山东邓格庄金矿与昆嵛山花岗岩的定位时代及其地质意义

EMPLACEMENT AGES OF THE DENGGEZHUANG GOLD DEPOSIT AND THE KUNYUSHAN GRANITE AND THEIR GEOLOGICAL IMPLICATIONS

昆嵛山花岗岩为中生代复式岩体,并非前寒武纪侵入体。邓格庄金矿的容矿岩体(瓦善片麻状二长花岗岩)是昆嵛山复式岩体的中期侵入体。它的黑云母^(40)Ar-^(39)Ar坪年龄为129.01Ma。^(40)Ar-^(39)Ar等时线年龄130.68Ma。邓格庄金矿的定位年龄为118Ma。含金热液不是容矿岩体直接分异出的岩浆期后热液。

On the basis of isotope chronological studies, the emplacement age of the Denggezhuang gold deposit has been determined to be 118 Ma, the biotite 40Ar-39Ar plateau age of the Washan gneis-sic monzonitic granite 129. 01 Ma and the 40Ar-39Ar isochron age 130. 68 Ma. The Kunyushan granite is a Mesozoic composite intrusion rather than a Precambrian one. Three intrusion stages are recognized; the early stage: Bamenzoujia-Duoguding granodiorite; the middle stages: Washan gneissic monzonitic granite; the late stage; Wuzhaoshan gneissic garnet-bearing monzonitic granite. The emplacement depth of the Kunyushan granite is more than 10 or 15 km. Its cooling from 350℃ to 300℃ took about 12 Ma, with an average cooling speed of 4. 2℃/Ma. The uplift speed was about 1 mm/a. The emplacement depth of the gold deposit is less than 1 km. The time interval between the host rock cooling to 350℃ and the formation of the gold deposit is about 12 Ma and their emplacement depth difference is more than 12 km. So the Denggezhuang gold deposit is not a postmagmatic type.