40Ar/39Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change

The FLK Zinj paleolandscape: Reconstruction of a 1.84 Ma wooded habitat in the FLK Zinj-AMK-PTK-DS archaeological complex, Middle Bed I (Olduvai Gorge, Tanzania)

“…Tuff IB is an ash-fall tuff dated 1.848 ±0.003 Ma. It is mineralogically distinct from Tuff IC, but both tuffs yield indistinguishable argon-argon ages of 1.848 ± 0.008 Ma and 1.848 ± 0.003 Ma (Deino, 2012). Hence, sediments and paleosols between tuffs IB and IC were likely deposited within a time interval of 0.011 Ma (Magill et al 2016).…”

“…Each sample is composed of 3-5 sub-samples collected less than 50 cm apart, 0-2 cm under Tuff IC. This sampling procedure ensures the identification of the vegetation pattern existing in the Zinj paleolandscape immediately prior to the deposition of Tuff IC at about 1.84 Ma (Deino, 2012). Different samples were sometimes collected very close by because of lateral facies change such as at PTK in Trench 10/2013 (samples DB14-11 and -09) and in Trench 22/2014 (samples DB14-46 to -48) ( Fig.…”

Hominin taxic diversity: Fact or fantasy?

“…Kullmer (2008) uses biostratigraphy to generate an age range of c.2.5-2.3 Ma for a maxilla assigned to P. boisei from Malema. Based on argon dating and magnetostratigraphy, the specimens from Bed I and Bed II at Olduvai Gorge span the range from c.1.92 to 1.15 Ma, with OH 3, OH 36, and possibly OH 38 from Upper Bed II as the youngest specimens (Tamrat et al, 1995;Deino, 2012). The Peninj 1 mandible has an age range of c.1.5-1.3 Ma based on potassiumargon and argon dating (Dom ınguez-Rodrigo et al, 2009 …”

The Ngorongoro Volcanic Highland and its relationships to volcanic deposits at Olduvai Gorge and East African Rift volcanism

“…The bulk of 40 Ar/ 39 Ar data come from an unpublished Ph.D. dissertation by P. Manega (1993); for completeness, these results are included here in the Discussion. Additional 40 Ar/ 39 Ar dating of Olduvai and Laetoli is currently in progress (Blumenschine et al, 2003;Deino et al, 2012). This contribution is part of an ongoing study to formulate a geochemical and geochronological framework for the Tanzanian EAR-related volcanism.…”

“…The tephra serve as the primary basis for basin-wide correlations as well as providing detailed chronological control for the research conducted by OLAPP. Geochronological study at Olduvai includes KeAr (Curtis and Hay, 1972;Drake and Curtis, 1987;Manega, 1993), 40 Ar/ 39 Ar (Walter et al, 1991(Walter et al, , 1992Manega, 1993;Deino et al, 2012), paleomagnetics (Grommé and Hay, 1963, 1967, 1971Grommé et al, 1970;Tamrat et al, 1995;Deino et al, 2012), amino acid racemization (Manega, 1993), and Electron Spin Resonance (ESR; Skinner et al, 2003). These data provide the current temporal framework for the Olduvai section and constrain the timing of fault movement (e.g., Macintyre et al, 1974;Hay, 1976;Dawson, 1992) and tectonic development of the region (e.g., Foster et al, 1997).…”