1 3 Int J Earth Sci (Geol Rundsch) (2017) 106:311–339 DOI 10.1007/s00531-016-1320-5 ORIGINAL PAPER Reconstructing the pre-Quaternary landscape in Agnew– Lawlers area, Western Australia with emphasis on the Permo-Carboniferous glaciation and post-glacial weathering Walid Salama 1,2,3 · Ravi R. Anand 1,2 Received: 3 November 2015 / Accepted: 9 March 2016 / Published online: 13 April 2016 © Her Majesty the Queen in Right of Australia 2016 to an intensive, post-Permian chemical weathering. The exposed basement rocks were deeply weathered into residual saprolite, whereas the Permo-Carboniferous sed- iments were differentiated into three chemostratigraphic units. The diamictite and rhythmite of the lower unit are unweathered and preserves the signature of the glacial/ interglacial weathering. Mineralogical and geochemi- cal changes dominated in this unit are related mainly to diagenesis at shallow depth (eogenesis) with no sig- nificant compaction. The formation of a paragenetic diagenetic sequence of chlorite, ferroan dolomite and pyrite indicates diagenesis has occurred under reducing and alkaline conditions below the permafrost and mod- ern water table. Mineralogical and geochemical changes dominated in the middle unit are linked mainly to eoge- netic redox reactions. The formation of smectite and fer- ruginous cements in this unit is attributed to weathering of ferromagnesian and opaque heavy minerals under oxic and slightly alkaline conditions. Mineralogical and geo- chemical changes dominated in the upper unit is related mainly to Post-Permian chemical weathering, where almost all rock-forming minerals are altered to kaolin- ite and alkali and alkaline earth elements are leached forming bleached white saprolitic diamictites. A change in clay minerals from kaolinite in the weathered Permo- Carboniferous succession to smectite in the overlying Cenozoic succession demarcates the unconformity and probably reflects a change to an arid climatic condi- tion. Chemically, the Cenozoic succession shows a sharp increase in Ti/Al and La/Ce ratios and a decrease in Ce anomaly that remain constant in the Permo-Carbonifer- ous section. These mineralogical and chemical variations through the Phanerozoic stratigraphic section can be used to follow the landscape and climatic evolution since the late Palaeozoic glaciation. Abstract The pre-Quaternary stratigraphic section in Agnew–Lawlers area consists of Permo-Carboniferous glacial sediments, unconformably overlain by Tertiary clastics of palaeochannel sequence and Quaternary allu- vial and colluvial sediments. The unique Permo-Car- boniferous glacial sedimentary succession in the Yilgarn Craton has not been studied in detail in terms of verti- cal chemostratigraphic variations, basin and landscape evolution, diagenesis and post-Permian weathering over- prints. In Agnew–Lawlers district, continental facies of glacial diamictites, glaciofluvial sandstones and gla- ciolacustrine rhythmites vary in thickness from 28 m to 181 m and is preserved beneath Cenozoic sediments as relict landforms in highly irregular, asymmetrical and poorly drained basins. The Permo-Carboniferous sedi- ments were mechanically weathered and eroded by gla- ciers from the surrounding Archaean basement palaeo- highs under a cold arid climate. Textural relationships of diamictites indicate that they were derived from proximal and distal source rocks. The denuded palaeotopography of the basement palaeohighs (source rocks) and Permo- Carboniferous sediments were subjected simultaneously Electronic supplementary material The online version of this article (doi:10.1007/s00531-016-1320-5) contains supplementary material, which is available to authorized users. * Walid Salama walid.salama@csiro.au 1 CSIRO, Mineral Resources, ARRC, 26 Dick Perry Avenue, Kensington, Perth, WA 6151, Australia 2 The Deep Exploration Technologies CRC, The University of Adelaide, Adelaide, SA 5005, Australia 3 Geology Department, Faculty of Science, Cairo University, Giza 12613, Egypt