Landsat 8 and Alos DEM geological mapping reveals the architecture of the giant Mesoproterozoic Kunene Complex anorthosite suite(Angola/Namibia)  

作　　者：Jeremie Lehmann Alan M.Brower Trishya M.Owen-Smith Grant M.Bybee Ben Hayes 

机构地区：[1]Department of Geology,University of Johannesburg,South Africa [2]Jurumani Solutions,Midrand 1685,South Africa [3]School of Geosciences,University of the Witwatersrand,2050 Johannesburg,South Africa

出　　处：《Geoscience Frontiers》2023年第5期308-328,共21页地学前缘（英文版）

基　　金：supported by a National Research Foundation(NRF)Thuthuka Grant(TTK14052367805);the DSI-NRF Centre of Excellence for Integrated Mineral and Energy Resource Analysis(DSI-NRF CIMERA)。

摘　　要：The quasi-monomineralic composition and huge spatial extent of massif-type anorthosites make detecting lithological regions and boundaries challenging.We use processed Landsat 8 OLI multispectral images and ALOS digital elevation models integrated with field and petrographic observations to characterize the architecture of the≥17,000 km2 Mesoproterozoic Kunene Complex(KC)anorthosite suite in Angola and Namibia.Images of false colour composite bands 6,4 and 1 and band ratios 4/2(ferric minerals),6/5(ferrous minerals)and 6/7(OH-bearing minerals),as well as assessment of the PCA and MNF matrices of eigenvectors and eigenvalues from Landsat 8 data using available spectral libraries,have substantially improved the interpretation of the Kunene Complex rock types and structures.The dataset shows that the reflectance signature of KC anorthositic rocks is primarily a function of the degree of metasomatism,which is most significant in olivine-poor rock types.The weathering intensity of the olivine-bearing anorthosite substrate is another control on the remote sensing signal.Our remote sensing and field-based approach has enabled us to divide the KC anorthosite suite into six distinct spectral and architecture domains and at least four distinct magmatic plutons when considering available high-precision geochronological data.The northernmost pluton(ca.1380 Ma)of massive,olivine-bearing anorthosite shows distinct remote sensing signatures in the band ratio and MNF images marked by the dominance of OH-bearing and subordinate ferric minerals.The central pluton(1412–1400 Ma)is composed of NNE-to N-striking steeply dipping interlayered olivine-bearing and olivinepoor anorthosite,which correspond to ridges of dark-coloured,low albedo rocks with subordinate slightly oxidised ferrous mineral spectral signatures,and valleys of low albedo and OH-bearing mineral spectral signatures.A NNE-striking tectonic zone along a linear belt of KC granite gneiss separates the northern and central plutons.To the south is a NNW-to NNE-striking l

关 键 词：Remote sensing Structural geology LANDSAT 8 Alos DEM LINEAMENTS Proterozoic massif-type anorthosite 

分 类 号：P612[天文地球—矿床学]