TY  - JOUR
A1  - Margirier, Audrey
A1  - Braun, Jean
A1  - Gautheron, Cecile
A1  - Carcaillet, Julien
A1  - Schwartz, Stephane
A1  - Jamme, Rosella Pinna
A1  - Stanley, Jessica
T1  - Climate control on Early Cenozoic denudation of the Namibian margin as deduced from new thermochronological constraints
JF  - Earth & planetary science letters
N2  - The processes that control long term landscape evolution in continental interiors and, in particular, along passive margins such as in southern Africa, are still the subject of much debate (e.g. Braun, 2018). Although today the Namibian margin is characterized by an arid climate, it has experienced climatic fluctuations during the Cenozoic and, yet, to date no study has documented the potential role of climate on its erosion history. In western Namibia, the Brandberg Massif, an erosional remnant or inselberg, provides a good opportunity to document the Cenozoic denudation history of the margin using the relationship between rock cooling or exhumation ages and their elevation. Here we provide new apatite (UThSm)/He dates on the Brandberg Inselberg that range from 151 +/- 12 to 30 +/- 2 Ma. Combined with existing apatite fission track data, they yield new constraints on the denudation history of the margin. These data document two main cooling phases since continental break-up 130 Myr ago, a rapid one (similar to 10 degrees C/Myr) following break-up and a slower one (similar to 12 degrees C/Myr) between 65 and 35 Ma. We interpret them respectively to be related to escarpment erosion following rifting and continental break-up and as a phase of enhanced denudation during the Early Eocene Climatic Optimum. We propose that during the Early Eocene Climatic Optimum chemical weathering was important and contributed significantly to the denudation of the Namibian margin and the formation of a pediplain around the Brandberg and enhanced valley incision within the massif. Additionally, aridification of the region since 35 Ma has resulted in negligible denudation rates since that time. (C) 2019 Elsevier B.V. All rights reserved.
KW  - climate
KW  - Early Eocene Climatic Optimum
KW  - apatite (U-Th-Sm)/He thermochronology
KW  - denudation
KW  - weathering
KW  - Namibian passive margin
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2019.115779
SN  - 0012-821X
SN  - 1385-013X
VL  - 527
PB  - Elsevier
CY  - Amsterdam
ER  -