CAJ | 학술논문

对陕西省周至地区北秦岭晚古生代—中生代柳叶河盆地上三叠统石英砂岩进行单颗粒锆石LA-ICP-MS U-Pb同位素分析。以岩浆锆石为主的77个测试点给出的年龄值形成7个年龄组：256~475Ma、1500~1680Ma、1750~2190Ma、2190~2310Ma、2400~2650Ma、2700~2800Ma和2850~2960Ma。其中最年轻的锆石年龄为256±4Ma，最老的锆石年龄是2954±25Ma。峰值年龄以1750~2190Ma古元古代年龄组为代表（占总测点的64%）。将柳叶河盆地上三叠统与石炭系碎屑锆石年龄结构进行对比，前者新元古代年龄结构缺失，表明晚古生代介于柳叶河与鄂尔多斯盆地间的北秦岭北部具新元古代年龄结构的古陆，晚三叠世相对沉降，成为盆地次要物源区。结合与周缘地体年龄结构对比，北秦岭南部二郎坪群、秦岭群、丹凤群、南缘的沉积楔形体刘岭群及北秦岭与加里东期活动陆缘沟-弧-盆体系相关的岩浆作用产物此时则成为盆地主要物源区。北秦岭内部北降南升。柳叶河盆地上三叠统碎屑锆石与鄂尔多斯盆地西南缘上三叠统延长组砂岩碎屑锆石较好的可对比性，以及柳叶河盆地北侧源区（北秦岭北部）的构造变动、化石等证据表明，柳叶河盆地与鄂尔多斯盆地在晚三叠世很有可能连通，柳叶河盆地可能代表鄂尔多斯盆地的南部边缘。
대합서성주지지구북진령만고생대—중생대류협하분지상삼첩통석영사암진행단과립고석LA-ICP-MS U-Pb동위소분석。이암장고석위주적77개측시점급출적년령치형성7개년령조：256~475Ma、1500~1680Ma、1750~2190Ma、2190~2310Ma、2400~2650Ma、2700~2800Ma화2850~2960Ma。기중최년경적고석년령위256±4Ma，최로적고석년령시2954±25Ma。봉치년령이1750~2190Ma고원고대년령조위대표（점총측점적64%）。장류협하분지상삼첩통여석탄계쇄설고석년령결구진행대비，전자신원고대년령결구결실，표명만고생대개우류협하여악이다사분지간적북진령북부구신원고대년령결구적고륙，만삼첩세상대침강，성위분지차요물원구。결합여주연지체년령결구대비，북진령남부이랑평군、진령군、단봉군、남연적침적설형체류령군급북진령여가리동기활동륙연구-호-분체계상관적암장작용산물차시칙성위분지주요물원구。북진령내부북강남승。류협하분지상삼첩통쇄설고석여악이다사분지서남연상삼첩통연장조사암쇄설고석교호적가대비성，이급류협하분지북측원구（북진령북부）적구조변동、화석등증거표명，류협하분지여악이다사분지재만삼첩세흔유가능련통，류협하분지가능대표악이다사분지적남부변연。
In this paper, the authors collected quartz sandstone samples from late Triassic Liuyehe basin of North Qinling Mountains in Zhouzhi area, Shaanxi Province, and conducted LA-ICP-MS detrital zircon U-Pb isotope analysis. The results show that the 77 analytical points of the magmatic detrital zircons yielded seven age groups: 256~475Ma, 1500~1680Ma, 1750~2190Ma, 2190~2310Ma, 2400~2650Ma, 2700~2800Ma, and 2850~2960Ma. Among the ages, the youngest age is 256 ± 4Ma, whereas the oldest age is 2954±25Ma;the major Paleoproterozoic age group (1750~2190Ma) accounts for 64%of the total measured points. The zircon age comparison between the Carboniferous Liuyehe basin and the late Triassic Liuyehe basin shows that the Neoproterzoic age is lacking in the Late Triassic Liuyehe basin, which indicates that the uplifting northern part in EW-trending North Qinling Mountains located between Liuyehe basin and Ordos basin during the Carboniferous was removed in Late Triassic and became the secondary prove?nance of Liuyehe basin. A comparative study of the age structure of the peripheral terranes shows that the southern part of North Qin?ling Mountains, including the Erlangping, Qinling, Danfeng and Liuling groups as well as the magmatic material developed in the Caledonian trench-arc-basin system along the Shangdan suture zone, became the major provenance for the basin. Combined with the paleontologic evidence, the similarity in detrital zircon age distribution pattern between the Triassic Liuyehe basin and the Yan?chang formation in southwest Ordos basin strongly suggests that the Liuyehe basin was probably connected with the southern Ordos basin and represented the southern margin of the Ordos basin during the Late Triassic.