Sedimentology of the Malawi Rift: Facies and stratigraphy of the Chiwondo Beds, northern Malawi

Betzler, Christian; Ring, Uwe

doi:10.1006/jhev.1995.1004

Cited by 39 publications

(23 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is suggested from surface geological observations in its northern part that the Malawi Rift started filling with fluviatile deposits produced from the erosion of Karoo sedimentary rocks before the domination of lacustrine silt deposits when Lake Malawi flooded the rift [ Flannery and Rosendahl , ; Betzler and Ring , ]. Seismic data suggest that the rift sedimentary fill can reach up to 2 to 3 km thickness in the deepest parts of half‐grabens in the northern part of the rift and the rift sedimentary fill becomes thinner southward until it diminishes completely in the Shire Segment where the rift is floored by Precambrian rocks (Figure a) [ Specht and Rosendahl , ; Flannery and Rosendahl , ].…”

Section: The Malawi Riftmentioning

confidence: 99%

Hierarchical segmentation of the Malawi Rift: The influence of inherited lithospheric heterogeneity and kinematics in the evolution of continental rifts

et al. 2015

View full text Add to dashboard Cite

We used detailed analysis of Shuttle Radar Topography Mission-digital elevation model and observations from aeromagnetic data to examine the influence of inherited lithospheric heterogeneity and kinematics in the segmentation of largely amagmatic continental rifts. We focused on the Cenozoic Malawi Rift, which represents the southern extension of the Western Branch of the East African Rift System. This north trending rift traverses Precambrian and Paleozoic-Mesozoic structures of different orientations. We found that the rift can be hierarchically divided into first-order and second-order segments. In the first-order segmentation, we divided the rift into Northern, Central, and Southern sections. In its Northern Section, the rift follows Paleoproterozoic and Neoproterozoic terrains with structural grain that favored the localization of extension within well-developed border faults. The Central Section occurs within Mesoproterozoic-Neoproterozoic terrain with regional structures oblique to the rift extent. We propose that the lack of inherited lithospheric heterogeneity favoring extension localization resulted in the development of the rift in this section as a shallow graben with undeveloped border faults. In the Southern Section, Mesoproterozoic-Neoproterozoic rocks were reactivated and developed the border faults. In the second-order segmentation, only observed in the Northern Section, we divided the section into five segments that approximate four half-grabens/ asymmetrical grabens with alternating polarities. The change of polarity coincides with flip-over full-grabens occurring within overlap zones associated with~150 km long alternating border faults segments. The inherited lithospheric heterogeneity played the major role in facilitating the segmentation of the Malawi Rift during its opening resulting from extension. Key Points:• Segmentation of the Malawi Rift is studied using SRTM DEM and magnetic data • The rift is hierarchically divided into first-order and second-order segments • Lithospheric heterogeneity controls firstand second-order segmentation

show abstract

Section: The Malawi Riftmentioning

confidence: 99%

Hierarchical segmentation of the Malawi Rift: The influence of inherited lithospheric heterogeneity and kinematics in the evolution of continental rifts

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The freshwater lakes Lake Albert and Lake Malawi belong to the western branch of the EARS. The tectonic history as well as litho-and biostratigraphy of the lakes have been comprehensively described (Pickford et al, 1993;Senut and Pickford, 1994;Betzler and Ring, 1995;Ring and Betzler, 1995;Beuning et al, 1997;Van Damme and Pickford, 2003;Bobe et al, 2007).…”

Section: Samplesmentioning

confidence: 99%

Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

Brügmann

Krause²,

Brachert

et al. 2012

Biogeosciences

View full text Add to dashboard Cite

Abstract. This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120–9336 μg g−1) as well as for Sr (9–2150 μg g−1). The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel–dentin junction by a factor of 1.3–1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that Ba mobility decreased with increasing aridification due to preferential deposition with clay and Fe-oxide-hydroxide or barite on the watershed of Lake Albert.

show abstract

“…Geologically, the whole of Malawi falls within the western branch of the East African Rift system, which includes the Albertine, Tanganyika, Rukwa and Malawi rifts (Ebinger ). The Malawi Rift is composed of a sequence of north–south orientated half‐grabens with a sharp escarpment on the eastern side and a segmented ramp opposite to it (Betzler and Ring ). The northernmost Tukuyu–Karonga half‐graben is bounded to the east by the Livingstone Fault.…”

Section: Introductionmentioning

confidence: 99%

Ochre fingerprints: Distinguishing among Malawian mineral pigment sources with Homogenized Ochre Chip LA–ICPMS

et al. 2014

View full text Add to dashboard Cite

In this study, we compared the effectiveness of instrumental neutron activation analysis (INAA) of bulk ochre to laser ablation-inductively coupled plasma mass spectrometry of homogenized ochre chips (HOC LA-ICPMS) at distinguishing among three ochre sources in northern Malawi. Both techniques upheld the Provenance Postulate; however, HOC LA-ICPMS required less sample material than INAA and facilitated fast, inexpensive replicate observations that allowed for more robust statistical analysis. Our results indicated that HOC LA-ICPMS is a maturing technique that will be a valuable option for analysing artefacts that require minimally destructive sampling but are too large to fit into the laser cell for direct ablation. With regard to the statistical procedures used, stepwise canonical discriminant analysis was demonstrated to be a highly effective method for distinguishing among ochre sources, even in the presence of significant intra-source and intra-sample heterogeneity. Continued development of the HOC sample preparation technique will expand the range of archaeological ochre artefacts that can be included in provenance studies and prevent bias towards artefacts of convenient-to-analyse dimensions.

show abstract

Sedimentology of the Malawi Rift: Facies and stratigraphy of the Chiwondo Beds, northern Malawi

Cited by 39 publications

References 0 publications

Hierarchical segmentation of the Malawi Rift: The influence of inherited lithospheric heterogeneity and kinematics in the evolution of continental rifts

Hierarchical segmentation of the Malawi Rift: The influence of inherited lithospheric heterogeneity and kinematics in the evolution of continental rifts

Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

Ochre fingerprints: Distinguishing among Malawian mineral pigment sources with Homogenized Ochre Chip LA–ICPMS

Contact Info

Product

Resources

About