Lake natron tanzania12/15/2023 ![]() ![]() ![]() ![]() The cherts, which consist of finely crystalline quartz, occur in massive bedded and nodular outcrops of irregular shape, with white coatings having reticulate surface patterns (Baker 19). The occurrences have been recorded at RHS-Mugulud and MHS-Bayasi sites in western Lake Natron.Ĭhert has formed from two sodium silicate minerals, magadiite (NaSi 7 O 13 (OH) 3-3H 2) and kenyaite (NaSi 11O 20 5(OH) 4–3H 2O) in the uppermost deposits of Lakes Natron and Magadi. 2), best known for the australopithecine mandible that fits the famous Olduvai Zinjanthropus skull, Australopithecus boisei ( Paranthropus boisei), as if they belonged to the same individual, and also for containing the earliest Acheulean sites contemporary to Konso Gardula sites in Ethiopia (Isaac and Curtis 1974 Schick and Toth 2006). Located to the west of Lake Natron is Peninj (Penin) (Fig. On the southeast, the basin is bounded by the prominent Gelai shield volcano which rises gently from the shores of the lake to an altitude of ca. 2013) before rising to the Manyara escarpment (Fig. South of Natron lies the Engaruka sedimentary basin separated from Natron by Oldonyo Lengai (2,878 m), an active carbonatite explosive volcano that erupted as recently as 2007/2008, the Kerimasi volcano, and a horst created by oblique faults (Luque et al. The Sonjo Faults limit the basin to the west. In the south, the rift tectonics give rise to two parallel escarpments, the Sambu and Sanjan. The slopes consist of Plio-Pleistocene sediments which are devoid of important fossils, unlike in the west, although they abound with artifacts. On the east, the Natron basin is punctuated by a network of horsts and grabens oriented north–south, a feature typical of the rift axis in Kenya and Tanzania (Baker 1963, 1986), and the gradient is less steep and forms part of the Gelai hills. 1997 Isaac and Curtis 1974 Manega 1993 Sherrod et al. Radiometric ages from these stratigraphic units suggest that Humbu and Monik Formations were deposited between 1.8 and 1.1 mya (Foster et al. They grade upward from the deltaic Humbu Formation to the lake deposits of the Monik Formation (Sherrod et al. The basin has a protracted history of volcanism, sedimentation, and faulting with the sedimentary deposits accumulating before about 2 million years ago (mya). Massive outcrops of volcanoes aside, the salient geographical features here are the escarpments dominated by Nguruman, and extending from the northern basin into the west lake margin. The Shombole Volcano (1,565 m) separates the Magadi and Natron sub-basins while Oldonyo Sambu (2,045 m) was the barrier during the Lower Pleistocene (Luque et al. At times, Lakes Natron and Magadi were joined as one paleolake, Orolonga, but they are now separated after a shift that occurred around 9,000 BP (Baker 1958 Vanetti 2009/2010). Both Lakes Natron and Magadi are situated on the rift floor of the Eastern Rift Valley System (Gregory Rift), bounded to the east and north by volcanoes, and escarpments to the west (Fig. It is this river that provides most of the surface water to the lake. 1, 2) is a half graben that forms a long chain of tectonic basins, considerably larger than the northern half of the greater basin, i.e., the Magadi sub-basin and Ewaso Ngiro River floodplain in southern Kenya. ![]()
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