Ricardo L. Silva
1459 Oxford Street
PO BOX 15000
Halifax NS B3H 4R2
Life Sciences Centre
3rd Floor Bio/ES Wing
B.Sc. Geology (Coimbra University), Ph.D. Geology (Coimbra University)
Research: Mesozoic carbonate related sequence stratigraphy, paleoenvironmental/paleogeographical interpretation, and source rock characterization in organic-rich marine and non-marine carbonate/shale series
Dr Ricardo L. Silva applies innovative scientific research in the fields of Carbonate Sedimentology, Stratigraphy, and Geochemistry (elemental, isotopic and organic) to the study of organic-rich intervals, Paleoceanography, Paleoenvironments, and singular events in the geological record (Oceanic Anoxic Events). His research is focused on the Triassic–Jurassic time interval and is supported by the evaluation and reanalysis of the existing and available organic geochemistry datasets, the observation and geochemical study of selected cores and cuttings from offshore wells, and integration with time-equivalent outcrops and well data from Canada and associated conjugate margins, namely Morocco, Portugal, Spain, England, and Ireland.
Currently, Dr Silva is developing independent research focused in two interconnected areas of research regarding the global record of organic-rich intervals in the geological archive: a) Paleoceanography and Paleoenvironments and b) Diagenesis of organic matter in carbonate depositional systems and petroleum research. These two areas of research have a direct application to the comprehension of current Global Changes (Ocean Studies), Sedimentology, and Paleoceanography of the Atlantic margins and Petroleum System Analysis.
Top 5 scientific contributions to carbonate Sedimentology, Paleoceanography, and Paleoenvironments
a) Silva, R.L., Carlisle, C.*, Wach, G. 2017. The carbon isotopic record of the Lower Jurassic in the Slyne Basin (Ireland). Marine and Petroleum Geology, 86, 499-511
Observed that local and regional conditionings (including diagenesis) have an important role governing δ13C of carbonate and organic matter during the Lower Jurassic (Slyne Basin, Ireland). In a previously unexplored paleogeographical domain regarding stable carbon isotopes, the δ13C record shows positive values during the Upper Sinemurian, a negative trend followed by a minor positive trend during the uppermost Sinemurian–Lower Pliensbachian, a negative trend during the lowermost Lower Toarcian, and then the return to more positive δ13C values. Despite the biostratigraphic uncertainty, the coarse resolution of the dataset, and the complex assessment of diagenetic effects, we suggest that the δ13C record of the studied well records the Raricostatum Zone positive CIE, the Sinemurian-Pliensbachian Boundary Event, and the negative CIE associated with the T-OAE. The T-OAE positive CIE is not clearly defined in the obtained dataset. The slight post T-OAE negative CIE recovery to more positive values and the continuation of a relatively high organic content is coeval with a regional organic matter preservation interval observed in several Northern-European locations. This study is a new and valuable addition to the understanding of the extent and causes of the secular events that led to the T-OAE subsequent recovery interval. It is also a contribution to lowering the risk of hydrocarbon exploration efforts in Ireland's offshore, allowing the integration with known time-equivalent source rock outcrops on the Atlantic conjugate margins of Canada, UK, Morocco, Portugal, and Spain
b) Silva, R.L., Duarte, L.V., 2015. Organic matter production and preservation in the Lusitanian Basin and Late Pliensbachian climatic hot snaps. Global and Planetary Change, 131, 24–34
Based on the integration of sedimentological, biostratigraphical, geochemical, and organic petrographic evidence, we suggested that the black shales dated from the Ibex–Margaritatus zones in the Lusitanian Basin (Portugal), corresponding to widespread mucilage and microbial outbreaks, were driven by extreme climate warming coupled with high oceanic productivity and intermittently stratified epeiric seas. Regionally, these “hot snaps” may have promoted the observed rapid but short-lived expansion of Tethyan ammonites into Boreal domains or led to decrease benthic diversity. Ensuing cooling during the Margaritatus Chronozone was accompanied by a southwards influx of northwards ammonite fauna or radiation of cyst-forming dinoflagellates. Worldwide preservation of organic matter during the Late Pliensbachian seems to have resulted in decreased atmospheric CO2 levels through geological storage of carbon, triggering and/or amplifying the Spinatum Chronozone icehouse event. Ultimately, this cooling event may have led to the occurrence of permafrost and/or methane gas hydrates in locations easily disturbed by the subsequent Early Toarcian warming, or/and volcanic activity.
c) Silva, R.L., Mendonça Filho, J.G., Azerêdo, A.C., Silva, T.F., Duarte, L.V., 2014. Palynofacies and TOC analysis of marine and non-marine sediments across the Middle-Upper Jurassic boundary in the central-northern Lusitanian Basin (Portugal). Facies, 60, 255–276.
Described a new kind of kerogen particle (intraclasts) from the Oxfordian of the Lusitanian Basin (Portugal). These particles correspond to the remnants of cohesive microbial mats, inclusively showing some structures resembling mat-forming filamentous cyanobacteria. These particles are a testimony of a complex association of cyanobacteria, formed in a nearby environment and subjected to reworking to become finally incorporated in sediment. Importantly, these intraclasts highlight the paleoenvironmental complexity of the Oxfordian in the Lusitanian Basin.
d) Silva, R.L., Mendonça Filho, J.G., da Silva, F.S., Duarte, L.V., Silva, T.F., Ferreira, R.*, Azerêdo, A.C. 2012. Can biogeochemistry aid in the palaeoenvironmental/early diagenesis reconstruction of the ~187 Ma (Pliensbachian) organic-rich hemipelagic series of the Lusitanian Basin (Portugal)?. Bulletin of Geosciences, 87, 373–382
Data on lipids, carbohydrates and proteins of the most expressive black shale (s.l.) intervals of the Early–Late Pliensbachian (Early Jurassic, ~187 Ma) organic-rich hemipelagic series of the Lusitanian Basin (Portugal) were determined using a method that has been successfully applied over the last two decades in the characterization of biomass and very immature sediments. The overall match between lipid contents (biogeochemistry) and specific depositional/early diagenetic conditions in carbonate systems favour the idea that biogeochemistry is a useful tool for the study of ancient organic-rich carbonate sedimentary series.
e) Silva, R.L., Duarte, L.V., Comas-Rengifo, M.J., Mendonça Filho, J.G., Azerêdo, A.C., 2011. Update of the carbon and oxygen isotopic records of the Early–Late Pliensbachian (Early Jurassic, ~187 Ma): Insights from the organic-rich hemipelagic series of the Lusitanian Basin (Portugal). Chemical Geology, 283, 177–184
Based on the most complete carbon isotopic dataset to date, we evoked that the Late Pliensbachian corresponds to a widespread organic matter preservation interval (Late Pliensbachian OMPI) with an associated positive carbon excursion. This paper coined the definition of Organic Matter Preservation Interval.
Other significant scientific achievements
-The extensive Jurassic organic-rich intervals in the Western European and African conjugate margins suggest that exploration for hydrocarbons in Atlantic Canada can test alternative (and new) play concepts, improving chances of success. Expensive deep-water oil and gas developments ($100’s of millions to $billions) are in place or planned along continental slopes around the world; it is critical to understand these complex deposits to help reduce the risk and expense of these developments. Understanding the geologic processes increases our understanding of the controls on source rock potential and reservoir delivery systems and develops exploration and production models where few exist (Silva et al., 2015 CSEG Recorder)
-Elaborated and presented a comprehensive scheme of (2nd-order) Transgressive-Regressive facies cycles for the Early–Middle Jurassic interval and (3rd-order) genetic sequences for the Lower–Upper Pliensbachian in the Lusitanian Basin, Portugal. Recognized the temporal equivalence between black shale occurrences and sequence stratigraphic architecture between the Lusitanian, Basque-Cantabrian and Asturias Basins (Duarte et al., 2010 Geologica Acta; Silva et al., 2015 Elsevier book chapter).
-Investigated the utility of constrained sparse spike inversion (CSSI) applied to a small 3D seismic volume at Penobscot in the Sable sub-Basin, offshore Nova Scotia, Canada. This acoustic impedance 3D volume facilitated the interpretation of: (1) low impedance Cretaceous reservoir sandstones, in both complex confined channel systems and extensive unconstrained marginal marine systems; (2) polygonal fault systems (PFS) in a high impedance, late Cretaceous chalk; and (3) the interfingering of low impedance shales and high impedance carbonates at the margin of the Jurassic Abenaki Carbonate Bank (Campbell et al., 2015 Marine and Petroleum Geology).
-Shown that the isotopic composition of several samples of fossil wood from the Sinemurian of the Lusitanian Basin, Portugal, were severely affected by sedimentary and diagenetic processes. It was shown that future isotopic studies on fossil wood should involve a more detailed diagenetic screening, such as the one presented in this study, to ensure a proper understanding of the biological (mostly biodegradation) or diagenetic processes affecting the isotopic composition of the studied samples (Silva et al., 2013 Geochemical Journal);
-detailed characterization and paleoenvironmental interpretation of a singular and rare example of subtidal carbonate stromatolites of Sinemurian age in the Lusitanian Basin, Portugal (e.g. Azerêdo et al., 2010, facies);
-improvement of several ammonite biostratigraphic boundaries, with a profound impact in the lithostratigraphy and regional correlations.