Luis A. González
My general research interests are in:
- Stable isotope chemistry and its application to continental paleoclimatology.
- Carbonate geochemistry with emphasis on isotopic and trace elemental chemistry.
- Carbonate geology with emphasis on karst development and carbonate deposition in marine and karst systems.
- Carbonate diagenetic processes.
- Quaternary Paleoclimates
- Cretaceous Paleoclimate and Paleohydrology
- Experimental Carbonate Growth
- Hydrocarbon Bearing Concretions in South Central Puerto Rico
- Sedimentology and Diagenesis of Isla de Mona, Puerto Rico
A significant portion of my current research emphasizes the utilization of the isotopic composition, mineralogy, growth history and growth patterns of speleothems (cave formations such as stalagmites, stalactites, and flowstone) to extract paleoclimatic and paleoenvironmental signals. Research has been conducted in the North American Midwest (Iowa, Illinois, Missouri, Minnesota, and Wisconsin), Asia (Vietnam and Nepal), and the Caribbean (Jamaica, Puerto Rico). Current research efforts focus on northern South America.
Particular efforts include:
- The development of seasonal proxies from stalagmite growth patterns and isotopic composition
- Development of absolute chronologies using stalagmite growth banding.
- Development of infiltration-precipitationg proxy utilizing growth banding and isotopic composition.
The image at right is a Laser Scanning Confocal Microscopy fluorescent image of a stalagmite (image taken at The University of Iowa Central Electron Microscopy Facility). The light (bright) bands are fluorescent and the gray (dark) bands are non-fluorescent. These bands are believed to represent spring-to-summer (bright) and fall-to-spring (dark) calcite growth. Fluorescent growth banding allow us to identify yearly growth and thus generate absolute chronologies. Image height is approximate 0.6 mm.
- Frappier, A. B., Sahagian, D., Carpenter, S. J., González, L. A., Frappier, B. R., 2007, A stalagmite stable isotope record of recent tropical cyclone events: Geology, v.35, p. 111-114.
- Frappier, A., Sahagian, D., González, L. A., and Carpenter, S. J., 2002, El Niño events recorded by stalagmite carbon isotopes: Science, v. 298, p. 565.
- Baker, R. G., Bettis III, E. A., Denniston, R. F., González, L. A., Strickland, L. E., and Krieg, J. R., 2002, Holocene paleoenvironments in southeastern Minnesota chasing the prairie-forest ecotone: Palaeogeography, Palaeoecology, Palaeoclimatology v. 177, p. 103-122.
- Denniston, R. F., González, L. A., Asmerom, Y., Polyak, V., Reagan, M. K., Saltzman, M. R., 2001, A high- resolution speleothem record of climatic variability during the Allerød-Younger Dryas transition in Missouri, central United States: Palaeogeography, Palaeoecology, Palaeoclimatology, v. 176, p. 147-155.
- Baker, R. G., Bettis, E. A. III, Denniston, R. F., and González, L. A., 2001, Plant remains, alluvial chronology, and cave speleothem isotopes indicate abrupt Holocene climatic change at 6ka in Midwestern USA, Global and Planetary Change, v. 28, p.285-291.
- Denniston, R. F., González, L. A., Asmerom, Y., Reagan, M. K., and Recelli-Snyder, H., 2000, Speleothem carbon isotopic records of early Holocene environments in the Ozark Highlands, U.S.A. Quaternary International, v. 67, p. 21-27.
- Denniston, R. F., González, L. A., Asmerom, Y., Baker, R. G., Reagan, M. K. Bettis, E. A. III, 1999, Evidence for increased cool season moisture during the middle Holocene: Geology, v. 27 (9), p. 815-818.
- Baker, R. G., González, L. A., Raymo, M., Bettis III, E. A., Reagan, M. K., and Dorale, J. A., 1998, Comparison of multiple proxy records of Holocene environments in Midwestern USA: Geology, v. 26, (12), p. 1131-1134.
- Figure at right from Baker et al. 1998:
- Figure 3. A: Carbon isotopic composition of speleothem calcite for Cold Water Cave stalagmites 1S and 3L. B: Carbon isotopic composition of Roberts Creek alluvial sedimentary organic matter. Values of d13C for sedimentary organic matter are averages of three analyses, and error bars represent standard deviation (1s). Note similarity in timing of all three records, and correlation with plant records in Figure 2. C: Estimates of percent contribution of C4 plants through time to the soil and sedimentary biomass over Cold Water Cave based on carbon isotopic composition of sedimentary organic matter and a composite of stalagmite carbon isotopic record.
- Denniston, R. F., González, L. A., Asmerom, Y., Sharma, R. H., and Reagan, M. K, 2000, Speleothem evidence for changes in Indian summer monsoon precipitation over the last 2300 years: Quaternary Research, v. 53 (2), p. 196-202.
- Left: Overturned Tata during overnight flooding of a tributary of the Narayani River of South Central Nepal (which becomes the Gandak River of northern India, a Ganga tributary)
- Photograph: L. Gonzalez, summer 1998
- González, L. A., 1996, Use of stalagmites in High Resolution Paleoclimatic Studies: in Mikami, T, Matsumoto, E., Ohta, S., and Sweda, T., eds., Paleoclimate and Environmental Variability in Austral-Asian Transect during the Past 2000 Years, PROCEEDINGS of the 1995 Nagoya IGBP-PAGES/PEP-II Symposium , Nagoya University, Nagoya, Japan, p. 144-151.
- Dorale, J. A., González, L. A., Reagan, M. K., Pickett, D. A., Murrell, M. T., and Baker, R. G., 1992, A high resolution record of Holocene climate change in speleothem calcite from Cold Water Cave, northeast Iowa: Science, v. 258, p. 1626-1630.
Cretaceous Paleoclimate and Paleohydrology
This research is a collaborative effort with G. Ludvigson (Kansas Geological Survey), B. Witzke (Iowa Department of Natural Resources Geological Survey Bureau), R. Brenner (University of Iowa), David Ufnar (University of Southern Mississippi) focusing on the use of isotopic geochemistry of early diagenetic siderite and calcite to extract paleoenvironmental information. This research effort aims to improve our understanding of paleohydrology of coastal lowlands of the Cretaceous Western Interior Basin. The initiation of this research was spearheaded by Dr. Ludvigson who recognized that sphaerosiderites encountered in association with paleosol horizons in paleo-coastal (humid) lowland sequences had great potential to preserve important paleoenvironmental information.
The first major achievement of our research was documenting the systematic behavior of sphaerosiderite isotopic chemistry (Ludvigson et al., 1998) that can be used as a proxy for the isotopic composition of paleogroundwaters in coastal lowlands. We have generated large data sets for the eastern margin of the Cretaceous Western Interior Basin and for the northernmost portions of the western margin (e.g., White et al, 2000; Ufnar et al., in review) and produced a paleolatitudinal sphaerosiderite d18O trend (35 to 70° N). One of the surprises of our data set is that it implies a precipitation paleolatitudinal d18O trend that is much steeper than the modern trend. This is counterintuitive, if we assume that present day temperature-d18O relationships apply to the past. Under my direction, we have taken next logical progression and are using the sphaerosiderite d18O to quantify changes in the hydrologic cycle. Our initial approach utilized well-known amount-effect relationship with efforts led by Post-Doctoral Research Associate T. White (White et al, 2000 Geology). Osotopic mass balance modeling efforts were led by former Ph.D. student D. Ufnar (Ufnar et al., 2002 and 2004), both approaches yield estimates that imply precipitation rates that are at least double and up to four times higher than present day rates.
As part of this research we have identified unique setting where co-occurrence of what appear to be coeval calcite and sphaerosiderite phreatic cements formed in regional aquifers, allow us to estimate regional vs. local groundwater compositions (sphaerosiderite vs. siderite and/or calcite). The regional aquifer phreatic cements are significantly lighter than nearby locally recharged humid paleosol sphaerosiderites. The regional phreatic cement data also exhibit a poleward paleolatitudinal d18O trend towards more depleted isotopic compositions. The combination of coastal lowland sphaerosiderite data with regional aquifer cement will allow to develop models to quantify contributions from local vs. regional (e.g., high altitude melts on western margin catchments, and continental effects on eastern margin broad low altitude catchments).
Our current data gathering efforts and modeling results provide us with unique means to quantify changes in the hydrologic cycle. Our empirical data from terrestrial settings and mass balance model results serve to test and validate GCM simulations and their applicability to Greenhouse world conditions. We are extending the latitudinal cover of our studies to include the sub-tropical to tropical belts and in the coming years we will be sampling Albian sequences in Texas and New Mexico, and sequences in Mexico and Colombia.
- Suarez, M. B., Gonzalez, L.A., and Ludvigson G.A., 2011, Quantification of a greenhouse hydrologic cycle from equatorial to polar latitudes: the mid-Cretaceous water bearer revisited: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 307, p. 301-312
- Ludvigson, G. A., Joeckel, R. M., Gonzalez, L. A., Gulbranson, E. L., Rasbury, E. T., Hunt, G. J., Kirkland, J. I., and Madsen, S., 2010, Correlation of Aptian-Albian carbon isotope excursions in continental strata of the Cretaceous foreland basin of eastern Utah: Journal of Sedimentary Research, v.80, p.955-974. doi: 10.2110/jsr.2010.086
- Driese, S. G., Ludvigson, G. A., Roberts, J. A., Fowle, D. A., González, L. A., Smith, J. J., Vulava, V. M., and McKay, L. D., 2010, Micromorphology and Stable Isotope Geochemistry of Historical Pedogenic Siderite Formed in PAH-Contaminated Alluvial Clay Soils, Tennessee, USA: Journal of Sedimentary Research, v.80, p.943-954. doi: 10.2110/jsr.2010.087
- Suarez, M. B., González, L. A., and Ludvigson, G. A., 2010, Estimating the oxygen isotopic composition of equatorial precipitation during the mid-Cretaceous: Journal of Sedimentary Research, v.80, p.480-491. doi: 10.2110/jsr.2010.048
- Ludvigson, G. A., Witzke, B. J., Joeckel, R. M., Ravn, R. L., Phillips Jr., P. L., González, L. A., and Brenner, R. L., 2010, New insights on the sequence stratigraphic architecture of the Dakota Formation in Kansas-Nebraska-Iowa from a decade of sponsored research activity: Kansas Geological Survey, Current Research in Earth Sciences, Bulletin v. 258, 41p.
- Suarez, M. B., González, L. A., Ludvigson, G. A., Vega, F. J. and Alvarado-Ortega, J., 2009, Isotopic composition of low-latitude paleo-precipitation during the early Cretaceous: GSA Bulletin, v. 121, p. 1584-1596.
- Phillips Jr., P. L., Ludvigson, G. A., Joeckel, R. M., González, L. A., Brenner, R. L., and Witzke, B. J., 2007, Sequence stratigraphic controls on synsedimentary cementation and preservation of dinosaur tracks: example from the Late Albian Cretaceous Dakota Formation, southeastern Nebraska, U.S.A.: Palaeogeography, Palaeoecology, Palaeoclimatology, v. 246, p.367-389, doi:10.1016/j.palaeo.2006.10.013
- Ufnar, D. F, Ludvigson, G. A., González, L. A., Brenner, R. L, and Witzke, B. J., 2004, High latitude meteoric d18O compositions: paleosols siderite in the mid-Cretaceous Nanushuk Formation, North Slope, Alaska: Geological Society of America Bulletin, v. 116, p. 463-473
- Ufnar, D. F, González, L. A., Ludvigson, G. A., Brenner, R. L, and Witzke, B. J., 2004, Diagenetic overprinting of the sphaerosiderite paleoclimate proxy: are records of pedogenic groundwater d18O values preserved? Sedimentology, v.51, pp. 127-144. doi: 10.1046/j.1365-3091.2003.00615.x.
- Brenner, R. L., Ludvigson, G. A., Witzke, B. J., Phillips, P. L., White, T. S. Ufnar, D. F., González, L. A., Joeckel, R. M., Goettemoeller, A., and Shirk, B. J., 2003, Aggradation of gravels in tidally influenced fluvial systems, upper Albian (Lower Cretaceous) on the cratonic margin of the North American Western Interior foreland basin: Cretaceous Research, v. 24, p. 439-448.
- Ufnar D. F., González, L. A., Ludvigson, G. A., Brenner, R. L., and Witzke, B. J., 2002, The mid-Cretaceous water bearer: isotope mass balance quantification of the Albian hydrologic cycle: Palaeogeography, Palaeoecology, Palaeoclimatology v. 188, p. 51-71.
- Ufnar D. F., González, L. A., Ludvigson, G. A., Brenner, R. L., and Witzke, B. J, 2001, Stratigraphic implications of meteoric sphaerosiderite d18O compositions in paleosols of the Cretaceous (Albian) Boulder Creek Formation, NE British Columbia foothills, Canada: Journal of Sedimentary Research, v. 71, No. 6, p. 119-130.
- White, T. S., González, L. A., Ludvigson, G. A., and Poulsen, C. J., 2001, Middle Cretaceous Greenhouse Hydrologic Cycle of North America: Geology, v. 29, no. 4, p. 363-366.
- Ludvigson, G. A., González, L. A., Metzger, R. A., Witzke, B. J., Brenner, R. L., Murillo, A. P., and White, T. S., 1998, Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology: Geology, v 26 (11), p. 1039-1042.
Hydrocarbon Bearing Concretions South Central Puerto Rico
Petroleum exploration efforts in Puerto Rico have focused on Tertiary basins that are believe to hold the greatest potential of yielding exploitable hydrocarbons, yet, in these basins neither hydrocarbons nor potential source rocks have been discovered. The only documented occurrence of hydrocarbons in the island of Puerto Rico are carbonate concretions of the Cretaceous Cariblanco Formation. Hydrocarbons in these concretions are preserved as inclusions within calcite cements and a light mature oil is present in voids in the concretions. Recent petrographic, isotopic and organic chemistry studies by the PI and colleagues indicate that 1) significant hydrocarbons were generated during the formation of these concretions; 2) hydrocarbon generation was linked to elevated geothermal gradients and faulting associated with the emplacement of the Late Cretaceous intrusives; and 3) the fate of the hydrocarbons might have been linked to either the Cretaceous deformation of regional Paleocene to Eocene motions along the Great Southern Puerto Rico Fault Zone. Research focus on 1) the diagenetic history of concretionary carbonates in the Cariblanco and associated units, limestone units within the Cariblanco and overlying units and calcite veins associated with Cretaceous to Eocene faulting; 2) 40Ar/39Ar dating of intrusive bodies; 3) geometric and kinematic studies of faults, folds, and veins; to determine the links between a) hydrocarbon generation and migration, b) carbonate deposition (concretions, limestones, and veins), c) igneous intrusions, d) faulting and folding, e) vein formation/deformation, and f) regional tectonics.
- González, L. A., Neuhoff, P. S., Larue, D. K.,Uribe, R. M., and Ruiz, H. M., in review, Diagenesis of hydrocarbon bearing concretions in south-central Puerto Rico: Tectonism and early hydrocarbon generation. Submitted to AAPG Bulletin, 20 ms p., 11, figs. 1 table.
Isla de Mona
Isla de Mona is an uplifted carbonate plateau that lies halfway between Puerto Rico and Hispaniola (Dominican Republic). The island is made of Miocene to Pliocene shallow water carbonates and is fringed on its western and southern sides by Pleistocene reef terraces.
Research on Isla de Mona focuses on the diagenesis of the Miocene to Pliocene carbonates. Extensive cavern development and massive dolomitization of these carbonates (Isla de Mona Dolomite and Lirio Limestone) are early diagenetic features and are associated with repeated sea-level oscillation. During the Miocene and earliest Pliocene the island was at or near sea level. No definitive middle or late Pliocene deposits are known and it is likely that the island remain exposed throughout much of this time. A number of Pleistocene fringing-reef deposits (terraces) can be found at elevations ranging from over 60 meter to 6 meters indicating that the island was uplifted in episodic fashion during the Pleistocene.
The Miocene carbonates of Isla de Mona exposes the only known late Miocene reef complex in the Caribbean.
- González, L. A., Ruiz, H. M, Taggart, B. E., Budd, A. F., and Monell, V., 1997, Geology of Isla de Mona Puerto Rico: in Vacher, H. L., and Quinn, T. M., eds., Geology and Hydrogeology of Carbonate Islands, Developments in Sedimentology, vol. 54, Elsevier, p. 327-358.
Current Graduate Students
- Alejandra Rodriguez-Delgado
- Christine Frasca
- Ted Morehouse
- Rebecca Toten
Former Graduate Students
University of Kansas
- Aisha Al-Suwaidi - MS 2007
- Stacy M. Rosner - MS 2006
University of Iowa
- Roger Gomez - MS 2004
- Heather Steffe - MS 2004
- Vionette DeChoudens-Sanchez - MS 2003
- Heidi Dowd - MS 2003
- Leah Young - MS 2002
- Jennifer Obrad - MS 2002
- Mary Ellis - MS 2001
- Aaron Suzuki - MS 1998
- Mary Clare Jones (Maxwell) - MS 1997
- Suellen Leimkuehler - MS 1996
- Randy Locke - MS 1994
- Hector M. Ruiz - MS 1993
- Jeffrey A. Dorale - MS 1992
- Paul K . Knoerr - MS 1991