TY  - JOUR
A1  - Overduin, Pier Paul
A1  - Westermann, Sebastian
A1  - Yoshikawa, Kenji
A1  - Haberlau, Thomas
A1  - Romanovsky, Vladimir E.
A1  - Wetterich, Sebastian
T1  - Geoelectric observations of the degradation of nearshore submarine permafrost at Barrow (Alaskan Beaufort Sea)
JF  - Journal of geophysical research : Earth surface
N2  - Submarine permafrost degradation rates may be determined by a number of interacting processes, including rates of sea level rise and coastal erosion, sea bottom temperature and salinity regimes, geothermal heat flux and heat and mass diffusion within the sediment column. Observations of ice-bearing permafrost in shelf sediments are necessary in order to determine its spatial distribution and to quantify its degradation rate. We tested the use of direct current electrical resistivity to ice-bearing permafrost in Elson Lagoon northeast of Barrow, Alaska (Beaufort Sea). A sharp increase in electrical resistivity was observed in profiles collected perpendicular to and along the coastline and is interpreted to be the boundary between ice-free sediment and underlying ice-bearing submarine permafrost. The depth to the interpreted ice-bearing permafrost increases from <2 m below sea level to over 12 m below sea level with increasing distance from the coastline. The dependence of the saline sediment electrical resistivity on temperature and freezing was measured in the laboratory to provide validation for the field measurements. Electrical resistivity was shown to be effective for detection of shallow ice-bearing permafrost in the coastal zone. Historical coastal retreat rates were combined with the inclination of the top of the ice-bearing permafrost to calculate mean vertical permafrost degradation rates of 1 to 4 cm yr(-1).
Y1  - 2012
U6  - https://doi.org/10.1029/2011JF002088
SN  - 0148-0227
VL  - 117
IS  - 14
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ryberg, Trond
A1  - Haberland, Christian
A1  - Haberlau, Thomas
A1  - Weber, Michael H.
A1  - Bauer, Klaus
A1  - Behrmann, Jan H.
A1  - Jokat, Wilfried
T1  - Crustal structure of northwest Namibia: Evidence for plume-rift-continent interaction
JF  - Geology
N2  - The causes for the formation of large igneous provinces and hotspot trails are still a matter of considerable dispute. Seismic tomography and other studies suggest that hot mantle material rising from the core-mantle boundary (CMB) might play a significant role in the formation of such hotspot trails. An important area to verify this concept is the South Atlantic region, with hotspot trails that spatially coincide with one of the largest low-velocity regions at the CMB, the African large low shear-wave velocity province. The Walvis Ridge started to form during the separation of the South American and African continents at ca. 130 Ma as a consequence of Gondwana breakup. Here, we present the first deep-seismic sounding images of the crustal structure from the landfall area of the Walvis Ridge at the Namibian coast to constrain processes of plume-lithosphere interaction and the formation of continental flood basalts (Parana and Etendeka continental flood basalts) and associated intrusive rocks. Our study identified a narrow region (<100 km) of high-seismic-velocity anomalies in the middle and lower crust, which we interpret as a massive mafic intrusion into the northern Namibian continental crust. Seismic crustal reflection imaging shows a flat Moho as well as reflectors connecting the high-velocity body with shallow crustal structures that we speculate to mark potential feeder channels of the Etendeka continental flood basalt. We suggest that the observed massive but localized mafic intrusion into the lower crust results from similar-sized variations in the lithosphere (i.e., lithosphere thickness or preexisting structures).
Y1  - 2015
U6  - https://doi.org/10.1130/G36768.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 43
IS  - 8
SP  - 739
EP  - 742
PB  - American Institute of Physics
CY  - Boulder
ER  -