I work in Nicholas Tosca‘s group and my current DPhil research aims at providing physico-chemical constraints on different growth morphologies of carbonate crystals. Carbonate minerals and carbonate rocks are widespread across the geological record and on the surface of Earth, comprising important elements that allow us to probe deep into Earth’s past environmental conditions. Calcite crystals, in particular, are known to occur in a variety of forms, and to complicate matters one given morphology may usually result from somewhat different surface environmental processes. Thus, one important question is whether or not a given morphology can be directly interpreted as a proxy for some specific environmental condition. I am currently studying carbonate precipitation under variable alkaline conditions, and such solutions may also have provided the necessary conditions for the onset of life, although more likely at higher temperatures than what is being considered in our current experiments, and across a proton (pH) gradient.

I worked for 13 years in the oil and energy industry, before starting my DPhil. There I have applied inorganic and isotopic geochemistry as chemostratigraphic tools for stratigraphic correlation, geochemical modelling, palaeoenvironment reconstruction, and studies in diagenesis. In industry, I could extend my scientific interests to the search for solutions to rather applied geological problems, and I also have been able to develop a wider perception of our society’s demand for natural resources and for energy. Human society does not move forward without relying so much on Earth’s resources. And this is actually a general principle for all life, in such a way that this idea is connected with the broader underlying concepts regarding the onset of life itself. Interestingly, the growth of populations and of societies has a fundamental analogy with the growth of minerals: all consume resources from their surroundings in order to keep going, although this surficial perception may conceal an even more striking principle.

I developed my background in geochemistry, environmental sciences, geology and palaeoclimate. My MSc in Earth Sciences (Geochemistry) focused on tracing the origin and distribution of some classes of persistent organic pollutants (POPs) in an estuarine environment in southern Brazil, among them polycyclic aromatic hydrocarbons (PAHs) and some organochlorine compounds. I also did experimental work on the sorption behaviour of selected heavy metals as they derived from the use of fertilisers applied to tropical soils (my BSc concluding study).

I am keen to promote discussions on any of these topics and to engage in scientific outreach for the public. For this latter purpose I created my blog a few years ago (in Portuguese), where I’ve tried to raise awareness on issues concerning science and education for the Brazilian community.

  • Pietzsch, R., Tosca, N.J., Gomes, J.P., Roest-Ellis, S., Sartorato, A.C.,L., Tonietto, S.N., 2022. The role of phosphate on non-skeletal carbonate production in a Cretaceous alkaline lake. Geochimica et Cosmochimica Acta, in press. doi: 10.1016/j.gca.2021.09.032


  • Pietzsch, R., 2021. Comment on “Evaporitic carbonates in the pre-salt of Santos Basin – Genesis and tectonic implications”. Marine and Petroleum Geology, 104963. doi: 10.1016/j.marpetgeo.2021.104963


  • Pietzsch, R., Tedeschi, L.R., Martins, D.O., Anjos, C.W.D., Vazquez, J.C., Figueiredo, M.F. 2020. Environmental conditions of deposition of the Lower Cretaceous lacustrine carbonates of the Barra Velha Formation, Santos Basin (Brazil), based on stable carbon and oxygen isotopes: a continental record of pCO2 during the onset of the Oceanic Anoxic Event 1a (OAE 1a) interval? Chemical Geology 535, 119457. doi: 10.1016/j.chemgeo.2019.119457


  • Pietzsch, R., Martins, D.O., Tedeschi, L.R., Queiroz Neto, J.V., Figueiredo, M.F., Vazquez, J.C., Souza, R.S. 2018. Palaeohydrology of the Lower Cretaceous pre-salt lacustrine system, from rift to post-rift phase, based on elemental geochemistry, biostratigraphy and radiogenic strontium isotope data, Santos Basin, Brazil. Palaeogeography, Palaeoclimatology, Palaeoecology 507, 60–80. doi: 10.1016/j.palaeo.2018.06.043


  • Freire, A.F.M., Leite, C.M.M., Oliveira, F.M., Guimarães, M.F., Milhomem, P.S., Pietzsch, R., D’Ávila, R.S.F. 2017. Fluid escape structures as possible indicators of past gas hydrate dissociation during the deposition of the Barremian sediments in the RecôncavoBasin, NE, Brazil. Brazilian Journal of Geology 47, 79–93. doi: 10.1590/2317-4889201720160090


  • Pietzsch, Raphael, Patchineelam, Sambasiva R., Torres, João P.M. 2010. Polycyclic aromatic hydrocarbons in recent sediments from a subtropical estuary in Brazil. Marine Chemistry 118, 56–66. doi: 10.1016/j.marchem.2009.10.004


  • Pietzsch, R., Polivanov, H., Silva, A.S., Alamino, R.C.J., Campos, T.M.P. 2009. Study on the interaction of heavy metals on farmland in Petropolis, Rio de Janeiro, Brazil.  10.1144/EGSP22.I