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New Zealand’s Poverty Shelf Yields Wealth of Information on Shallow Marine Sediment Dispersal

J. G. Parra
California State University, Northridge, CA, [email protected]

The Poverty Shelf, North Island, New Zealand, offers an exceptional opportunity to examine the degree to which terrestrial, climatic, and anthropogenic signals are propagated onto a shelf and preserved in a tectonically active forearc basin. A total of 205 cores (94 Kasten, 87 box, and 24 vibra cores) were collected during a January 2005 MARGINS Source-to-Sink cruise aboard the R/V Kilo Moana. Representative sandy core samples examined in this study show three distinct sand types present within the shelf. Two types contain volcanic lithic debris originating from the Taupo volcanic zone located directly west of the Poverty Shelf: in one type (primary volcanic deposit?) volcanic lithics are the dominant component, whereas in the second type they are admixed with sedimentary lithic debris. The latter type likely represents reworked tephra associated with fluvial detritus. The third type is quartzo-feldspathic sand recycled from onshore sedimentary units or alternatively transported into the basin from the south. Anomalous greywacke pebbles in two box cores support the probability of such an extrabasinal source. This study provides a critical link between the modern onshore fluvial (Waipaoa River) and offshore deep-marine systems.

AAPG Search and Discovery Article #90088©2009 Pacific Section Meeting, Ventura, California, May 3-5, 2009