scholarly journals Mineralization of the Tuwu Porphyry Cu Deposit in Eastern Tianshan, NW China: Insights From In Situ Trace Elements of Chlorite and Pyrite

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei Tan ◽  
Qigui Mao ◽  
Mingjie Yu ◽  
Yan Sun ◽  
Xiaoqiang Lv
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Earth Element ◽  
Distribution Patterns ◽  
Eastern Tianshan ◽  
Nw China ◽  
Ree Distribution ◽  
Lree Enrichment ◽  
Stage Stage

The Tuwu porphyry copper deposit is located on the Dananhu-Haerlik island arc in eastern Tianshan, NW China. Based on geology, petrology, and in situ trace element studies of pyrite and chlorite, we redefined the characteristics of hydrothermal fluids and the following three mineralization stages: premineralization stage (stage Ⅰ), porphyry metallogenic stage (stage Ⅱ), and superimposed transformation stage (stage Ⅲ). Pyrite stage Ⅰ (Py-I) has the highest Co/Ni ratios, and the precipitation crystallization of chlorite (Chl-I2) has the similar rare earth element distribution patterns with those of volcanic rocks Carboniferous Qieshan (CQ), indicating intense volcanic hydrothermal activity. The Co/Ni ratios of Py-II1 and Py-II2 (stage Ⅱ) tend to decrease over time. Moreover, the rare earth element (REE) distribution patterns of Chl-II have similar LREE enrichment, and the Eu anomalies in Chl-II1, Chl-II2, and Chl-II3 range from positive to negative. The initial ore-forming fluid was mainly magmatic hydrothermal fluid, and with the late-stage addition of meteoric water and continuous sulfide precipitation, the trace element composition of the fluid changed, and the whole system became more oxidizing. Py-III (stage Ⅲ) has the lowest Co/Ni ratios, and the REE distribution pattern of Chl-III is characterized by LREE enrichment. Moreover, the Chl-III shows obvious shear deformation characteristics. The results indicate that the host rocks experienced intensely superimposed reformation. By combining and integrating our results with the regional evolution processes in the eastern Tianshan, we propose that the Tuwu porphyry deposit has undergone magmatic hydrothermal and metamorphic hydrothermal processes. Volcanism (stage Ⅰ) provided the space and initial conditions for the emplacement of the metallogenic body. With the emplacement of the plagiogranite porphyry (stage Ⅱ), the main copper mineralization occurred in the porphyry and surrounding rocks. After porphyry mineralization (stage Ⅲ), regional ductile shearing and collisional compression led to a copper reaction, and its accumulation along the faults formed an ore shoot.

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

2003 ◽  
Vol 40 (8) ◽  
pp. 1027-1051 ◽  
Author(s):  
D Canil ◽  
D J Schulze ◽  
D Hall ◽  
B C Hearn Jr. ◽  
S M Milliken
Keyword(s):  
Rare Earth ◽  
North America ◽  
Trace Element ◽  
Earth Element ◽  
Geochemical Data ◽  
Trace Element Data ◽  
Mantle Lithosphere ◽  
Western North America ◽  
Wyoming Province ◽  
Thick Mantle

This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450°C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110–260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tectonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

Paleoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard

2016 ◽  
Vol 53 (8) ◽  
pp. 788-794
Author(s):  
Živilė Žigaitė ◽  
Alexandre Fadel ◽  
Alberto Pérez-Huerta ◽  
Teresa Jeffries ◽  
Daniel Goujet ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Lower Devonian ◽  
Depositional Environment ◽  
Earth Element ◽  
Long Distance ◽  
Dental Tissues ◽  
Abundance Patterns ◽  
The Eu

In situ rare-earth element (REE) compositions have been measured in early vertebrate microremains from the Lower Devonian basin of Andrée Land (Svalbard), with the aim of obtaining information about their early depositional environment and potential reworking. Vertebrate microremains with different histology were used for the analyses, sourced from two different localities of marginal marine to freshwater sediments from geographically distant parts of the Grey Hœk Formation (Skamdalen and Tavlefjellet members). We selected thelodont and undescribed ?chondrichthyan scales, which allowed us to define potential taxonomic, histological, and taphonomic variables of the REE uptake. Results showed REE concentrations to be relatively uniform within the scales of each taxon, but apparent discrepancies were visible between the studied localities and separate taxa. The compilation of REE abundance patterns as well as REE ratios have revealed that thelodont and ?chondrichthyan originating from the same locality must have had different burial and early diagenetic histories. The shapes of the REE profiles, together with the presence and absence of the Eu and Ce anomalies, equally suggested different depositional and diagenetic environments for these two sympatric taxa resulting from either stratigraphical or long-distance reworking. The REE concentrations appear to have visible differences between separate dental tissues, particularly between enameloid and dentine of thelodonts, emphasizing the importance of in situ measurements in microfossil biomineral geochemistry.

Simultaneous determination of Sm–Nd isotopes, trace-element compositions and U–Pb ages of titanite using a laser-ablation split-stream technique with the addition of water vapor

2021 ◽  
Author(s):  
Le Zhang ◽  
Jia-Lin Wu ◽  
Yanqiang Zhang ◽  
Ya-Nan Yang ◽  
Pengli He ◽  
...  
Keyword(s):  
Rare Earth ◽  
Water Vapor ◽  
Laser Ablation ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Simultaneous Determination ◽  
Nd Isotopes ◽  
Trace Element Contents

Titanite is a widespread accessory nesosilicate with high trace-element contents including rare-earth elements, Th, and U, and is thus suitable for in situ isotopic and trace-element analyses and U–Pb dating....

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