Carlos Jaramillo

Humberto Carvajal

Humberto Carvajal

Humberto Carvajal


Department of ecological sciences 1001 E. 10th Street
Indiana University. Bloomington, IN 47405


Ph.D. Geology Student, Department of Geological Sciences, Indiana University (current)
M.Sc. Geology, Department of Geological and Atmospheric Sciences, Iowa State University (2007)
B.S., Geology, Industrial University of Santander, Bucaramanga-Colombia (2004)

Research and Teaching Experience

I’m currently involved in the project “Bioestratigrafía del Neotrópico”, where many geology tools are used in order to understand the geological evolution of Neotropics in response to tectonic, paleoclimatic and biological changes as recorded in sedimentary sequences worldwide.

Climate and Quaternary Research Group at the Geological and Atmospheric Sciences department, Iowa State University, 2005-2007.

Research Assistant. My tasks were to sample and process rock (Mesozoic, Tertiary and Quaternary Formations), soil, water and plant samples for stable isotope analyses (δ13C, δ18O, δ15N, δD, δ34S) and then analyze and to interpret the results of such analyses.


Teaching Assistant. My tasks consisted in teaching and grading introductory geology, geology for engineers and petroleum geology labs.


Research assistant for the Project “Thermal Maturity level of La Luna Formation in the Middle Magdalena Basin (Santander)”. Fundamentally I was evaluating the different bulk geochemical parameters that define a good marine petroleum source rock (TOC, Sulfur, Ro, Florescence), which lead to a better comprehension of source rocks in the Middle Magdalena Basin

Grants and Fellowships

Geological Society of America Student Research Grant (2006) with the proposal “Carbon Isotopic Composition of Plant-derived Organic Matter from a Tropical Sedimentary Sequence as a Recorder of Late Cretaceous-Early Paleogene Changes in the Carbon Cycle.”

Graduate student travel award-conferences grant. Awarded by the Center for
Global and Regional Environmental Research of the University of Iowa. (2006)

Graduate student travel award-Research grant (2006). Awarded by the Center for Global and Regional Environmental Research of the University of Iowa.

Grant: Promoción jovenes investigadores, segunda convocatoria (2004) corporacion geologica ARES (Translation: Grant “young researchers, second edition”, ARES geological corporation), with the proposal: “An update to the Thermal maturity level of La Luna Formation, in the Middle Magdalena Basin, Colombia”

Outstanding student, first academic term (2003)
Universidad industrial de Santander( UIS), Bucaramanga Colombia

Outstanding student, second academic term (2002)
Universidad industrial de Santander( UIS), Bucaramanga Colombia.


Current research focuses on the evaluation of perturbations in past carbon cycle dynamics using stable isotopes of carbon and geochemical biomarkers. In addition, a short term goal of the research is focused on see how the findings of such perturbations will allow the correlation of marine and terrestrial sequences. Previous research was related with the evaluation of thermal maturity levels of petroleum source rocks using organic petrography (vitrinite reflectance and fluorescence of organic matter).

After Zachos et al., 2001

(after Zachos et al., 2001)


The carbon isotopic composition of ancient atmospheric carbon dioxide (δ13CCO2) is a valuable tool to evaluate past changes in the dynamics of the carbon cycle. Some studies suggest that the isotopic composition of fossil plants can be used to estimate δ13CCO2, but those estimates have not been tested. Because changes in the isotopic composition of marine carbonate affect that of atmospheric carbon and thus that of plant-derived organic matter (δ13Cplant), I am assessing the inferred link between the carbon isotopic composition of sedimentary organic matter δ13CBULK and atmospheric δ13CCO2 values by performing δ13Cplant measurements on Mesozoic-Cenozoic sedimentary organic matter and by comparing these values with those recorded in marine carbonates. The assumption is that the incorporation of carbon isotopes into ancient plant biomass occurred in a similar fashion to what occurs during modern photosynthesis. Because plant physiology, microbial degradation, and rock diagenesis are processes that can modify δ13Cplant values, and thus δ13CBULK, and that are rarely carefully considered when performing δ13CCO2 estimations, I employ molecular biomarkers to evaluate potential microbial and preservation biases.


Although δ13C values from marine carbonates provide valuable information on past changes of the carbon cycle, the effect and response on terrestrial biomass cannot directly be inferred from these values. In order to have a more complete picture of these past changes in the carbon cycle, terrestrial-derived atmospheric δ13CCO2 values are then needed. For instance, studies on modern δ13CCO2 values demonstrate their usefulness by showing the impact of fossil fuel combustion and deforestation on the carbon cycle. Similarly, past δ13CCO2 values as inferred from δ13CBULKt could be an extremely useful tool to evaluate ancient carbon cycle dynamics because changes in the transfer of carbon between different carbon pools (lithosphere, oceans, and biomass) affect both δ13CCO2 and CO2 concentrations. Examples of these carbon dynamics include the consumption of atmospheric CO2 associated with increased weathering during uplifting, the release of CO2 associated with periods of increasing volcanic activity, and the transfer of carbon related to waxes and wanes of marine and terrestrial biomass associated with mass extinctions, the evolution or rise of a new kind of primary producers. The tight coupling between climate, atmospheric CO2, and productivity and their effects on the carbon cycle and the carbon isotope mass balance of the planet makes it important to have accurate and reliable δ13CCO2 values without any kind of biases.

After Jahren et al., 2005

(after Jahren et al., 2005)

Unfortunately, plant physiology, microbial degradation, and diagenesis are processes that constraint and, in some cases, modify δ13Cplant, thus eventually overprinting δ13CCO2 values estimated from δ13CBULK values. The use of molecular biomarkers provides a tool to circumvent these diagenetic biases because the isotopic values of key compounds originally present in plants remain constant through time.


(after GrÍcke, 2002)

My current research employs on n-alkanes, sesqui-, di, and triterpenoids present in plant waxes, which have a high preservation potential, are relatively abundant, easily identifiable, and preserve their original isotopic composition.


Typical chromatogram for the saturated fraction of selected samples from the South American tropics.

Published Abstracts of Papers Presented at Professional Meetings

Carvajal-Ortiz, Humberto, Mora, Germán, Jaramillo, Carlos. (2006) Carbon Isotopic Composition of Plant-derived Organic Matter from a Tropical Sedimentary Sequence as a Recorder of Late Cretaceous-Early Paleogene Changes in the Carbon Cycle. Poster Session. Geological Society of America Annual Meeting, Philadelphia, PA, USA.

Carvajal-Ortiz, Humberto, Garcia-Gonzalez, Mario. (2005) Supresion de la reflectancia de la vitrinita en la formacion la luna, valle medio del Magdalena, Colombia: implicaciones regionales (Vitrinite reflectance suppression in la Luna formation, middle Magdalena basin, Colombia: Regional consequences). XII congreso latinoamericano de geologia, Quito, Ecuador. ( In Spanish).

Carvajal-Ortiz H., García Gonzaléz, M. (2005) Fenómenos de Supresión de la Reflectancia De Vitrinita en La Formación La Luna, Valle Medio del Magdalena, Colombia (in Spanish). X Congreso Colombiano De Geología, Bogotá, Colombia

Research Interests

Stable isotope geochemistry; Geochemical biomarkers; Paleoclimatology; carbon cycle; Coal Geology; Petroleum Source rock evaluation