A morphotectonic study of an extensional fault zone in a magma-rich rift: the Baringo Trachyte Fault System, central Kenya Rift

Gall, Bernard Le; Tiercelin, Jean-Jacques; Richert, J.P.; Gente, Pascal; Sturchio, Neil C.; Stead, D.; Turdu, C. Le

doi:10.1016/s0040-1951(00)00069-x

Cited by 40 publications

(24 citation statements)

References 47 publications

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“…These locations lie along the general north-south trend of the grid-fault system that extends northward from Lake Bogoria and affects Ol Kokwe Island and the other Baringo islands (Tiercelin et al, 1987;Le Gall et al, 2000) (Figure 11(a and b1)). In the Bogoria basin, approximately 200 subaerial and sublacustrine hydrothermal spring vents occur along this north-south grid-fault system (Figure 1(b and c) and Figure 11(a and b2)).…”

Section: Discussionmentioning

confidence: 92%

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley

et al. 2006

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Lake Baringo, a freshwater lake in the central Kenya Rift Valley, is fed by perennial and ephemeral rivers, direct rainfall, and hot springs on Ol Kokwe Island near the centre of the lake. The lake has no surface outlet, but despite high evaporation rates it maintains dilute waters by subsurface seepage through permeable sediments and faulted lavas. New geochemical analyses (major ions, trace elements) of the river, lake, and hot spring waters and the suspended sediments have been made to determine the main controls of lake water quality. The results show that evaporative concentration and the binary mixing between two end members (rivers and thermal waters) can explain the hydrochemistry of the lake waters. Two zones are recognized from water composition. The southern part of the lake near sites of perennial river inflow is weakly influenced by evaporation, has low total dissolved species (TDS), and has a seasonally variable load of mainly detrital suspended sediments. In contrast, waters of the northern part of the lake show evidence for strong evaporation (TDS of up to eight times inflow). Authigenic clay minerals and calcite may be precipitating from those more concentrated fluids. The subaerial hot-spring waters have a distinctive chemistry and are enriched in some elements that are also present in the lake water. Comparison of the chemical composition of the inflowing surface waters and lake water shows (1) an enrichment of some species (HCO3-, Cl, SO42-, F, Na, B, V, Cr, As, Mo, Ba and U) in the lake, (2) a depletion in SiO2 in the lake, and (3) a possible hydrothermal origin for most F. The rare earth element distribution and the F/Cl and Na/Cl ratios give valuable information on the rate of mixing of the river and hydrothermal fluids in the lake water. Calculations imply that thermal fluids may be seeping upward locally into the lake through grid-faulted lavas, particularly south of Ol Kokwe Island. Copyright © 2006 John Wiley & Sons, Ltd

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Section: Discussionmentioning

confidence: 92%

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley

et al. 2006

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“…It could be related to the reactivation of the rifing in the Baringo-Bongoria Rift in central Kenya (Chapman and Brook, 1978;Hautot et al, 2000;Le Gall et al, 2000;Morley et al, 1992) or to the different stages of extension recorded in the basins of the North Tanzanian Divergence (2.5 and 1.5…”

Section: Pliocene-pleistocene Transition (27 Ma)mentioning

confidence: 99%

“…1b). Faults and geological contours from Chorowicz (2005), Le Gall et al (2000, 2004, 2005 Correlations were performed with respect to the sequence stratigraphy method and paleoenvironmental data (palynomorph, example in Figure 6 for well 1). The locations of the wells and outcrops are given in Figure 3.…”

Section: Acknowlegmentsmentioning

confidence: 99%

Deformation and sedimentary evolution of the Lake Albert Rift (Uganda, East African Rift System)

Simon

Guillocheau

Robin

et al. 2017

Marine and Petroleum Geology

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This study proposed a new reconstruction of the tectono-sedimentary evolution of the Lake Albert Rift based on a biostratigraphical, sedimentological and structural re-evaluation of the outcropping data and on an exceptional subsurface dataset.The infilling of the rift consists of lacustrine deposits wherein two major unconformities dated at 6.2 Ma and 2.7 Ma were characterized, coeval with major subsidence and climatic changes.Combined with the fault analysis, the evolution and distribution of the subsidence highlights a foursteps evolution of the rift after its initiation dated at 17.0 Ma.The first phase (17.0 -6.2 Ma) consists of low and diffuse extension associated with low accommodation rates ranging from 150 to 200 m/Ma. Restricted in the southern part of the basin, the depocenter location is poorly controlled by faults, meaning that the basin extension was potentially larger at this time.The second time interval (6.2 -2.7 Ma) shows an increase of accommodation rates with values reaching more than 800 m/Ma. These high rates combined with the location of the major depocenters down the bounding faults argue for a first true rifting phase.Between 2.7 Ma and 0.4 Ma, the accommodation rates decreases to reach less than 400 m/Ma and the individualization of major depocenters continue down the major fault in the southern, and northwestern parts of the basin.

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“…However, their nucleation and development in the downflexed Stratoid lava pile were probably controlled by volcanic structures, as follows. Provided that the wedge‐shaped pile of initially horizontal (Dalha–Stratoid) lava flows rotated westwards, towards the axis of the active magmatic zone, during early flexuring, the cooling joint pattern, known to generally act as tension fractures under tensile stress (Forslund and Gudmundsson, 1992; Le Gall et al. , 2000), likely evolved from an initially vertical attitude to an easterly inclined position with time (Fig.…”

Section: Kinematic Model and Discussionmentioning

confidence: 99%

Large‐scale flexuring and antithetic extensional faulting along a nascent plate boundary in the SE Afar rift

et al. 2011

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12New structural data from the SE Afar margin in Djibouti leads us to discriminate two 13 recent (<1 Ma) extensional fault networks between the Afar accreted crust, and the South 14 Danakil Block to the east. Emphasis is placed on the N-S-oriented Makarassou fault system 15 which dissects the prominent westward-(riftward-)facing topographic flexure between the 16 two structural domains. The most striking characteristic of the Makarassou fault belt is a 17closely-spaced network of continentward-dipping extensional faults, bounding domino blocks 18

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A morphotectonic study of an extensional fault zone in a magma-rich rift: the Baringo Trachyte Fault System, central Kenya Rift

Cited by 40 publications

References 47 publications

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley

Deformation and sedimentary evolution of the Lake Albert Rift (Uganda, East African Rift System)

Large‐scale flexuring and antithetic extensional faulting along a nascent plate boundary in the SE Afar rift

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