Volcanic and sedimentary origins remain distinctive in clay-rich horizons of Costa Rican lignites and peats

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6335324

Raymond, R Jr; Bish, D L; Archuleta, L M; Cohen, A D

Tertiary lignite and Recent peat deposits in Costa Rica were sampled to determine the origin of associated clay-rich horizons using x-ray diffraction and x-ray fluorescence techniques. A lignite deposit near Zent contains two types of clay-rich horizons. One type comprises two 2-5 cm thick partings composed mostly of kaolin clay with minor amounts of quartz. Mean Al/sub 2/O/sub 3/ and SiO/sub 2/ contents of the partings are 44.54 and 50.08 wt%. The second type both discontinuously overlies one of the kaolin partings and continuously underlies the lignite seam. This second type of horizon contains smectite as well as kaolin clays, more quartz than the partings, and pyrite. Comparable clay-rich horizons are present in Costa Rican peat deposits. A 30 cm thick clay parting of known volcanic origin occurring within a peat deposit north of Siquirres is composed of halloysite and minor amounts of quartz, gibbsite, and crystobalite. A clay-rich horizon of fluvial origin that directly underlies a peat deposit southeast of Los Chiles is composed of smectite and kaolin clays, quartz, albite, and iron-bearing minerals. Similarities between the partings in the peat at Siquirres and in the lignite at Zent suggest a volcanic origin for the lignite partings. Other clay-rich lignite horizons appear to have a sedimentary origin, similar to the underlying clay-rich horizon at Los Chiles, rather than being deposited directly as volcanic ashfall. Thus it appears that volcanic ashfall-derived materials can be distinguished from sedimentary materials in Costa Rican lignites and peats based on differences in bulk mineralogical and chemical compositions.

• Research Organization: Los Alamos National Laboratory, NM (USA)
• OSTI ID: 6335324
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
011000* -- Coal
Lignite
& Peat-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400 -- Geochemistry-- (-1989)
BROWN COAL
CARBONACEOUS MATERIALS
CENOZOIC ERA
CENTRAL AMERICA
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMISTRY
CLAYS
COAL
COAL DEPOSITS
COHERENT SCATTERING
COSTA RICA
DEVELOPING COUNTRIES
DIFFRACTION
EMISSION SPECTROSCOPY
ENERGY SOURCES
FLUORESCENCE SPECTROSCOPY
FOSSIL FUELS
FUELS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
LATIN AMERICA
LIGNITE
MATERIALS
MINERAL RESOURCES
MINERALOGY
MINERALS
ORGANIC MATTER
ORIGIN
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PEAT
PETROLOGY
QUARTZ
RESOURCES
SCATTERING
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
TERTIARY PERIOD
X-RAY DIFFRACTION