Age of Lucy and the First Family: Single-crystal 40Ar/39Ar dating of the Denen Dora and lower Kada Hadar members of the Hadar Formation, Ethiopia
- 1 January 1994
- journal article
- research article
- Published by Geological Society of America in Geology
- Vol. 22 (1) , 6-10
- https://doi.org/10.1130/0091-7613(1994)022<0006:aolatf>2.3.co;2
Abstract
Single-crystal laser-fusion 40Ar/39Ar analyses on previously undatable tephra deposits provide the first reliable dates for the important hominid fossils popularly called ''Lucy'' and the ''First Family,'' here dated to 3.18 and 3.20 Ma, respectively. These results help to establish an age framework for hominid and biostratigraphic evolution for the fossil-rich Hadar Formation. The abundance of well-preserved vertebrate fossils at Hadar can be attributed, in part, to an unusually high sediment-accumulation rate of approximately 80 cm/ka, which might be due to increased tectonic subsidence of the Hadar basin between 3.4 and 3.2 Ma. The new dates also provide supportive evidence that the boundary ages for the Kaena and Mammoth subchrons, of the geomagnetic polarity time scale, need to be increased by as much as 4% to 5%.This publication has 2 references indexed in Scilit:
- Geochronology and distribution of silicic volcanic rocks of Plio-Pleistocene age from the central sector of the Main Ethiopian RiftQuaternary International, 1992
- Age-probability spectra for examination of single-crystal dating results: Examples from Olorgesailie, southern Kenya RiftQuaternary International, 1992