Diagenesis of the fanglomerate of Little Florida Mountains (Miocene), southwestern New Mexico
James M. Kiely and W. C. James

Abstract:

The Fanglomerate of Little Florida Mountains is mainly composed of gravel-sized rhyolite clasts with arenaceous portions of the matrix classified as volcanic arenites (Q4F4RF92). The sand-sized rock fragment population is 96% volcanic and dominated by rhyolite grains (rhyolite 88%, intermediates 8%, basalt 4%). Authigenic products are diverse and primarily siliceous in composition (70% of total). Although there is overlap in the timing of some cement events, a paragenetic sequence is recognizable: (earliest) ( 1 ) limonite, (2) mixedlayer illite/smectite plus limonite, (3) megacrystalline quartz, (4) impure siliceous cements (silica ± limonite ± clay), (5) microcrystalline quartz, (6) illite, (7) opal, (8) calcite, (9) Ca-zeolite and (10) pyrite. Soil-forming processes and hydrothermal fluids may have had a major influence on cement type, amount and distribution.


Citation:

  1. Kiely, James M.; James, W. C., 1988, Diagenesis of the fanglomerate of Little Florida Mountains (Miocene), southwestern New Mexico, in: Cretaceous and Laramide tectonic evolution of southwestern New Mexico, Mack, G. H.; Lawton, T. F.; Lucas, S. G., New Mexico Geological Society, Guidebook, 39th Field Conference, pp. 175-184.

More information...