Kinematic and sedimentological evolution of the Manyara Rift in northern Tanzania, East Africa

2005 ◽  
Vol 142 (4) ◽  
pp. 355-368 ◽  
Author(s):  
UWE RING ◽  
HILDE L. SCHWARTZ ◽  
TIMOTHY G. BROMAGE ◽  
CHARLES SANAANE
Keyword(s):  
East Africa ◽  
Structural Evolution ◽  
Magmatic Activity ◽  
Fault Geometry ◽  
East African ◽  
Lower Member ◽  
Northern Tanzania ◽  
Southward Shift ◽  
Fluvial Sedimentation ◽  
African Rift

We describe the stratigraphical/sedimentological and structural evolution of the Manyara Rift in the Tanzania Divergence Zone, East Africa. The rift-related Manyara Beds on the shoaling side of the Manyara Rift were deposited between <1.7 and 0.4 Ma and can be separated into a lacustrine lower member and a fluvial upper member. The transition from lacustrine to fluvial sedimentation at ∼ 0.7 Ma appears to be related to a southward shift of major rift faulting. Fault geometry and the kinematics of the faults are consistent with major faulting during NE/E-directed extension. There is also evidence for other extensional directions including radial extension, which might be caused by magmatic activity and/or might reflect oblate strain symmetry where the East African Rift propagated into the Archaean Tanzania Craton and associated termination of rifting caused an increase in the strained area.

scholarly journals Hydrogeology and hydrogeochemistry of an alkaline volcanic area: the NE Mt. Meru slope (East African Rift – Northern Tanzania)

2011 ◽  
Vol 8 (5) ◽  
pp. 8255-8289 ◽  
Author(s):  
G. Ghiglieri ◽  
D. Pittalis ◽  
G. Cerri ◽  
G. Oggiano
Keyword(s):  
Major Ions ◽  
Volcanic Rocks ◽  
Volcanic Area ◽  
East African ◽  
Geochemical Composition ◽  
Fine Grained ◽  
Physico Chemical ◽  
Northern Tanzania ◽  
Hydraulic Gradients ◽  
African Rift

Abstract. The objective of this study is to analyze the geochemical conditions associated with the presence of fluoride (F−) in the groundwater of an area of Northern Tanzania. The studied aquifers are composed of volcanic rocks such as phonolitic and nephelinitic lavas, basalts, lahars of various ages and mantling ash. Sedimentary rocks consisting of fine-grained alluvial and lacustrine deposits occur as well. Samples collected from springs, borehole and surface water, during two monitoring surveys, were analyzed for the various physico-chemical and isotopic parameters. The geochemical composition of water is typically sodium bicarbonate. High values of F− (up to 68 mg l−1) were recorded. The highest values of fluoride agreed with the highest values of pH, sodium and bicarbonate. Dissolution of major ions, exchange processes and precipitation of Ca2+ from super-saturated solutions joined with the local permeability and hydraulic gradients, control the fluoride mobilization and the contamination of the area.

scholarly journals Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift

2020 ◽  
Author(s):  
G Corti ◽  
R Cioni ◽  
Z Franceschini ◽  
F Sani ◽  
S Scaillet ◽  
...  
Keyword(s):  
Rift Zone ◽  
Numerical Models ◽  
Ethiopian Rift ◽  
Magmatic Activity ◽  
Geological Data ◽  
East African ◽  
Ridge Segmentation ◽  
Pure Extension ◽  
African Rift ◽  
Ocean Ridge

© 2019, The Author(s). Continental rift systems form by propagation of isolated rift segments that interact, and eventually evolve into continuous zones of deformation. This process impacts many aspects of rifting including rift morphology at breakup, and eventual ocean-ridge segmentation. Yet, rift segment growth and interaction remain enigmatic. Here we present geological data from the poorly documented Ririba rift (South Ethiopia) that reveals how two major sectors of the East African rift, the Kenyan and Ethiopian rifts, interact. We show that the Ririba rift formed from the southward propagation of the Ethiopian rift during the Pliocene but this propagation was short-lived and aborted close to the Pliocene-Pleistocene boundary. Seismicity data support the abandonment of laterally offset, overlapping tips of the Ethiopian and Kenyan rifts. Integration with new numerical models indicates that rift abandonment resulted from progressive focusing of the tectonic and magmatic activity into an oblique, throughgoing rift zone of near pure extension directly connecting the rift sectors.

SPATIAL MODELLING OF FLUORIDE CONTAMINATION IN GROUNDWATER SYSTEMS IN THE EAST AFRICAN RIFT VALLEY REGIONS OF NORTHERN TANZANIA

2020 ◽  
Author(s):  
Julian Ijumulana ◽  
◽  
Fanuel J. Ligate ◽  
Fanuel J. Ligate ◽  
Prosun Bhattacharya ◽  
...  
Keyword(s):  
Rift Valley ◽  
East African Rift ◽  
Spatial Modelling ◽  
East African ◽  
Fluoride Contamination ◽  
Northern Tanzania ◽  
Groundwater Systems ◽  
African Rift

scholarly journals Highlights in the geological Research of central East Africa

Afrika Focus ◽  
1985 ◽  
Vol 1 (1-2) ◽  
Author(s):  
Peter Van den Haute
Keyword(s):  
East Africa ◽  
Geological Structure ◽  
Radiometric Dating ◽  
General View ◽  
Geological History ◽  
East African ◽  
Principle Of Superposition ◽  
General Outline ◽  
Mountain Belts ◽  
African Rift

The present paper offers a general view of the geological history of central East Africa. It is meant to inform persons involved in all kinds of African research about the physical background of this enormous continent. As the text is intended for people with no specific training in the earth sciences, an extensive introductory part has been dedicated to the general principles and methods of historical geology. The principle of superposition and the meaning of a major unconformity are shortly explained. Also the significance of fossils and of radiometric dating is elucidated with respect to the reconstruction of geological history. Further on a general outline is given of the great mountain belts of the African continent dating back from thé earliest geological times (Precambrian), followed by a more detailed discussion of these belts in central East Africa. As to the younger structures of this region, attention has been focused on the large elongated furrow known as the East African rift. The major characteristics of this important feature in the earth's crust are described and its genesis is briefly discussed. KEYWORDS : Central East Africa, geological structure, Precambrian, rift. 

Palaeomagnetic investigations on the East African rift in Northern Tanzania

1985 ◽  
Vol 2 (2-3) ◽  
pp. 265-274 ◽  
Author(s):  
H.J Mauritsch ◽  
M.M Pondaga
Keyword(s):  
East African Rift ◽  
East African ◽  
Northern Tanzania ◽  
African Rift

Neogene–Recent rifting and volcanism in northern Tanzania: relevance for comparisons between the Gardar province and the East African Rift valley

1997 ◽  
Vol 61 (407) ◽  
pp. 543-548 ◽  
Author(s):  
J. B. Dawson
Keyword(s):  
Rift Valley ◽  
East African Rift ◽  
Fold Belt ◽  
East African ◽  
Volcanic Province ◽  
Northern Tanzania ◽  
Tectonic Position ◽  
African Rift

AbstractThe tectonic position of the intraplate, alkaline volcanic province of N. Tanzania in a broad rift-controlled area astride the boundary between the Tanzania Craton and the circum-cratonic Mozambique Fold Belt, strongly resembles that of the Gardar province of S. Greenland. Earlier-identified petrological analogies between Gardar magmatism and that in the Kenya sector of the East African Rift Valley can be extended to volcanism in N. Tanzania, and analogies specifically with the Gardar agpaitic suite are strengthened by the occurrence of eudialyte and aenigmatite in some Tanzanian peralkaline, silicic volcanics.

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