World Library  
Flag as Inappropriate
Email this Article
 

Mountain Lake cluster

Mountain Lake Cluster is located in Alberta
Mountain Lake Cluster
Mountain Lake Cluster
Location of the Mountain Lake cluster in north-central Alberta, Canada.

The Mountain Lake cluster consists of two diatremes or volcanic pipes in Northern Alberta, Canada. It was emplaced during a period of kimberlite volcanism in the Late Cretaceous epoch.[1]

Although they were originally described as kimberlite or kimberlitic, the Mountain Lake (ML) rocks were later reclassified as alkaline ultramafic volcanics,[2] hybrid alkaline ultramafic rocks,[3] basanite or alkali olivine basalt.[4] Due to extensive clay alteration that obliterated much of their original mineralogy, the question of their proper classification remains unsettled.[3]

Contents

  • Location and Geological Setting 1
  • Age 2
  • Lithology and Mineralogy 3
  • See also 4
  • References 5

Location and Geological Setting

The ML pipes form part of the Northern Alberta kimberlite province, along with the nearby Birch Mountains kimberlite field and the Buffalo Head Hills kimberlite field. They were discovered in 1989-90 just north of Mountain Lake, which lies about 75 km (47 mi) northeast of Grande Prairie, Alberta. The ML south pipe measures 400 m (1,300 ft) by 650 m (2,130 ft), covering an area of 29 hectares (72 acres), and the north pipe measures 250 m (820 ft) by 350 m (1,150 ft), covering an area of 8.75 ha (21.6 acres).[2]

The ML pipes are hosted within the nonmarine sedimentary rocks of the Wapiti Formation and were erupted onto an inland alluvial plain. The uppermost strata of the Wapiti have been removed by erosion in the area, and most of the bedrock is covered by glacial and post-glacial sediments of Quaternary age. The ML volcaniclastic rocks are more resistant to erosion than the surrounding Wapiti Formation rocks, so the ML cluster forms a small hill.[5]

Age

Fossil pollen grains from mudstone clasts and laminated lacustrine sediments interbedded with the ML rocks are consistent with an emplacement age of from 68 to 76 Ma (million years ago), or the Campanian to early Maastrichtian stage of the Late Cretaceous.[1] Fission track dating of apatite gives ages of 72 to 78 Ma.[2] Magnetostratigraphic polarity determinations, coupled with the palynostratigraphic results and radiometric dates, indicate that the ML rocks are not older than 79.1 Ma.[6]

Lithology and Mineralogy

The ML cluster consists of volcaniclastic rocks that are interpreted as representing volcanic crater or diatreme deposits. They include euhedral to broken and pellet-shaped grains of olivine that are supported in a fine-grained groundmass, along with xenoliths derived from sedimentary rocks, crystalline Precambrian rocks, and a variety of types of volcanic rocks. In many examples both the olivine and the groundmass have been totally altered to smectite clay, and in some specimens the clay has been further altered to zeolite minerals and quartz.[3] Although they include diamond indicator minerals[7] such as chromite and several types of garnet (G5, G9, G11 and spessartine), the ML rocks are not considered to have a high potential for diamonds.[3]

See also

References

  1. ^ a b Eccles, D.R., Heaman, L.M., Luth, R.W. and Creaser, R.A. (2003). "Petrogenetic considerations for the Late Cretaceous Northern Alberta kimberlite province. 8th International Kimberlite Conference, Extended Abstract, 5 p.". Retrieved 2014-08-13. 
  2. ^ a b c 8th International Kimberlite Conference: Selected Papers: Volume 1: The C. Roger Clement Volume, Elsevier Science, 2004, p. 437 - 440 ISBN 0-444-51775-8 (accessed via Google books)
  3. ^ a b c d Skupinski, A. and Langenberg, C.W. 2002. Petrography of the Mountain Lake pipe, Grande Prairie area, Alberta, Canada. Alberta Geological Survey, Special Report 15, 39 p.
  4. ^ Eccles, D.R. (2014). "Northern Alberta kimberlite province: The first 20 years. Alberta Geological Survey, ERCB/AGS Bulletin 65, 116 p.". Retrieved 2014-10-19. 
  5. ^ Leckie, D.A., Kjarsgaard, B. et al. 1997. Geology of a Late Cretaceous possible kimberlite at Mountain Lake, Alberta – Chemistry, petrology, indicator minerals, aeromagnetic signature, age, stratigraphic position and setting. Geological Survey of Canada, Open File 3441, 202 p.
  6. ^ Kravchinsky, V.A., Eccles, D.R., Zhang, R. and Cannon, M. 2009. Paleomagnetic dating of the northern Alberta kimberlites. Canadian Journal of Earth Sciences, vol. 46, no. 4, p. 231-245.
  7. ^ Alberta Geological Survey: Kimberlite, Indicator Minerals and Diamonds
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.