Geochemistry, zircon U–PB ages and HF isotopes of the Muong Luan granitoid pluton, Northwest Vietnam and its petrogenetic significance

Abstract

The Indosinian Orogeny plays a significant role in tectonic background and magmatic evolution in Indochina and surrounding regions. Being a part product of the Indosinian magmatism in northwest Vietnam during late Permian-middle Triassic period, Muong Luan granitoid pluton dominantly consists of granodiorite, less diorite and granite. This pluton is located in the Song Ma suture and assigned to the Dien Bien complex. Geochemically, the Muong Luan granitoid rocks are characterized by a wide range of SiO 2 contents (59.9-75.1 wt%) and high K 2 O contents. They display typical features of I-type granites. The presence of hornblende and no muscovite and cordierite in the rocks further supports for I-type character of granitoids. The emplacement age of the Muong Luan pluton obtained by LA-ICP-MS U-Pb zircon is at 242-235 Ma, corresponding to Indosinian time. Zircon ε Hf values of-5.6 to-10.4, in combination with moderate Mg values of 34-45 suggested that the Muong Luan granitoid was derived from partial melting of mafic crustal source rocks, which are probably Paleoproterozoic in age as revealed by Hf model ages (T DM2 = 1624-1923 Ma).

Petrology of the Permian-Triassic granitoids in Northwest Vietnam and their relation to the amalgamation of the Indochina and Sino-Vietnam composite terranes

“…The reported data include: (1) Nam Meng diorite and gabbro diorite have the U-Pb age of 276 Ma (Liu et al, 2012), or 289-296 Ma (Hieu et al, 2017); (2) Nam Rom granodiorite and Bt-Amf granite have younger U-Pb age of 244-233 Ma (Hieu et al, 2019), or 229-217 Ma (Liu et al, 2012); (3) Kim Boi Bt granite has U-Pb age of 242 Ma (Tran et al, 2016);…”

“…The Early Paleozoic to Late Paleozoic -Early Mesozoic (Permian-Triassic) granitoids are distributed along the TSFB (primarily concentrated in the northwest segment) with distinct geochemical characteristics (Liu et al, 2012;Roger et al, 2014;Manaka et al, 2014;Shi et al, 2015;Wang et al, 2016). Based on the recent zircon U-Pb dating, the TSFB granitoids were formed in a period of 70 My, from 290 to 220 Ma (Liu et al, 2012;Roger et al, 2014;Zaw et al, 2014;Shi et al, 2015;Hieu et al, 2015Hieu et al, , 2017Hieu et al, , 2019Wang et al, 2016). Moreover, different granite types indicated a complicated crustal evolution of the study area.…”

Evolution of supracrustal rocks of the Indochina Block: Evidence from new detrital zircon U–Pb ages of the Kontum Massif, Central Vietnam

“…These main episodes can be recognized independently from the three metamorphic Complexes (Nakano et al, 2013;Bui et al, 2020). Among them, Permian to Triassic episode is the most significant event and is generally accepted as a result of the continental collision between the Indochina Block and the South China Block (e.g., Osanai et al, 2004Osanai et al, , 2008Nakano et al, 2009Nakano et al, , 2013Thanh et al, 2019;Hieu et al, 2020a). Nakano et al (2004) and Osanai et al (2004Osanai et al ( , 2008 revealed the high-to ultrahigh-pressure metamorphism before the retrograde ultrahigh-temperature granulite facies metamorphism, which displays clockwise P-T path.…”

“…Wang et al (2018) indicated that the Permian-Triassic igneous activity along the Indochina-South China collision belt can be classified as arc-related magmatism at~247 Ma, syn-collisional magmatism at 247-237 Ma, and subsequent post-collisional magmatism at 237-200 Ma. Besides, Hieu et al (2020a) summarized the collision-related magmatism as the subduction-related stage (290-260 Ma), syn-collisional stage (250-240 Ma), and post-collisional stage (240-210 Ma). Based on these subdivisional tectonic interpretations, most of the Permian magmatic products were formed as a result of the subduction-related tectonism.…”

“…Regarding this, unraveling the Precambrian evolutionary histories of the Indochina Block as a part of the Precambrian continental blocks of Asia is important to reconstruct the break-up and amalgamation process of the supercontinent. In addition, the Indochina Block collided with the South China Block on its north along the Song Ma suture (e.g., Cai and Zhang, 2009;Nakano et al, 2010Nakano et al, , 2013Yonemura et al, 2013;Faure et al, 2014;Hieu et al, , 2017Thanh et al, 2019;Hieu et al, 2020a) (Fig. 1a).…”