In the middle to late Mesozoic period, the Korean Peninsula was in an active continental margin with an accretionary complex developed in the direction of trench to the southeast. The Cretaceous Gyeongsang Basin is the largest nonmarine basin distributed in the southeastern part of the Korean Peninsula and is generally considered to be a transtensional or an extensional basin formed by the oblique subduction of the Paleo-Pacific (Izanagi) Plate or Izanagi slab rollback. The pre-volcanic sedimentary succession of the Gyeongsang Basin is subdivided into the Sindong and Hayang groups as the age decreases and this sedimentary succession is unconformably overlain by the Yucheon Group, which consists of intermediate to felsic volcanic rocks with minor volcaniclastic sediments and forms a volcanic arc (the Gyeongsang Arc). Because the Gyeongsang Basin was geographically developed behind the Japanese Arc during the Cretaceous period, and the Gyeongsang Arc was considered an extension of the Japanese Arc, the Gyeongsang Basin was considered a backarc basin, although sedimentation in the basin occurred before the development of the Japanese Arc and Gyeongsang Arc. Here, we reinterpret the tectonic setting and basin formation mechanism in the pre-volcanic stage of the Gyeongsang Basin by synthesizing the results of provenance studies on the Sindong and Hayang groups. The sediments were derived from western and northwestern sources (the Yeongnam Massif), which currently do not contain records of Early Cretaceous arc magmatism. The modal and geochemical compositions of these sediments and detrital zircon U–Pb ages suggest that the sediments were derived from arc-related crystalline basement rocks of the Yeongnam Massif with a record of Early Cretaceous (143–100 Ma) arc magmatism. We propose that the pre-volcanic stage of the Gyeongsang Basin was a forearc basin formed between the Yeongnam Massif (then arc) and the Jurassic accretionary complex on the seaside and that the basin may have been formed by extensional stresses related to the subduction of an oceanic plateau during the Early Cretaceous.

中生代中晚期，朝鲜半岛处于活动大陆边缘，向东南向海沟方向发育增生杂岩。白垩纪庆尚盆地是分布在朝鲜半岛东南部的最大非海相盆地，一般认为是古太平洋（伊邪那岐）板块或伊邪那岐板块回滚倾斜俯冲形成的跨张或伸展盆地。庆尚盆地的前火山沉积层序随着年龄的减少被细分为新东组和河阳组，这个沉积层序不整合地覆盖在由中长英质火山岩和少量火山碎屑沉积物组成的柳川组上。弧（庆尚弧）。由于白垩纪庆尚盆地在地理上发育于日本岛弧之后，而庆尚岛弧被认为是日本岛弧的延伸，因此庆尚盆地被认为是弧后盆地，尽管盆地的沉积发生在日本岛弧发育之前弧和庆尚弧。在这里，我们通过综合对新东群和河阳群的物源研究结果，重新解释庆尚盆地前火山阶段的构造背景和盆地形成机制。沉积物来自西部和西北部的来源（岭南地块），目前不包含早白垩世弧形岩浆作用的记录。这些沉积物的模态和地球化学组成以及碎屑锆石 U-Pb 年龄表明，这些沉积物来源于岭南地块的弧相关结晶基岩，具有早白垩世（143-100 Ma）弧岩浆作用的记录。我们认为庆尚盆地的前火山阶段是在岭南地块（当时的弧）和海边的侏罗纪增生杂岩之间形成的弧前盆地，该盆地可能是由与俯冲相关的伸展应力形成的早白垩世的海洋高原。