Discovery of the Early Paleozoic post-collisional granites in northern margin of the Erguna massif and its geological significance

Abstract

The Luoguhe intrusion, located in Mohe County, Heilongjiang Province, is mainly composed of monzogranite, quartz diorite and granodiorite, with minor diorite, tonalite, quartz monzodiorite, quartz monzonite, syenogranite and alkali-feldspar granite. The intrusion can be divided into two lithological units, i.e. quartz diorite and monzogranite units, with affinities to high-K calc-alkaline series. The quartz diorite unit (SiO 2 : 54.79% -58.30%, Na 2 O/CaO: 0.79-1.53 and Shand index: 0.77-0.82) belongs to metaluminous rocks. And the monzogranite unit (SiO 2 : 65.29%-66.45%, Na 2 O/CaO: 1.73-3.43 and Shand index <1.05) can be considered as weakly peraluminous rocks. The intrusion is characterized by high REE abundance (∑REE = 180.2-344.3 μg/g), medium-strong negative Eu anomalies (δ Eu = 0.33-0.82), weak REE fractionation [(La/Yb) N = 4.12-10.45], enrichments in Rb, Th, U, K, La, Ce, Nd, Hf, Zr and Sm, but strong depletions of Ba, Nb, Ta, Sr, P and Ti. These characteristics of major, REE and trace elements indicate that the intrusion was formed in a transitional tectonic setting from compressional to extensional regime, which can be classified as post-collisional granitoids. SHRIMP U-Pb zircon analyses yield ages of 517±9 and 504±8 Ma for the quartz diorite and monzogranite units, respectively. The discovery of Early Paleozoic post-collisional granites in the northern margin of the Erguna massif indicates that the northern branch of Paleo-Asian Ocean between Siberian plate and Erguna massif was closed in the Early Paleozoic and the Salair orogeny ended ca. 500 Ma ago.

Zircon U–Pb ages of the metamorphic supracrustal rocks of the Xinghuadukou Group and granitic complexes in the Argun massif of the northern Great Hinggan Range, NE China, and their tectonic implications

“…1a) and is bounded by the Mesozoic Mongolia-Okhotsk suture to the northwest and the Paleozoic Tianshan-South Mongolia-Great Hinggan Range suture to the southeast. The Phanerozoic granitoids and Mesozoic intermediate-acidic volcanic rocks are widespread in the massif and are marked by discontinuously distributed Precambrian metamorphic terrains (Qin et al, 1999;Miao et al, 2004;Ge et al, 2005;Wu et al, 2005). It is believed that the Argun and the Central Mongolia massifs were connected during the Early Paleozoic and constituted the Central Mongolia-Argun united massif (Wang et al, 1991;Li, 1998;Ren et al, 1999;Sorokin et al, 2004a) (Fig.…”

“…The Mesozoic terrestrial volcano-sedimentary sequence, including the Early-Middle Jurassic conglomerates, sandstones and siltstones and the Late Jurassic-Early Cretaceous andesitic basalts, andesites, dacites and rhyolites, is distributed in the central part of the study area. Intrusive rocks, mainly Khanka-Salair, Hercynian and Indosinian-Yanshanian in age, are widely exposed in the western and eastern parts of this area (Qin et al, 1999;Miao et al, 2004;Ge et al, 2005;Wu et al, 2005).…”

“…Recent geochronological studies (Wilde et al, 2000(Wilde et al, , 2003Wu et al, 2001a;Miao et al, 2004Miao et al, , 2007Sorokin et al, 2004a,b;Ge et al, 2005Ge et al, , 2007 have shown that many Precambrian massifs in the Mongolia-Hinggan orogenic belt, such as the Jiamusi, Songnen and Argun massifs, were not as old as previously considered. It was argued that the Xinghuadukou Group was no older than the Late Mesoproterozoic (Wu et al, 2001b;Miao et al, 2004Miao et al, , 2007 and that these granitic complexes mainly emplaced between 460 Ma and 527 Ma (Wilde et al, 2000(Wilde et al, , 2003Sorokin et al, 2004a,b;Ge et al, 2005Ge et al, , 2007Wu et al, 2005). Therefore, the formation age and tectonic evolution of the basement of the Argun massif are still debated and need to be determined accurately.…”

Geochronology and geochemistry of Late Cretaceous–Paleocene granitoids in the Sikhote-Alin Orogenic Belt: Petrogenesis and implications for the oblique subduction of the paleo-Pacific plate

“…1a), including the Erguna, Xing'an, Songliao and Bureya-Jiamusi-Khanka massifs and the Sikhote-Alin Orogenic Belt (SAOB; Fig. 1a; Kotov et al, 2009;Li et al, 2010;Sorokin et al, 2010a;Sun et al, 2013;Wu et al, 2005;Yu et al, 2008;Zhou et al, 2011).…”

LA-ICP-MS U–Pb dating and Hf isotopic compositions of detrital zircons from the Permian sandstones in Da Xing’an Mountains, NE China: New evidence for the eastern extension of the Erenhot–Hegenshan suture zone

“…The Erguna block, located in the northwestern-most part of NE China (Fig. 1B), is characterized by Proterozoic to Paleozoic strata and granites, which are covered by Mesozoic sediments and volcanic rocks in the Mohe and Labudalin-Genhe basins (HBGMR, 1993;Wu et al, 2005;Ge et al, 2005). The Xing'an block consists of voluminous Mesozoic volcanic rocks and granitoids, and minor Paleozoic sedimentary strata and granitoids.…”