Geochemical and geochronological studies of Abor volcanic rocks of eastern Himalaya
نویسندگان
چکیده
The Indian Plate began drifting northward after the Gondwana breakup and collided with Eurasian during Early Cenozoic, resulting in consequential development of Himalayan–Tibetan Orogeny. Several microcontinents were rifted from amalgamated Plate, magmatism along continental margin. Abor volcanic rocks (AVRs) eastern Himalaya represent one such magmatism, emplacement mechanism, timing which is still a topic debate. AVR comprises mafic silicic rocks; present study concerns petrography geochemistry rocks. U–Pb geochronology on three samples shows weighted mean age 130 ± 1 Ma, 143 1.2 155 16 Ma. Whole-rock eight Mg# 45.48 to 57.7, except for sample 37.4, variable contents CaO (4.4–9.5 wt%), K2O (0.1–2.6%), Lost ignition (LOI) (0.9–3.6 wt%; average 2.4), K2O/Na2O ratios (0.02–0.6 single 1.0), Y/Nb (0.55–1.66, value 2.44), medium high Zr/Nb (10.1–14.1) Zr/Y (5.4–18.14). Sr-isotopic results 11 show that initial 87Sr/86Sr vary between 0.7049 0.7110, εNd(t) values range +1.176 −2.250. Geochemical isotopic data suggest studied AVRs (mafic) are subalkaline tholeiitic affinity. These have intraplate characteristics sourced metasomatized mantle rifting event subcontinent Late Jurassic Cretaceous.
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ژورنال
عنوان ژورنال: Geological Journal
سال: 2021
ISSN: ['1099-1034', '0072-1050']
DOI: https://doi.org/10.1002/gj.4268