Dataciones Rb/Sr en el complejo plutónico Táliga Barcarrota (CPTB) (Badajoz)

Abstract

The Plutonic Complex of Táliga-Barcarrota crops out in the core of the Olivenza-Monesterio anticline, where it intrudes the Upper Precambrian and Lower Cambrian metasediments. As this Complex is made of a) the Circular Pluton of Barcarrota, where the core is constituted by gabbros, diorites and pegmatoides and the outer rim shows quartz monzonites, quartz syenites and hypersolvus granites, and b) the NW-SE elongated Táliga Massif, almost entirely made of biotite orthogneisses, the sampling and the analyses were done in accordance with this double character of the Complex. Taking into account the K/Ar ages obtained on amphiboles, biotites and muscovites and the two Rb/Sr "isochrones" (whole rocks), it is concluded that 1) the Táliga Massif has an intrusion age of 525±2.5 M.A and a subsecuent pervasive recrystallization during the first hercynian phase, 385 ± 11 M.A, and 2) the Barcorrota Complex has an intrusion age of 505±5 M.A, as it is shown by the K/Ar and the Rb/Sr systematics. Also the Barcarrota Plutonic rocks have lower initial Sr87/Sr86 (O,7031±5X1O-6 than the Táliga orthogneisses (0.70836±9Xl0-5) pointing to a mantle versus. Crostal origin for both groups of magmas.