An Anisian peripheral foreland basin in the northern Yangtze Block, implications for the collision between the South and North China Blocks

LA-ICP-MS zircon U-Pb isotopic data for the sandstone samples from the Middle to Upper Triassic successions in the northern Sichuan Basin and Zigui Basin. Four sandstone samples were collected from the lowermost Upper Triassic strata that unconformably overlie the Leikoupo Formation for detrital zircon analysis. The Upper Triassic Xujiahe Formation is generally considered to mark the transition from a marine platform to a terrestrial basin on the upper Yangtze Block (Meng et al., 2005). In the Guangyuan and Wangcang areas, we collected three sandstone samples from the lower portion of the Xujiahe Formation. At the Ma’antang train station, we collected one sandstone sample from the Ma’antang Formation, which is a transitional deposit from marine to terrestrial environments in front of Longmen Shan. The analysis was conducted with laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) at the Key Laboratory of Continental Collision and Plateau Uplift, Chinese Academy of Sciences (CAS). Analytical methods were described in detail by Cai et al. (2012) and are briefly described here. A total of 362 zircon grains from 4 samples produced data of sufficient precision for geochronological interpretation.四川盆地北部与秭归盆地中三叠统至上三叠统地层砂岩样品的激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）锆石U-Pb同位素数据。本次共采集4件采自不整合覆于雷口坡组之上的最底部上三叠统地层的砂岩样品，用于碎屑锆石分析。上三叠统须家河组通常被视作上扬子地块从海相台地向陆相盆地转型的标志性地层（Meng等，2005）。在广元与旺苍地区，我们采集了3件须家河组下部的砂岩样品。在马角坝火车站，我们采集了1件采自马角坝组的砂岩样品，该组为龙门山前海相-陆相过渡环境的沉积地层。本次分析在中国科学院（CAS）大陆碰撞与高原隆升重点实验室采用激光剥蚀电感耦合等离子体质谱仪完成。本次分析的详细方法已由Cai等（2012）发表，本文仅作简要概述。本次共从4件样品中获得362颗锆石的有效数据，其分析精度足以用于年代学解释。