Paleozoic multiple accretionary and collisional processes of the Beishan orogenic collage

Abstract

The Beishan orogenic collage is located in the southernmost part of the Altaids, and connects the Southern Tien Shan suture to the west with the Solonker suture to the east. The orogen was previously regarded as early Paleozoic in age in contrast to the surrounding southern Altaid collages, which are Late Paleozoic or even Early Mesozoic. This paper reviews the tectonic units of the Beishan orogen, which along a north-south traverse consists of several arcs and ophiolitic me ´langes. These tectonic units were thrust imbricated and overprinted by strike-slip faulting during Permian-Triassic times, and the youngest strata involved in the deformation are Permian. Stitching plutons are Late Permian in age. Peaks of magmatic-metamorphictectonic activity, and paleomagnetic and paleogeographic data indicate that the Beishan orogenic collage evolved by development of several, Early to Mid-Paleozoic arcs in different parts of the Paleoasian Ocean. The Late Paleozoic collage is characterized by three active continental margins or island arcs that are separated by two ophiolitic me ´langes. The northernmost active margin is represented by the Queershan arc, which may have lasted until the Permian. The Shibanshan unit is the southernmost, subductionrelated continental arc along the northern margin of the Dunhuang block. In the Late Carboniferous to Permian the eastern end (promontory) of the Tarim Craton probably collided with the Chinese eastern Tien Shan arc, forming a new active continental margin, which interacted with the Beishan Late Paleozoic archipelago, generating a complicated subduction-accretionary orogen; this is suggested to be one of the last phases in the development of the long-lived Altaid accretionary orogenesis. The new model for this orogen bridges the gap between the western and eastern ends of the southern Altaids. The modern Timor-Australia collision zone with its many surrounding arcs is an appropriate analog for the Altaids in the Late Paleozoic.

Linking the Alxa Terrane to the eastern Gondwana during the Early Paleozoic: Constraints from detrital zircon U–Pb ages and Cambrian sedimentary records

“…The Alxa Terrane is located to the south of the Central Asian Orogenic Belt (Windley et al, 2007;Xiao et al, 2010;Safonova et al, 2011;Yarmolyuk et al, 2012;Feng et al, 2013;Kröner et al, 2014;Zheng et al, 2014). The Ordos Terrane (North China Terrane) lies to the east, separated from the Alxa Terrane by the Mesozoic Helan Shan thrust belt which was caused by the eastward compression of the Alxa Terrane (Liu, 1998;Darby and Ritts, 2002).…”

Polyphase deformation of a Paleozoic forearc–arc complex in the Beishan orogen, NW China

“…Ophiolitic mélanges separating these units are from N to S: the Hongshishan, Shibanjing-Xiaohuangshan, Xichangjing-Niujuanz, and Liuyuan. Detailed descriptions of the lithostratigraphy of each tectonic unit and ophiolitic mélange are in Xiao et al (2010).…”

“…1b), is a key area for understanding the tectonic evolution of the southern Altaids (Song et al, 2013a;Xiao et al, 2010). The Beishan orogenic collage is marked by the presence of distinct lithotectonic terranes, which were welded together during the Paleozoic (Fig.…”

“…TC, Tarim Craton; NCC, North China Craton; SCC, South China Craton; (b), simplified tectonic map of the southern and eastern Altaids with Fig. 2 outlined (Xiao et al, 2009a of the Beishan orogenic collage Li et al, 2012;Mao et al, 2012a;Qu et al, 2011;Song et al, 2013aSong et al, , 2013cXiao et al, 2010;Y. Zhang et al, 2011;Zhang et al, 2012a).…”

“…To date, the scarcity of systematic studies of the deformation history of the arcs and their accretionary complexes has hampered detailed understanding of the subduction-accretion-collision processes of the Beishan orogenic collage. For example, key topical questions are: was the Beishan orogenic collage formed by prolonged multiple accretionary-collisional processes in the Paleozoic, and terminated in the late Permian to middle Triassic Mao et al, 2012b;Xiao et al, 2010), or was it formed by collision of two microcontinents during the Silurian to Devonian, and underwent post-orogenic extension in the late Paleozoic? (Zuo et al, 1990(Zuo et al, , 2003.…”