Profiling mass extinction: the K-T event from swamp to deep ocean

Collection of K-T boundary slab

Scientists collecting a rock slab spanning the K-T boundary at Wharanui Point, coastal eastern Marlborough. Cretaceous strata are to the right and the K-T boundary lies at the base of the dark interval, which is c. 1 m thick. Photo: M. Dow

The popular media present the extinction of dinosaurs and other fossil groups by a meteorite impact 66 million years ago as an established fact. But paleontologists are still doubtful about the cause, pointing to extinctions which were selective, and to others which were gradual rather than sudden. Until now, it has been widely thought that the biota of high latitudes were somehow protected from the most severe effects of the meteorite impact. If the primary killing mechanism was a global cloud of dust from the impact shutting off sunlight for months to years and causing freezing conditions and light levels too low for photosynthesis, then perhaps high-latitude flora and fauna were pre-adapted for this “impact winter”. The long-standing enigma with this scenario is that there is no evidence that Southern Hemisphere dinosaurs, or their marine counterparts which are plentiful in New Zealand rocks, escaped mass extinction at the end of the Cretaceous period.

Main findings:

A multidisciplinary team of geoscientists has examined the fossil and sedimentary record of this mass extinction in selected New Zealand sites, representing a high-latitude transect from fresh-water swamp to the deep sea. New Zealand had separated from Antarctica by 66 million years ago but was still close to the pole at approximately 60°S. Their study has shown that the effects of the impact were just as sudden and dramatic as has previously been documented for lower latitudes and regions closer to the impact site. Warm-climate species on land and in the sea suffered sudden extinction or massive decline in numbers. In contrast, opportunistic cool-tolerant species bloomed, apparently in response to the freeing up of nutrients or living space. Both terrestrial and oceanic ecosystems were fundamentally altered by the after-effects of the impact, with the diverse biological communities of the Cretaceous period being replaced first by opportunistic species, and subsequently by relatively few species tolerant of cool climatic conditions. These were the predominant life forms in New Zealand for over 1 million years following the impact.

Thus, the effects of the meteorite impact in Southern Hemisphere realms are shown to be just as severe as has been documented for lower-latitude regions and apparently with much slower recovery due to a prolonged episode of cool climatic conditions. The study concluded that fundamental disruption to the global carbon cycle, due to extinctions of marine plankton and massive vaporisation of carbonate target rocks, resulted in long-term changes in global climate, especially evident in temperate and polar southern regions.

Major publications:
  • Willumsen, P. S., 2011. Maastrichtian to Paleocene dinocysts from the Clarence Valley, South Island, New Zealand. Alcheringa: An Australasian Journal of Palaeontology 35: 199-240.
  • Willumsen, P. S., 2006. Palynodinium minus sp. nov., a new dinoflagellate cyst from the Cretaceous/Paleogene transition in New Zealand; its significance and palaeoecology. Cretaceous Research 27: 954-963.
  • Bauluz, B., Peacor, D.R., Hollis, C.J., 2004. TEM study of meteorite impact glass at New Zealand Cretaceous-Tertiary sites: evidence for multiple impacts or differentiation during global circulation? Earth and Planetary Science Letters 6984, 1-11.
  • Vajda, V., Raine, J.I., Hollis, C.J., Strong, C.P., 2004. Global effects of the Chixculub Impact on terrestrial vegetation - review of the palynological record from New Zealand Cretaceous/Tertiary boundary, in: Dypvik, H., Burchell, M., Claeys, P. (Eds.), Cratering in marine environments and on ice. Springer, Germany, pp. 57-74.
  • Field, B.D., Hollis, C.J., 2003. Orbitally controlled cyclicity around the Cretaceous-Cenozoic boundary, Marlborough, New Zealand. New Zealand Journal of Geology and Geophysics 46, 235-241.
  • Hollis, C.J., 2003. The Cretaceous-Tertiary boundary event in New Zealand: profiling mass extinction. New Zealand Journal of Geology and Geophysics 46, 307-321.
  • Hollis, C.J., 2003. Fatal impact: the asteroid impact that wiped out the dinosaurs. Alpha 116, 1-8.
  • Hollis, C.J., Rodgers, K.A., Strong, C.P., Field, B.D., Rogers, K.M., 2003. Paleoenvironmental changes across the Cretaceous/Tertiary boundary in the northern Clarence Valley, southeastern Marlborough, New Zealand. New Zealand Journal of Geology and Geophysics 46, 209-234.
  • Hollis, C.J., Strong, C.P., 2003. Biostratigraphic review of the Cretaceous/Tertiary Boundary transition, mid-Waipara River section, North Canterbury, New Zealand. New Zealand Journal of Geology and Geophysics 46, 243-254.
  • Hollis, C.J., Strong, C.P., Rodgers, K.A., Rogers, K.M., 2003. Paleoenvironmental changes across the Cretaceous/Tertiary boundary at Flaxbourne River and Woodside Creek, eastern Marlborough, New Zealand. New Zealand Journal of Geology and Geophysics 46, 177-197.
  • Su, S., McArdle, B.H., Rodgers, K.A., Hollis, C.J., 2003. Wavelet analysis of variations in geochemical and microfossil data across the Cretaceous/Tertiary boundary at Flaxbourne River. New Zealand Journal of Geology and Geophysics 46, 199-208.
  • Vajda, V., Raine, J.I., 2003. Pollen and spores in marine Cretaceous/Tertiary boundary sediments at mid-Waipara River, North Canterbury, New Zealand. New Zealand Journal of Geology and Geophysics 46, 255-273.
  • Vajda, V., Raine, J.I., Hollis, C.J., 2001. Indication of global deforestation at the Cretaceous/Tertiary boundary by New Zealand fern spike. Science 294, 1700-1702.

Principal Investigator: Chris Hollis

Associate Investigators:

  • Ian Raine, GNS Science
  • Percy Strong, GNS Science
  • Brad Field, GNS Science
  • Poul Schiøler, GNS Science
  • Karyne Rogers, GNS Science
  • Graeme Wilson
  • Stephen Killops, The Open University ,UK
  • Michael Hanna, Victoria University of Wellington
  • Vivi Vajda, Lund University
  • Pi Suhr Willumsen, Aarhus University