Age of the granitic magmatism and the W-Mo mineralization in skarns of the Serido belt (NE Brazil) based on zircon U-Pb (SHRIMP) and molybdenite Re-Os dating

作者：de Hollanda Maria Helena B M; Souza Neto Joao A; Archanjo Carlos J^*; Stein Holly; Maia Ana C S

来源：Journal of South American Earth Sciences, 2017, 79: 1-11.

DOI：10.1016/j.jsames.2017.07.011

• Re-Os molybdenite
• U-Pb SHRIMP
• W-Mo skarns
• Granitoids
• Serido belt
• Brazil

Over five hundred W-Mo skarns have been reported in the Neoproterozoic Serido belt in the north-eastern Brazil. The origin of these mineralizations has been attributed to metasomatic reactions occuring after the infiltration of hydrothermal fluids that are mostly derived from the plutonic magmatic activity that ranged between approximately 600 and 525 Ma. Here we date molybdenite using N-TIMS on Re-Os analysis of three major scheelite deposits (Brejui, Bonfim and Bodo) hosted in the skarn horizons of the metasedimentary sequence. Molybdenite is an integral part of the mineralizations that include scheelite in skarns and, in the Bonfim deposit, gold concentrate in late brittle faults. The Re-Os ages are 554 +/- 2 Ma (Brejui), 524 +/- 2 Ma (Bonfim) and 510 +/- 2 Ma (Bodo). The age of the Brejui molybdenite, however, appears to be anomalous based on the local geology of the deposit, which is located next to the contact of a batholith dated ca. 575 Ma. In turn, the Bonfim molybdenite yields similar ages in replicated samples with variable high Re contents. New U-Pb SHRIMP ages of four biotite (leuco)granite plutons vary from 577 +/- 5 Ma to 526 +/- 8 Ma, which overlap with molybdenite crystallization. These results indicate a close connection between the W-Mo mineralizations and the plutonic activity that intruded the belt after the peak HT/LP metamorphism. The latest pulses of felsic magmatism, which were contemporaneous with the emplacement of Be-Ta-Nb-Li pegmatites, therefore constitute a potential guide in the Serido belt for prospective W-Mo deposits.

• 出版日期2017-11