Global and local controls on depositional cyclicity: Canterbury basin, New Zealand
text The eastern margin of the South Island of New Zealand is part of a continental fragment that rifted from Marie Byrd Land in Antarctica beginning at about 80 Ma. High rates of sediment supply since the middle Miocene have resulted in the preservation of a high-frequency, seismically resolvable r...
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ftunivtexas:oai:repositories.lib.utexas.edu:2152/2075 2023-05-15T13:44:26+02:00 Global and local controls on depositional cyclicity: Canterbury basin, New Zealand Lu, Hongbo Fisher, W. L. Fulthorpe, Craig Stephen, 1954- 2004 electronic application/pdf http://hdl.handle.net/2152/2075 eng eng b60817471 http://hdl.handle.net/2152/2075 68811260 3145396 Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. Sedimentation and deposition--New Zealand--Canterbury Basin Thesis 2004 ftunivtexas 2020-12-23T22:18:22Z text The eastern margin of the South Island of New Zealand is part of a continental fragment that rifted from Marie Byrd Land in Antarctica beginning at about 80 Ma. High rates of sediment supply since the middle Miocene have resulted in the preservation of a high-frequency, seismically resolvable record of depositional cyclicity in the offshore Canterbury basin. In addition, along-strike currents have influenced deposition, modifying sequence architecture while forming large sediment drifts. High-resolution multichannel seismic (MCS) data provide insights into the interplay of global (eustastic) and local controls (tectonics and current activity) responsible for continental margin depositional cyclicity and sequence architecture. At least eleven large, elongate sediment drifts are identified within the Neogene shelf-slope sediment prism. The drifts were deposited in water depths of 300-750 m and developed in response to a northward flowing current. Their subsequent evolution is influenced by sediment supply, relative sea-level change, and seafloor morphology. Unconformities created by paleoslope erosion at the landward edges of drift moats differ from sequence boundaries by being strongly diachronous. Nineteen regional sequence-bounding unconformities are interpreted. Correlation with oxygen isotopic records suggests that eustasy controls the timing of sequence boundaries. In contrast, sequence thickness, shelf edge stacking patterns, internal seismic facies, and slope inclination, are strongly influenced by local processes, principally the along-strike currents responsible for drift development. Sequences with conventional clinoform geometries along strike from active drifts suggest that currents might influence clinoform formation even in locations lacking seismic evidence of current reworking. Reconstruction of Australian-Pacific relative plate motion reveals divergence in the central Southern Alps prior to ~20.1 Ma, followed by increasing average rates of convergence, with a marked increase after ~6 Ma. Sedimentation rates, calculated from sequence volumes, correlate well with convergence rates since ~11.5 Ma, indicating that tectonism has been the dominant control on sediment supply. In particular, high rates of sediment supply since 6 Ma, may reflect previously recognized increased plate convergence and Southern Alps uplift. In contrast, high sedimentation rate from ~15-11.5 Ma correlates with low convergence rates and is therefore probably a response to global climatic forcing and eustasy. Geological Sciences Thesis Antarc* Antarctica Marie Byrd Land The University of Texas at Austin: Texas ScholarWorks Pacific New Zealand Byrd Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) |
institution |
Open Polar |
collection |
The University of Texas at Austin: Texas ScholarWorks |
op_collection_id |
ftunivtexas |
language |
English |
topic |
Sedimentation and deposition--New Zealand--Canterbury Basin |
spellingShingle |
Sedimentation and deposition--New Zealand--Canterbury Basin Lu, Hongbo Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
topic_facet |
Sedimentation and deposition--New Zealand--Canterbury Basin |
description |
text The eastern margin of the South Island of New Zealand is part of a continental fragment that rifted from Marie Byrd Land in Antarctica beginning at about 80 Ma. High rates of sediment supply since the middle Miocene have resulted in the preservation of a high-frequency, seismically resolvable record of depositional cyclicity in the offshore Canterbury basin. In addition, along-strike currents have influenced deposition, modifying sequence architecture while forming large sediment drifts. High-resolution multichannel seismic (MCS) data provide insights into the interplay of global (eustastic) and local controls (tectonics and current activity) responsible for continental margin depositional cyclicity and sequence architecture. At least eleven large, elongate sediment drifts are identified within the Neogene shelf-slope sediment prism. The drifts were deposited in water depths of 300-750 m and developed in response to a northward flowing current. Their subsequent evolution is influenced by sediment supply, relative sea-level change, and seafloor morphology. Unconformities created by paleoslope erosion at the landward edges of drift moats differ from sequence boundaries by being strongly diachronous. Nineteen regional sequence-bounding unconformities are interpreted. Correlation with oxygen isotopic records suggests that eustasy controls the timing of sequence boundaries. In contrast, sequence thickness, shelf edge stacking patterns, internal seismic facies, and slope inclination, are strongly influenced by local processes, principally the along-strike currents responsible for drift development. Sequences with conventional clinoform geometries along strike from active drifts suggest that currents might influence clinoform formation even in locations lacking seismic evidence of current reworking. Reconstruction of Australian-Pacific relative plate motion reveals divergence in the central Southern Alps prior to ~20.1 Ma, followed by increasing average rates of convergence, with a marked increase after ~6 Ma. Sedimentation rates, calculated from sequence volumes, correlate well with convergence rates since ~11.5 Ma, indicating that tectonism has been the dominant control on sediment supply. In particular, high rates of sediment supply since 6 Ma, may reflect previously recognized increased plate convergence and Southern Alps uplift. In contrast, high sedimentation rate from ~15-11.5 Ma correlates with low convergence rates and is therefore probably a response to global climatic forcing and eustasy. Geological Sciences |
author2 |
Fisher, W. L. Fulthorpe, Craig Stephen, 1954- |
format |
Thesis |
author |
Lu, Hongbo |
author_facet |
Lu, Hongbo |
author_sort |
Lu, Hongbo |
title |
Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
title_short |
Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
title_full |
Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
title_fullStr |
Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
title_full_unstemmed |
Global and local controls on depositional cyclicity: Canterbury basin, New Zealand |
title_sort |
global and local controls on depositional cyclicity: canterbury basin, new zealand |
publishDate |
2004 |
url |
http://hdl.handle.net/2152/2075 |
long_lat |
ENVELOPE(-130.000,-130.000,-78.000,-78.000) |
geographic |
Pacific New Zealand Byrd Marie Byrd Land |
geographic_facet |
Pacific New Zealand Byrd Marie Byrd Land |
genre |
Antarc* Antarctica Marie Byrd Land |
genre_facet |
Antarc* Antarctica Marie Byrd Land |
op_relation |
b60817471 http://hdl.handle.net/2152/2075 68811260 3145396 |
op_rights |
Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
_version_ |
1766201657982451712 |