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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原日本和东亚的二叠纪构造演化：来自碎屑锆石年代学和晶体形态的见解


日本二叠纪砂岩碎屑锆石年龄和形态的组合分析为东亚碰撞引起的造山演化提供了证据，揭示了其古地理环境。这项研究比较了日本西南部内区二叠纪弧前增生杂岩（Akiyoshi 带）和弧后盆地沉积物（Maizuru 带）的已发表数据和新测量数据。弧前沉积物和弧后沉积物的下部主要由约 300–250 Ma 的锆石颗粒组成，这些锆石颗粒接近沉积年龄，通常呈角状至次角状。这些沉积物形成于与古老大陆地壳隔离的晚古生代火山弧周围，其烃源岩在侵蚀和搬运前立即暴露，并在相对较短的时间内直接搬运到沉积地点。相比之下，弧后沉积物的上部通常含有大约 2,700–1,800 和 500–250 Ma 锆石颗粒，这些锆石颗粒通常比其沉积年龄更古老，并且呈圆形。这些粮食来自古生代火山弧、前寒武纪陆块等多个来源，受到长途运输和运输过程中强烈的磨损作用。综合碎屑锆石资料强调，洋弧-弧后盆地-大陆边缘体系沿东亚东缘形成，二叠纪火山弧与中朝地块东缘碰撞。碎屑锆石年龄和弧后沉积物形状的变化为模拟东亚二叠纪碰撞提供了约束。 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，少量来自大陆地壳的碎屑被供应到弧前。