Triassic igneous activities in the east flank of the East Kunlun orogenic belt: the Daheba complex example

Petrogenesis and Tectonic Implications of the Triassic Granitoids in the Ela Mountain Area of the East Kunlun Orogenic Belt

“…In the primitive mantle-normalized trace element diagram (Figure 7f), the samples were relatively enriched in some LILEs (e.g., Rb, Th, U, K, and Pb), and depleted in some HFSEs (e.g., Nb, Ta, P, and Ti). (e,f) DHB porphyritic diorite, the grey line for regional MMEs were from [2,5], and they indicate previous MMEs of the same period of the DHB porphyritic diorites (241-235 Ma) in the east section of the East Kunlun Orogenic Belt. The chondrite values were from [26].…”

“…Abbreviations: syn-COLG = syn-collision granites; VAG = volcanic arc granites; WPG = within plate granites; ORG = ocean ridge granites. Data sources: The data for Regional igneous rocks (P1: 254-246 Ma) were from [1,4]; the data for Regional igneous rocks (P2: 244-232 Ma) were from [1][2][3][4][5]69]; the data for Regional igneous rocks (P3: 230-218Ma) were from [2,9,70].…”

“…Among them, the granodiorite often contains MMEs, and the volcanic rocks are mostly rhyolite, dacite, andesite, and pyroclastic rocks of the same period. The zircon Hf isotope results showed that the magma was mainly derived from the partial melting of the lower crust of the Mesoproterozoic, and some of them mixed with a small amount of mantle material [2,3,5,6]. In terms of sedimentary assemblages, the Middle Triassic Xilikete Formation has the characteristics of marine-continental sedimentary assemblages [73] and an angular unconformity contact with the Late Triassic continental volcanic rocks (Elashan Formation and Babaoshan Formation, Figure 13), indicating that the East Kunlun Orogenic Belt was in a rapid uplift stage during the Middle Triassic, representing the collision between the BayanHar Block and the Eastern Kunlun Block and the disappearance of the Paleo-Tethys Ocean, resulting in local deposition.…”

“…The East Kunlun Orogenic Belt is a typical multi-cycle complex orogenic belt that retains information related to the evolution of the Proto-Teyhys Ocean and the Paleo-Tethys Ocean, and records the information and dynamic process of the formation and evolution of the northern Qinghai-Tibet Plateau. Among them, with the exposure of voluminous magmatic rocks related to the northward subduction of the Paleo-Tethys Ocean in the Late Paleozoic-Early Mesozoic as the main feature, many scholars have carried out relevant research on this area [1][2][3][4][5][6]. However, there has been controversy over the origin, petrogenesis, tectonic background, and deep process of the huge granitic magma in the late Permian-Triassic period in the East Kunlun Orogenic Belt at present.…”

“…In particular, different scholars have different views on the final closure time of the Paleo-Tethys Ocean. For example, (1) some researchers believe that the Paleo-Tethys Ocean in the East Kunlun Orogenic Belt was closed in the late Permian, and the Triassic granites are the products of the post-collision environment [4,7,8]; (2) some have proposed that the Permian-Early Triassic granites were mostly subduction magmatic rocks, and the collision orogenic movement began in the Middle Triassic [1,9]; (3) others have pointed out that the subduction of the Paleo-Tethys Ocean in the East Kunlun Orogenic Belt lasted until the Late Triassic, and the Early-Middle Triassic granite was the product of continental margin arc magmatism under subduction environment [5,6,10]; and (4) some believe that the oceanic basin was not closed in the Late Triassic, and that the Paleo-Tethys oceanic crust continued to subduct, with the Triassic magmatism related to the subduction of the oceanic crust [11,12].…”