Karol Faehnrich

About

My name is Karol Faehnrich, I am a researcher at the Uppsala University in Sweden. My research focuses on the tectonic evolution of continental margins. I have worked on various projects across the circum-Arctic, in Svalbard Archipelago, northern Greenland, Ellesmere Island, or east-central Alaska. I have also worked in Australia, investigating paleoenvironments and sea level fluctuations during appearance of the first complex multicellular life in the Ediacaran. I combine modern stratigraphy and provenance analyses with deformation dating and igneous geochemistry to investigate complex tectonic boundaries and co-evolution of continental margins and environment. My work is always grounded in geologic mapping and extensive fieldwork with the application of geochronology, thermochronology or stable and radiogenic isotope geochemistry.

Contact: karol.faehnrich[at]geo.uu.se

Research Projects

Sea-level fluctuations and changing paleoenvironments during the appearance of the Ediacara Biota in South Australia

The rise and diversification of metazoans in the late Ediacaran (570-540 Ma) have been linked to global sea-level changes, driving the expansion of shallow-marine habitat. However, the regional record of these changes often remains ambiguous. In this project I revisit paleoenvironments and sea-level fluctuations recorded in the late Ediacaran strata exposed throughout the Flinders Ranges in South Australia. Here, the sandstone beds preserve soft-bodied organisms across large surfaces, offering a rare glimpse into the paleoecology of whole communities. I investigate what these environments were and their impact on the Ediacara Biota. The sandstones that preserve the fossils fill an erosive surface, which creates 2-10 m depressions and southeast-oriented deep valleys reaching 300 m in depth and more than 5 km in width. We find evidence that they represent submarine canyons formed during global sea-level fall that infilled during rapid sea-level rise. These canyons controlled the distribution of paleoenvironments, with strong currents prevailing along their axial zone, exerting control over paleocommunities and paleoecology of the first animals on our planet.

Tectonic evolution of North Greenland

North Greenland remains one of the least geologically investigated regions in the Arctic and is a critical location to test models for the tectonic development of the broader Arctic–North Atlantic region. In this project, I led a work package during GEOEO 2024 expedition on the Swedish icebreaker Oden investigating bedrock geology across a major fault system (Harder Fjord Fault Zone), trying to understand Neoproterozoic-Carboniferous evolution of this margin. The project involves tracking changes in sediment sources from the Ediacaran to the latest Silurian when the margin transition from rift basin to passive and then convergent margin. We are trying to understand which terrane collided with Greenland forming extensive fold-and-thrust belt towards the Devonian. We also deployed seismometers to image the deep crust to upper mantle architecture across major tectonic boundaries. Apart from testing tectonic models, we collaborate with glaciologists and climate scientists to better understand how bedrock geology controlled ice retreat across North Greenland.

Displacement along the Porcupine Fault System and opening of the Canada Basin

The Porcupine Fault System of northern Yukon and Alaska is an important tectonic boundary that separates far-traveled fragment of continental crust (North Slope subterrane) from northwestern North America. Tectonic models suggested its major role in the mid-Paleozoic transfer of terranes across the Arctic, as well as strike-slip displacement during the Mesozoic opening of the Arctic Ocean. In this project, we investigated differences in stratigraphy and provenance across this boundary, as well as the timing of brittle deformation. We defined a new sequence of Tonian (ca. 720-1000 Ma) rocks exposed within this area, proposed that they originated several hundreds of kilometers away from their current location, and mapped a complex array of faults related to sinistral and dextral displacement. The Ar-Ar thermochronology and U-Pb dating of vein calcite suggest activity of the fault system in the early Cretaceous during the formation of the Canada Basin (part of the Arctic Ocean), supporting oblique spreading within the basin and coupled displacement of the Arctic Alaska during this time.

Ediacaran to early Cambrian rifting along the northern edge of North America

The Neoproterozoic to early Paleozoic evolution of North America is characterized by a protracted history of rifting and passive margin development, during the break-up of the supercontinent Rodinia. Along the northern margin, the beginning of continental break-up is often associated with the emplacement of Franklin Large Igneous Province around 720 Ma and the separation of ancestral North America and Siberia. However, passive margin sedimentation started in the late Neoproterozoic to early Paleozoic, more than 150 million years later. In this project, we investigated the Yelverton Formation, a suite of mixed volcanics, carbonates and siliciclastic, exposed on northern Ellesmere Island. The carbonates have an isotopic composition characteristic of Ediacaran deposits. The trace element and isotope geochemistry of volcanic rocks suggested the generation of magma during decompression melting from two mantle sources during the formation of an oceanic basin. We suggested that these data reflect rifting along this margin in Ediacaran and early Cambrian that resulted in the formation of microcontinents along the edge of North America.

Assembly of the Svalbard Archipelago

The Svalbard archipelago consists of three basement provinces bounded by N-S-trending strike-slip faults that were juxtaposed during the middle Paleozoic. However, the exact timing and relation of strike-slip displacement to the Caledonian orogeny that resulted from the collision between Laurentia and Baltica remains unclear. In this project, we investigated the sinistral Vimsodden-Kosibapasset Shear Zone in southwest Svalbard. We integrated 40Ar/39Ar muscovite geochronology with microstructural and mineral chemistry data to determine the timing of movement along the shear zone. We determined that displacement occurred ca. 420 Ma, in late Silurian–Early Devonian, and was contemporaneous with the main phase of continental collision in Greenland and Scandinavia. The displacement overlaps with the onset of syn-orogenic sedimentation in fault-controlled basins in northern Svalbard, which likely formed a pull-apart system at the time.

Selected Publications

Canadian Journal of Earth Sciences, 2025

Canadian Journal of Earth Sciences, 2023

Lithosphere, 2021

Geology, 2021

Field work

I had an opportunity to work in many places across the circum-Arctic that I show below, collaborating with geologists from many universities and geological surveys.

Photos

A few photos from the field.

More Photos

Contact

Karol Faehnrich

Uppsala University

karol.faehnrich[at]geo.uu.se

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