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| Titel |
The Moho in Australia and New Zealand |
| VerfasserIn |
Michelle Salmon, Brian Kennett, Malcolm Sambridge, Tim Stern |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077602
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| Zusammenfassung |
| Australia and New Zealand share in part a history in the Gondwana supercontinent.
Australia has a long and complex tectonic history with the last major accretion in the
early Paleozoic, whereas New Zealand is still undergoing major plate boundary
processes.
The Australian continent is relatively well covered with both active and passive seismic
techniques. Multiple sources of information are therefore available for building a model
of Moho depth. Results from on-shore and off-shore refraction experiments are
supplemented by receiver functions from a large number of portable stations and the
recently augmented set of permanent stations. Moho picks from more than 10500
km of full-crustal reflection profiles provide valuable additional constraints. The
composite data set provides good sampling of much of Australia, though coverage
remains low in some remote desert areas. The various datasets provide multiple
estimates of the depth to Moho in many regions, and the consistency between the
different techniques is high. Some of the thinnest crust lies beneath the Archean
craton in the Pilbara, and in the neighbourhood of the Simpson desert. Thick crust is
encountered beneath parts of the Proterozoic in Central Australia, and beneath
the Paleozoic Lachlan fold belt in southeastern Australia. There are a number of
zones of sharp contrast in depth to Moho, notably in the southern part of Central
Australia.
Despite most of the continental material around New Zealand being submerged, Moho
data for this region is mainly onshore concentrating on the Australia–Pacific plate
boundary. Two major wide-angle reflection transects provide the bulk of the active
source data with just a few traditional reflection profiles offshore. The plate bound-
ary provides an abundance of local earthquakes for tomographic imaging and this
data is supplemented with receiver functions from both portable and permanent
networks.Onshore the combined coverage is as dense as that of Australia, although it could
be argued that a higher spatial resolution is required to capture the nature of the
Moho of tectonically active New Zealand. Three regions of thickened crust can be
identified, one beneath the Southern Alps, another beneath Fiordland, and below
the Wanganui Basin between the North and South Island. Thin crust is identified
west of the volcanic arc, with extensive underplating below the back-arc region. |
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