Combination analyses of detrital zircon ages and morphology from Permian sandstones in Japan provide evidence of orogenic evolution caused by collision in East Asia and reveal their paleogeographic setting. This study compares published and newly measured data from Permian fore-arc accretionary complexes (Akiyoshi Belt) and back-arc basin deposits (Maizuru Belt) in the Inner Zone of Southwest Japan. The fore-arc deposits and lower part of the back-arc deposits consist mainly of approximately 300–250 Ma zircon grains that are close to the depositional ages and are generally angular to subangular. These sediments formed around the Late Paleozoic volcanic arc isolated from the older continental crust, and their source rocks were exposed immediately prior to their erosion and transport and were transported directly to the depositional site in a relatively short time. In contrast, upper part of the back-arc deposits generally contains approximately 2,700–1,800 and 500–250 Ma zircon grains, which are commonly older than their depositional ages and are rounded. These grains were supplied from multiple sources, such as the Paleozoic volcanic arc and Precambrian continental block, and were affected by long-distance transport and a strong abrasion effect during transport. Comprehensive detrital zircon data emphasize that the oceanic arc–back-arc basin–continental margin system formed along the eastern margin of East Asia, and that the volcanic arc collided with the eastern margin of the Sino-Korean Block during the Permian. The variation in detrital zircon ages and shapes of back-arc deposits provides a constraint for modeling the East Asian Permian collision. Detritus derived from continental crust was captured by a back-arc basin and blocked by the uplift zone of the volcanic arc. However, a small amount of detritus originating from the continental crust was supplied to the fore-arc.

中文翻译：

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原始日本和东亚的二叠纪构造演化：来自碎屑锆石地质年代学和晶体形态学的见解


对日本二叠纪砂岩碎屑锆石年龄和形态的综合分析提供了东亚碰撞导致造山演化的证据，并揭示了它们的古地理环境。本研究比较了日本西南部内陆二叠纪弧前增生杂岩（秋吉带）和弧后盆地沉积物（舞鹤带）的已发表和新测量的数据。前弧矿床和后弧矿床的下部主要由大约 300-250 马 的锆石晶粒组成，这些晶石接近沉积年龄，通常呈角状至近角状。这些沉积物形成于晚古生代火山弧周围，与较老的大陆地壳隔离开来，它们的烃源岩在侵蚀和运输之前立即暴露出来，并在相对较短的时间内被直接运送到沉积地点。相比之下，后弧矿床的上部通常包含大约 2,700-1,800 和 500-250 马 的锆石晶粒，这些晶石通常比其沉积年龄更古老，并且是圆形的。这些颗粒来自多个来源，例如古生代火山弧和前寒武纪大陆块，并受到长途运输和运输过程中强烈磨损效应的影响。综合碎屑锆石资料强调，大洋弧-弧后-盆-大陆缘系沿东亚东缘形成，二叠纪时期火山弧与中韩块体东缘碰撞。碎屑锆石年龄和弧后矿床形状的变化为东亚二叠纪碰撞建模提供了约束。 来自大陆地壳的碎屑被弧后盆地捕获，并被火山弧的隆起带阻挡。然而，来自大陆地壳的少量碎屑被供应到前弧。