Fault kinematics and tectonic stress in the seismically active Manyara–Dodoma Rift segment in Central Tanzania – Implications for the East African Rift

Macheyeki, Athanas S.; Delvaux, Damien; Batist, Marc De; Mruma, A.

doi:10.1016/j.jafrearsci.2008.01.007

Cited by 61 publications

(38 citation statements)

References 54 publications

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“…Macheyeki et al (2008) also report that calcium rich (calcrete cement) materials that fill highangle fractures were formed close to the subsurface with alternating periods of flooding and drying, in a geographically low-relief environment within the Bahi depression in which the HD lies. Limestone, a water soluble sedimentary rock, is excavated, broken into small pieces, burned on high heat open furnaces and plenty of water is then added to the heated rocks to break them into powder.…”

Section: Water Usability Based On Hydrogeochemical Parameters Nationmentioning

confidence: 91%

Origin and mechanisms of high salinity in Hombolo Dam and groundwater in Dodoma municipality Tanzania, revealed

et al. 2017

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The Hombolo dam (HD), in central Tanzania, is a shallow reservoir characterized by high salinity that limits its use for human activities. The origin of the salinity, mechanisms of reaching and concentrating in the dam remain unclear. These were assessed using hydrogeochemical facies, water type evolutions and mapping. The source of HD salinity was identified to be shallow groundwater (SG) and runoff from a seasonal floodplain with NaCl-rich lithological materails, along Little Kinyasungwe River that feeds the dam. The NaCl-rich lithological units, about 5-7 km upstream of the dam, were highly concentrated with NaCl to the extent that the local community was commercially separating table salt from them. The physicochemical parameters from these NaCl-rich lithological materials were well represented in HD and nearby groundwater sources, which suggests active water interactions. Water type evolution and surface hydrology assessments clearly showed that SG in the salty-floodplain was influenced by evaporation (ET) and was periodically carried to the HD. Clearly; HD water had high chemical similarity with the nearby SG. This agrees with previous studies that HD is partly fed by the local aquifer. However, this is the first attempt at mapping its physical origin. The origin of HD salinity was further supported by the spatial distribution of electrical conductivity (EC), where very high EC (up to 21,230 lScm ) was recorded in SG within the NaCl-rich lithological unit while water sources far away from the NaClrich materials had much lower EC values. Thus, the study disagrees with previous conclusions that HD salinity was sorely due to high dam surface ET but is primarily due to geological reasons. Comparisons of HD with a nearby Matumbulu dam (MD), another earthen dam in climatologically similar settings, reveals that MD water was less saline/ mineralised. This further shows that HD high salinity is most likely a geologic phenomenon, but local climatic factors, namely high ET, decreasing rainfall and warming trends are likely to have concentrated the salts further. Although HD is widely/ideally used for grape vine irrigation, it was clearly revealed that its prolonged usage would potentially affect the soil and grape productivity due to high salinity.

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Section: Water Usability Based On Hydrogeochemical Parameters Nationmentioning

confidence: 91%

Origin and mechanisms of high salinity in Hombolo Dam and groundwater in Dodoma municipality Tanzania, revealed

et al. 2017

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“…From fault scarp investigations and local seismicity there is evidence that the eastern branch continues southward into the Manyara-Dodoma segment. It has been suggested that it further proceeds to the southwest where it finally joins the western branch at the Mbeya triple junction (Macheyeki et al 2008). The two rift branches, thus, enclose the so-called Victoria micro-plate which is more or less identical to the Tanzania craton (Calais et al 2006) which is surrounded by Proterozoic mobile belts (e.g.…”

Section: Introductionmentioning

confidence: 99%

Crustal thinning beneath the Rwenzori region, Albertine rift, Uganda, from receiver-function analysis

Wölbern

Rümpker

Schumann

et al. 2010

Int J Earth Sci (Geol Rundsch)

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The Rwenzori mountains in western Uganda, with a maximum elevation of more than 5,000 m, are located within the Albertine rift valley. We have deployed a temporary seismic network on the Ugandan side of the mountain range to study the seismic velocity structure of the crust and upper mantle beneath this section of the rift. We present results from a receiver-function study revealing a simple crustal structure along the eastern rift flank with a more or less uniform crustal thickness of about 30 km. The complexity of inner-crustal structures increases drastically within the Rwenzori block. We apply different inversion techniques to obtain reliable results for the thickness of the crust. The observations expose a significantly thinner crust beneath the Rwenzori range with thickness values ranging from about 20-28 km beneath northern and central parts of the mountains. Our study therefore indicates the absence of a crustal root beneath the Rwenzori block. Beneath the Lake Edward and Lake George basins we detect the top of a layer of significantly reduced S-wave velocity at 15 km depth. This low-velocity layer may be attributed to the presence of partial melt beneath a region of recent volcanic activity.

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“…No faulting for the identified shorelines can be stated, which coincides with [37][38][39]. Since the shorelines are in a parallel sequence and only interrupted by fluvial processes tectonic activity has not, or only marginally, affected the absolute elevations of the detected paleo-shorelines since the formation of these structures.…”

Section: Resultsmentioning

confidence: 83%

“…The morphology of the landscape is strongly related to Quaternary volcanism and tectonic activity, which is still ongoing [36]. The basin is affected by minor en echelon step faults (NNE and E), whereas the lake sediments and the shorelines between Makuyuni and the lake are not disturbed by faulting [37][38][39]. The water supply originates from perennial springs and streams of the rift escarpment and from several seasonal drainages, of which the Makuyuni River and the Tarangire River are the largest.…”

Section: Study Area and Paleolake Evidencementioning

confidence: 99%

The Delineation of Paleo-Shorelines in the Lake Manyara Basin Using TerraSAR-X Data

2014

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Abstract:The purpose of this paper is to describe the delineation of paleo-shorelines using high resolution microwave images and digital image processing tools, and with that to contribute to the understanding of the complex landscape evolution of the Lake Manyara Basin. The surroundings of Lake Manyara are the focus of several paleo-archeological investigations, since the location is close to Olduvai Gorge, where paleo-anthropological findings can be traced back to homo habilis. In the catchment of Lake Manyara two hominin-bearing sites (0.78 to 0.63 Ma), lots of vertebrate fossils and hand axes from different periods were found. Understanding the development and extent of the lake is crucial for understanding the regional paleo-environment of the Quaternary. Morphological structures of shorelines and terraces east of Lake Manyara were identified from TerraSAR-X StripMap images. By applying a Canny edge detector, linear features were extracted and revised for different image acquisitions using a contextual approach. Those features match literature and field references. A digital elevation model of the region was used to map the most distinct paleo-shorelines according to their elevation.

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Fault kinematics and tectonic stress in the seismically active Manyara–Dodoma Rift segment in Central Tanzania – Implications for the East African Rift

Cited by 61 publications

References 54 publications

Origin and mechanisms of high salinity in Hombolo Dam and groundwater in Dodoma municipality Tanzania, revealed

Origin and mechanisms of high salinity in Hombolo Dam and groundwater in Dodoma municipality Tanzania, revealed

Crustal thinning beneath the Rwenzori region, Albertine rift, Uganda, from receiver-function analysis

The Delineation of Paleo-Shorelines in the Lake Manyara Basin Using TerraSAR-X Data

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