中文摘要：

贺兰山北段晚三叠世地层分布较广泛,其物源问题是进行鄂尔多斯盆地西北部原盆边界恢复和其两侧盆地该时期面貌恢复的关键,而对此存在一定的争议。该研究以贺兰山北段的沉积—构造背景为约束,通过晚三叠世地层的砾石成分、古流向、稀土元素、锆石测年及沉积趋势等物源分析方法综合运用,指出贺兰山北段晚三叠世不存在东部物源,银川古隆起不存在;物源来自西北部的阿拉善地块和兴蒙造山带太古代—古元古代的变质岩（片麻岩和变粒岩等）和岩浆岩,部分为阿拉善地块古生代和早中三叠世的沉积岩及岩浆岩。贺兰山西北部具有近物源和快速堆积的特点。同时,贺兰山北段晚三叠世物源具有多源性,其经历了多期的构造改造,恢复物源区演化模式对周邻造山带和块体的演化具有深远意义。

英文摘要：

Based on the sedimentary and tectonic background of the north of Helan Mountains,the paper discussed the features of the provenance through comprehensive analysis of the conglomerate component and gravel features,paleo-current direction,rare earth element,zircon dating and sedimentary trending.The conglomerate at the bottom of Upper Triassic mainly distributed in four different areas of Taerlin,Beisi,Shuimogou and Rujigou in Helan Mountain shows that the gravels were composed of quartzite,quartz sandstone,carbonate and granite. Paleocurrent data from various researchers reveal that the main current direction was northwest：wards which meant the river flowed from the northwest to the southeast in Triassic.And there was a successive paleo-current direction throughout the Triassic.The result is also closely consistent to the paleocurrent in Shigouyi and Ciyaobao area in the west margin of Ordos Basin and they all indicate that there was a common provenance from the northwest.The rare earth element in sandstone can also give certain clues of the provenance.Nineteen samples were chosen to detect the quantity of rare elements from the Upper Triassic,Pre-Cambrian and Cambrian to Middle Triassic.The paper also collects other rare element data of the gneiss and granulite of Helanshan Group in the northwest margin of Helan Mountain and of the granite formed during Hercynian to Indosinian period to the west of Helan Mountains.This pattern is almost the same as that in strata from Cambrian to Mid-Triassic and Pre-Cambrian as well as the granite formed between Hercynian and Indosinian period,which supports that the provenance is from the corresponding rocks formed earlier than Late Triassic.The age peaks of the U-Pb dating of zircon show the provenance of Late Triassic is related to the metamorphic rock in Archean and Paleo-proterozoic and also the magnetic rock during Hercynian and Indosinian period. Meanwhile,sedimentary environment analysis indicates that the gravels become smaller and sedimentary facies turns from alluvi