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Evidence from landscape evolution may provide critical constraints for past geodynamic processes, but has been limited by the large uncertainties of topographic reconstructions. Here we present continuous 30-million-year rock uplift histories for three catchments in the Calabrian forearc of southern Italy, using a data-driven inversion of tectonic geomorphology measurements. We find that rock uplift rates were high (>1 mm yr−1) from about 30 to 25 million years ago (Ma) and progressively declined to <0.4 mm yr−1 by ~15 Ma, then remained low before abruptly increasing around 1.5–1.0 Ma. These uplift rates do not match the forearc’s subduction velocity record, implying that uplift was not dominated by crustal thickening due to subduction-driven sediment influx. Through comparisons with slab descent reconstructions, we instead argue that the forearc uplift history primarily reflects the progressive establishment and abrupt destruction of an upper-mantle convection cell with strong negative buoyancy. We suggest that the convection cell vigour increased as the slab-induced mantle flow field began to interact with the 660-km mantle transition zone, causing uplift rates to decline from 25 to 15 Ma. Then, once the slab encountered the transition zone, the fully established convection cell subdued uplift rates, before being disrupted by slab fragmentation in the Quaternary, driving rapid forearc uplift.
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Tectonic and Paleoclimatic Setting for Hominin Evolution in Eastern Africa
As dynamic processes in the Earth’s mantle stretch and thin large sectors of the African plate, broad plateaus interrupted by deep valleys and flanking mountains have formed at the Earth’s surface. These vertical and horizontal crustal movements occur concurrent with global climate changes, both of which happen over diverse spatial and temporal scales. Together, they modulated eastern Africa’s habitats for early hominins, and for flora and fauna in general. The habitat for hominin evolution, therefore, is shaped by bottom-up and top-down processes. Broad plateau uplift in Ethiopia had initiated by 30 Ma, coincident with or after flood magmatism at 45 Ma when dry seasonal woodland environments initiated in eastern Africa. The fossil-rich sedimentary sequences partially filling the 30–70-km-wide rift basins record the history of human evolution, as well as the complex interplay between climate change, uplift, volcanism, and faulting in equatorial Africa. The lake shorelines and hydrothermal systems served as oases for hunter-gatherers, and the rough topography of the faulted landscape may have served as refugia. Here, we outline the relevant time–space patterns to establish the geodynamic and paleoclimatic context for human evolution in eastern Africa.
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- Award ID(s):
- 2039963
- PAR ID:
- 10464165
- Date Published:
- Journal Name:
- Elements
- Volume:
- 19
- Issue:
- 2
- ISSN:
- 1811-5209
- Page Range / eLocation ID:
- 82 to 87
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.2138/gselements.19.2.82
