Lower crustal melting via magma underplating: Elemental and Sr–Nd–Pb isotopic constraints from late Mesozoic intermediate–felsic volcanic rocks in the northeastern North China Block

Island Arc ◽  
2011 ◽  
Vol 20 (4) ◽  
pp. 477-499 ◽  
Author(s):  
CHAOWEN LI ◽  
FENG GUO ◽  
WEIMING FAN
Keyword(s):  
North China ◽  
Volcanic Rocks ◽  
Crustal Melting ◽  
North China Block ◽  
Late Mesozoic ◽  
Felsic Volcanic ◽  
Lower Crustal ◽  
Felsic Volcanic Rocks ◽  
Isotopic Constraints

scholarly journals Studying to use volcanic ashes and felsic volcanic rocks in Vietnam teritory as the treatment materials for environment pollution – preliminary results

2018 ◽  
Vol 2 (1) ◽  
pp. 29-36
Author(s):  
Keyword(s):  
Volcanic Rocks ◽  
Viet Nam ◽  
Environment Pollution ◽  
Late Mesozoic ◽  
Preliminary Results ◽  
Sample Heating ◽  
Volcanic Ashes ◽  
Felsic Volcanic ◽  
Northwest Region ◽  
Felsic Volcanic Rocks

The felsic volcanic rocks and tuff aged from Late Mesozoic to Kainozoic occur in many places in Viet Nam Territory, such as Tu Le area (in Northwest Region), Binh Gia area, Binh Lieu area (Northest Reigion), Nha Trang area, Dalat area (Central Region). The mafic volcanic ashes aged from Late Neogen to Quarternary distribute in central part of Vietnam such ash Con Co Island, Van Hoa High land. The samples of the tuff rock of Don Duong Stratum collected from field trip in Da Lat area have been treated (burned) at 650oC, 750oC, 900oC. The experimental results show that these materials, after treatment (heating in funace at the temperature 650oC, 750oC and 900oC) expressed absortion capacity up to 90% of selected organic matters (MO, MD) and heavy Metal (Pb2+) in the testing solutions. Among them, the sample heating at 900oC is the best material for Pb2+ absorption. The preliminary results show that the volcalnic felsic rocks and volcanic ashes in Viet Nam, after suitable treatments, can be used as an enviroment treatment materials.

scholarly journals Generation of late Mesozoic felsic volcanic rocks in the Hailar Basin, northeastern China in response to overprinting of multiple tectonic regimes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zheng Ji ◽  
Qi-An Meng ◽  
Chuan-Biao Wan ◽  
De-Feng Zhu ◽  
Wen-Chun Ge ◽  
...  
Keyword(s):  
Partial Melting ◽  
Early Cretaceous ◽  
Lower Crust ◽  
Late Jurassic ◽  
Volcanic Rocks ◽  
Late Mesozoic ◽  
Hailar Basin ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks ◽  
Zircon Saturation

Abstract We performed zircon U–Pb age dating and geochemical analyses of late Mesozoic felsic volcanic rocks in the Hailar Basin, NE China, with the aim of eclucidating their emplacement ages, origin and geodynamic significance. The volcanic rocks consist of dacites, rhyolites and rhyolitic tuffs. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating results suggest that the rocks were erupted during the Late Jurassic–Early Cretaceous (161–117 Ma). They belong to the high-K calc-alkaline series and can be divided into two groups. Group I rocks are metaluminous to weakly peraluminous, contain low concentrations of heavy rare earth elements (HREEs) and high field strength elements (HFSEs), and have low zircon saturation temperatures (average 786 °C), all of which indicate an I-type affinity. In contrast, Group II rocks have higher HREE and HFSE concentrations and zircon saturation temperatures (average 918 °C), suggesting an A-type affinity. All the felsic volcanic rocks have positive εHf(t) values of 1.43–12.32 with two-stage model ages of 1110–401 Ma. Our data indicate that the I-type felsic volcanic rocks formed from magmas generated by partial melting of a dominantly juvenile mica-bearing K-rich basaltic lower crust, whereas the A-type felsic volcanic rocks originated from the partial melting of a dry mafic–intermediate middle–lower crust that was dehydrated but not melt depleted. Based on the present results and previous research, we propose that the Late Jurassic I- and A-type felsic volcanic rocks in the Hailar Basin were formed in a post-collisional environment related to break-off of the subducted oceanic slab of the Mongol–Okhotsk Ocean and the subsequent gravitational collapse of the orogenically-thickened crust after closure of the ocean. In contrast, the Early Cretaceous I- and A-type felsic volcanic rocks were erupted in an extensional setting related to rollback of the subducted Paleo-Pacific Plate.

Geochemistry and Isotope Composition of Paleoproterozoic Granites and Felsic Volcanics of the Elash Graben: Evidence of the Heterogeneity of the Early Precambrian Crust

2021 ◽  
Vol 62 (10) ◽  
pp. 1175-1187
Author(s):  
A.D. Nozhkin ◽  
O.M. Turkina ◽  
K.A. Savko
Keyword(s):  
Isotope Composition ◽  
Volcanic Rocks ◽  
Rare Metal ◽  
Temporal Association ◽  
Metal Deposit ◽  
Wide Range ◽  
Rare Metal Deposit ◽  
Geochronological Study ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Abstract —The paper presents results of a petrogeochemical and isotope–geochronological study of the granite–leucogranite association of the Pavlov massif and felsic volcanics from the Elash graben (Biryusa block, southwest of the Siberian craton). A characteristic feature of the granite–leucogranites is their spatial and temporal association with vein aplites and pegmatites of the East Sayan rare-metal province. The U–Pb age of zircon from granites of the Pavlov massif (1852 ± 5 Ma) is close to the age of the pegmatites of the Vishnyakovskoe rare-metal deposit (1838 ± 3 Ma). The predominant biotite porphyritic granites and leucogranites of the Pavlov massif show variable alkali ratios (K2O/Na2O = 1.1–2.3) and ferroan (Fe*) index and a peraluminous composition; they are comparable with S-granites. The studied rhyolites of the Tagul River (SiO2 = 71–76%) show a low ferroan index, a high K2O/Na2O ratio (1.6–4.0), low (La/Yb)n values (4.3–10.5), and a clear Eu minimum (Eu/Eu* = 0.3–0.5); they are similar to highly fractionated I-granites. All coeval late Paleoproterozoic (1.88–1.85 Ga) granites and felsic volcanics of the Elash graben have distinct differences in composition, especially in the ferroan index and HREE contents, owing to variations in the source composition and melting conditions during their formation at postcollisions extension. The wide range of the isotope parameters of granites and felsic volcanic rocks (εNd from +2.0 to –3.7) and zircons (εHf from +3.0 to +0.8, granites of the Toporok massif) indicates the heterogeneity of the crustal basement of the Elash graben, which formed both in the Archean and in the Paleoproterozoic.

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