 | | Report (issue) | | 61 GOVERNMENT OF KENYA MINISTRY OF COMMERCE AND INDUSTRY GEOLOGICAL SURVEY OF KENYA GEOLOGY OF THE ... AREA SOUTH OF MAGADI DEGREE SHEET 58, N.W. QUARTER (with coloured geological map) by B. H. BAKER, B...number concerned. GEOLOGY OF THE AREA SOUTH OF MAGADI DEGREE SHEET 58, N.W. QUARTER (with coloured geological...south of Magadi completes the account of the southern end of the Rift Valley as it occurs in Kenya. The Magadi...Magadi area itself was described by Mr. Baker in Report No. 42 (1958). During the mapping of the continuation |  | | Report (issue) | | COLONY AND PROTECTORATE OF KENYA GEOLOGICAL SURVEY OF KENYA OF THE MAGADI AREA DEGREE SHEET 51, S.W...item reference number concerned. GEOLOGY OF THE MAGADI AREA DEGREE SHEET 51, S.W. QUARTER (with two coloured...Sc, F.G.S. Geologist \Ç>5U5 FOREWORD The Magadi soda lake is one of the natural wonders of the world...as a whole. As the rocks of the area, apart from lake beds, consist almost entirely of late Tertiary and...mineral deposits was small. Yet Magadi has provided more mineral wealth for Kenya than any other part of the |  | | Report (chapter) | | 2015 Tectonics and volcanism of the southern Kenya Rift Valley and its influence on rift sedimentation...SUM M A RY: Volcanism in the northern half of the Kenya Rift Valley began at 30 Ma, and in the southern...graben of the rift floor. In the central sector lake basins spread broadly over pyroclastic deposits...Hypersaline lakes with trona evaporites in the Natron-Magadi basin were caused by the arid climate, eruption...into closed structural basins. Evolution of the Kenya Rift Valley during the last 30 Ma is now moderately |  | | Report (chapter) | | University of Pennsylvania on June 30, 2015 Lake Magadi, Kenya: a model for rift valley hydrochemistry and...H.P. Eugster SUMMARY: Previous studies on Lake Magadi, Kenya, and the Green River Formation of Wyoming...between these two settings, to determine whether Lake Magadi can serve as a reference for rift valley environments...recognizing saline alkaline lake deposits in the geologic column. Magadi inflow waters are influenced...transported during flood events. In contrast, Eocene Lake Gosiute and its mudflats had more gentle gradients |  | | Journal (article/letter/editorial) | | four localities (Lake Magadi, Kenya; Alkali Lake, Oregon; Lac Tchad, Africa; Trinity County, Calif.) t'here...alteration product of magadiite in the High Magadi Beds in Kenya IxrnooucuoN Two new hydrous sodium silicate...Thesemineralsoccur in Pleistocenesaline lake depositsin the Lake Magadi area,Kenya. Magadiite appearsto be a direct...transformation of magadiite to chert by the action of fresher waters percolatingthrough the lake beds.Plates and la)'ersof...la)'ersof chert, that still preserve the laminations of the original deposit, have been found in some |  | | Journal (article/letter/editorial) | | (1969) Inorganic Bedded Cherts from the Magadi Area, Kenya HANS P. EUGSTV~ Earth and Planetary Sciences...Maryland Received February 6, 1969 Abstract. The High Magadi beds can be divided into a lower and an upper sequence...been possible to establish that the cherts of the "Chert Series" are stratigraphically equivalent to the...the magadiite horizons. The transition magadiite-chert has been observed in many places and may occur over...sodium by percolating waters. The resulting bedded chert may preserve the fine lamination present in magadiite |  | | Journal (article/letter/editorial) | | S A S S O C I A T E D W I T H T H E S A L I N E LAKE DEPOSITS OF EAST AFRICA * James R. O'NEIL U.S. Geological...general with lake salinities as inferred from geologic evidence, indicating that most chert was formed...formed from its precursor in contact with lake water trapped at the time of deposition. A few of the analyzed...we conclude that precursors were transformed to chert in fluids of widely varying salinity and aNa+[aH+...aNa+[aH+ ratio. 1. Introduction The origin of chert has been a controversial subject for many decades, with |  | | Report (issue) | | Data: Monoclinic, probable. Point Group: n.d. with chert cores. Physical Properties: As nodular concretions...30(5) ¯ = 95± 54(5)0 X-ray Powder Pattern: Lake Magadi, Kenya; pattern varies with interlayer Na:H2 O:... (1) Lake Magadi, Kenya. (2) Na2 Si22 O41 (OH)8 ² 6H2 O: Occurrence: As concretions, with chert cores...perhaps as a reaction product between the two (Lake Magadi, Kenya); in altered volcanic rocks (Trinity Co....Magadiite, quartz. Distribution: From Lake Magadi, Rift Valley, Kenya. In Niger, at Kafra. In the USA, from |  | | Journal (article/letter/editorial) | | VOL. 53, NOVEMBER_DECEI{BER, FROM TRINITY 1968 COUNTY, CALIFORNIA J. L. McArno, Jn., Department of Chemistry...in Trinity county, california, with chemical composition ecluivalent to magadiite from Kenya. X-ray powder...structures, were first describedfrom the Lake Magadi basin in Kenya (Eugster, 1967) and Iater encountered... 1967) and in the High Natron beds south of Lake Magadi (magadiiteand kenyaite, R.L. Hay, pers.comm)...north of Trinity Lake (seeWeed Sheet GeologicalMap, Sec.30, T 37 N, R 6 W). Unlike the Kenya and Oregon occurrences |  | | Report (issue) | | 61.9608(46) Z = [2] X-ray Powder Pattern: Lake Magadi, Kenya. 15.41 (100), 3.44 (80), 3.146 (50), 3.30...(3) 78.96 5.82 15.22 100.00 (1) Lake Magadi, Kenya. (2) Alkali Lake Playa, Oregon, USA. (3) Na2Si14O28(OH)2∙8H2O...precipitated by evaporation of saline brines (Lake Magadi); in veins cutting playa sediments and in muds...associated with alkali salts and brines (Alkali Lake Playa, Oregon); in altered volcanic rocks (Trinity...Canada). Association: Kenyaite, calcite (Lake Magadi); kanemite (Lake Chad); bavenite, pectolite, apophyllite |  | | Journal (article/letter/editorial) | | Contr. Mineral. and Petrol. 17, 255--274 (1968) Chert and Its Sodium-Silicate Precursors in Sodium-Carbonate...California Received December 18, 1967 Abstract. Chert has formed from two sodium-silicate minerals, magadiite...Pleistocene deposits of lakes Magadi and Matron in Kenya and Tanzania. The chert consists of finely crystalline...Pleistocene lacustrine deposits in the vicinity of Lake Magadi, Lake Natron, and Olduvai Gorge. Although magadiite...deposits, the chert in these beds probably formed from a sodium-silicate precursor. All of the chert-bearing |  | | Journal (article/letter/editorial) | | SCT horizons is similar to the type reported for Magadi-type cherts, which are commonly interpreted as...of SCT deposits is totally unrelated to alkaline-lake genetic processes, it is concluded that cherts showing...microcrystalline quartz may have a different origin than Magadi-type deposits. INTRODUCTION A peculiar grid-work...groundmass of Pleistocene high-alkali cherts from Lake Magadi, Kenya (Fig. 2a). The authors proposed that the...volumeby-volume replacement of magadiite by quartz during the chert genesis in an alkaline environment. Following the |  | | Journal (article/letter/editorial) | | have formed in the evaporative setting of a playa-lake complex. Hydrologicallyand sedimentologicallysucha...in a fairly dilute lake. Most Precambrianmagadiite must have beenconvertedto chert during early diagenesis...Perry and Tan (1973). In the playa-lake model, inflow into the lake is primarily through springs,with...proceedingin the playa flats fringing an alkaline lake. This accounts for the paucity of clastics found...predictedbecauseof lack of equilibrium. Solidsforming in the lake are magadiite (or a sodium silicate gel), greenalite |  | | Journal (article/letter/editorial) | | MINERALOGIST, VOL. 54, JULY_AUGUST, FROM ALKALI 1969 LAKE, OREGON Tnon,rs P. RooNev, U. S. Air Force Combri...associated with alkali saits and brines at Alkali Lake playa, Oregon. Magadiite has apparently precipitated...and kenyaite (NaSirOro,r[(oH)n. 3HrO), from Lake Magadi, Kenya. The magadiite apparently precipitated from...converted magadiite to kenyaite and finally to chert. According to Eugster, this simple inorganic mechanism...studies,white chert-like veins of magadiite were observedin playa sediments of Alkali Lake, Oregon, and |  | | Journal (article/letter/editorial) | | A NEW HYDROUS SODIUM SILICATE MINERAL FROM LAKE MAGADI, KENYA1 Rrcneno A. SunppanD AND Anrrrun J. Guon...three drill holes in the Evaporite Series of Lake Magadi, Kenya. The makatite occurs as white spherulites...(116),2.882(42) (225).The nameis from the Masai(Kenya)word,emakot, which means soda-in allusion to the...257-259) during an investigation of chert in the deposits of Lake Magadi, Kenya. Hay found white acicular crystals...in drill hole B from the northcentral part of Lake Magadi (Fig. 1). The material gave a distinctive but |  | | Journal (article/letter/editorial) | | (2002) 169– 192 www.elsevier.com/locate/precamres Chert in the Palaeoproterozoic Bartle Member, Killara...Yerrida Basin, Western Australia: a rift-related playa lake and thermal spring environment? F. Pirajno, K. Grey...accepted 16 April 2001 Abstract Palaeoproterozoic chert in the Bartle Member of the Killara Formation, Yerrida...environment associated with rifting at about 2.2 Ga. The chert member contains silica pseudomorphs after evaporite...comparison with rocks of the Afar region and Lake Magadi in the East African Rift System. The Bartle Member |  | | Journal (article/letter/editorial) | | disequilibria in early diagenetic minerals from Lake Magadi sediments, Kenya: Dating potential and CLAUDE HILLAIRE-MARCEL...the southern end of the Gregory Rift Valley, Lake Magadi occupies the bottom of a relatively large drainage...silty-clay units deposited during Late Pleistocene high lake stands. These units consist of a mixture of detrital...14Cchronology already established for the most recent high lake level episode in the basin ( lO,~-12,~ yr BP). ~urn-~~~tes...lacustrine unit was deposited during a former high Lake Magadi level, possibly during the lacustrine episode |  | | Report (issue) | | FLUORITE IN THE EASTGATE ZEOLITE DEPOSIT, CHURCHILL COUNTY, NEVADA By Richard A. Sheppard and Arthur J. Gude...FLUORITE IN THE EASTGATE ZEOLITE DEPOSIT, CHURCHILL COUNTY, NEVADA By Richard A. Sheppard and Arthur J. Gude...lacustrine sediments of Quaternary age in the Lake Magadi region of Kenya (Surdam and Eugster, 1976). The fluorite...Highway 2 in the southeastern part of Churchill County (fig. 1). The deposit is about 5 km west of the...discontinuous layers of nodules of Magadi-type chert. This distinctive chert occurs as lobate nodules that |  | | Report (chapter) | | the Lake Bogoria basin, Kenya Rift Valley R.W. Renaut, J.J. Tiercelin & R.B. Owen SUMMARY: Lake Bogoria...Bogoria is a perennial, saline, alkaline closed lake fed by hot springs and ephemeral runoff. Detailed studies...both from exposures around the shoreline and from lake bottom cores, have provided abundant evidence for...vivianite. Modern and ancient saline, alkaline lake deposits are well known for their abundant and varied...in the rift valley lake basins of East Africa. Of the East African lakes, Magadi is often regarded as |  | Kaufman, Aaron, Margaritz, Mordeckai, Paul, Michael, Hillaire-Marcel, Claude, Hollos, George, Boaretto, Elisabetta, Taieb, Maurice (1990) The 36C1 ages of the brines in the Magadi-Natron basin, East Africa. Geochimica et Cosmochimica Acta, 54 (10) 2827-2833 doi:10.1016/0016-7037(90)90017-f | Journal (article/letter/editorial) | | 2827-2833 in U.S.A. The 36C1 ages of the brines in the Magadi-Natron basin, East Africa AARON KAUFMAN, I MORDECKAI...the East African Rift which includes both Lake Magadi and Lake Natron forms a closed basin within which...consistent with the time of the first appearance of the lake. These older brines also have lower I80 and ‘H values...accumulated brine, together with the known age of the Lake Magadi basin, may be used to estimate the importance...contribute less than 6% of the total 36C1present in the lake. INTRODWXION the basin, and its brines record |  | | Journal (article/letter/editorial) | | hydrous sodium silicates from the northern bank of Lake Chad: occurrence, petrology and genesis D. Sebag...the Holocene in N'Guigmi interdunal depressions (Lake Chad), which led to the precipitation of various...evolution, of which the ®nal stage is probably Magadi-type chert. The study of various deposits of these minerals...Keywords: Arid environment; Diagenesis; Holocene; Lake Chad; Silicate minerals; Sodium 1. Introduction...metastability of the mineral (they transform into chert). Despite numerous analyses and syntheses of these |  | | Report (chapter) | | of algal blooming and mortality in a stratified lake (Donovan 1980). Many carbonate laminites and some...organic-rich laminites contain chert nodules, interpreted as magadi-type chert enclosing pseudomorphs after...source rocks were deposited from saline, alkaline lake waters. Introduction The source-rock potential...1980) using a widely-quoted model of lake stratification and lake-margin sedimentation. The Middle ORS...transgression, with fluviatile incursions at low lake level (Mykura 1976). Sediment accumulation was generally |  | | Report (volume) | | facies of the Gila Conglomerate near Buckhorn, Grant County, New Mexico, U.S. Geological Survey Bulletin 1763...Facies of the Gila Conglomerate Near Buckhorn, Grant County, New Mexico By ARTHUR J. GUDE, 3rd, and RICHARD...Facies of the Gila Conglomerate Near Buckhorn, Grant County, New Mexico (U.S. Geological Survey Bulletin ;...tuff, etc.-New Mexico-Grant County. 2. Lake sediments-New Mexico-Grant County. 3. Gila Conglomerate (Ariz...(Ariz. and N.M.) 4. Geology-New Mexico-Grant County. I. Sheppard, Richard A. II. Title. Ill. Series. Qe75 |  | | Journal (article/letter/editorial) | | reactions in the sedimentary deposits of the Lake Magadi region, Kenya RONALD C. SURD AM Department of Geology...M a g a d i basin in the Eastern Rift Valley of Kenya have been investigated. Samples were available f...the t r a n s f o r m a t i o n of magadiite to chert. Analcime in the drill-core samples grew at the...This gel f o r m s at the lake shore a n d is w a s h e d i n t o the lake d u r i n g flooding conditions...glasses, a n d the brines they come in contact with. Lake M a g a d i represents a u n i q u e o p p o r t |  | | Journal (article/letter/editorial) | | makatite (Sheppard et al. 1970)at Lake Magadi, Kenya, and kanemite at Kanem, Lake Chad (Johan and Maglione, 1972)...from the Magadi area (alluvial channel, Lake Magadi) provided by the Magadi Soda Comp., Kenya, was studiedfor...adjoining silicate layers into pairs. Brindthe magadi area (Eugster, 1969).However, the transfor- ley...natural process in the field as an open system county, California (Gude and Sheppard, 1972)is in fact...regular developedplates;(e) natural kenyaite(Lake Magadi, Kenya); (f) run 27 Z (100'C?2 years, 9:222:l\, |
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Lake Magadi, Kajiado County, Kenya