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天华山火山盆地是北武夷地区最重要的火山盆地之一,发育有打鼓顶组和鹅湖岭组中酸性火山岩地层以及中酸性侵入岩,在盆地西北缘发育与火山-侵入岩密切相关的冷水坑超大型Ag-Pb-Zn矿.本文对天华山盆地中火山岩、侵入岩(或次火山岩)进行了详细的锆石U-Pb年代学研究.研究结果表明,打鼓顶组下段晶屑凝灰岩、上段安山岩锆石U-Pb年龄分别为(144±1)和(142±1)Ma;鹅湖岭组第一亚段沉凝灰岩、第三亚段流纹质熔结凝灰岩锆石U-Pb年龄分别为(140±1)和(137±1)Ma.三个侵入岩体(石英正长斑岩、碱长花岗斑岩、流纹斑岩)的年龄别为(144±1),(140±1)和(140±1)Ma,均为早白垩世.而对与冷水坑矿床密切相关的花岗斑岩测试了两个样品的U-Pb锆石年龄,结果分别为(158±1)和(157±1)Ma,暗示花岗斑岩为形成于晚侏罗世的侵入岩.本次测年结果为进一步讨论冷水坑矿田的成矿时代及矿床类型提供了新的证据.
The Tianhuashan volcanic basin is one of the most important volcanic basins in the northern Wuyi area. There are medium-acidic volcanic rocks and moderate-acid intrusives in the Taigu Formation and Ehulhuling Formation. In the northwest margin of the basin, cold water is closely related to volcanic-intrusive rocks Pits and super-large-scale Ag-Pb-Zn mines.The zircon zircon U-Pb chronology of middle-volcanic rocks and intrusive rocks (or sub-volcanic rocks) in the Tianhuashan Basin is studied in this paper.The results show that the lower part of the Dajintnding Formation is dominated by crystal tuff, The zircon U-Pb ages of the upper andesite are (144 ± 1) and (142 ± 1) Ma, respectively. The zircon U-Pb ages of the first subduction tuff in the Ehulling Formation and the rhyolitic tuff in the third sub-stage are (140 ± 1) and (137 ± 1) Ma.The ages of the three intrusive rocks (quartz ± phorphic porphyry, alkali-bearing granite porphyry and rhyolite porphyry) were (144 ± 1) and ± 1) and (140 ± 1) Ma, respectively, were of the Early Cretaceous.The U-Pb zircon ages of two samples were tested for the granite porphyry closely related to the Lengshuikou deposit and the results were (158 ± 1) ) And (157 ± 1) Ma, respectively, indicating that the granite porphyry is an intrusive rock formed in the Late Jurassic .This dating results is to further discuss the mineralization age and the types of ore deposits in Lengshukeng ore field New evidence.