record of inception of the Antarctic Circumpolar Current and coeval glacio-eustatic Iowstand?

• Main Authors: Craig S. Fulthorpe, Robert M. Carter, Kenneth G. Miller, Julia Wilson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1995
• Subjects: sequence stratigraphy; sea-lev; Antarctic; New Zealand; Pacific; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.505.1187; http://rockbox.rutgers.edu/kgmpdf/96-fulthorpe.m%26pgeo.pdf

New Zealand, is the product of a long-term (80 Ma), tectonically controlled relative sea-level cycle with a megasequence geometry analogous to the sequence stratigraphic model of Vail (Am. Assoc. Petrol GeoL Stud. GeoL No. 27, 1, 1-10, 1987). The condensed section of the megasequence, resolvable in detail in outcrop and on seismic profiles, comprises a basin-wide pelagic to hemipelagic limestone interval. A regional mid-Oligocene unconformity, the Marshall Paraconformity, lies within the limestone interval onshore and correlates with hiatuses in at least two, and possibly three, offshore exploration wells and with a temporary lithological change from limestone to quartz sand at a fourth. Strontium isotopic age estimates confirm that a 2-4 Ma hiatus is associated with onshore outcrops of the Marshall Paraconformity (between-32 and 29 Ma), which correlates with the opening of the Pacific sector of the Southern Ocean and the postulated mid-Oligocene sea-level fall of Haq et aL (Science 235, 1156-1167, 1987; Spec. Pub/. Soc. Econ. Paleonotol. Mineral No. 42, 71-108, 1988). Lowering of base level, coupled with cooling and enhancement of current activity, may have caused the temporary cessation of limestone deposition and a regional hiatus. This hypothesis reconciles the apparently contradictory palaeogeographical evidence for a regional