【摘要】 在前人地质研究基础上,采用颗粒锆石U-Pb法、Pb-Pb蒸发法,并引用了已发表的角闪石Ar-Ar法资料对中国西南哀牢山双沟蛇绿岩进行了同位素地质年代学研究。龙塘辉长岩锆石U-Pb下交点年龄（362±41）Ma,角闪石⁴⁰Ar/³⁹Ar坪年龄（349±13）Ma;双沟斜长花岗岩U-Pb年龄（328±16）Ma。这些研究表明哀牢山古洋盆形成于泥盆纪与石炭纪之交;哀牢山、金沙江、可可西里以及松大（Song da）洋可能同时形成,构成扬子板块大陆古特提斯边缘海。更多还原

【Abstract】 Zircon ages have been determined from ophiolitic rocks of gabbro and plagiogranite at Sh’uangguo, Ailao mountains, southwestern China. 6 analyses of zircons from the Longtang gabbro define a lower intercept age of (362±41) Ma, and an upper intercept age of (2 119±70) Ma. 40Ar/39Ar determination of hornblende from the Longtang gabbro gives a plateau age of (349±13) Ma, that is only slightly lower than (362 ±41) Ma, representing the rifting age of the Ailaoshan Palaeotethyan ocean. Zircons from the Shuangguo plagiogranite are of two types, most of them are colourless, transparent and euhedral crystals, 6 analyses of euhedral zircons give 206Pb/238U age of (328±16) Ma calculated by Tera-Wasserburg method, reflecting the age of palaeotethyan oceanic crust. Using 207Pb/206Pb evaperation method, a few zircons of yellow, an-hedral grains with older age of (911±31) Ma are recognized from the Shuangguo plagiogranite. The old zircons both from gabbro and plagiogranite indicate contamination of continental basement during the emplacement of these rocks.A process of late Devonian-early Carboniferous rifting and oceanic crust forming of the Ailaoshan paleotethys is suggested by this work. Furthermore, the Ailaoshan paleotethyan ocean may extend to Jinsajing and HoH XiL in the north, and correlate Song da to the south, constituting a marginal basin of the south China plate.更多还原