Indiana University Bloomington

Enrique Merino

Enrique Merino

Professor Emeritus

Geochemistry

Office: GY527
Phone: 812-855-5088
Email: merino@indiana.edu

Education

  • Ph.D., l973, Geology and Geophysics, University of California at Berkeley
  • Ingeniero de Minas, l967, School of Mining Engineering, Madrid

Research

After an early interest in water–rock equilibrium relations in sedimentary basins and in calculating the distribution of species dissolved in natural waters, I became interested in the dynamics of geochemical phenomena.  It is through its reaction–transport dynamics, not through equilibrium, that a geochemical system may develop a characteristic spatial repetitive pattern. With collaborators, I studied stylolitization and metamorphic banding, intracrystalline oscillatory zoning of trace elements in calcite, orbicular zoning, the genesis of agate banding, the genesis of zebra veins in dolomites and in serpentinized ultrabasics, and the genesis of Banded Iron Formations – all cases of what I called in 1984 geochemical self–organization, and all produced by disequilibrium and feedback. Understanding and modeling each of those self–organizational patterns requires finding out which feedbacks take place in its genesis and incorporating them into the continuity equation. Petrography is essential, both to help construct the reaction–transport models and to check their spatial predictions.

Starting in 1990 I became interested in the geochemical dynamics, or chemical geodynamics, of larger scale phenomena, weathering and dolomitization, ore deposit genesis and metamorphism. Since these involve mineral replacement, understanding their dynamics required first understanding how replacement happens. Replacement of B by A is identified by its characteristic spatial properties – to preserve both volume and morphological details (as ghosts). These properties in turn require that A growth and B dissolution be strictly simultaneous and take place at mutually equal rates. The coupling factor that equalizes the rates turns out to be the growth–driven stress. The guest mineral, via the local stress it generates as it grows, pressure-dissolves the adjacent host mineral. The induced stress self–adjusts so as to always equalize the volumetric rates of guest mineral growth and host pressure–solution: this is why replacement preserves solid volume – the feature that petrographers have long reported. This discovery has led to insights into the dynamics of weathering (Merino et al., 1993), of bauxite (or terra rossa) formation (Merino and Banerjee, 2008), of metamorphic reactions such as the replacement of periclase by brucite in marbles, and of burial dolomitization (Merino and Canals 2011)

For example, we have discovered petrographically that the red clays known as terra rossa, or bauxite, form not residually or as a sediment as long held, but by replacement of the underlying limestone – a surprise to geochemists and soils scientists – and that the replacement, by releasing acid which generates additional dissolution porosity, may trigger the reactive–infiltration instability that "carves" the dissolution funnels and sinkholes of the karst limestone that contains the terra rossa itself – a surprise to geomorphologists. The chemical dynamics imposed by the replacement ends up explaining why bauxite and karst are associated.

Understanding the physics of replacement helps unravel the old problem of burial dolomitization, a paradigm of metasomatism: the dolomite–for–calcite replacement, because it is self–accelerating via the Ca2+ pore fluid concentration, because it happens by pressure–solution, and because crystalline carbonates are strain–rate–softening, spontaneously passes – continuously – from replacive to displacive dolomite growth, and this is why characteristic sets of displacive, self–organized dolomitic zebra veins occur in burial dolostones the world over.

SELECTED ARTICLES, GROUPED IN SIX AREAS

I) DIAGENESIS, AQUEOUS GEOCHEMISTRY

Merino, E. (l975) Diagenesis in Tertiary sandstones from Kettleman North Dome, California I. Diagenetic mineralogy. Jour. Sed. Petrology, 45, 320 336. [pdf]

Merino, E. (l975) Diagenesis in Tertiary sandstones from Kettleman North Dome, California II. Interstitial solutions: distribution of aqueous species at l00°C and relation to the diagenetic minerals. Geochim. Cosmochim. Acta, 39, p. l629–45. DOI [pdf]

Merino, E. (l979) Internal consistency of a water analysis and uncertainty of the calculated distribution of aqueous species at 25°C. Geochim. Cosmochim. Acta, 43, l533–l542. DOI [pdf]

Merino, E., Girard, J.–P., May, M.T., and Ranganathan, V. (1997) Diagenetic mineralogy, history, and dynamics of Mesozoic arkoses, Hartford rift basin, Connecticut. J. Sedimentary Research 67, 212–224. [pdf]

II) GEOCHEMICAL SELF–ORGANIZATION

Merino, E., Ortoleva, P. and Strickholm, P. (l983) Generation of evenly spaced pressure solution seams during (late) diagenesis: a kinetic theory. Contrib. Mineral. Petrology, v.82, p. 360–370. DOI [pdf]

Merino, E. (l984) "Survey of geochemical self patterning phenomena." In Nicolis G and Baras F (eds), Chemical Instabilities. Applications in Chemistry, Engineering, Geology, Materials Science, NATO Advanced Science Series C, v. l20, p. 305–328, Reidel Publ. [pdf]

Ortoleva, P., Merino, E. and Strickholm, P. (l982) Kinetics of metamorphic layering in anisotropically stressed rocks. Amer. J. Science, 282, p. 6l7–643. [pdf]

Merino, E. (1987) Textures of low temperature self organization. In Rodríguez Clemente R. and Tardy Y., eds., Geochemistry of the Earth’s Surface. Consejo Superior Investigaciones Científicas (Spain) and Centre Natl. Recherche Scientifique (France), Madrid, p. 597 610. PDF

Ortoleva, P., Merino, E., Moore, C., and Chadam, J. (1987) Geochemical self organization, I. Feedbacks, quantitative modeling. Amer. J. Science 287, p. 979–1007. DOI [pdf]

Wang, Yifeng and Merino, E. (1993) Oscillatory magma crystallization by feedback between the concentrations of reactants and mineral growth rates. J. Petrology 34, p. 369–382.[pdf]

Merino, E. (2005) Very–high-temperature, closed–system origin of agates in basalts: New model, old and new evidence. In Kile D, Michalski T. and Modreski P. (eds), A Symposium on Agate and Microcrystalline Quartz; Golden, Colorado, Sept 9-11. [pdf]

Wang, Yifeng and Merino, E. (1992) Dynamic model of oscillatory trace element zoning in calcite: inhibition, double layer, self–organization. Geochim. Cosmochim. Acta 56, p. 587–596. DOI [pdf]

Merino, E. (1992) Self–organization in stylolites. American Scientist 80, p. 466–473. [pdf]

Wang, Yifeng and Merino, E. (1995) Origin of fibrosity and banding in agates from flood basalts. Amer. J. Science 295, p. 49–77. DOI [pdf]

Merino, E., Wang, Yifeng, and Deloule, É. (1995) Genesis of agates in flood basalts: Twisting of chalcedony fibers and trace element geochemistry. Amer. J. Science 295, p. 1156–1176. DOI [pdf]

Merino, E. and Wang, Yifeng (2001) Self–organization in rocks: Occurrences, observations, modeling, testing – with emphasis on agate genesis. In: Hans-Jürgen Krug & Jörn H. Kruhl (eds), Non–Equilibrium Processes and Dissipative Structures in Geoscience, Yearbook "Self–Organization" vol 11, p.13–45, Berlin, Duncker and Humblot, 380 p. [pdf]

Merino, E., Canals, À., and Fletcher, R.C. (2006) Genesis of self–organized zebra textures in burial dolomites: Displacive veins, induced stress, dolomitization. Geologica Acta v. 4, p. 383–393. DOI [pdf]

Merino, E., Banerjee, A. (2008) Terra rossa genesis, implications for karst, and eolian dust: A geodynamic thread. Journal of Geology, v. 116, p. 62–75. DOI [pdf]

Wang, Yifeng, Xu, H., Merino, E., and Konishi, H. (2009) Generation of Banded Iron Formations by internal dynamics and leaching of oceanic crust. Nature Geoscience, November issue, v. 2, p. 781–784. DOI [pdf]

Merino, E., Canals, À. (2011) Self–accelerating dolomite–for–calcite replacement: Self–organized dynamics of burial dolomitization and associated mineralization. Amer. J. Science, v. 311, p. 573–607. DOI [pdf]

Merino, E., Wang, Yifeng, and Banerjee, A. (2012) Self–organized dynamics of karst limestone landscapes and coupled terra rossa formation. Abstr 1483537. AGU Fall Meeting, San Francisco Dec 2013.

III) DYNAMIC MODELING OF REACTION FRONTS

Ortoleva, P., Chadam, J., Merino, E., Hettmer, J., Moore, C., and Ripley, E. (l986) Redox front propagation and banding modalities. Physica D, 19, p. 334–354. DOI [pdf]

Chadam, J., Hoff, D., Merino, E., Ortoleva, P., and Sen, A. (1986) Reactive infiltration instability. IMA J. Appl. Math., 36, p. 207–221. DOI [pdf]

Ortoleva, P., Chadam, J., Merino, E., and Sen, A. (1987) Geochemical self organization, II. The reactive infiltration instability in water rock systems. Amer. J. Science 287, p. 1008–1040. DOI [pdf]

Merino, E., Wang, Yifeng (2001) Self–organization in rocks: Occurrences, observations, modeling, testing – with emphasis on agate genesis. In: Hans–Jürgen Krug and Jörn H. Kruhl (eds), Non–Equilibrium Processes and Dissipative Structures in Geoscience, Yearbook "Self–Organization" v 11, p. 13–45, Berlin, Duncker and Humblot, 380 p. [pdf]

Banerjee, A. and Merino, E. (2011) Terra rossa genesis by clay–for–limestone replacement: III. Dynamic quantitative model. J. Geology 119, p. 259–274. DOI [pdf]

IV) PHYSICS OF REPLACEMENT

Merino, E., Nahon, D., and Wang, Yifeng (1993) Kinetics and mass transfer of replacement: application to replacement of parent minerals and kaolinite by Al, Fe and Mn oxides during weathering. Amer. J. Science 293, p. 135–155. DOI [pdf]

Merino, E. and Dewers, T. (1998) Implications of replacement for reaction-transport modeling. Journal of Hydrology, v.209, p. 137–146. DOI [pdf]

Fletcher, R.C. and Merino, E. (2001) Mineral growth in solid rock: kinetics and rheology in replacement, vein formation, and tectonic crystallization. Geochim. Cosmochim. Acta, v. 65 (Special Issue dedicated to H.C. Helgeson, no. 21), p. 3733–3748. DOI [pdf]

Fletcher R.C. and Merino E. (2001) Mineral growth in rocks: interacting stress and kinetics in veins growth, replacement, and water-rock interaction. In: R. Cidu, editor, Water-Rock Interaction, pp.161-164, Lisse, A.A. Balkema. PDF

Merino, E., and Canals, À. (2011) Self–accelerating dolomite–for–calcite replacement: Self–organized dynamics of burial dolomitization and associated mineralization. Amer. J. Science, v. 311, p. 573–607. DOI [pdf]

Merino, E. (2013) "Kinetic–rheological insights uncovered by the self–accelerating brucite–for–periclase replacement. The blind spot of geochemists." AGU Abstract 1787774, San Francisco, Dec 2013

V) WEATHERING: LATERITE, CALCRETE, BAUXITE, TERRA ROSSA AND KARST

Merino, E., Nahon, D., and Wang, Yifeng. (1993) Kinetics and mass transfer of replacement: application to replacement of parent minerals and kaolinite by Al, Fe and Mn oxides during weathering. Amer. J. Science 293, p. 135–155. DOI [pdf]

Wang, Yifeng., Nahon, D., and Merino, E. (1994) Dynamic model of the genesis of calcretes replacing silicate rocks in semi–arid regions. Geochim. Cosmochim. Acta 58, p. 5131–5145. DOI [pdf]

Wang, Yutian, Wang, Yifeng, and Merino, E. (1995) Dynamic weathering model: Constraints required by coupled dissolution and pseudomorphic replacement. Geochim. Cosmochim. Acta 59, p. 1559–1570. DOI [pdf]

Nahon, D. and Merino, E. (1997) Pseudomorphic replacement in tropical weathering: Evidence, geochemical consequences, and kinetic–rheological origin. Amer. J. Science, v. 297, p. 393–417. DOI [pdf]

Merino, E., Banerjee, A. (2008) Terra rossa genesis, implications for karst, and eolian dust: A geodynamic thread. Journal of Geology, v. 116, p. 62–75. DOI [pdf]

Meert, J.G., Pruett, F., and Merino, E. (2009) An ’inverse conglomerate’ paleomagnetic test and timing of in–situ terra rossa formation at Bloomington, Indiana. Journal of Geology 117, p. 126–138. DOI [pdf]

Banerjee, A. and Merino, E. (2011) Terra rossa genesis by clay–for–limestone replacement: III. Dynamic quantitative model. J. Geology 119, p. 259–274. DOI [pdf]

Merino E., Wang, Yifeng, and Banerjee, A. (2012) Self–organized dynamics of karst limestone landscapes and coupled terra rossa/bauxite formation. Abstr 1483537. AGU Fall Meeting, Dec 2012.

VI) DOLOMITIZATION DYNAMICS, DOLOMITIC ZEBRA VEINS

Merino, E., Canals, À., and Fletcher, R.C. (2006) Genesis of self–organized zebra textures in burial dolomites: Displacive veins, induced stress, and dolomitization. Geologica Acta v. 4, p. 383–393. DOI [pdf]

Merino, E. and Canals, À. (2011) Self–accelerating dolomite–for–calcite replacement: Self–organized dynamics of burial dolomitization and associated mineralization. Amer. J. Science, v. 311, p. 573–607. DOI [pdf]

VII) OTHER PUBLICATIONS

Merino, E. (2005) Very–high-temperature, closed–system origin of agates in basalts: New model, old and new evidence. In Kile D, Michalski T. and Modreski P. (eds), A Symposium on Agate and Microcrystalline Quartz; Golden, Colorado, Sept 9-11. [pdf]

Zhang, Y., Person, M., and Merino, E. (2005) Hydrologic and geochemical controls on soluble benzene migration in sedimentary basins. Geofluids 5, p. 83–105. [pdf]

Merino, E., Nahon, D., and Wang, Yifeng (1999) Simultaneous replacement, redox, and self-organization in the weathering of Mn–rich shales at Moanda, Gabon. In Armannsson, H. (ed), Geochemistry of the Earth’s Surface, Balkema, Rotterdam, p. 393-395.

Wang, Yifeng and Merino, E. (1993) Oscillatory magma crystallization by feedback between the concentrations of reactants and mineral growth rates. J. Petrology 34, p. 369–382.[pdf]

Merino, E., Harvey, C. and Murray, H. (1989) Aqueous chemical control of the tetrahedral aluminum content of quartz, halloysite and other low–temperature aluminosilicates. Clays and Clay Minerals 37, p. 135–142. [pdf]

Ortoleva, P., Merino, E. and Strickholm, P. (l982) Kinetics of metamorphic layering in anisotropically stressed rocks. Amer. J. Science, 282, p. 6l7–643. [pdf]