A digital rock density map of New Zealand

Robert Tenzer, Pascal Sirguey, Mark Rattenbury, Julia Nicolson

Research output: Journal article publicationJournal articleAcademic researchpeer-review

41 Citations (Scopus)

Abstract

Digital geological maps of New Zealand (QMAP) are combined with 9256 samples with rock density measurements from the national rock catalogue PETLAB and supplementary geological sources to generate a first digital density model of New Zealand. This digital density model will be used to compile a new geoid model for New Zealand. The geological map GIS dataset contains 123 unique main rock types spread over more than 1800 mapping units. Through these main rock types, rock densities from measurements in the PETLAB database and other sources have been assigned to geological mapping units. A mean surface rock density of 2440kg/m3for New Zealand is obtained from the analysis of the derived digital density model. The lower North Island mean of 2336kg/m3reflects the predominance of relatively young, weakly consolidated sedimentary rock, tephra, and ignimbrite compared to the South Island's 2514kg/m3mean where igneous intrusions and metamorphosed sedimentary rocks including schist and gneiss are more common. All of these values are significantly lower than the mean density of the upper continental crust that is commonly adopted in geological, geophysical, and geodetic applications (2670kg/m3) and typically attributed to the crystalline and granitic rock formations. The lighter density has implications for the calculation of the geoid surface and gravimetric reductions through New Zealand.
Original languageEnglish
Pages (from-to)1181-1191
Number of pages11
JournalComputers and Geosciences
Volume37
Issue number8
DOIs
Publication statusPublished - 1 Aug 2011
Externally publishedYes

Keywords

  • Crust
  • Database
  • Density
  • Geological mapping
  • Gravimetry
  • Rock types

ASJC Scopus subject areas

  • Information Systems
  • Computers in Earth Sciences

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