کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4677975 1634826 2011 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
An astronomically-tuned climate framework for hominins in the Turkana Basin
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
An astronomically-tuned climate framework for hominins in the Turkana Basin
چکیده انگلیسی

Understanding the influence of orbital climate cycles on hominin evolution remains a key challenge in paleoanthropology. The two major unresolved issues are: the absence of a climate proxy yielding high-resolution (< 20 kyr) terrestrial climate records, and the lack of age control on hominin fossil occurrences at sufficiently high resolution. Here we present a novel climate proxy, strontium isotope ratios (87Sr/86Sr) of lacustrine fish fossils from the Turkana Basin, that solves these issues by recording orbitally forced variation in summer monsoon intensity over the Ethiopian Highlands. We successfully applied the climate proxy to a ~ 150 kyr time interval of ~ 2 million year old paleolake deposits containing hominin fossils. Existing age control of the studied interval was improved by a new magnetostratigraphic record precisely locating the base of the Olduvai chron (C2n) near the bottom of the sequence. Spectral analysis demonstrates that 87Sr/86Sr variability is primarily determined by precession, which enables us to place hominin fossils in an astronomically-tuned climate framework. The Sr climate proxy is potentially applicable to all hominin-bearing lake deposits in the Turkana Basin, ranging in age from ~ 4.2 to 0.8 million years ago (Ma). Our results demonstrate that between ~ 2 and 1.85 Ma the Turkana Basin remained well-watered and inhabited by hominins even during periods of precession maxima when summer monsoon intensity was lowest. This is in contrast to other basins in the East African Rift System (EARS) that were impacted heavily by precession-forced droughts. We hypothesize that during lake phases, the Turkana Basin was an aridity refugium for permanent-water dependent fauna – including hominins – over the precessional climate cycles.

Research highlights
► 87Sr/86Sr of paleolake Turkana fish reflects orbital variation in Ethiopian monsoon.
► 87Sr/86Sr record from early paleolake Lorenyang reveals ~ 6 precession cycles.
► Hominins were present in both wet and dry periods of the precession cycles.
► We hypothesize that the lacustrine Turkana Basin was an aridity refugium for hominins.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 307, Issues 1–2, 1 July 2011, Pages 1–8
نویسندگان
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