TY - JOUR
T1 - Alteration and lithogeochemistry in the Masara gold District, Eastern Mindanao, Philippines, as tools for exploration targeting
AU - Villaplaza, Barbie Ross B.
AU - Buena, Alfred Elmer
AU - Pacle, Nichole Anthony D.
AU - Payot, Betchaida D.
AU - Gabo-Ratio, Jillian Aira S.
AU - Ramos, Noelynna T.
AU - Dimalanta, Carla B.
AU - Faustino-Eslava, Decibel V.
AU - Queaño, Karlo L.
AU - Yumul, Graciano P.
AU - Yonezu, Kotaro
N1 - Funding Information:
The authors would like to thank the USAID – Science, Technology, Research and Innovation for Development (STRIDE) [Grant Number: 0213997-G-2015-019-00 ] and the Apex Mining Company, Inc. for the financial and logistical support of this study. The members of the University of the Philippines – National Institute of Geological Sciences (UP-NIGS) Rushurgent Working Group laboratory are also acknowledged for constructive discussions. Thanks are also due to the students of the 2015 Geology 215 Class of UP-NIGS for their contributions in updating the geologic map of the area. The authors are also grateful for the review and helpful comments of Dr. David Müller.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/12
Y1 - 2017/12
N2 - The intermediate to low sulfidation epithermal gold deposit in Masara, Compostela Valley, Eastern Mindanao, Philippines, is associated with a diorite porphyry from the Late Miocene Lamingag Intrusive Complex. Detailed mineralogical investigation of the host rocks in the deposit reveals five major alteration zones and at least two mineralizing events. A potassic alteration zone characterized by stockwork magnetite veins, secondary biotite and magnetite and an early-stage chlorite-sericite alteration composed of quartz + chlorite + illite + sericite + pyrite ± biotite ± magnetite ± calcite assemblages are interpreted to be linked with an earlier porphyry copper system in the area. These were overprinted by late-stage chlorite-sericite alteration consisting of quartz + chlorite + illite + sericite + pyrite ± adularia ± magnetite ± epidote and sericite assemblages which generally contain quartz + illite + sericite + pyrite. These alteration overprints are inferred to be related to a younger low to intermediate-sulfidation epithermal gold mineralization which involved near-neutral fluids. Advanced argillic alteration comprising quartz + kaolinite + magnetite + dickite ± illite ± calcite was also observed in the area. Isocon analysis shows that alteration zones associated with epithermal mineralization are generally characterized by enrichment in SiO2 and K2O and depletion of CaO and Na2O as well as additions of Au, Cu, Zn and Pb. Pearce Element Ratio (PER) analysis indicates high degrees of sericitization in the altered diorite porphyry, tuff and quartz diorite units. At least three major alteration centers are defined based on the spatial distribution of the Alteration Index of surface samples calculated from the PER analysis. The results of this study support the use of whole-rock geochemistry as a complement to traditional techniques in exploration geochemistry.
AB - The intermediate to low sulfidation epithermal gold deposit in Masara, Compostela Valley, Eastern Mindanao, Philippines, is associated with a diorite porphyry from the Late Miocene Lamingag Intrusive Complex. Detailed mineralogical investigation of the host rocks in the deposit reveals five major alteration zones and at least two mineralizing events. A potassic alteration zone characterized by stockwork magnetite veins, secondary biotite and magnetite and an early-stage chlorite-sericite alteration composed of quartz + chlorite + illite + sericite + pyrite ± biotite ± magnetite ± calcite assemblages are interpreted to be linked with an earlier porphyry copper system in the area. These were overprinted by late-stage chlorite-sericite alteration consisting of quartz + chlorite + illite + sericite + pyrite ± adularia ± magnetite ± epidote and sericite assemblages which generally contain quartz + illite + sericite + pyrite. These alteration overprints are inferred to be related to a younger low to intermediate-sulfidation epithermal gold mineralization which involved near-neutral fluids. Advanced argillic alteration comprising quartz + kaolinite + magnetite + dickite ± illite ± calcite was also observed in the area. Isocon analysis shows that alteration zones associated with epithermal mineralization are generally characterized by enrichment in SiO2 and K2O and depletion of CaO and Na2O as well as additions of Au, Cu, Zn and Pb. Pearce Element Ratio (PER) analysis indicates high degrees of sericitization in the altered diorite porphyry, tuff and quartz diorite units. At least three major alteration centers are defined based on the spatial distribution of the Alteration Index of surface samples calculated from the PER analysis. The results of this study support the use of whole-rock geochemistry as a complement to traditional techniques in exploration geochemistry.
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U2 - 10.1016/j.oregeorev.2017.09.004
DO - 10.1016/j.oregeorev.2017.09.004
M3 - Article
AN - SCOPUS:85030540789
VL - 91
SP - 530
EP - 540
JO - Ore Geology Reviews
JF - Ore Geology Reviews
SN - 0169-1368
ER -