Geochemical History of Calcite Precipitation in Tertiary Sandstones, Northern Apennines, Italy

  1. Sadoon Morad
  1. K. L. Milliken1,
  2. E. F. McBride1,
  3. W. Cavazza2,
  4. U. Cibin3,
  5. D. Fontana4,
  6. M. D. Picard5 and
  7. G. G. Zuffa3

Published Online: 17 APR 2009

DOI: 10.1002/9781444304893.ch10

Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution

Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution

How to Cite

Milliken, K. L., McBride, E. F., Cavazza, W., Cibin, U., Fontana, D., Picard, M. D. and Zuffa, G. G. (1998) Geochemical History of Calcite Precipitation in Tertiary Sandstones, Northern Apennines, Italy, in Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution (ed S. Morad), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304893.ch10

Author Information

  1. 1

    Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA

  2. 2

    Departimento di Scienze Mineralogiche, Universita di Bologna, Piazza Porta S. Donato 1, 40127 Bologna, Italy

  3. 3

    Departimento di Scienze Geologiche, Universita di Bologna, via Zamboni 63–67, 40126 Bologna, Italy

  4. 4

    Departimento di Scienze della Terra, Universita di Modena, via Santa Eufemia, 19, 41100 Modena, Italy

  5. 5

    Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA

Publication History

  1. Published Online: 17 APR 2009
  2. Published Print: 29 MAY 1998

ISBN Information

Print ISBN: 9780632047772

Online ISBN: 9781444304893

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Keywords:

  • geochemical history of calcite precipitation in tertiary sandstones in northern Apennines, Italy;
  • ten tertiary stratigraphical units;
  • sampling and methods;
  • petrography;
  • acid soluble carbonate in mudrock;
  • detrital and authigenic carbonate in sandstones

Summary

In order to better understand the origin and controls of calcite cementation in marine sandstone we studied ten Tertiary lithostratigraphical units exposed in the northern Apennines, Italy, which display a variety of patterns of calcite cement. Five of the units studied were deposited in piggy-back (satellite) basins, and five were deposited in foreland basins. Burial depths of cemented units in piggy-back basins range from 0 to 1300 m, whereas burial depths of foreland basin rocks range from 500 to >7000 m.

Petrographic data and stable isotopes indicate that detrital carbonate particles (rock fragments and marine skeletal debris) in both sandstones and intercalated mudrocks were the main sources of calcium and carbon in cement. Cementation took place at or near maximum burial depth in most of the shallowly buried units, and at somewhat less than the maximum burial depth for the deeply buried units. Oxygen isotopes indicate that (i) the Intra-Apenninic Pliocene, Antognola and Ranzano stratigraphical units were cemented by fluids with negative δ18O values (i.e. deeply circulated meteoric water from nearby mountains); (ii) the Bismantova, Borello and Loiano formations were cemented by water with a meteoric component; (iii) all the foreland basin units contain calcites with δ18O that is permissive of fluids that ranged from slightly negative to markedly positive (−2 to +7‰). δ18O-enriched values of δ18Owater are compatible with plausible depths and temperatures of cementation of the three deepest formations, where water evolved from silicate reactions dominated, but not for the less deeply buried ones. Possible replacement of earlier-formed calcite by higher-temperature material cannot be ruled out for the deepest-buried formations.

Multiple samples taken from concretions vary less than 2‰ (and commonly less than 1‰) in δ13C and δ18O from core to margin, without any consistent trend. In contrast, variations in isotopic values between concretions in the same formation are greater: oxygen isotopes commonly differ by 4‰ (locally greater) within a single formation. A combination of variations in temperature and water composition seems to be the cause. In the Loiano Formation there is a significant difference between δ18O values of bedding-parallel concretions and fault-parallel concretions, which reflects different times of cementation.

Variations in Mg, Fe, and Mn concentrations reflect zoning in some of the concretion calcites examined. Covariations between these minor and trace elements differ greatly both between formations and between samples within a single formation. From limited temporal information it appears that the availability of Mg and Fe was greatest relatively early in diagnesis, whereas Mn was mobilized in at least two distinct pulses, one early and one late.

Burial depth and its attendant temperature played a more important role in diagenesis than whether a formation was deposited in a piggy-back or a foreland basin.