综合定年标准样品研制——以青藏高原伦坡拉盆地丁青湖组凝灰岩为例  

Development of reference material for multiple methods:A case study on tuff from Dingqinghu Formation in Lunpola Basin,Tibetan Plateau

作　　者：安洁 吴林[1,2,3] 任荣[4] 刘博 张志勇[1,2,3] 王楠 王非 郑波[7] AN Jie;WU Lin;REN Rong;LIU Bo;ZHANG ZhiYong;WANG Nan;WANG Fei;ZHENG Bo(State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,College of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]中国科学院地质与地球物理研究所,岩石圈演化与环境演变全国重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]中国石油勘探开发研究院,北京100083 [5]东北大学深部金属矿山安全开采教育部重点实验室,东北大学资源与土木工程学院,沈阳110819 [6]中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550081 [7]西南石油大学地球科学与技术学院,成都610500

出　　处：《岩石学报》2024年第8期2306-2320,共15页Acta Petrologica Sinica

基　　金：中国石油天然气股份有限公司勘探开发研究院开放课题(2022-KFKT-36);国家自然科学面上基金项目(42372252);青年基金项目(42102131、41503055)联合资助。

摘　　要：现今已有的(U-Th)/He、裂变径迹标准样品数量较少,仅有墨西哥的Durango磷灰石、美国的FCT锆石和缅甸的MK-1磷灰石,且多数是针对单定年方法的标样。为了研究青藏高原伦坡拉(LPL)盆地丁青湖组的凝灰岩能否成为多定年方法的标样,我们在凝灰岩中挑选合适的磷灰石和锆石颗粒进行多重年代学定年分析,获得了多个定年结果,并对其进行相互验证。其中,LPL磷灰石(U-Th)/He年龄为24.4±0.3Ma(1s),加权平均方差(MSWD)为4.25;LPL的锆石(U-Th)/He年龄为19.2±0.5Ma(1s),其MSWD为2.5;LPL磷灰石裂变径迹年龄为22.8±0.8Ma, LPL磷灰石U-Pb年龄为16.3±13.9Ma, MSWD为0.29。将LPL磷灰石与Durango磷灰石、MK-1磷灰石对比后认为LPL磷灰石有两种来源,所以不适合作为(U-Th)/He年龄标样。将LPL锆石与FCT锆石、蓬莱锆石做比较后,可以看出LPL锆石年龄结果较好,精确度和准确度较高且年龄分散性较弱,是一个潜在的(U-Th)/He年龄标样。At present,there are only a few reference standards used in(U-Th)/He and fission track geochronology such as Durango apatite in Mexico,FCT zircon in the United States and MK-1 apatite in Myanmar,and most of them are standards for single dating method.Three independent thermochronological methods are used to predict the same eruption age by apatite and zircon.Whether the tuff is suitable for single or combined fission track,(U-Th)/He and apatite U-Pb dating age reference standards is evaluated by observing age reproducibility and dispersion.In this paper,the tuff of Dingqinghu Formation in Lunpola Basin of Tibetan Plateau is selected as research samples,and the apatite and zircon are selected for cross-calibration between multi-geochronological methods.The Lunpola(LPL)apatite yields a weighted average(U-Th)/He age of 24.4±0.3Ma(1s)with MSWD of 4.25.While 21 LPL zircon single crystals get a weighted average age of 19.2±0.5Ma(1s)with MSWD of 2.5.The fission track age of LPL apatite is 22.8±0.8Ma,while the U-Pb age of LPL apatite is 16.3±13.9Ma with MSWD of 0.29.After comparing LPL apatite with Durango and MK-1 apatite,we infer that there are two populations of apatite crystals.Therefore,it is not suitable for LPL apatite to be used as a(U-Th)/He reference standard.After comparing LPL zircon with FCT and Penglai zircons,we conclude that LPL zircon has good age results with high accuracy and precision,and low age dispersion,and can be used as a potential(U-Th)/He reference standard.

关 键 词：标样 磷灰石 锆石 (U-Th)/He定年 裂变径迹定年 

分 类 号：P588.21[天文地球—岩石学] P597.3[天文地球—地质学]