File:North Table Mountain & South Table Mountain (Pleistocene orendite volcanic centers in the Leucite Hills, Wyoming, USA) 4 (48944095881).jpg

North Table Mountain & South Table Mountain - orendite volcanic centers in the Pleistocene of Wyoming, USA. (looking east from Boar's Tusk)

Southwestern Wyoming's Leucite Hills are a group of Pliocene to Pleistocene volcanic centers that erupted lamproite lavas, a rare extrusive igneous lithology. Based on chemistry and mineral content, the Leucite Hills lamproite lavas have been categorized as wyomingite, orendite, or madupite.

Volcanism in this area may possibly be due to Yellowstone Hotspot fringe melting of the mantle. The lamproites appear to be derived from lherzolite-harzburgite mantle rocks that were metasomatically enriched in phlogopitic veins at >1.2 Ga (the latter may be caused by Precambrian subduction along the Wyoming Craton margin).

At center-left is North Table Mountain, which is reportedly composed of orendite lamproite. At center-right is South Table Mountain, which consists of olivine orendite.

Age of North Table Mountain: Pleistocene, 1.43-1.47 Ma Age of South Table Mountain: Pleistocene, 2.53-2.55 Ma

Locality: North Table Mountain (= North Table Mesa) & South Table Mountain (= Table Mountain), north-central Leucite Hills Volcanic Province, Great Divide Basin, north of the town of Superior, southwestern Wyoming, USA

Example references on Leucite Hills geology:

Lange, R.A., I.S.E. Carmichael & C.M. Hall. 2000. 40Ar/39Ar chronology of the Leucite Hills, Wyoming: eruption rates, erosion rates, and an evolving temperature structure of the underlying mantle. Earth and Planetary Science Letters 174: 329-340.