Early Cretaceous highly positive ε Nd felsic volcanic rocks from the Hinggan Mountains, NE China: origin and implications for Phanerozoic crustal growth

Abstract

An early Cretaceous (135 ± 2 Ma) felsic volcanic suite of dacite and rhyolite from Huolinhe, NE China is characterized by large ion lithophile element and light REE enrichment and high field strength element (HFSE, e.g., Nb and Ta) and Ti-P depletion, and bulk silicate earth-like Sr [ 87 Sr/ 86 Sr(i) = 0.70409-0.70481], quite radiogenic Nd [e Nd (t) = ?3.98 to ?5.88], Pb [e.g., 206 Pb/ 204 Pb(i) = 18.46-18.55] and Hf [e Hf (t) *?9.2] isotope compositions. Compared with contemporaneous mafic rocks in the region, these felsic rocks have even higher Nd and Hf isotopic ratios, precluding an origin through differentiation of coeval mantle-derived magmas. Isotope calculation results suggest that these magmas were derived from a preexistent mixture composed of mainly juvenile crust (70-80%), and a subordinate recycled crustal component (20-30%) having highly radiogenic Sr and Pb and unradiogenic Nd and Hf. About 25-30% melting of such a mixed source produced the primary dacitic magma. The rhyolites, which have relatively low MgO, FeOwere differentiates of the dacites after removal of a fractional assemblage of hornblende ? plagioclase ? K-feldspar ? apatite ? zircon. Considering the prolonged events (from 262 to 130 Ma) that produced such highly positive e Nd felsic igneous rocks in the region, we prefer a pre-Mesozoic crustal growth model related to arc accretion associated with the Paleo-Asian Ocean subduction.

Formation of the Jurassic Changboshan‐Xieniqishan highly fractionated I‐type granites, northeastern China: implication for the partial melting of juvenile crust induced by asthenospheric mantle upwelling

“…This can exclude the possibility of the involvement of melts produced by partial melting of delaminated eclogitic lower crust. Moreover, unlike the lithospheric mantle beneath the eastern block of the NCC, replaced by much younger lithospheric mantle sometime after the Palaeozoic (Gao et al, 2002(Gao et al, , 2004, the Guo et al, 2009;Ying et al, 2010a). Accordingly, we can deduce that the delamination of lower crust is not a significant process occurring during the Jurassic in NE China.…”

“…However, high‐Mg adakitic rocks have not been reported in NE China, and most of the Late Mesozoic basalts in this area show high 206 Pb/ 204 Pb values (17.791–18.797, L.C. Zhang et al ., 2008; Guo et al ., ; Ying et al ., ). Accordingly, we can deduce that the delamination of lower crust is not a significant process occurring during the Jurassic in NE China.…”

Geochronology and geochemistry of late Mesozoic volcanic rocks in the Wenkutu area, Great Xing'an Range, China

“…Underplating can provide heat sources for volcanic activity, leading to the recycling of crustal material (Gao et al, ). The felsic volcanic rocks in the area are characterized by high initial values of Nd of Early Cretaceous from the crust (Guo, Fan, Li, Gao, & Miao, ). By comparison, the Mesozoic volcanic rocks in the Longjiang Basin reflect magma derived from the crust and are a product of crustal partial melting during closure of the Mongolia Okhotsk Ocean (Li, Gao, Bian, Chen, & Ding, ).…”

“…Underplating can provide heat sources for volcanic activity, leading to the recycling of crustal material (Gao et al, 2005). The felsic volcanic rocks in the area are characterized by high initial values of Nd of Early Cretaceous from the crust (Guo, Fan, Li, Gao, & Miao, 2009…”

A ~2.5 Ga magmatic arc in NE China: New geochronological and geochemical evidence from the Xinghuadukou Complex

“…The middle part of the Songliao‐Xilinhot Block is covered by the Mesozoic Songliao Basin. These micro‐blocks are characterized by similar rocks assemblage, and they are (a) mid‐ to high‐grade facies Precambrian metamorphic rock units, metamorphosed by some Pan‐African period event (Zhou, Wilde, Zhang, Ren, & Zheng, ); (b) Palaeozoic to Mesozoic volcano‐sedimentary sequence (Han et al, ; Han, Liu, et al, ); and (c) Palaeozoic to Mesozoic volcanics and granitoids, which manifest the continental growth (Guo, Fan, Li, Gao, & Miao, ; Jahn, Wu, & Hong, ; Wu et al, ; Yang et al, ).…”