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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2002
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| Online Access: | https://www.redalyc.org/articulo.oa?id=57219311 |
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Table of Contents:
- The early Middle Miocene paleoenvironmental setting of New Zealand Brad D. Field Martin P. Crundwell James P. Kennett Peter R. King Craig M. Jones George H. Scott Ciencias de la Tierra 608 588 590 eustasy isotopes New Zealand has a middle Miocene (~16.4-11.2 Ma) sedimentary record that extends fromterrestrial through to distal oceanic paleoenvironmental settings available for study in outcrop,petroleum exploration wells and deep sea drillholes. We use this data to establish a new model forthe region at the beginning of middle Miocene times on a palinspastic base map, as a starting pointfor the study of later middle Miocene global cooling and its effects.The New Zealand record provides useful clues to SW Pacific circulation patterns and theeffects of global cooling during the middle Miocene. The New Zealand subcontinent extended overseveral degrees of paleolatitude and probably formed a north-south barrier to warm, South Pacificgyre circulation, forcing warm-temperate surface currents to pass up the western coast. To thesouth, cold circumpolar currents entered the Pacific and passed up the SE margin of paleo-NewZealand. Shelves were narrow in the north and west but broadened to several tens of kilometres widein the east and south.Age-recalibration of published stable isotope data from DSDP sites 608, 588 and 590 showsthe main cooling period of the middle Miocene coincides with the New Zealand Lillburnian Stage.There also appears to have been a short period of cooling of bottom waters around 16.3 Ma (thebase of the New Zealand Clifdenian Stage), perhaps recording climatic instability just prior tobuildup of the East Antarctic Ice Sheet. Though we cannot yet determine if the ~16 Ma cooling wasassociated with glacioeustatic sea level fall, the proximal sedimentary record for New Zealand atthis time is consistent with a fall, followed by a rise. There is good evidence for contemporaneoustectonism and this might account for much or all of the fall. However, because the fall in relative sealevel occurred in several basins, on either side of the plate boundary, a purely tectonic origin wouldrequire it to be a New Zealand-wide event. 2002 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57219311 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.3 Vol.19