TITLE:
+-Evidence of Porphyry Deposits in the Ntem Complex: A Case Study from Structural and Hydrothermal Alteration Zones Mapping through Landsat-8 OLI, Aeromagnetic and Geological Data Integration in the Yaounde-Sangmelima Region (Southern Cameroon)
AUTHORS:
Stephane Patrick Assembe, Theophile Ndougsa Mbarga, Françoise Enyegue A. Nyam, Paul Claude Ngoumou, Arsene Meying, Daniel Herve Gouet, Alain Zanga, Jean Daniel Ngoh
KEYWORDS:
Porphyry Centres, Hydrothermal Ore Deposits, Ntem Complex, Remote sensing, Aeromagnetics, Southern Cameroon
JOURNAL NAME:
Advances in Remote Sensing,
Vol.9 No.2,
June
8,
2020
ABSTRACT: A semi-regional study was
carried out in the Yaounde-Sangmelima area, a densely vegetated tropical region
of southern Cameroon located in the Central Africa Fold Belt (CAFB)/Congo
Craton (CC) transition zone. Towards structural lineaments and predictive
hydrothermal porphyry deposits mapping, an integrated analysis of Landsat-8 OLI
data, aeromagnetic, geological and mineral indices maps was performed. The
Remote sensing using False colour composite images involving bands combinations
and Crosta method (features oriented principal components analysis) enabled the
mapping of the gneisses and schists domains without a clear differentiation
between the Yaounde and Mbalmayo schists; despite the reflectance anomalies
evidenced NW of Akonolinga, hydrothermal alterations in the study area failed
to be detected. Besides, aeromagnetics depicted a moderately fractured northern
zone (the CAFB) contrasting with a high densely fractured zone (the CC, known
as Ntem complex). The Ntem complex displays signatures of a meta-igneous, an
intrusive complex, greenstone relics south of Sangmelima and hydrothermal
activity. Indeed, CET porphyry analysis tool detected many porphyry centres. In
general, the study revealed many lineaments including contacts, fractures
faults zones and strike-slips. The major aeromagnetics structures are SW-NE to
WSW-ENE and WNW-ESE to NW-SE while those from Landsat-8 are NE-SW, WNW-ESE,
NW-SE, WSW-ENE and NW-ESE to NNW-SSE. Together, these structures depict
trans-compressions or trans-tensions corresponding to a broad NE-SW
strike-slips channel that affect both the CAFB and the Ntem Complex, and they
control the intrusions thus confirming a pervasive hydrothermal activity within
the Ntem Complex. The proximity or coincidence of these porphyry centres with
some mapped Iron-Gold affiliated mineral indices and porphyry granites indicate
the possible occurrence of many hydrothermal ore deposits. These results show
the high probability for the Ntem complex to host porphyry deposits so they may
serve to boost mineral exploration in the Yaounde-Sangmelima region and in the
entire southern Cameroon as well.