Ar-40/Ar-39 DATING OF ALUNITE FROM THE PUEBLO VIEJO GOLD-SILVER DISTRICT, DOMINICAN REPUBLIC

作者：Arribas Antonio; Arribas Isabel; Draper Grenville; Hall Chris; Kesler Stephen E^*; McEwan Craig; Muntean John L

来源：Economic Geology and the Bulletin of the Society of Economic Geologists, 2011, 106(6): 1059-1070.

New Ar-40/Ar-39 ages for alunite from the Moore and Monte Negro deposits in the Pueblo Viejo district, as well as from a newly discovered alunite-bearing zone on Loma la Cuaba west of the known deposits, are reported here. The ages range from about SO to 40 Ma, with closely adjacent samples exhibiting very different ages. Interpretation of these results in the context of estimated closure temperatures for alunite and the geologic and tectonic evolution of Hispaniola does not lead to a simple conclusion about the age of mineralization. The simplest interpretation, that mineralization was caused by a buried Late Cretaceous (similar to 80 Ma) intrusion, is complicated by lack of intrusions of this age in the area and absence of alteration in overlying limestone. The alternative interpretation, that mineralization was formed during Early Cretaceous (similar to 110 Ma) magmatism and that the Ar-40/Ar-39 ages were completely reset by Late Cretaceous thrusting, is complicated by a lack of information on the timing and thermal effects of thrusting in central Hispaniola. Alunite studies have yielded similar unclear results in other pre-Cenozoic ore systems, notably those of the Lachlan fold belt in Australia.

• 出版日期2011-10