My research focuses on reconstructing and understanding the evolution of our oceans over geological time. Much of this work derives from chemistry and stratigraphy, and spans four general topics.
Earth and its oceans have experienced major changes over time. This is spectacularly documented for the last 100 million years, as stratigraphic records can be recovered, analysed and correlated from terrestrial, shallow marine and deep marine sequences. My work includes the generation and modeling of carbon isotope records, documenting and understanding changes in marine microfossils, and determining how and why primary productivity has varied. Key intervals of interest have been the late Paleocene-early Eocene and the late Miocene-Early Pliocene.
Clathrate hydrates of gas (“gas hydrates) are solids comprised of low molecular weight gases and water that form at moderately high pressure and moderately low temperature. Enormous quantities of methane hydrates occupy pore space of sediment along modern continental slopes where microbes produce sufficient gas to saturate pore waters. My research has included generation of gas hydrate phase boundary conditions, collecting samples using pressure cores, generating pore water profiles to understand their formation, and placing gas hydrates into the global carbon cycle.
Mixed Siliclastic-Carbonate Margins:
Some continental margins, both at present-day and formed in the past, receive large amounts of sediment from terrigenous siliciclastic sources (e.g., rivers) and marine carbonate sources (e.g., coral reefs). Modern examples include the Great Barrier Reef and coast of Belize. How do these systems evolve over time, especially when considering changes in sea-level and climate, which will change the amount and location of sediment discharge? My work addresses this problem by dating changes in sediment mass flux across over time.
Sediment Hosted Ore Deposits
Numerous types of ore deposits occur in sedimentary rocks. This can result from primary precipitation and or the replacement of sedimentary layers. So far, I have worked on microplaty hematite ores that lie within banded iron formation of Western Australia, vanadium deposits in weathered oil shale of Queensland, and stratiform barite deposits in the Gulf of Mexico.
GSU33006 Stratigraphy: Earth through time
GLU44001 Paleoceanography and Paleoclimatology
Geoscience Capstone Projects:
Presently, I co-supervise projects with Micha Ruhl on the stratigraphy of Mississippi age limestones in Ireland.
Future projects typically involve some combination of chemistry and stratigraphy
I typically am involved in external service to the international geoscience community. Presently, I am editor of the GSA journal, GEOLOGY.
Publications Since Coming to Trinity
I have been author or co-author on about 130 peer-reviewed papers. The following are the papers published since becoming a professor at TCD. (* = supervised student st time work was performed).
Westacott, S., C.J.Hollis, K. Pascher, G.R. Dickens & P.M Hull (2023) Radiolarian size and silicification across the Paleocene-Eocene boundary and into the early Eocene. Palaeogeography, Palaeoclimatology, Palaeoecology, 609, Article 111287 (in press).
Dallanave, E., R. Sutherland, G.R. Dickens, L. Chang, E. Tema, L. Alegret, C. Agnini, T. Westerhold, C. Newsam, A.R. Lam, W. Stratford, J. Collot, S. Etinenne & T. von Dobeneck (2022). Absolute paleolatitude of northern Zealandia from the middle Eocene to the Miocene. J. Geophysical Res., 127, e2022JB024736.
Xue, P., L. Chang, G.R. Dickens & E. Thomas (2022). A depth transect of ocean deoxygenation during the Paleocene-Eocene thermal maximum: magnetofossils in sediment cores from the southeast Atlantic. J. Geophysical Res., 127, e2022JB024714.
Reghellin, D., H.K. Coxall, G.R. Dickens, S. Galeotti & J. Backman (2022). The late Miocene-early Pliocene biogenic bloom in the Eastern Equatorial Pacific: new insights from Integrated Ocean Drilling Program Site 1335. Paleoceanography and Paleoclimatology, 37 e2021PA004313
Stratford, W.R., R. Sutherland, G.R. Dickens, P. Blum, J. Collot, M. Gurnis, S. Saito, A. Bordenave, S. J. G. Etienne, C. Agnini, L. Alegret, G. Asatryan, *J. Bhattacharya, L. Chang, M.J. Cramwinckel, E. Dallanave, M.K. Drake, M. Giorgioni, D.T. Harper, H.H.M. Huang, A.L. Keller, A.R. Lam, H. Li, H. Matsui, H.E.G. Morgans, C. Newsam, Y-H. Park, K.M. Pascher, S.F. Pekar, D.E. Penman, T. Westerhold & X. Zhou (2022). Timing of Eocene compressional plate failure during subduction initiation, northern Zealandia, southwestern Pacific. Geophysical Journal International, 229(3), 1567-1585. [doi.org/10.1093/gji/ggac016]
Sutherland, R., Z. Dos Santos, C. Agnini, L. Alegret, A.R. Lam, T. Westerhold, M.K. Drake, D.T. Harper, E. Dallanave, C. Newsam, M.J. Cramwinckel, G.R. Dickens, J. Collot, S.J.G. Etienne, A. Bordenave, W.R. Stratford, X. Zhou, H. Li & G. Asatryan (2022). Neogene Mass Accumulation Rate of Carbonate Sediment Across Northern Zealandia, Tasman Sea, Southwest Pacific. Paleoceanography and Paleoclimatology, 37. [doi: 10.1029/2021PA004294]
Meister, P., G. Herda, E. Petrishcheva, S. Gier, G.R. Dickens, C. Bauer & B. Liu (2022). Microbial Alkalinity Production and Silicate Alteration in Methane Charged Marine Sediments: Implications for Porewater Chemistry and Diagenetic Carbonate Formation. Frontiers in Earth Science, 9, Article 756591. [doi: 10.3389/feart.2021.756591]
Fokkema, C.D., S. Buijs, O.M. Bialik, A. Meilijson, N.D. Waldmann, Y. Makovsky, J. Frieling, G.R. Dickens & A. Sluijs (2022). Late Paleocene to middle Eocene carbon isotope stratigraphy of the Northern Negev, Southern Israel: potential for paleoclimate reconstructions. Newsletters of Stratigraphy, 55. [doi: 10.1127/nos/2022/0684]
*Barefoot, E.A., J.A. Nittrouer, B.Z. Foreman, E.A. Hajek, G.R. Dickens, T. Baisden & L. Toms (in press). Evidence for enhanced fluvial channel mobility and fine sediment export due to precipitation seasonality during the PETM. Geology.
Luciani, V., *R. D’Onofrio, G.R. Dickens & B.S. Wade (2021). Dextral to sinistral coiling switch in planktic foraminifer Morozovella during the Early Eocene Climatic Optimum. Global and Planetary Change, 206. [https://doi.org/10.1016/j.gloplacha.2021.103634].
Alegret, L., D.T. Harper, C. Agnini, C. Newsam, T. Westerhold, M. J. Cramwinckel, E. Dallanave, G.R. Dickens & R. Sutherland (2021). Early Eocene wamring in the Tasman Sea: First record of hyperthermal events from offshore Zealandia. Paleoceanography and Paleoclimatology, 36(5).
*Bhattacharya, J., L.Y. Yeung, *L. Cong, G.R. Dickens & T. Sun (2021). Size‐fraction‐specific stable isotope variations as a framework for interpreting early Eocene bulk sediment carbon isotope records. Paleoceanography and Paleoclimatology, 36(5). [https://doi.org/10.1029/2020PA004132]
Mallarino, G., *J.M. Francis, S.J. Jorry, J.J. Daniell, A.W. Droxler, G.R. Dickens, L. Beaufort, S.J. Bentley, B.N. Opdyke, & L.C. Peterson (2021). Timescale dependent sedimentary record during the past 130 kyr from a tropical mixed siliciclastic–carbonate shelf edge and slope: Ashmore Trough (southern Gulf of Papua). Sedimentology, doi10.1111/sed.12867.