scholarly journals U-Pb zircon and Hf composition of granite Song Ma block

2019 ◽  
Vol 2 (4) ◽  
pp. 167-175
Author(s):  
Tai Minh Nguyen ◽  
Hoa Xuan Tran ◽  
Giang Thi Truong Nguyen ◽  
Cuong Chi Truong ◽  
Minh Pham
Keyword(s):  
Isotope Composition ◽  
Biotite Granite ◽  
Hf Isotope ◽  
Geochemical Characteristics ◽  
Composition Analysis ◽  
Viet Nam ◽  
Early Triassic ◽  
Late Permian ◽  
Weighted Mean ◽  
Mineral Assemblages

The granite of the Song Ma block mainly consists of two types of granite: biotite granite and hornblende-biotite granite. Biotite granites have the percent of plagioclase (35– 45%), K-feldspar (25–35%), quartz (~20%) and biotite (~10%). Biotite-hornblende granite with the content of plagioclase (40–50%), Kfeldspar (10–15%), hornblende (5–10%) and biotite (5%). Zircon crystals were selected from the granite of Song Ma block are V0741, V0856 and V1006 samples with the LA-ICPMS U-Pb analyses gave concordant ages concentrated at 257±4Ma, 262±3Ma and 241±6Ma (weighted mean). Those ages are older than the results of the previous research. The mineral assemblages and geochemical characteristics show the typical of I-type granites. The results of Hf isotope composition analysis give the value of εHf(t) from +7.3 to +13.9, which is proven the sources of the granite Song Ma block similar to the granite of Phan Si Pan zone, NW Viet Nam during the period from late Permian to early Triassic.

scholarly journals The LA-ICP-MS U-Pb zircon age of rhyolite from the Dong Trau formation and its geological significances

2018 ◽  
Vol 1 (T5) ◽  
pp. 270-277
Author(s):  
Hieu Trung Pham
Keyword(s):  
Primary Magma ◽  
Early Triassic ◽  
Late Permian ◽  
Weighted Mean ◽  
Zircon Age ◽  
Analytical Results ◽  
Icp Ms ◽  
Magma Crystallization ◽  
Sr Method

Zircons separated from an rhyolite sample in the Dong Trau formation, in the southern of Hà Tĩnh province were dated to determine the protolith age for the complex. Sixteen LA-ICP-MS U-Pb zircon analyses give concordant ages concentrated at 256 Ma (weighted mean). These results indicate the protolith age of the rhyolite (primary magma crystallization age). The value of this age are close to the analytical results pf the whole rock by Rb-Sr method and biotite Rb-Sr method. Therefore the crystallization age of the rhyolite from the Đồng Trầu formation corresponded period late Permian to early Triassic.

scholarly journals Geochemical characteristics of the Muong Hum alkaline granite in the Phan Si Pan zone, Northwestern Vietnam

2017 ◽  
Vol 1 (T2) ◽  
pp. 114-123
Author(s):  
Minh Pham ◽  
Hieu Trung Pham ◽  
Hoang Kim Nguyen
Keyword(s):  
Geochemical Characteristics ◽  
Red River ◽  
Large Igneous Province ◽  
Direct Result ◽  
Chemical Characteristics ◽  
Late Permian ◽  
Alkaline Granite ◽  
Igneous Province ◽  
Mineral Assemblages ◽  
Alkaline Feldspar

Alkaline granites of the Muong Hum are distributed mainly in the NW Phan Si Pan zone. The granite closely has striped or clear gneissoid structures, coinciding with general NW-SE trends. It consists mainly of plagioclase (~20–30 %), alkaline feldspar (~30–50 %), quartz (~20–25 %), biotite (~1–5 %), aegirine (~1–3 %), and riebeckite (~1–2 %). It has 10,000×Ga/Al ratios of 4.70–4.93, A/CNK values of 0.87–0.90, and negative Eu-anomalies as well as apparent depletion of Ba, Sr, Ti, and P. The mineral assemblages and chemical characteristics show that it is typical of A-type granites. Compared with other adjacent Late Permian to Early Triassic A-type granitic plutons, geochemical characteristics of the Muong Hum granite are similar to the Phu Sa Phìn, Phan Si Pan, Ye Yen Sun, and Nam Xe-Tam Duong granites in NW Vietnam as well as the Taihe, and Panzhihua granites in SW China. Thus, the Phan Si Pan zone must have been a displaced portion of the Emeishan large igneous province. This might be a direct result of the left-lateral Cenozoic Red River shear zone.

Late Permian to Triassic isotope composition of sulfates in the Eastern Alps: palaeogeographic implications

2016 ◽  
Vol 155 (4) ◽  
pp. 797-810 ◽  
Author(s):  
ANA-VOICA BOJAR ◽  
STANISLAW HAŁAS ◽  
HANS-PETER BOJAR ◽  
ANDRZEJ TREMBACZOWSKI
Keyword(s):  
Isotopic Composition ◽  
Isotope Composition ◽  
Eastern Alps ◽  
Upper Permian ◽  
Early Triassic ◽  
Late Permian ◽  
Sulfur Isotopic Composition ◽  
Entire Area ◽  
Minor Elements ◽  
Thermal Overprint

AbstractLate Permian to Triassic phases from the evaporite deposits of the Northern Calcareous Alps (NCA) and Central Alpine Mesozoic (CAM) were analysed for sulfur and oxygen isotope compositions. For the Upper Permian, most of the δ34S values are in the 11 to 12‰ range. Röt-type sulfates of Early Triassic age are characterized by a heavy sulfur isotopic composition of c. 26‰. The spatial compilation of the available data concerning the isotopic composition of Röt-type sulfates demonstrates that these evaporites are distributed over the entire area of the NCA. Their occurrences are associated with Early Triassic high-temperature conditions of the seawater and a widespread anoxia. The development of sulfates of Carnian–Norian age situated in the CAM is more modest; sulfates are characterized by a δ34S value of c. 15‰. The δ18O values show a broader distribution from 9 to 22‰, related to several factors such as type of deposit, recrystallization processes and bacterial sulfate reduction. The sulfate–sulfide thermometer applied to samples from NCA deposits indicates a thermal overprint of between 215 and 315°C. Microbeam measurements support zonation of minor elements in sphalerite. Sphalerite microstructure indicates thermal overprinting, with no microbial structure being preserved.

scholarly journals Geochronology, geochemistry, Sr–Nd–Hf isotope composition of the late Permian adakite in West Ujimqin, Inner Mongolia: petrogenesis and tectonic implications

2021 ◽  
pp. 1-13
Author(s):  
Yuxu Fan ◽  
Qinghui Xiao ◽  
Tingdong Li ◽  
Yang Cheng ◽  
Yan Li ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Major And Trace Elements ◽  
Hf Isotope ◽  
Geodynamic Setting ◽  
Stage Model ◽  
Late Permian ◽  
The West ◽  
Central Asian ◽  
High Level ◽  
Oceanic Slab

We report herein on new zircon U–Pb ages, the major and trace elements of whole-rock, and the Sr–Nd–Hf isotope composition for adakitic intrusives collected from the West Ujimqin district in the Southeast region of the Central Asian Orogenic Belt (CAOB). These data provide important constraints on the petrogenetic evolution and geodynamic setting of late Permian magmatism in the Southeast CAOB. The U–Pb dating of zircon shows that the ages of Seerbeng pluton and Nuhetingshala pluton in West Ujimqin are 255.3 ± 0.71 and 254.4 ± 1.2 Ma, respectively, which signifies that these are products of magmatic activity in the late Permian. The adakitic intrusives are characterized by high levels of Sr (Sr ≥ 741 ppm), low Y, low Yb, high Sr:Y ratios, and strongly fractionated rare earth elements (10.3 < LaN/YbN < 22.5), which is similar to the features of the adakite. The magmatic zircons exhibit positive Hf values (+8.1 to +13.3), and young two-stage model ages vary from 430 to 760 Ma. The high εNd(t) and low (87Sr:86Sr)i indicate that the adakitic granite derived from the partial melting of subducted oceanic slab. The high level of Mg# [100 × Mg/(Mg + Fe) in atomic number] and abundant Cr–Ni indicate that magmatic melts interacted with olivine rocks in the mantle. Considering these results and the regional rock assemblies, we conclude that the Paleo-Asian Ocean had not yet completely closed in the late Permian, and northward subduction continued, with the subducted slab possibly breaking off.

EARLY CORDILLERAN ARC DEVELOPMENT RECORDED IN LATE PERMIAN AND EARLY TRIASSIC PLUTONS OF THE NORTHERN MOJAVE DESERT, CALIFORNIA

2016 ◽  
Author(s):  
M. Robinson Cecil ◽  
◽  
Mary Ann Ferrer ◽  
Nancy R. Riggs ◽  
Kathleen M. Marsaglia
Keyword(s):  
Mojave Desert ◽  
Early Triassic ◽  
Late Permian

Nature and origin of the volcanic ash beds near the Permian–Triassic boundary in South China: new data and their geological implications

2019 ◽  
Vol 157 (4) ◽  
pp. 677-689 ◽  
Author(s):  
Binsong Zheng ◽  
Chuanlong Mou ◽  
Renjie Zhou ◽  
Xiuping Wang ◽  
Zhaohui Xiao ◽  
...  
Keyword(s):  
Trace Element ◽  
Continental Margin ◽  
South China ◽  
Volcanic Ash ◽  
Active Continental Margin ◽  
Main Body ◽  
Early Triassic ◽  
Late Permian ◽  
Triassic Boundary ◽  
Permian Triassic Boundary

AbstractPermian–Triassic boundary (PTB) volcanic ash beds are widely distributed in South China and were proposed to have a connection with the PTB mass extinction and the assemblage of Pangea. However, their source and tectonic affinity have been highly debated. We present zircon U–Pb ages, trace-element and Hf isotopic data on three new-found PTB volcanic ash beds in the western Hubei area, South China. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons yields ages of 252.2 ± 3.6 Ma, 251.6 ± 4.9 Ma and 250.4 ± 2.4 Ma for these three volcanic ash beds. Zircons of age c. 240–270 Ma zircons have negative εHf(t) values (–18.17 to –3.91) and Mesoproterozoic–Palaeoproterozoic two-stage Hf model ages (THf2) (1.33–2.23 Ga). Integrated with other PTB ash beds in South China, zircon trace-element signatures and Hf isotopes indicate that they were likely sourced from intermediate to felsic volcanic centres along the Simao–Indochina convergent continental margin. The Qinling convergent continental margin might be another possible source but needs further investigation. Our data support the model that strong convergent margin volcanism took place around South China during late Permian – Early Triassic time, especially in the Simao–Indochina active continental margin and possibly the Qinling active continental margin. These volcanisms overlap temporally with the PTB biocrisis triggered by the Siberian Large Igneous Province. In addition, our data argue that the South China Craton and the Simao–Indochina block had not been amalgamated with the main body of Pangea by late Permian – Early Triassic time.

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