[auscope-geosciml] CGI lithology vocabulary - "doleritic rock" [SEC=UNCLASSIFIED]

Oliver.Raymond at ga.gov.au Oliver.Raymond at ga.gov.au
Thu Aug 4 02:52:54 EDT 2011

Hi Steve,

I'm mapping GA lithology terms to CGI terms and have an issue with the way dolerites and microdiorites are handled in the CGI Simple Lithology vocabulary. viz,

- Basic igneous rock
  - Basalt
  - Gabbroic rock
       - Gabbro

- Doleritic rock

- Intermediate composition igneous rock
     - Andesite
  - Dioritoid
       - Dioritic rock
             - Diorite

The definition of "Doleritic rock" is "Dark colored gabbroic (basaltic) or dioritic (andesitic) rock intermediate in grain size between basalt and gabbro and composed of plagioclase, pyroxene and opaque minerals; often with ophitic texture. Typically occurs as hypabyssal intrusions. Includes dolerite, microdiorite, diabase and microgabbro."

My problem is that "dolerite" is a basic composition rock, but it is lumped into a "Doleritic rock" category which includes both basic and intermediate composition rocks and does not occur under any compositional category parent.  A query for "Basic igneous rocks" using the CGI vocabulary will not find any "dolerites".  Similarly, a query for "Intermediate composition igneous rock" will not find any "microdiorites".

The "Gabbroic rock" and "Dioritic rock" categories do not respectively include any intermediate or basic composition rocks.  Why are dolerites and microdiorites treated differently to gabbros and diorites, basalts and andesites?

Can we split "Doleritic rock" into its basic and intermediate parts and include them under the appropriate compositional headings?



Ollie Raymond

Project Leader
National Geological Maps and Data Standards Project<http://www.ga.gov.au/minerals/projects/current-projects/geological-maps-standards.html>
Geoscience Australia

Interoperability Working Group<https://www.seegrid.csiro.au/wiki/bin/view/CGIModel/InteroperabilityWG>
IUGS Commission for the Management and Application of Geoscience Information

Address: GPO Box 378, Canberra, ACT, 2601, Australia | ABN: 80 091 799 039
Ph: +61 2 62499575  |  Fax: +61 2 62479992  |  Email: oliver.raymond at ga.gov.au<mailto:oliver.raymond at ga.gov.au>  |  Google Map<http://maps.google.com/maps?f=q&hl=en&geocode=&q=canberra+australia&ie=UTF8&ll=-35.344028,149.158362&spn=0.007684,0.016404&t=h&z=17&iwloc=addr&om=1>

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