Topographic development of the Southern Alps recorded by the isotopic composition of authigenic clay minerals, South Island, New Zealand
Open Access
- 22 March 1999
- journal article
- Published by Elsevier BV in Chemical Geology
- Vol. 155 (3-4), 279-294
- https://doi.org/10.1016/s0009-2541(98)00165-x
Abstract
The Southern Alps are developing as a consequence of oblique collision between the Pacific and Australian plates. The Southern Alps lie on the west side of the South Island of New Zealand and create a massive rain shadow where greater than 12 m/year of rain falls on the west coast and semiarid conditions exist to the east. The rain-out effect across the mountains causes precipitation west of the Southern Alps to have δD and δ values averaging −30‰ and −5.5‰, whereas precipitation in the rain shadow to the east is isotopically lighter (δD=−72‰ and δ=−9.8‰). Such large differences in the isotopic composition of precipitation would not have existed prior to the development of significant topography. We have examined the topographic evolution of the Southern Alps using oxygen isotope analyses of authigenic kaolinites formed in the rain shadow to the east of the mountains between the Cretaceous (low topography) and the Pleistocene. Changes in the isotopic composition of authigenic clay minerals forming in equilibrium with meteoric water in the stratigraphic sequence record the development of Southern Alps topography and the resultant rain shadow. Our oxygen isotope analyses of authigenic kaolinites show a 5–6‰ decrease in the early Pliocene, from ∼18.2‰ in older rocks, to ∼12.3‰ in younger rocks. In addition, smectite is abundant in all samples from the Late Miocene to Recent, but is conspicuously absent in most older rocks, suggesting a change to a generally drier climate roughly coincident with the isotopic shift in kaolinites. This method may be useful in unraveling timing of development of mountain belts elsewhere in the world.
Keywords
This publication has 52 references indexed in Scilit:
- An Oxygen-Isotope Study of Weathering in the Eastern Amazon Basin, BrazilPublished by Wiley ,2013
- Diachronous uplift of the Tibetan plateau starting 40?Myr agoNature, 1998
- Isotopic evidence for shifts in atmospheric circulation patterns during the late Quaternary in mid–North AmericaGeology, 1996
- Geochronologic constraints of the uplift and metamorphism along the Alpine Fault, South Island, New ZealandNew Zealand Journal of Geology and Geophysics, 1995
- The effect of net-transfer reactions on the isotopic composition of mineralsBeiträge zur Mineralogie und Petrographie, 1990
- Stable-isotope geochronology of the Australian regolithGeochimica et Cosmochimica Acta, 1989
- Oxygen isotope dating of the Australian regolithNature, 1988
- Recent rapid uplift in the Bolivian Andes: Evidence from fission-track datingGeology, 1987
- Age of metamorphism and uplift in the Haast Schist Group at Haast Pass, Lake Wanaka and Lake Hawea, South Island, New ZealandNew Zealand Journal of Geology and Geophysics, 1985
- Stratigraphic, structural, and metamorphic relationships in the Dansey Pass area, Otago, New ZealandNew Zealand Journal of Geology and Geophysics, 1974