Lithology and relative weathering in a paleosol sequence on Mount Kenya, East Africa

Vortisch, Walter; Mahaney, William C.

doi:10.1201/9781003211457-25

Cited by 4 publications

(5 citation statements)

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“…Within the mineralogy assessed across the toposequence, the slow genesis of metahalloysite-halloysite postulated by Vortisch et al (1987) and Mahaney (1990Mahaney ( , 1991 seems to follow previous research outlined from other sites on the mountain. If metahalloysite-halloysite are found in weathered sediment (paleosols) <100 ka in age, the occurrence is considered to be the end-product of reworking of preweathered sediment from older sites.…”

Section: Clay and Primary Mineralogysupporting

confidence: 70%

“…The summit site (TV23: Fig. 4) has been the subject of previous publications (Vortisch et al, 1987;Mahaney, 1990). Two paleosol bodies occupy the full ~4.4 m depth of section, lithic units differentiated by Arabic numbers, Unit 1 left undefined by convention.…”

Section: Resultsmentioning

confidence: 99%

“…As with TV61, the mineral distribution in TV61A (Table 2, Supplement) follows a similar pattern with metahalloysite virtually nil, while halloysite ranges from small to moderate amounts in lithic unit 4 and in the saprolite. Once again, as in TV61, gibbsite tends to form when halloysite or metahalloysite decline, the co-relationship attributed to extreme leaching of Si from both clay species (Vortisch et al, 1987). Hematite and goethite follow the distribution in TV61with hematite higher in small amounts than trace quantities of goethite.…”

Section: Tv61a-tv61bmentioning

confidence: 89%

“…Scanning steps for oriented samples were 0.02° 2θ from 2 to 55° 2θ. A semi-quantitative mineral composition was determined from peak integral intensities of halloysite, metahalloysite, gibbsite, hematite, goethite, generic plagioclase, pyroxene, and magnetite (Whittig, 1965;Vortisch et al, 1987).…”

Section: Laboratory Sediment Analysismentioning

confidence: 99%

“…The enlargement shown in Fig. 10C provides details of strands of gibbsite clustered center to left with metahalloysite dominating on a gibbsite-free grain in the upper right (reprinted from Vortisch et al, 1987, andMahaney, 2002: 164-165).…”

Section: Mineralogymentioning

confidence: 99%

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Studia Quaternaria

2021

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Stacks of the Pleistocene tills and associated airfall/slopewash/colluvial sediment abound on East African Mountains but few localities exist where thick deposits of middle to Late Pleistocene age can be studied to bedrock with topography the main soil-forming agent over <0.8 Ma. Two tills form the main structure of the catena, the oldest buried in the crest, backslope and footslope of the deposit, the youngest forming the crest and upper backslope, with massive colluvial infill forming a still younger sediment mass superposed on older sediment in the lower backslope, footslope and toeslope, the latter all radiocarbon dated to within the last glaciation (Liki on Mt. Kenya; Weichselian in Europe, Wisconsin in North America). The moraine stack, first identified by J.W. Gregory in the late 19th century, as belonging to the ‘Older Glaciation’ (Illinoian in North America; Teleki on Mt. Kenya), is much older than originally thought with tills and other paraglacial sediment extending to saprolitic bedrock, paleomagnetic assessment and relative weathering indices placing the mass in the Brunhes Chron. These results demonstrate that despite erosion and weathering, paleosols in toposequences near the margins of successive glaciations retain properties allowing reconstruction of environmental changes over long periods of time.

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Section: Clay and Primary Mineralogysupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Tv61a-tv61bmentioning

confidence: 89%

Section: Laboratory Sediment Analysismentioning

confidence: 99%

Section: Mineralogymentioning

confidence: 99%

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