TU Darmstadt / ULB / TUbiblio

Upper Miocene to Pleistocene sedimentary record and its paleo-environmental implications in the Kaiso-Tonya area (Northern Albert Rift).

Brüsch, D. and Hornung, Jens and Petschick, R. and Lenz, O. K. and Schneider, S. and Hinderer, Matthias (2015):
Upper Miocene to Pleistocene sedimentary record and its paleo-environmental implications in the Kaiso-Tonya area (Northern Albert Rift).
In: DYNAMIC EARTH · from Alfred Wegener to today and beyond, Berlin, In: Geo Berlin 2015, Berlin, 04.10.-07.10.2015, [Online-Edition: http://www.geoberlin2015.de/assets/book_of_abstracts_geoberl...],
[Conference or Workshop Item]

Abstract

This project focuses on the western branch of the East African Rift System (EARS) and its related climatic changes. The study area lies in the western part of Uganda, north of the over 5000 m high Rwenzori Mountains situated along the eastern coast of Lake Albert. The aim of this sedimentological study was, to close existing terrestrial gaps in the paleoenvironmental and paleoclimatic record as well as the lack of a multi proxy approach to make conclusions more robust and meaningful. Therefore, a further focus was not only the sedimentology itself but also clay mineralogy, gamma-ray, petrographical as well as magnetic susceptibility and palynology. We logged � 230m in the Kaiso-Tonya area at a centimeter to decimeter scale with sedimentological and geophysical methods. First results show an interfering system of near shore, lacustrine, deltaic towards a finally fully fluvial environment in the Pleistocene. The Rwenzori Mountains and an accelerated up-lift of the rift-flank combined with a subsidence of the rift floor most likely led to a general aridisation trend. That trend is supported by a gradual increase of smectite from 55% up to 80% towards the Pliocene and a decrease of kaolinite from around 35% to 5%. We found a two-fold hierarchy of stratigraphic baselevel cycles at macro- and mesoscale. Wavelet analyses of lithofacies and magnetic susceptibility (MS) indicate a significant cyclicity at 7m that is caused by lake level changes and related intermittently fluctuating sediment supply. Surprisingly the MS readings remain constant in the negative range despite abundant ironcrusts and impregnations. Heavy mineral studies of intercalated sand layers show a significant increased zircon content up to 70% in the Pliocene and support changed trans- port pathways and/or changed provenance caused by increased tectonism towards the Pliocene. Pa- lynological data will be available at the conference.

Item Type: Conference or Workshop Item
Erschienen: 2015
Creators: Brüsch, D. and Hornung, Jens and Petschick, R. and Lenz, O. K. and Schneider, S. and Hinderer, Matthias
Title: Upper Miocene to Pleistocene sedimentary record and its paleo-environmental implications in the Kaiso-Tonya area (Northern Albert Rift).
Language: English
Abstract:

This project focuses on the western branch of the East African Rift System (EARS) and its related climatic changes. The study area lies in the western part of Uganda, north of the over 5000 m high Rwenzori Mountains situated along the eastern coast of Lake Albert. The aim of this sedimentological study was, to close existing terrestrial gaps in the paleoenvironmental and paleoclimatic record as well as the lack of a multi proxy approach to make conclusions more robust and meaningful. Therefore, a further focus was not only the sedimentology itself but also clay mineralogy, gamma-ray, petrographical as well as magnetic susceptibility and palynology. We logged � 230m in the Kaiso-Tonya area at a centimeter to decimeter scale with sedimentological and geophysical methods. First results show an interfering system of near shore, lacustrine, deltaic towards a finally fully fluvial environment in the Pleistocene. The Rwenzori Mountains and an accelerated up-lift of the rift-flank combined with a subsidence of the rift floor most likely led to a general aridisation trend. That trend is supported by a gradual increase of smectite from 55% up to 80% towards the Pliocene and a decrease of kaolinite from around 35% to 5%. We found a two-fold hierarchy of stratigraphic baselevel cycles at macro- and mesoscale. Wavelet analyses of lithofacies and magnetic susceptibility (MS) indicate a significant cyclicity at 7m that is caused by lake level changes and related intermittently fluctuating sediment supply. Surprisingly the MS readings remain constant in the negative range despite abundant ironcrusts and impregnations. Heavy mineral studies of intercalated sand layers show a significant increased zircon content up to 70% in the Pliocene and support changed trans- port pathways and/or changed provenance caused by increased tectonism towards the Pliocene. Pa- lynological data will be available at the conference.

Title of Book: DYNAMIC EARTH · from Alfred Wegener to today and beyond
Place of Publication: Berlin
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences > Earth Science > Applied Sedimentary Geology
Event Title: Geo Berlin 2015
Event Location: Berlin
Event Dates: 04.10.-07.10.2015
Date Deposited: 26 Jan 2016 19:06
Official URL: http://www.geoberlin2015.de/assets/book_of_abstracts_geoberl...
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