Kerley Wanderson Andrade

A intrusão diamantífera Abel Régis (Carmo do Paranaíba, MG): kimberlito ou lamproíto?

Hundreds of kimberlite or related intrusions are known in the Alto Paranaiba Diamondiferous Province, in the states of Minas Gerais and Goias. The Abel Regis intrusion, located in Carmo do Paranaiba county is one of these bodies that was discovered in the 1970´s by De Beers, and has generally been recognized as kimberlite. Neoproterozoic metasedimentary rocks of the Bambui Group are found in the intrusion area. These rocks are cut by the Cretaceous(?) body outcropping as a nearly circular section with 1,400 m in diameter. Distinct petrographic facies, including crater facies, can be recognized in the body. As the previous data was not informative about the mineralogical features of the intrusion, studies were also performed with electron microprobe, which indicated significant changes in relation to the allowed concepts. The most important were: the local predominance of Cr-spinel in relation to ilmenite, Mg-poor ilmenites, and an abundant presence of the K-feldspar sanidine. These characteristics, added to the cup-shaped body, point out that the Abel Regis intrusion could probably present a lamproitic affinity.