Palynologic evidence for iron-oxide ash fall at La Perla, an Oligocene Kiruna-type iron ore deposit in northern Mexico
Por:
Corona-Esquivel, R, Martinez-Hernandez, E, Henriquez, F, Nystrom, JO, Tritlla, J
Publicada:
1 ene 2010
Resumen:
La Perla is an Oligocene deposit of apatite iron ore located in northern Mexico. The main ore types are massive ore, ore breccia and powdery ore. The latter is of special genetic interest because it contains well-preserved palynomorphs; fossil pollen representing several plant families growing in the region of investigation during the late Paleogene-Neogene; the assemblages include angiosperm and gymnosperm pollen grains, and also fossil fungal spores from two genera, Frasnacritetrus and Dyctiosporites, indicative of Eocene to Miocene age. The beds of powdery ore are stratified and size-sorted, but in some places there is no discernible stratification. The ore consists of a friable open framework of anhedral to euhedral hematite plates, or less commonly, martitized magnetite octahedra. Locally, the ore is even unconsolidated. The ore minerals show no abrasive rounding or other epiclastic features, and the high porosity of the iron-oxide crystal aggregate embedding the palynomorphs rule
Filiaciones:
Corona-Esquivel, R:
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
Martinez-Hernandez, E:
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
Tritlla, J:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Queretaro 76230, Mexico
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