In situ magnetic susceptibility and gamma radiation data in the Candela-Monclova intrusive belt, Northeast Mexico: case studies of the Cerro Colorado and Cerro Marcelinos plutons

Authors : Jose Alberto Batısta Rodriguez, Edgar Rodriguez, Pedro Rodrıguez Riojas, Roberto Dıaz Martinez, Antonıo Rodrıguez Vega, Felıpe De Jesus Lopez Saucedo

Pages : 579-595

Doi:10.3906/yer-1905-21

View : 14 | Download : 10

Publication Date : 9999-12-31

Article Type : Makaleler

Abstract :The Cerro Marcelinos CM and Cerro Colorado CC plutons are part of the Candela-Monclova intrusive belt NE Mexico , which is mid-Eocene in age 43-35 Ma . It intrudes into the Sabinas Basin, primarily made up of limestones, of Lower and Upper Cretaceous age. Around several intrusions, including the CM and CC plutons, mineralizations are known. However, how much hidden mineralizations would occur is not known. Trends within the plutons and in contact aureoles are also poorly described at present. Therefore, we provide here in situ magnetic susceptibility MS and gamma ray spectrometry GS data along two composite transects, one in each pluton, to delineate such potential trends. The data show variations of 0.003 × 10-3 SI and 104 × 10-3 in MS and of 7.1 nGy/h and 196 nGy/h in GS with a clear relation to rock type and amount of metasomatism. The radioactive contents in the outcrops of contact metamorphic rocks indicate a contact metasomatism with differing degrees of alteration during emplacement of the plutons. The host limestones have magnetic minerals incorporated during the intrusion process. MS and GS indicate an increase in the degree of acidity towards the center of both plutons, possibly associated with the later stages of the magmatic differentiation process. The MS could divide the igneous rocks into two groups, weakly magnetic group 1 with MS ≤ 3 × 10-3 SI and strongly magnetic group 2 with MS > 3 × 10-3 SI , associated with the magnetite and ilmenite series, respectively. These classes provide useful information regarding the internal magnetic zoning in the plutons, which can be associated with mineralizations of mainly Au and Cu. Mainly, the magnetite series group 2 delimited more perspective zones for mineral exploration. This zoning in MS could guide future mineral exploration in both plutons.
Keywords : Candela-Monclova intrusive belt, Cerro Colorado pluton, Cerro Marcelinos pluton, magnetic susceptibility, gamma spectrometry