Zeolites Replacing Plant Fossils in the Denver Formation: Lakewood, Colorado

Modreski, Peter J.; Verbeek, Earl R.; Grout, M.A.

doi:10.1080/00357529.1984.11764438

Cited by 4 publications

(3 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although marcasite is common in plant remains within lignite (Brinkmann, 1977), coexistence of clinoptilolite and marcasite has not been previously reported; however, an unusual occurrence of well-developed crystals of heulandite, as long as 4 mm, in fossil wood from the Denver Formation of Colorado was reported by Modreski et al (1983). Modreski et al (1983) employed the heating treatment described by Mumpton (1960) rather than the Si/A1 ratios used in the present study to identify the heulandite.…”

Section: Discussionmentioning

confidence: 90%

“…Similar processes probably resulted in the crystallization ofopal-CT and clinoptilolite within the fossil roots investigated in this study. The relatively extensive space available for crystal growth allowed crystallization of extremely large zeolite crystals in the fossil roots of our study and in the petrified wood studied by Modreski et al (1983).…”

Section: Discussionmentioning

confidence: 95%

“…Modreski et al (1983) employed the heating treatment described by Mumpton (1960) rather than the Si/A1 ratios used in the present study to identify the heulandite. According to Modreski et al (1983) alteration of volcanic glass in the Denver Formation released Si and other soluble ions into the ground water. The heulandite in plant structures precipitated from these Si-rich solutions.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Kaolinite, Opal-CT, and Clinoptilolite in Altered Tuffs Interbedded with Lignite in the Jackson Group, Texas

Senkayi

1987

Clays and clay miner.

View full text Add to dashboard Cite

Abstract--The mineralogy of partially kaolinized strata interbedded with lignite at the San Miguel mine, Atascosa County, Texas, was investigated by X-ray powder diffraction and optical and scanning electron microscopy. The San Miguel lignite occurs in the lower Jackson Group (late Eocene) of southern Texas. Based on mineralogical and micromorphological data, some of these clay partings are probably volcanic in origin and were exposed to variable degrees of in situ kaolinization in a swamp environment. Coexistence of kaolinite, clinoptilolite, and opal-CT in several of these strata suggests that the partially kaolinized volcanic layers were subjected to a subsequent resilication process following burial. Kaolinite is the dominant mineral in the oldest and most kaolinized volcanic layer (underclay) below the lowest lignite bed (seam D). The kaolinite exhibits a well-developed vermicular morphology. The youngest volcanic layer, which occurs stratigraphically above the uppermost lignite seam, is characterized by pseudomorphs of volcanic glass shards and consists mainly of clinoptilolite. Movement of siliceous ground water from this layer to the underlying strata apparently provided silica-rich solutions from which opal-CT and large (as long as 300 #m) euhedral crystals of clinoptilolite precipitated in the fossilized plant roots, veinlets, and fractures within the underlying strata. Micromorphological relationships between the Si-rich (opal-CT and clinoptilolite) and sulfide (marcasite and pyrite) minerals in the fossil roots and fractures suggest that the marcasite formed before and pyrite after the resilication process.

show abstract

Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 95%