Upcoming Seminars
May 23rd, 2024
Paleomagnetism of Mesoproterozoic mafic dykes of Congo/São Francisco - Implications on transition from Nuna to Rodinia supercontinent
- Johanna Salminen
University of Helsinki, Finland
Reconstructing ancient paleogeography is key to exploring Earth’s evolution in deep time. Currently three supercontinent cycles have been identified and supercontinents have been named from oldest to youngest: Nuna/Columbia, Rodinia, and Pangea. Supercontinents have been suggested to be preceded by the ~200 Myr earlier assembly of smaller landmasses (Wang et al., 2020), such as Umkondia before Rodinia and Gondwana before Pangea. While the Congo-São Francisco (C/SF) craton is a main building block in Gondwana due to its central location and it has been suggested to be part of Umkondia (C/SF-Kalahari-India-Amazonia) (e.g., Choudhary et al., 2019), its connection to Rodinia and Nuna has been controversial.
Here, a paleomagnetic record of Mesoproterozoic mafic dyke swarms in Angola and Brazil is used to reconstruct the paleogeography of C/SF during the supercontinent Nuna cycle. Comparison of the high-quality 1500 Ma Curaça paleomagnetic pole of C/SF (Salminen et al., 2016) with coeval, global robust poles and the large igneous province record indicates the proximity of C/SF with Amazonia-West Africa and Nuna core cratons (Baltica-Laurentia-Siberia), therefore supporting C/SF participation in the construction of the supercontinent Nuna. However, when using the recently obtained 1385 Ma Virei paleomagnetic pole of C/SF (Salminen et al., 2024) together with coeval global poles, a distinct reconstruction is obtained. The 1385 Ma Virei pole requires a substantial transform motion and large-magnitude azimuthal rotation (~85°) of the C/SF craton between 1500 Ma and 1385 Ma, which could be related to an early stage in the Nuna break-up. It also requires a large rotation of C/SF relative to Laurentia between 1385 Ma and the Neoproterozoic assembly of Rodinia.
Past Seminars
New age constraints on Ediacaran Oman provide a temporal framework for sedimentary and biogeochemical change at the dawn of animal life
- Marjorie Cantine
University of Washington
A Mesoarchean oxygen oasis expanded: new trace element and stable isotope data from the 2.8 Ga Mosher Carbonate, Steep Rock Lake, Canada
- Dylan Wilmeth
Grand Valley State University
Novel high-resolution geochemical methodologies for quantitative element maps and authigenic stable metal isotopic compositions in microbialites
- Simon V. Hohl
State Key Laboratory of Marine Geology, Tongji University, Shanghai, PR China
Petro-tectonic analysis of the Farmington Canyon Complex, Utah: Implications for Paleoproterozoic rifting of Superia and assembly of Laurentia
- Adolph Yonkee
Department of. Earth & Environmental Sciences, Weber State University
Phosphorites Under the Microscope: Microbial Ecology and the Phosphorus Cycle Across the PꞒ-Ꞓ Boundary
-Cecilia Sanders
Johns Hopkins University
The secret life of a Paleoarchean granitic dome: The cryptic internal structure of the Mt Edgar dome (East Pilbara Terrane) and the hints it provides about the formation of early continental crust
-Nicolas Roberts
Hamilton College
Oxygen isotopes in hydrothermally altered ocean crust record seawater δ18O evolving with continental growth and emergence
-Benjamin Johnson
Iowa State University
On the Reliability and Fragility of the Carbonate Paleoclimate Archive
-Mohammed Hashim
Woods Hole Oceanographic Institution
Four Million Year Long Marinoan Snowball Earth
-Adrian Tasistro-Hart
University of California, Santa Barbara
Reconstructing phosphorus levels in the Proterozoic
-Romain Guilbaud
The National Centre for Scientific Research (CNRS), Toulouse, France
Models for Earth's climate and biogeochemical evolution over the Precambrian
-Benjamin Mills
University of Leeds, UK
Some new perspectives on what iron isotopes can and can’t tell us about the origin of Precambrian iron formations.
-Andy W. Heard
Woods Hole Oceanographic Institution
Carbon cycling in Paleoproterozoic Mountain Belts
Insights from graphitic-pyritic shear zones in N. Saskatchewan and Alberta
-Jonathan Toma
Yale University
Thallium: the platypus of metals
- Chad Ostrander
University of Utah
Proterozoic crustal evolution of the Guyana Shield, and new insights from its mafic dike record
- Mauricio Ibañez-Mejia
University of Arizona
Looking at Mesoproterozoic tectonics from a Grenvillian perspective
- Félix Gervais1
Alexandre Beaudry1, Charles Kavanagh-Lepage1, Abdelali Moukhsil2
1 Polytechnique Montréal, Montreal, Quebec, Canada; 2 Ministère des Ressources naturelles du Québec, Quebec, Canada; *felix.gervais@polymtl.ca
Precambrian lifeforms, reconstructed
- Akshay Mehra
University of Washington
