^(40)Ar/^(39)Ar Plateau Age Spectra of Feldspars and Their Geological Implications  

作　　者：戴潼谟 李正华 许景荣 蒲志平 邱华宁 胡振铎 

机构地区：[1]Guangzhou Branch, Institute of Geochemistry, Academia Sinica, Guangzhou, 510640 [2]Beijing Research Institute of Uranium Geology, Beijing, 100029

出　　处：《Chinese Journal Of Geochemistry》1992年第3期193-200,共8页中国地球化学学报

基　　金：his project was financially supported by the National Natural Science Foundation of China

摘　　要：The paragenic minerals plagioclase,perthite,biotite,hornblende and pyroxene in acid-granite alkali-granite,monzonite and volcanic rocks collected from seven areas different in thermal history have been determined.On the basis of 14 plateau age spectra and isochron ages of paragenic miner-als in conjunction with the observed mineral textures ,the suitability of plateau age spectra of plagioclase and perthite and their thermo-chronological significance are discussed in this paper.The results indicate that undisturbed feldspar gives satisfactory^40Ar-^39Ar plateau ages in consis-tence with those of paragenic minerals.This means that feldspars from the undisturbed area are suita-ble for ^40Ar-^39Ar dating .On the other hand,the age spectra of feldspars as well as of biotite,pyroxene and hornblende affected by tectonic or thermodynamic events appear unsmooth at varying temperatures,thus complicating their interpretation.Feldspars may give an emplacement age of a rock and /or that of the latest thermodynamic event,depending on the intensity of the event and the retentivity of Ar in the mineral.The paragenic minerals plagioclase, perthite, biotite, hornblende and pyroxene in acid-granite, alkali-granite, monzonite and volcanic rocks collected from seven areas different in thermal history have been determined. On the basis of 14 plateau age spectra and isochron ages of paragenic miner- als in conjunction with the observed mineral textures, the suitability of plateau age spectra of plagioclase and perthite and their thermo-chronological significance are discussed in this paper. The results indicate that undisturbed feldspar gives satisfactory^(4o) Ar-^(39)Ar plateau ages in consis- tence with those of paragenic minerals. This means that feldspars from the undisturbed area are suita- ble for^(40) Ar-^(39)Ar dating. On the other hand, the age spectra of feldspars as well as of biotite, pyroxene and hornblende affected by tectonic or thermodynamic events appear unsmooth at varying temperatures, thus complicating their interpretation. Feldspars may give an emplacement age of a rock and /or that of the latest thermodynamic event, depending on the intensity of the event and the retentivity of Ar in the mineral.

关 键 词：氩同位素 长石 光谱 斜长石 黑云母 酸性花岗岩 火山岩 

分 类 号：P588.14[天文地球—岩石学]