Carbonates and Evaporites

, Volume 20, Issue 2, pp 116–130 | Cite as

Dolomite microstructures and reaction mechanisms of dolomitization on the triassic Latemar buildup, Dolomites, northern Italy

  • Kathryn A. SchubelEmail author
  • David R. Veblen
  • David C. Elbert


The wavelengths of nanometer-scale structural modulations in calcium-rich dolomite on the Latemar buildup, Dolomites, northern Italy vary as a function of composition, which is controlled by the temperature of dolomitizing fluids, and contact time with these fluids. Dolomites formed at the highest temperatures are the most magnesian and those formed at the lowest temperatures are the most calcian. The wavelengths of structural modulations, which are visible in brightfield and high-resolution transmission electron microscope images, increase with increasing temperature of formation. Long wavelength modulations are associated with more magnesium rich dolomite that formed at high temperatures.

Three generations of dolomite, formed under subaerial sedimentary to subsurface hydrothermal conditions, partially replace Triassic Latemar limestones. Early exposure cap dolomite (52 to 57 mole % CaCO3) formed at earth surface temperatures and is host to mottles and diffuse modulations with wavelengths of 2 to 7.5 nm. Subsurface hydrothermal dolomite, formed by platform-scale circulation of hot Triassic seawater, comprises a kilometer-scale mushroom-shaped body of massive replacement dolomite and saddle dolomite cement that crosscuts platform sediments (Wilson et al. 1990; Hardie et al. 1991). Massive replacement dolomite from the stem consists of dolomite breccia and saddle dolomite cement. Saddle dolomite cements (49 to 55 mole % CaCO3) formed at high temperatures are host to sharp modulations with wavelengths of 7.5 to 15 nm and ribbon microstructures (1 to 2.5 nm across). Dolomite breccias (52 to 56 mole % CaCO3) are modulated; modulations wavelengths are 5 to 20 nm. Dolomites from the cap of the dolomite body, formed at lower temperatures than those in the stem, are more calcium rich, (51 to 58 mole % CaCO3), and are host to modulations with wavelengths of 0.5 to 12.5 nm.

Incommensurate superstructure reflections have been recognized in SAED patterns of calcium rich dolomite from the Latemar buildup. Incommensurate c-reflections have been observed approximately halfway between the principal reflections in the [110]* and [014]* directions. Superstructure reflections overlap the a- and b-reflections of the host dolomite and extend asymmetrically toward the center of the diffraction pattern. The c-reflections are elongated perpendicular to the structural modulations and are produced by quasiperiodic domains (less than approximately 2.5 nm wide) with wavelengths of 5 to 20 nm. The superstructure phase associated with these extra reflections has smaller reciprocal lattice dimensions than the sublattice, hence larger unit cell dimensions. The superstructure phase is metrically monoclinic and is interpreted to incorporate more calcium than the host dolomite, as suggested by previous workers (cf. Reeder and Wenk 1979; Gunderson and Wenk 1981; Reeder 1981, 1983; Wenk and Zhang 1985; Van Tendeloo et al. 1985; Reeder and Prosky 1986; Reeder et al. 1990; Reksten 1990a; Wenk et al. 1991; Reeder 1992; Ward and Reeder 1992).


Dolomite Dolomitization Middle Triassic SAED Pattern Dolomite Crystal 
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  1. BARBER, D.J. and KHAN, M.R., 1987, Composition-induced microstructures in rhombohedral carbonates:Mineralogical Magazine, v. 51, p. 71–86.Google Scholar
  2. BLAKE, D.F. and PEACOR, D.R., 1985, TEM/STEM microanalysis of Holocene fresh-water magnesian carbonate cements form the Coast Range of California:American Mineralogist, v. 70, p. 388–394.Google Scholar
  3. BOSELLINI, A. 1984, Progradation geometries of carbonate platfroms: examples from the Triassic of the Dolomites, northern Italy:Sedimentology, v. 31, p. 1–24.Google Scholar
  4. BOSELLINI, A. and Rossi, D., 1974, Triassic carbonate buildups of the Dolomites, northern Italy,in L. Laporte, ed., Reefs in time and space; selected samples from the recent and ancient, Society of Economic Paleontologists and Mineralogists Special Publication 18. SEPM (Society for Sedimentary Geology), Tulsa, OK, p. 209–233.Google Scholar
  5. CARBALLO, J.D., LAND, L.S., and MISER, D.E., 1987, Holocene dolomitization of supratidal sediments by active tidal pumping, Sugarloaf Key, Florida:Journal of Sedimentary Petrology, v. 57, p. 153–165.Google Scholar
  6. CARLSON, W.D., 1983, The polymorphs of CaCO3 and the aragonite-calcitetransformation,in R.J. Reeder, ed., Carbonates: Mineralogy and Chemistry, Reviews in Mineralogy, v. 11, p. 191–225.Google Scholar
  7. CARLSON, W.D., and ROSENFELD, J.L., 1981, Optical determination of topotactic aragonite-calcite growth kinetics: metamorphic implications:Journal of Geology, v. 89, p. 615–638.Google Scholar
  8. DUNN, P.A., 1991, Diagenesis and cyclostratigraphy: An example from the Middle Triassic Latemar platform, northern Italy. Unpublished Ph.D. dissertation, The Johns Hopkins University, Baltimore, Maryland.Google Scholar
  9. FRISIA, S., 1994, Mechanisms of complete dolomitization in a carbonate shelf: comparison between the Norian Dolomia Principale (Italy) and the Holocene of Abu Dhabi Sabkha,in, B. Purser, M. Tucker, and D. Zenger, eds., Dolomites A Volume in Honour of Dolomieu, Special Publication 21 of the International Association of Sedimentologists, Blackwell Scientific, Oxford, p. 55–74.Google Scholar
  10. FRISIA, S. and WENK, H-R., 1993, TEM and AEM of pervasive, multi-step dolomitization of the Upper Triassic Dolomia Principale (northern Italy):Journal of Sedimentary Petrology, v. 63, p. 1049–1058.Google Scholar
  11. GAETANI, M., FOIS, E., JADOUL, F., and NICORA, A., 1981, Nature and evolution of Middle Triassic carbonate buildups in the Dolomites, Italy:Marine Geology, v. 44, p. 25–57.Google Scholar
  12. GAINES, A.M, 1974, Protodolomite synthesis at 100°C and atmospheric pressure:Science, v. 183, p. 518–520.Google Scholar
  13. GEBELEIN, C.D., STEINEN, R.P., GARRETT, P., HOFFMAN, E.J., QUEEN, J.M., and PLUMMER, L.N., 1980, Subsurface dolomitization beneath the tidal flats of central West Andros Island, Bahamas,in D.H. Zenger, J.B. Dunham, and R.L. Ethington, eds., Concepts and Models of Dolomitization, Special Publication, no. 28, Society for Sedimentary Geology, p. 31–49.Google Scholar
  14. GOLDHAMMER, R.K., 1987, Platform carbonate cycle, Middle Triassic of northern Italy: the interplay of local tectonics and global eustasy. Unpublished Ph.D. dissertation, The Johns Hopkins University, Baltimore, Maryland, 468 p.Google Scholar
  15. GOLDHAMMER, R.K. and HARRIS, M.T., 1989, Eustatic controls on the stratigraphy and geometry of the Latemar buildup (Middle Triassic), the Dolomites of northern Italy,In P.D. Crevello, J.L. Wilson, J.F. Sarg, and J.F. Read, eds., Controls on Carbonate Platform and Basin Development: Society of Economic Paleontologists and Mineralogists Special Publication, no. 44, p. 323–338.Google Scholar
  16. GOLDHAMMER, R.K., DUNN, P.A., and HARDIE, L.A., 1987, High frequency glacio-eustatic sea level oscillations with Milankovitch characteristics recorded in Middle Triassic platform carbonates is northern Italy:American Journal of Science, v. 287, p. 853–89.Google Scholar
  17. GOLDHAMMER, R.K., DUNN, P.A., and HARDIE, L.A., 1990, Depositional cycles, composite sea-level changes, cycle stacking patterns, and the hierarchy of stratigraphic forcing: Examples from Alpine Triassic platform carbonates:Geological Society of America Bulletin, v. 102, p. 535–562.Google Scholar
  18. GOLDSMITH, J.R. and GRAF, D.L., 1958, Structural and compositional variations in some natural dolomites:Journal of Geology, v. 66, p. 678–693.Google Scholar
  19. GOLDSMITH, J.R. and HEARD, H.C., 1961, Subsolidus pahse relations in the system CaCO3−MgCO3:Journal of Geology, v. 69, p. 45–74.Google Scholar
  20. GRAF, D.L. and GOLDSMITH, J.R., 1956, Some hydrothermal syntheses of dolomite and protodolomite:Journal of Geology, v. 64, p. 173–187.Google Scholar
  21. GREGG, J.M., HOWARD, S.A., and MAZZULLO, S.J., 1992, Early diagenetic recrystallization. of Holocene (<3000 years old) peritidal dolomites, Ambergris Cay, Belize:Sedimentology, v. 39, p. 143–160.Google Scholar
  22. GUNDERSON, S.H. and WENK, H-R., 1981, Heterogeneous microstructures in oolitic carbonates:American Mineralogist, v. 66, p. 789–800.Google Scholar
  23. HAHN, T., 1996, International tables for crystallography. A. Kluwer Academic Publishers, Dordrecht, p. 878.Google Scholar
  24. HARDIE, L.A., 1977a, Algal structures in cemented crusts and their environmental significance,In L.A. Hardie, ed., Sedimentation on the Modern Carbonate Tidal Flats of Northwest Andros Island, Bahamas, Johns Hopkins University Studies in Geology, no. 22, Baltimore, Maryland, p. 159–177.Google Scholar
  25. HARDIE, L.A., ed., 1977b, Sedimentation on the Modern Carbonate Tidal Flats of Northwest Andros Island, Bahamas. The Johns Hopkins University Press, Studies in Geology, no. 22, Baltimore, Maryland, 202 p.Google Scholar
  26. HARDIE, L.A., 1987, Perspectives: Dolomitization: a critical view of some current views:Journal of Sedimentary Petrology, v. 57, p. 166–183.Google Scholar
  27. HARDIE, L.A., BOSELLINI, A., and Goldhammer, R.K., 1986, Repeated subaerial exposure of subtidal carbonate platforms, Triassic, northern Italy: Evidence for high frequency sea level oscillations on a 104 year scale:Paleoceanography, v. 1, p. 447–457.Google Scholar
  28. HARDIE, L.A., WILSON, E.N., and GOLDHAMMER, R.K., 1991, Cyclostratigraphy and dolomitization of the Middle Triassic Latemar buildup, the Dolomites, northern Italy: Dolomieu Conference on Carbonate Platforms and Dolomitization, Guidebook Excursion F, Ortesei Tourist Office, the Dolomites, Italy, 56 p.Google Scholar
  29. HARRIS, M.T., 1988, Margin and foreslope deposits of the Latemar carbonate buildup (Middle Triassic), the Dolomites, northern Italy. Unpublished Ph.D. dissertation, The Johns Hopkins University, Baltimore, Maryland, 433 p.Google Scholar
  30. KATZ, A. and MATHEWS, A., 1977, The dolomitization of CaCO3: an experimental study at 252–295°C:Geochimica et Cosmochimica Acta, v. 41, p. 297–308.Google Scholar
  31. LAND, L.S., 1985, The origin of massive dolomite.Journal of Geological Education, v. 33, p. 112–125.Google Scholar
  32. MCKENZIE, J. A., 1981, Holocene dolomitization of calcium carbonate sediments from the coastal sabkhas of Abu Dhabi, U.A.E.: A stable isotope study:Journal of Geology, v. 89, 185–198.Google Scholar
  33. MISER, D.E., SWINNEA, J.S., and STEINFINK, H., 1987, TEM observations and X-ray crystal-structure refinement of a twinned dolomite with a modulated microstructure:American Mineralogist, v. 72, p. 188–193.Google Scholar
  34. MORSE, J.W. and CASEY, W.H., 1988, Ostwald processes and mineral paragenesis in sediments:American Journal of Science, v. 288, p. 537–560.Google Scholar
  35. REEDER, R.J., 1981, Electron optical investigation of sedimentary dolomites:Contributions to Mineralogy and Petrology, v. 76, p. 148–157.Google Scholar
  36. REEDER, R.J., 1983, Crystal chemistry of the rhombohedral carbonates,In R.J. Reeder, ed., Carbonates: Mineralogy and Chemistry. Reviews in Mineralogy, v. 11, p. 1–47.Google Scholar
  37. REEDER, R.J., 1992, Carbonates: growth and alteration microstructures.In P.R. Buseck, ed., Minerals and reactions at the atomic scale: transmission electron microscopy, reviews in mineralogy. Mineralogical Society of America, Washington, D.C., v. 27, p. 381–422.Google Scholar
  38. REEDER, R.J. and PROSKY, J.L., 1986, Compositional sector zoning in dolomite:Journal of Sedimentary Petrology, v. 56, p. 237–247.Google Scholar
  39. REEDER, R.J. and WENK, H.-R., 1979, Microstructures in low temperature dolomites:Geophysical Review Letters, v. 6, p. 77–80.Google Scholar
  40. REKSTEN, K., 1990a, Modulated microstructures in calcian ankerite:American Mineralogist, v. 75, p. 807–812.Google Scholar
  41. REKSTEN, K., 1990b, Superstructures in calcian ankerite:Physics and Chemistry of Minerals, v. 17, p. 266–270.Google Scholar
  42. REKSTEN, K., 1990c, Superstructures in calcite:American Mineralogist, v. 75, p. 807–812.Google Scholar
  43. ROSEN, M.R. and COSHELL, L., 1992, A new location of Holocene dolomite formation, Lake Hayward, Western Australia:Sedimentology, v. 39, p. 161–166.Google Scholar
  44. ROSEN, M.R., MISER, D.E., STARCHER, M.A., and WARREN, J.K., 1989, Formation of dolomite in the Coorong region, South Australia:Geochimica et Cosmochimica Acta, v. 53, p. 661–669.Google Scholar
  45. ROSEN, M.R., MISER, D.E. and WARREN, J.K., 1988, Sedimentology, mineralogy and isotopic analysis of Pellet Lake, Coorong region, South Australia:Sedimentology, v. 35, p. 105–122.Google Scholar
  46. SCHUBEL, K.A., 1997, Reaction mechanisms of dolomitization, an integrated TEM, SEM, Geochemical, Petrographic and Field Approach. Unpublished Ph.D. Dissertation, Johns Hopkins University, Baltimore, MD, p. 352.Google Scholar
  47. SCHUBEL, K.A., ELBERT, D.C., and VEBLEN, D.R., 2000, Incommensurate c-domain superstructures in calcian dolomite from the Latemar buildup, Dolomite Mountains, Northern Italy:American Mineralogist, v. 85, p. 858–862.Google Scholar
  48. SCHUBEL, K.A. and VEBLEN, D.R., 2005, Textural and compositional analysis of multiple dolomite generations from the Latemar buildup, Dolomites, northern Italy.Carbonates and Evaporites, v. 20, no. 2, p. 148–160.Google Scholar
  49. SCHUBEL, K.A., VEBLEN, D.R., and MALONE, M.J., in press, Microstructures and textures of experimentally dolomitized Bahamian ooids: implications for reaction mechanisms of dolomitization:Carbonates and Evaporites.Google Scholar
  50. SHINN, E.A., 1968, Selective dolomitization of recent sedimentary structures:Journal of Sedimentary Petrology, v. 38, p. 612–616.Google Scholar
  51. SHINN, E.A., GINSBURG, R.N., and LLOYD, R.M., 1965, Recent supratidal dolomite from Andros Island, Bahamas: Society of Economic Paleontologists and Mineralogists Special 13. Society of Economic Paleontologists and Mineralogists, Tulsa, OK, p. 112–123.Google Scholar
  52. VAN TENDELOO, G., WENK H.-R. and GRONSKY, R., 1985, Modulated structures in calcian dolomite: A study by electron microscopy:Physics and Chemistry of Minerals, v. 12, p. 333–341.Google Scholar
  53. VON DER BORCH, C.C. and JONES, J.B., 1976, Spherular modern dolomite from the Coorong area, South Australia:Sedimentology, v. 23, p. 587–591.Google Scholar
  54. WARD, W.B. and REEDER, R.J., 1992, The use of growth microfabrics and transmission electron microscopy in understanding replacement processes in carbonates,in R. Rezak and D. Lavoie, eds., Carbonate Microfabrics, Springer-Verlag, New York, p. 253–264.Google Scholar
  55. WENK, H-R., BARBER, D.J., and REEDER, R.J., 1983, Microstructures in carbonates.In R.J. Reeder, ed., Carbonates: Mineralogy and Chemistry, Reviews in Mineralogy, v. 11, p. 301–367.Google Scholar
  56. WENK, H-R., MEISHING, HU, LINDSET, T., and MORRIS, J.W. Jr., 1991, Superstructures in ankerite and calcite:Physics and Chemistry of Minerals, v. 17, p. 527–539.Google Scholar
  57. WENK, H-R. and ZHANG, F., 1985, Coherent transformations in calcian dolomites:Geology, v. 13, p. 457–460.Google Scholar
  58. WILSON, E.N., 1989, Dolomitization of the Triassic Latemar buildup, Dolomites, northern Italy. Unpublished Ph.D. dissertation, The Johns Hopkins University, Baltimore, Maryland, 272 p.Google Scholar
  59. WILSON, E.N., HARDIE, L.A., and PHILLIPS, O.M., 1990, Dolomitization front geometry, fluid flow patterns, and the origin of massive dolomite: the Triassic Latemar Buildup, northern Italy:American Journal of Science, v. 290, p. 741–796.Google Scholar
  60. YOSE, L.A., 1993, Stratal Patterns and Lithofacies in Triassic Carbonate Slope Deposits of the Dolomites, Italy: implications for Sequence Stratigraphy and Global Sea Level: Doctoral Dissertation, Johns Hopkins University, 308 p.Google Scholar
  61. YOSE, L.A., 1991, Sequence stratigraphy of carbonate buildups developed in an active tectonic/volcanic setting; Triassic (late Ladinian and Carnian) of the Dolomites, northern Italy:American Association of Petroleum Geologists Bulletin, v. 75, p. 698–699.Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  • Kathryn A. Schubel
    • 1
    Email author
  • David R. Veblen
    • 2
  • David C. Elbert
    • 2
  1. 1.Department of Geology and Environmental GeosciencesLafayette CollegeEaston
  2. 2.Morton K. Blaustein Department of Earth and Planetary SciencesJohns Hopkins UniversityBaltimore

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