Geochronological and geochemical investigation of the late Mesozoic volcanic rocks from the Northern Great Xing’an Range and their tectonic implications

Abstract

Precise age dating and systematic geochemical investigation were performed on the widely distributed late Mesozoic volcanic rocks in the North Great Xing'an Range (NGXR). In situ zircon U-Pb age measurements indicate that the volcanic eruption commenced from 163 Ma ago and lasted to 113 Ma ago. These volcanic rocks show a wide range in compositions from basaltic andesite, trachyandesite and trachydacite to rhyolite. The majority of volcanic rocks exhibit high-K calc-alkaline affinity with the subordinate showing shoshonitic features. The volcanic rocks are characterized with low MgO contents, LILE, LREE enrichment and HFSE depletion. Elemental and isotopic variations suggest that fractional crystallization with the predominant removal of olivine and orthopyroxene play an important role in the evolution of magma. Most of the basic and intermediate volcanic rocks are generated from an enriched lithospheric mantle which was metasomatised by fluids released from subducted slabs during the closure of the Paleo-Asian and Mongol-Okhotsk oceans. The generation of such widely distributed volcanic rocks was caused by the decompressional partial melting of enriched lithospheric mantle in an extensional regime, which resulted from the gravitational collapse and upwelling of asthenosphere after the final closure of the Mongol-Okhotsk oceans in late Jurassic and from then the Mongol-Okhotsk orogen turned into the post-orogenic stage.

Geochronological framework of Mesozoic volcanic rocks in the Great Xing’an Range, NE China, and their geodynamic implications

“…Zhang et al (2008) analyzed eight samples using zircon U-Pb and 40 Ar/ 39 Ar techniques and got an eruption span of 186-121 Ma for this formation. Recently, we re-dated several samples that collected from the same sites of Wang et al (2006) using SHRIMP zircon U-Pb technique, and the acquired zircon U-Pb age is 164 Ma, which is highly consistent with the whole rock matrix 40 Ar/ 39 Ar data within the errors (Ying et al, 2010). Wang et al (2006) analyzed eight samples from this formation and concluded that the Shangkuli formation erupted during 124-120 Ma, while Zhang et al (2008)'s data suggested that this formation erupted during 135-111 Ma with most activity between 130 and 120 Ma.…”

“…As mentioned above, the volcanic rocks in the northern Great Xing'an Range have been dated by previous work (Wang et al, 2006), and more age data have been accumulated recently for these volcanic rocks (Zhang et al, 2008;Ying et al, 2010), so we just give a brief summary of the age data for the volcanic rocks from the northern Great Xing'an Range in this contribution. Age measurements will only focused on the volcanic rocks from the southern Great Xing'an Range, as no systematic, high precision isotopic age data available so far, and this work provides original, comprehensive and reliable age information for these volcanic rocks.…”

SIMS zircon U–Pb and molybdenite Re–Os geochronology, Hf isotope, and whole-rock geochemistry of the Wunugetushan porphyry Cu–Mo deposit and granitoids in NE China and their geological significance

“…Chen et al, 2011), Middle-Late Jurassic (Ying et al, 2008;Xu et al, 2013;Tang et al, 2014), and Early Cretaceous (Cogne et al, 2005;Metelkin et al, 2007). What's more, extensive studies on the Early Mesozoic granitoids on southeastern part of Mongol-Okhotsk Orogen have revealed that these rocks, mainly including granodiorites, monzogranites, syenogranites, biotite granite, and diorites, are widely distributed and are regarded as having formed in an active continental margin related to the southwards subduction of the Mongol-Okhotsk oceanic plate (Kovalenko et al, 1995;Dergunov, 2001;Parfenov et al, 2001;Tomurtogoo et al, 2005;F.Y.…”

“…Located primarily on the Xing'an and Erguna blocks, the northern part of the Great Xing'an Range in NE China is known for large exposures of Mesozoic granites and volcanic rocks (Fan et al, 2003;Ge et al, 2005;F. Wang et al, 2006;Ge et al, 2007;L.C. Zhang et al, 2008), and also is an important polymetallic metallogenic belt hosting different types of hydrothermal deposits (Liu et al, 2001;Mao et al, 2003;D.G.…”

A short-lived but significant Mongol–Okhotsk collisional orogeny in latest Jurassic–earliest Cretaceous

“…5). 40 Ar-39 Ar and U-Pb dating of basalts, andesites, and rhyolites of this formation that are exposed in the western part of the basin yielded an age range of 164-147 Ma Ying et al, 2010) Table 1). There is an angular unconformity between the Upper Jurassic strata and the overlying Lower Cretaceous strata, suggesting that the basin underwent uplift and erosion during the latest Jurassic-earliest Cretaceous (J.…”