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Papers by James Boles

Numerical modeling of the origin of calcite mineralization in the Refugio‐Carneros fault,

New Zealand Journal of Geology and Geophysics, 1991

Post-Jurassic folding and uplift of the Southland Syncline has fractured and faulted a thick sequ... more Post-Jurassic folding and uplift of the Southland Syncline has fractured and faulted a thick sequence of relatively impermeable marine rocks. Laumontite and stilbite crystallised contemporaneous with the deformation from fluids migrating along permeable fractures and faults. Published isotopic analyses of framework oxygen in these zeolites indicate that the veins near the stratigraphic top of the section, relative to those near the base. crystallised in either isotopically light (meteoric) water or at a relatively constant temperature when the section was subvertical. Regardless, the reactions are relatively late and are related to folding and uplift, rather than maximum burial conditions. Laumontite crystals in the veins are nucleation sites for replacement of adjacent country rock ; thus, veins influenced a greater volume of the rock than they occupy

In arkosic sandstones of the San Joaquin and Los Angeles Basins presently at temperatures between... more In arkosic sandstones of the San Joaquin and Los Angeles Basins presently at temperatures between 35 C and 174 C, trace amounts of authigenic K-NHâ-feldspar are present as microfracture fillings and overgrowths on detrital K-feldspar. Microchemical analyses of this authigenic phase reveal up to 80 mole % buddingtonite. The largest ammonium concentrations are observed in a sandy interval of the

AGU Fall Meeting Abstracts, Dec 1, 2006

Using the surface forces apparatus, which can measure small changes in thickness occurring even a... more Using the surface forces apparatus, which can measure small changes in thickness occurring even at essentially geological timescales, we have measured dissolution of quartz sheets when pressed against muscovite mica surfaces in aqueous electrolyte solution, but no dissolution is observed under dry conditions. It is postulated that the dissolved quartz may reprecipitate outside the contact junction as a fragile silica gel, which could be the main factor limiting the rate of further dissolution.

Journal of Geochemical Exploration, Jun 1, 1992

AAPG Bulletin, 1987

Calcite cements occur as thin bands (up to 1 m thick by 200 m long) in a Stevens turbiditic sands... more Calcite cements occur as thin bands (up to 1 m thick by 200 m long) in a Stevens turbiditic sandstone (upper Miocene) reservoir at North Coles Levee. These cements formed from evolved marine power water and show up to 10 mole % of mainly Fe + Mg. Stable isotopic analysis and estimated isotopic compositions of pore fluid indicate the cements

Three types of formation waters are recognized in the San Joaquin basin (Fisher and Boles, 1990),... more Three types of formation waters are recognized in the San Joaquin basin (Fisher and Boles, 1990), all of which are involved in calcite cementation. They are meteoric, mixed marine-meteoric, and diagenetically modified marine waters (Boles and Ramseyer, 1987; Fisher and Boles, 1990). These studies show. .. .. . GEOLOGICAL BACKGROUND The San Joaquin basin of California (Fig. 1) contains. .. .. . CARBONATE CEMENTS Carbonate cements preserve the degree of compaction at the time of cementation in sandstones. Cement volume, when completely filling intergranular pore space, has been used as an indicator. .. .. .

American Journal of Science, Oct 1, 1977

American Association of Petroleum Geologists eBooks, 1984

Secondary porosity in Miocene Stevens sandstones of the North Coles Levee Field results from diss... more Secondary porosity in Miocene Stevens sandstones of the North Coles Levee Field results from dissolution of calcite, ferroan dolomite, and calcic plagioclase (An30). Kaolinite is a leach product of plagioclase, and mass balance calculations indicate that alumina is conserved on a thin-section scale. Iron released from dissolution of Fe-carbonate is possibly conserved in late-stage pyrite. Detrital K-feldspar and early formed albite fracture filling in plagioclase are unaffected by the leach fluids, suggesting that these components are stable with respect to the leach fluids, whereas the anorthite component is unstable. Thermodynamic considerations indicate present-day pore waters at 100°C, 260 bars fluid pressures, are nearly at equilibrium for the reaction: [EQUATION] and for a similar reaction involving dolomite. Compaction following or perhaps contemporaneous with leaching has resulted in at least two diagenetic events. One involves albitization of plagioclase at stressed grain contacts with quartz, possibly as a result of higher silica activities stabilizing albite at these contacts. The other involves crushing of detrital biotite resulting in crystallization of carbonate adjacent to it. This phenomenon is due to depletion of H+ in the pore water adjacent to newly formed mica surfaces as K+^glH+ exchange occurs between pore water and mica.

New Zealand Journal of Geology and Geophysics, Apr 1, 1974

About 260 km of mainly Triassic rocks on the north limb of the Southland Syncline, Hokonui Hills,... more About 260 km of mainly Triassic rocks on the north limb of the Southland Syncline, Hokonui Hills, Southland, consist of a thick sequence of steeply dipping, mainly marine, volcanogenic sedimentary rocks.Changes in strike and numerous faults with a conspicuous strike-slip component indicate the area has undergone a compressive stress in a NW-SE direction. The compressive stress post-dates the folding of

Contributions to Mineralogy and Petrology, 1978

In subsurface samples of Wilcox (Eocene) sandstones, calcite cements occur above 2315m depths, wh... more In subsurface samples of Wilcox (Eocene) sandstones, calcite cements occur above 2315m depths, whereas ankerites occur at depths from 2560 m (temperatures 125 ~ C) to at least 4650 m (temperatures 210~ Microprobe analyses indicate that some shallow ankerites have appreciable excess calcium, analogous to protodomites. Ankerites at depths greater than 3200m have compositions of about CaMgo.sFeo.5(C03) 2. Oxygen isotope data suggests that the ankerites are similar to low temperature hydrothermal dolomites and that they have probably formed in pore fluids with higher O 18/O 16 ratios than sea water. The isotopic data also suggest that the ankerites have formed over a more limited temperature interval than they occur today. The ankerite is believed to have formed from calcite by the reaction 4 CaCO 3 q'-Fe2 + + Mg 2 + = 2 CaMgo. 5Fe0. s(CO3) 2 +2Ca 2+ Iron and magnesium for this reaction was apparently released by the breakdown of smectite to illite in mixed-layer clays. Bulk chemical analyses suggest that some iron was transferred from shales into sandstones. Mass balance and chemical considerations are compatible with this model.

American Mineralogist, Oct 1, 1972

Geological Society, London, Special Publications, 1987

ABSTRACT

American Journal of Science, Feb 1, 1982

AAPG Bulletin, May 1, 1990

... Title, Mass transfer in sandstones as indicated from bulk chemical analysis. Creator/Author, ... more ... Title, Mass transfer in sandstones as indicated from bulk chemical analysis. Creator/Author, Boles, JR ; Dobson, PF (Univ. ... Detrital components in the sandstones are quartz, plagioclase, and K-feldspar, in proportions of 2/1/1, and variable amount of smectite clay. ...

Mineralogy and Geology of Natural Zeolites, 1977