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Morphological variability of clinoforms within the Giant Foresets Formation of the northern Taranaki Basin, New Zealand

Migdalys Salazar
The University of Texas at Austin, Jackson School of Geosciences, Austin, Texas, USA
[email protected]

The study of morphological variations within continental-margin clinoforms is of critical importance to the understanding of transport mechanisms affecting the shelf margin region. In this study, variations in clinoform morphologies within the Plio-Pleistocene Giant Foresets Formation were documented by interpreting clinoform architectures in along-dip regional seismic sections in the northern Taranaki Basin, New Zealand.

Seismic geomorphological interpretations and paleontological studies were combined to better understand the succession. Measurements of clinoform parameters including height and length, and foreset declivity were obtained from nine seismic units. Progradation and aggradational rates were also computed based on these measurements. Three distinct morphologies were identified within the clinoform packages: gentle and smooth, steep and rough, and sigmoidal. The best curve fittings for these slope profiles correspond to linear, exponential, and Gaussian distribution functions.

Gentle and smooth clinoform morphologies are associated with moderate to high sediment input and most likely related to a low degree of canyon incision and basin/slope fan deposition during the early Pliocene. The steeper and dissected clinoforms located within the middle portion of the succession are associated with a higher degree of canyon incision and sediment bypass toward the basin. High progradation levels and backarc rifting seem to be the main controls for the deposition of this interval. Finally, sediment supply increased during the deposition of the shallower, oversteepened section. These sigmoidal clinoform packages might be associated to increasing aggradational rates and action of alongshore currents, generating an increased chance to preserve sediments in the roll-over region of the clinoforms.

 

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects