Occurrence and origin of glauconite in the Cambro-Ordovician Bliss Formation of southern New Mexico and West Texas (U.S.A.)
Author:
Krainer Karl1, Tropper Peter2, Krenn Kurt3, Lucas Spencer G.4
Affiliation:
1. Institute of Geology, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria 2. Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria 3. NAWI Graz Geocenter, Institute of Earth Sciences, University of Graz, Heinrichstraße 26, A-8010 Graz, Austria 4. New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104, U.S.A.
Abstract
ABSTRACTIn southern New Mexico and West Texas, USA, the Late Cambrian–Early Ordovician Bliss Formation is a relatively thin and dominantly siliciclastic succession that was deposited on the Proterozoic basement during a major global transgression. The Bliss Formation can be divided into two members: 1) a lower, coarser-grained member composed mostly of sandstone (quartz arenite and subarkose) that lacks glauconite and calcite cement, and 2) an upper, finer-grained member that includes glauconitic sandstone, arkosic sandstone, and mixed siliciclastic–carbonate siltstone to fine-grained sandstone, intercalated with thin carbonate beds of grainstone, packstone, and rudstone. Iron oolite and oolitic sandstone are locally exposed at the base of the upper member. Sandstone of the lower member represents upper-shoreface to foreshore deposits, whereas sedimentary structures in the upper member indicate deposition in a middle- to lower-shoreface setting, and locally in a tidal-flat environment. Intercalated carbonate beds are storm layers (tempestites). Glauconite grains are abundant in the upper member as mostly rounded to well-rounded, spheroidal to ovoidal pellets. Two types of glauconite grains are present: homogeneous, dark green grains with high K2O contents (> 8 wt.%; stage 4) and mottled pellets composed of a mixture of glauconite and apatite. Glauconite of the Bliss Formation is not autochthonous as proposed by earlier workers, but of allochthonous (parautochthonous) origin. Thus, the glauconite grains were reworked from deeper shelf environments in northern Mexico to the south and were transported and deposited under regressive–transgressive conditions. Mottled glauconite grains formed by the reworking of phosphatized and glauconitized micritic sediments during regression and were transported and deposited by storm-induced currents, particularly in storm layers during transgressive events. Homogeneous, mature glauconite grains probably were derived from the reworking of glauconitized fecal pellets or completely glauconitized micritic sediments during regressive–transgressive cycles. The world-wide occurrence of glauconite in Cambrian–Early Ordovician sediments indicates that glauconite formation during that period can be considered as a “global event.”
Publisher
Society for Sedimentary Geology
Reference77 articles.
1. Amorosi, A., 1995, Glaucony and sequence stratigraphy: a conceptual framework of distribution in siliciclastic sequences: Journal of Sedimentary Research, v.65, p.419– 425. 2. Amorosi, A., 1997, Detecting compositional, spatial and temporal attributes of glaucony: a tool for provenance research: Sedimentary Geology, v.109, p.135– 153. 3. Avigad, D., Sandler, A., Kolodner, K., Stern, R.J., McWilliams, M., Miller, N., and Beyth,M., 2005, Mass-production of Cambro-Ordovician quartz-rich sandstone as a consequence of chemical weathering of Pan-African terranes: environmental implications: Earth and Planetary Science Letters, v.240, p.818– 826, doi:10.1016/j.epsl.2005.09.021. 4. Babcock, L.E., Peng, S.C., Brett, C.E., Zhu, M.Y., Ahlberg, P., Bevis, M., and Robison,R.A., 2015, Global climate, sea level cycles, and biotic events in the Cambrian Period: Palaeoworld, v.24, p.5– 15, doi:10.1016/j.palwor.2015.03.005. 5. Bailey, S.W., 1980, Summary of recommendations of AIPEA nomenclature Committee: Clay Minerals, v.15, p.85– 93.
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