Paleoproterozoic–Paleozoic tectonic evolution of the Longshou Shan, western North China craton

Abstract

The Longshou Shan of western China is the northern backstop of the Cenozoic Himalayan-Tibetan orogen and occupies a key linkage between the Tarim continent and North China craton which separate the pre-Cenozoic Tethyan orogenic system and Central Asian orogenic system. Therefore, the Paleoproterozoic–Paleozoic evolution of this region is critical to understanding the extent of overprinting Cenozoic deformation, construction of the Eurasian continent, and relationships between the pre-Cenozoic Tethyan orogenic system and Central Asian orogenic system. Here we present detailed field observations and results of geochronological and major and trace element and Sr-Nd isotope geochemical analyses of samples from the Longshou Shan to decipher its complex Paleoproterozoic–Paleozoic tectonic history. Our results show that the Paleoproterozoic basement rocks of the Longshou Shan were part of the North China craton and involved in Paleoproterozoic northern North China orogeny. A ca. 965 Ma granitoid in the Longshou Shan provides key evidence for a spatial linkage between northern Tibetan continents, the North Tarim continent, and the North China craton in the early Neoproterozoic. The presence of Early Ordovician granitoids and arc volcanic rocks in the Longshou Shan suggest that bivergent subduction of Qilian oceanic lithosphere occurred during the early Paleozoic. Crustal shortening and thickening during Ordovician–Carboniferous orogenesis are evidenced by the presence of several unconformities in the Longshou Shan. Late Carboniferous arc granites exposed in the study area are likely associated with the southward subduction of the Paleo-Asian Ocean to the north and with Permian siliciclastic strata sourced from a proximal arc-subduction system, based on detrital zircon ages. Although the tectonic history of the Long- shou Shan can be traced back to Neoproterozoic time, most of the recorded deformation and uplift of the region occurred during the early Paleozoic Qilian orogeny and late Paleozoic Central Asian orogeny. Furthermore, we interpret that the several orogenic events recorded in the Longshou Shan (i.e., northern North China, Qilian, and Central Asian orogenies) are spatially and temporally correlative along strike with those recorded in the Tarim and North China cratons.

Paleoproterozoic Plate Tectonics Recorded in the Northern Margin Orogen, North China Craton

“…Here we have provided more support for the assertion that the Paleoproterozoic Northern Margin orogen stretched north-south over a distance of ∼200 km across the North China. In addition, we suggest that the western extent of Paleoproterozoic Northern Margin orogen may at least continue to the Longshou Shan of the western Alax block in the North China craton (Wu et al, 2021;Wu, Li et al, 2022), defining a west-east width of ∼1,600 km. These refined dimensions should be considered in attempts to restore the configuration of Archean-Paleoproterozoic cratons within supercontinents.…”

“…The craton consists of Archean-Paleoproterozoic metamorphic basement rocks and unmetamorphosed to weakly metamorphosed Meso-and Neoproterozoic cover successions (e.g., T. M. Kusky et al, 2016;Zhai & Santosh, 2011;Zhao et al, 2005;Zhao & Zhai, 2013). The North China craton is traditionally divided into the Archean Eastern and Western blocks that are separated by the ∼1,600-km-long, northeast-trending Neoarchean Central Orogenic Belt (e.g., T. M. Kusky & Li, 2003; T. M. Kusky et al, 2007; J. P. Wang et al, , 2019Wu et al, 2018;Wu, Li et al, 2022;Wu, Wang et al, 2022) (Figure 1a). The Central Orogenic Belt is also referred to as the Paleoproterozoic Trans-North China Orogen in the tectonic model of Zhao et al (2001Zhao et al ( , 2005, Trap et al (2012), and subsequent papers.…”

The Long-Term Tectonism of the Longshou Shan in the Southwest Alxa Block—Constrained by (U-Th)/He Thermochronometric Data

“…The Longshou Shan area functions as an exceptionally important geological laboratory due to its intricate structural faults, the strata of varying ages encompassing the Precambrian advanced metamorphic rock series and the Phanerozoic, as well as the presence of multiple unconformities [14]. These indicators suggest that the crystalline basement surface of the Longshou Shan forms a complex erosion surface, likely recording the uplift of basement rocks due to multi-stage tectonic movements during East Asia's Phanerozoic era [15].…”

Passive margins in accreting Archaean archipelagos signal continental stability promoting early atmospheric oxygen rise

“…The North China Craton (NCC) is divided into an old Eastern Block with magmatic ages of 2.9-2.55 Ga and isolated fragments up to 3.8 Ga 7 , the Neoarchaean Central Orogenic Belt (COB), the Archaean Western Block, and the Inner Mongolia-Northern Hebei Orogen that progressively accreted to the Eastern Block in the Paleoproterozoic (Fig. 1a) [8][9][10] . These accretionary events culminated in NCC's collision with the Columbia Supercontinent at 1.85 Ga, causing widespread high grade metamorphism and Tibetan-style crustal thickening [8][9][10][11] .…”

“…1a) [8][9][10] . These accretionary events culminated in NCC's collision with the Columbia Supercontinent at 1.85 Ga, causing widespread high grade metamorphism and Tibetan-style crustal thickening [8][9][10][11] .…”