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.

Petrogenesis of Silicic Rocks from the Phan Si Pan - Tu Le region of the Emeishan Large Igneous Province, Northwestern Vietnam

2021 ◽  
pp. SP518-2020-253
Author(s):  
Thuy Thanh Pham ◽  
J. Gregory Shellnutt ◽  
Tuan-Anh Tran ◽  
Steven W. Denyszyn ◽  
Yoshiyuki Iizuka
Keyword(s):  
Basaltic Magma ◽  
Red River ◽  
Granitic Rocks ◽  
Large Igneous Province ◽  
Weighted Mean ◽  
Emeishan Large Igneous Province ◽  
Icp Ms ◽  
Igneous Province ◽  
Single Grain ◽  
Host Rocks

AbstractThe Permian silicic rocks in the Phan Si Pan (PSP) uplift area and Tu Le (TL) basin of NW Vietnam (collectively the PSP-TL region) are associated with the Emeishan Large Igneous Province (ELIP). The Permian Muong Hum, Phu Sa Phin, and Nam Xe - Tam Duong granites, and Tu Le rhyolites are alkali ferroan A1-type granitic rocks, which likely formed by fractional crystallization of high-Ti basaltic magma that was contaminated by melts derived from the Neoproterozoic host rocks. Zircon U-Pb LA-ICP-MS geochronology yielded weighted-mean 206Pb/238U ages of 246 ± 3 Ma to 259 ± 3 Ma for granites, and 249 ± 3 Ma and 254 ± 2 Ma for rhyolites. This is contrasted with previously-published high precision U-Pb ages, obtained using CA-ID-TIMS method applied on the same zircon grains, which suggest that the calculated LA-ICP-MS U-Pb ages are variably inaccurate by up to 10 Ma, though at the single-grain level dates generally agree within uncertainty. The similarity of rock texture, whole-rock geochemistry, emplacement ages, and fractionation phases between the PSP-TL region and silicic rocks in the Inner Zone ELIP (i.e., Panzhihua, Binchuan) suggests they were spatially proximal before being sinistrally displaced along the Ailao Shan-Red River shear zone.

Chapter 2.1b Ferrar Large Igneous Province: petrology

2021 ◽  
pp. M55-2018-39 ◽  
Author(s):  
David H. Elliot ◽  
Thomas. H. Fleming
Keyword(s):  
Ross Sea ◽  
Lower Jurassic ◽  
Weddell Sea ◽  
Geochemical Characteristics ◽  
Large Igneous Province ◽  
Geographical Pattern ◽  
Chemical Type ◽  
Igneous Province ◽  
Intrusive Rocks ◽  
Basic Rocks

AbstractThe Lower Jurassic Ferrar Large Igneous Province consists predominantly of intrusive rocks, which crop out over a distance of 3500 km. In comparison, extrusive rocks are more restricted geographically. Geochemically, the province is divided into the Mount Fazio Chemical Type, forming more than 99% of the exposed province, and the Scarab Peak Chemical Type, which in the Ross Sea sector is restricted to the uppermost lava. The former exhibits a range of compositions (SiO2 = 52–59%; MgO = 9.2–2.6%; Zr = 60–175 ppm; Sri = 0.7081–0.7138; εNd = −6.0 to −3.8), whereas the latter has a restricted composition (SiO2 = c. 58%; MgO = c. 2.3%; Zr = c. 230 ppm; Sri = 0.7090–0.7097; εNd = −4.4 to −4.1). Both chemical types are characterized by enriched initial isotope compositions of neodymium and strontium, low abundances of high field strength elements, and crust-like trace element patterns. The most basic rocks, olivine-bearing dolerites, indicate that these geochemical characteristics were inherited from a mantle source modified by subduction processes, possibly the incorporation of sediment. In one model, magmas were derived from a linear source having multiple sites of generation each of which evolved to yield, in sum, the province-wide coherent geochemistry. The preferred interpretation is that the remarkably coherent geochemistry and short duration of emplacement demonstrate derivation from a single source inferred to have been located in the proto-Weddell Sea region. The spatial variation in geochemical characteristics of the lavas suggests distinct magma batches erupted at the surface, whereas no clear geographical pattern is evident for intrusive rocks.

scholarly journals Toxic mercury pulses into late Permian terrestrial and marine environments

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 830-833 ◽  
Author(s):  
Stephen E. Grasby ◽  
Xiaojun Liu ◽  
Runsheng Yin ◽  
Richard E. Ernst ◽  
Zhuoheng Chen
Keyword(s):  
Trophic Levels ◽  
Large Igneous Province ◽  
Late Permian ◽  
Volcanic Emissions ◽  
Loading Rates ◽  
Siberian Traps ◽  
Igneous Province ◽  
Permian Extinction ◽  
Potential Impact ◽  
Normal Background

Abstract Large spikes in mercury (Hg) concentration are observed globally at the latest Permian extinction (LPE) horizon that are thought to be related to enhanced volcanic emissions of the Siberian Traps large igneous province (LIP). While forming an effective chemostratigraphic marker, it remains unclear whether such enhanced volcanic Hg emissions could have generated toxic conditions that contributed to extinction processes. To address this, we examined the nature of enhanced Hg emissions from the Siberian Traps LIP and the potential impact it may have had on global ecosystems during the LPE. Model results for a LIP eruption predict that pulses of Hg emissions to the atmosphere would have been orders of magnitude greater than normal background conditions. When deposited into world environments, this would have generated a series of toxic shocks, each lasting >1000 yr. Such repeated Hg loading events would have had severe impact across marine trophic levels, as well as been toxic to terrestrial plant and animal life. Such high Hg loading rates may help explain the co-occurrence of marine and terrestrial extinctions.

scholarly journals Nature of Cretaceous dolerite dikes with two distinct trends in the Damodar Valley, eastern India: Constraints on their linkage to mantle plumes and large igneous provinces from 40Ar/39Ar geochronology and geochemistry

Lithosphere ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 40-52 ◽  
Author(s):  
Rajesh K. Srivastava ◽  
Fei Wang ◽  
Wenbei Shi ◽  
Anup K. Sinha ◽  
Kenneth L. Buchan
Keyword(s):  
Sedimentary Basins ◽  
Geochemical Characteristics ◽  
Large Igneous Province ◽  
Mantle Plumes ◽  
Eastern India ◽  
Group I ◽  
Igneous Provinces ◽  
Damodar Valley ◽  
Igneous Province ◽  
Reunion Plume

Abstract Two distinct sets of Cretaceous dolerite dikes intrude the Chhotanagpur gneissic complex of eastern India, mostly within the Damodar Valley Gondwanan sedimentary basins. One dike set trends NNE to ENE, whereas the other set, which includes the prominent Salma dike, trends NW to NNW. One dike from each set in the Raniganj Basin was dated using the 40Ar/39Ar method in order to resolve a controversy concerning the emplacement age of the Salma dike. The NE-trending dike yielded a plateau age of 70.5 ± 0.9 Ma, whereas the NNW-trending Salma dike is much older, with a plateau age of 116.0 ± 1.4 Ma. These results demonstrate that the Salma dike was emplaced at ca. 116 Ma and not at ca. 65 Ma, as suggested in an earlier study. Geochemical characteristics of the two dikes are also distinct and indicate that they belong to previously identified high-Ti and low-Ti dolerite groups, respectively. The observed geochemical characteristics of both dike sets are comparable with the geochemistry of basalts of the Kerguelen Plateau, Bunbury Island, and Rajmahal Group I and suggest a connection to mantle plumes. The new age data presented herein indicate that these two magmatic episodes in the eastern Indian Shield were related to the ca. 120–100 Ma Kerguelen mantle plume and its associated Greater Kerguelen large igneous province and the ca. 70–65 Ma Réunion plume and its associated Deccan large igneous province, respectively.

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.

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