Genesis and implications of the Late Jurassic Hailesitai granites in the northern Greater Khingan Range: evidence from zircon U–Pb dating and Hf isotope

Abstract

The tectonic setting and geodynamic model of the Greater Khingan Range (GKR) is highly controversial due to the lack of reliable geological, isotopic and geochronological evidence. In the current study, the Hailesitai pluton, located at the west of the suture between the northern and southern GKR in the east of the Central Asian Orogenic Belt, is selected to address this issue. These granites of the high potassium calc-alkaline series belong to the A1-type granites with typical geochemical characteristics including high contents of Al2O3, extremely low contents of Ti, P, enriched LREE, LILE, depleted HFSE, and a medium Eu negative anomaly. Laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) zircon U−Pb dating indicates that the granites can be divided into two stages: c. 152 and c. 161 Ma. The intrusion of A1-type granites at ~161 Ma implies that intra-plate orogenesis of the northern GKR started at c. 161 Ma at latest. The Hailesitai pluton has relatively homogeneous Hf isotope compositions with a εHf (t) value (+6.0 − +9.0), and two-stage depleted mantle model ages of 579−738 Ma show that the original magma is a mixture of juvenile and crustal source rocks. Extensional collapse of the Mongol−Okhotsk belt between the Siberia block and the northern GKR resulted in the formation of late Jurassic A1-type granites in the northern GKR. The Hailesitai pluton formed in response to post-orogenic extensional collapse of the Mongol–Okhotsk belt, coupled with back-arc extension related to Palaeo-Pacific plate subduction.

Petrogenesis and Tectonic Setting of Early Cretaceous Intrusive Rocks in the Northern Ulanhot Area, Central and Southern Great Xing’an Range, NE China

“…In terms of the regional structure, the Tayuan-Xiguitu fault zone, Heihe-Hegenshan fault zone, and Yilan-Yitong fault zone indicate the boundaries of these blocks from northwest to southeast [6,18,40,67,68], and the Solonker-Xar Moron suture zone marks the final collage demarcation line between the North China Craton and the blocks of NE China during the Late Permian-Middle Triassic period [17,35,69,70]. Since the Mesozoic era, NE China has experienced multi-stage structural superposition and tectonic reformation of the PPO and Mongol-Okhotsk Ocean tectonic domains, forming extensive Mesozoic volcanic and granitic rocks (Figure 1c) [16,17,26,43,53,71] and constraining the patterns of crustal growth and crust-mantle interaction in this region [7,24,25,32,63,72]. With the development of research, the subduction of the Mongol-Okhotsk Ocean plate dated from the early Mesozoic [45,73,74], and this paleo-ocean closed in a scissor-like mode from west to east and eventually disappeared in the Amur region in the Late Jurassic [55,74].…”

Singularity Analysis of Volcanic Ages and Implications for Tectonic Setting in the Mesozoic, Great Xing’an Range, Northeast China

“…The second model that has been proposed involves the subduction of the Paleo-Pacific Plate beneath Eastern China [7,11,29]. There are several of lines of evidence that support this interpretation.…”

“…Both granitoids and volcanic rocks show a peak at about 125 Ma [9,11]. Furthermore, A1-type granitoids developed widely, and the high zircon saturation temperatures in intrusive rocks indicate that there was an extension in tectonic setting and the upwelling of asthenosphere in the Mesozoic in the GXR [7,37,38]. Therefore, the age peak at 125 Ma in the GXR may be linked to slab breakoff from the subducted Paleo-Pacific Plate.…”

“…The Great Xing'an Range (GXR, Figure 1), east of the Central Asian Orogenic Belt (CAOB or Altaid), is dominated by Mesozoic volcanic rocks and other associated igneous rocks [1][2][3][4]. There has been much debate concerning the tectonic setting in which these rocks formed, and two main proposals have been put forward: (1) subduction of the Mongol-Okhotsk Ocean from the north [5,6], and (2) subduction of the Pacific Plate from the east [4,7]. Previous studies suggested that the exact eruption ages and spatial distribution of the volcanic rocks and granites are the key factors for understanding the tectonic setting [4,[7][8][9][10][11].…”

“…There has been much debate concerning the tectonic setting in which these rocks formed, and two main proposals have been put forward: (1) subduction of the Mongol-Okhotsk Ocean from the north [5,6], and (2) subduction of the Pacific Plate from the east [4,7]. Previous studies suggested that the exact eruption ages and spatial distribution of the volcanic rocks and granites are the key factors for understanding the tectonic setting [4,[7][8][9][10][11]. This study attempts to address this issue from a new view point, using a singularity analysis method on the basis of a dataset (n = 823) of volcanic zircon U-Pb ages.…”