- Bravo Lake Formation
The Bravo Lake Formation is a
mafic volcanic belt andlarge igneous province [ [http://www.encyclopedia.com/doc/1G1-124343378.html Igneous rock associations in Canada 3. Large Igneous Provinces (LIPs) in Canada and adjacent regions: 3] Retrieved on2007-01-10 ] located at the northern margin of theTrans-Hudson orogeny on centralBaffin Island ,Nunavut ,Canada . It is exposed along a nearly continuous east-west passage for Unit km|120|0 and changes in stratigraphic thickness from 1 to 2.5 kilometers. [http://gsc.nrcan.gc.ca/baffin4d/proj/p21_e.php Central Baffin Island 4-D Project - Projects] : Paleoproterozoic mafic magmatism in central Baffin Island. Retrieved on2007-10-18 ] The formation is a rare alkaline-suite that formed as a result of submarinerift ing during thePaleoproterozoic period. [ [http://gac.esd.mun.ca/gac_2004/search_abs/sub_program.asp?sess=98&form=10&abs_no=280 Volcanology and geochemistry of the Bravo Lake Formation, Baffin Island, Nunavut] . Retrieved on2007-10-18 ] The Bravo Lake Formation is surprisingly undeformed by the Himalayan-scale forming event during the Trans-Hudsonian orogeny.The
stratigraphy of the Bravo Lake Formation starts with a basic section of iron-oxide richsandstone s,psammite s, and semi-pelites cover a series of deformed pillow lavas expanding in viscosity towards the west, and volcanic/clastic deposits andultramafic sill s. The lower volcanic section is covered bygarnet anddiopside bearing calc-silicate layers and finely layered metasediments comprising of course-grainedactinolite /hornblende /biotite followed by pelites and semi-pelites that are intruded by separated sills. In theRidge Lake area, the volcanic belt includes an interlayered series ofamphibolite ,gabbro , iron formation, sulphidic schist and metasediments.Geochemical results of pillow lavas and chill boundaries along five transects across the volcanic belt suggest the existence of three chemically different
magma types within the Bravo Lake Formation.Lavas of the
volcanic belt display geochemical characteristics similar to modern ocean-island-basalt groups. They range from moderately to intensely fractionated REE-profiles is similar to that fromtholeiitic basalt s to extremelyalkaline lavas inHawaii .ee also
*
List of volcanoes in Canada
*Volcanism in Canada
*Geography of Nunavut References
External links
* [http://gac.esd.mun.ca/gac_2003/search_abs/sub_program.asp?sess=98&form=10&abs_no=439 Paleoproterozoic alkaline magmatism of the Bravo Lake Formation of central Baffin Island, Nunavut]
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