substitutions exist at the same time.

scholarly journals Supplemental Material: Multiple sources and magmatic evolution of the Late Triassic Daocheng batholith in the Yidun Terrane: Implications for evolution of the Paleo-Tethys Ocean in the eastern Tibetan Plateau

2021 ◽  
Author(s):  
Pengsheng Dong ◽  
Guochen Dong
Keyword(s):  
Trace Elements ◽  
Geochemical Modeling ◽  
Major And Trace Elements ◽  
Late Triassic ◽  
Magmatic Evolution ◽  
Eastern Tibetan Plateau ◽  
Isotopic Data ◽  
Multiple Sources ◽  
Icp Ms ◽  
Tethys Ocean

Table S1: Mineral association of samples from the Daocheng batholith; Table S2: LA-ICP-MS U-Pb isotopic data for zircons from the Daocheng batholith; Table S3: Hf isotopic data for zircons from the Daocheng batholith; Table S4: Trace elements data for zircons from the Daocheng batholith; Table S5: Major and trace elements data for the Daocheng batholith; Table S6: Whole-rock Sr-Nd isotopic data of the Daocheng batholith; Table S7: Representative microprobe analyses of amphibole from the Daocheng batholith; Table S8: Partition coefficient for minerals used in geochemical modeling.

scholarly journals Copper Mineralization Potential of Late Triassic Granitoids in Northern Yidun Arc, SW China

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 337 ◽  
Author(s):  
Xing-Yuan Li ◽  
Jing-Ru Zhang ◽  
Hao Song ◽  
Chun-Kit Lai
Keyword(s):  
Age Dating ◽  
Late Triassic ◽  
Clear Correlation ◽  
Sw China ◽  
Copper Mineralization ◽  
Icp Ms ◽  
High Concentrations ◽  
T Values ◽  
Yidun Arc

Yidun arc is an important constituent of the Sanjiang Tethyan Domain in SW China. The Changdagou pluton, located in the northern part of the Yidun Arc, mainly consists of granodiorite. In this study, we conducted in-situ LA-ICP-MS zircon U-Pb dating, and trace element and Hf isotope analyses on the Changdagou granites. Age dating results yielded a weighted mean U-Pb age of 214.97 ± 0.98 Ma (MSWD = 1.2, 2σ), broadly coeval with extensive late Triassic magmatism across the Yidun Arc. All zircon grains analyzed showed high concentrations of Th, U, and HREE, with positive Ce and negative Eu anomalies. Logfo2 and CeN/CeN* values vary from FMQ −3.14 to FMQ +7.44 (average FMQ +3.98), and 14 to 172 (avg. 98), respectively. The zircon EuN/EuN* (avg. 0.22) ratios have no clear correlation with the CeN/CeN* ratios, suggesting that the former were mainly affected by the magma water content. In addition, zircon εHf(t) values vary in a narrow range (–2.9 to −4.9, avg. −3.4) that clusters around zero, indicating a greater component of mantle-derived magma. Hence, we propose that the Changdagou granodiorite was derived from a highly oxidized, “wet”, Cu-rich source, of the type likely to generate porphyry Cu mineralization. However, these parameters (logfO2, EuN/EuN*, (Ce/Nd)/Y, and εHf(t)) are all lower than those of intrusions associated with Cu ores at Pulang and Lannitang, which may explain why the Cu deposit discovered at Changdagou is small by comparison. Furthermore, on the basis of the decreasing trends of εHf, logfO2, and H2O content from south to north along the Yiduan arc, we infer that the northern segment of the Yidun arc (including Changdagou) was located further away from the subduction front.

scholarly journals Emeralds from the Most Important Occurrences: Chemical and Spectroscopic Data

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 561 ◽  
Author(s):  
Stefanos Karampelas ◽  
Bader Al-Shaybani ◽  
Fatima Mohamed ◽  
Supharart Sangsawong ◽  
Abeer Al-Alawi
Keyword(s):  
Spectroscopic Data ◽  
The Other ◽  
Lithium Content ◽  
Type I ◽  
Type Ii ◽  
Nickel Zinc ◽  
Cobalt Nickel ◽  
Water Band ◽  
Icp Ms ◽  
Vis Spectroscopy

The present study applied LA–ICP-MS on gem-quality emeralds from the most important sources (Afghanistan, Brazil, Colombia, Ethiopia, Madagascar, Russia, Zambia and Zimbabwe). It revealed that emeralds from Afghanistan, Brazil, Colombia and Madagascar have a relatively lower lithium content (7Li < 200 ppmw) compared to emeralds from other places (7Li > 250 ppmw). Alkali element contents as well as scandium, manganese, cobalt, nickel, zinc and gallium can further help us in obtaining accurate origin information for these emeralds. UV-Vis spectroscopy can aid in the separation of emeralds from Colombia and Afghanistan from these obtained from the other sources as the latter present pronounced iron-related bands. Intense Type-II water vibrations are observed in the infrared spectra of emeralds from Madagascar, Zambia and Zimbabwe, as well as in some samples from Afghanistan and Ethiopia, which contain higher alkali contents. A band at 2818 cm−1, supposedly attributed to chlorine, was observed only in emeralds from Colombia and Afghanistan. Samples with medium to high alkalis from Ethiopia, Madagascar, Zambia and Zimbabwe can also be separated from the others by Raman spectroscopy based on the lower or equal relative intensity of the Type I water band at around 3608 cm−1 compared to the Type II water band at around 3598 cm−1 band (with some samples from Afghanistan, Brazil and Russia presenting equal relative intensities).

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

Sign in / Sign up

Export Citation Format

Share Document