Crustal structure of the southern Kerguelen Plateau derived from P-wave velocity data

Tabea.Altenbernd [ at ]


The fabric of the southernmost Kerguelen Plateau (SKP) is of great interest since rock samples suggest a continental component in this part of the Kerguelen Plateau. We present a P-wave velocity and a density model derived from a research cruise conducted in East Antarctica in 2007. The seismic profile AWI-20070200 is a cross-section of the Princess Elizabeth Trough (PET) between the Princess Elizabeth Land (East Antarctica) and the SKP. It extends in a N to S direction and investigates the crustal structure of the SKP for ~250 km . The P-wave velocity model of the PET area reveals a 5 - 8 km thick, 2-3-layered oceanic crust, which thickness decreases towards the Kerguelen Plateau. In terms of processes, the oceanic crust in the PET seems to be unaffected by the Kerguelen hotspot magmatism, which should have resulted in overthickened crust. The oceanic crust in our model is underlain by upper mantle with velocities of 7.8 - 8.0 kms-1. The sedimentary cover is ~3.5 km thick with velocities of 1.6-3.7 kms-1. 0.5-1.2 km thick sediments with velocities of 1.8 - 2.4 kms-1 cover the crust of the SKP. The thickness of the underlying crust increases in three steps towards the north and reaches a maximum thickness of 22 km. The P-wave velocity structure of this unit is quite homogenous. The crust is characterized by 4 crustal layers, with velocities ranging between 4.0-4.8 kms-1 (crustal layer 1), 5.0-5.5 kms-1 (crustal layer 2), 5.6-6.0 kms-1 (crustal layer 3), and 6.7-7.0 kms-1 (lowermost crustal layer). The base of the crust is well defined by numerous reflected phases at the crust-mantle boundary. The thickness of the investigated crust of SKP is similar to that of northern and southern Kerguelen Plateau. In contrast, we could not identify velocities of 7.2-7.4 kms-1 in the lowermost crust of the SKP as reported for the lower crust beneath Northern Kerguelen Plateau

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AGU Fall Meeting, 11 Dec 2017 - 15 Dec 2017, New Orleans, USA.
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Altenbernd, T. and Jokat, W. (2017): Crustal structure of the southern Kerguelen Plateau derived from P-wave velocity data , AGU Fall Meeting, New Orleans, USA, 11 December 2017 - 15 December 2017 .

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