Jean-Baptiste Koehl

Centre for Earth Evolution and Dynamics

The present study is a detailed structural analysis of 3D seismic data in the Selis Ridge in the western part of the Loppa High in the Norwegian Barents Sea, to which new seismic attributes and spectral decomposition were applied. The analysis reveals that pre-Devonian basement rocks in the Barents Sea are crosscut by a 40–50 kilometers wide, sever...

Presentation of the following publications and discussion of their implications: -Koehl, J.-B. P. and Allaart, L.: The Billefjorden Fault Zone north of Spitsbergen: a major terrane boundary?, Polar Res., 40, 7668, 2021. doi.org/10.33265/polar.v40.7668 -Koehl, J.-B. P., Magee, C. and Anell, I. M.: Impact of Timanian thrust systems on the late Neopro...

In the Late Devonian–earliest Mississippian, Svalbard was affected by a short-lived episode of deformation named the Ellesmerian (Svalbardian) Orogeny. This event resulted in intense folding and thrusting in Devonian sedimentary successions. Deformation stopped prior to the deposition of Carboniferous–Permian sedimentary strata of the Billefjorden...

The Svalbard Archipelago consists of three basement terranes that record a complex Neoproterozoic–Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse- to rift-related extension (Devonian–Carboniferous and late Cenozoic). Previous studies suggest that thes...

The Svalbard Archipelago offers the most complete record of the geological history of Norway preserved as various rock units from 3.0 Ga to a few thousand years ago. Recent geological work has shown that the Earth’s crust beneath the Archipelago is transected by several kilometers thick and thousands of kilometers long networks of cracks. These lar...

Online presentation to the Institute for Geophysics, Polish Academy of Science (IG PAS)

The present contribution reexamines the geometry of a segment of a presumably long-lived fault in the Norwegian Arctic, the Balliolbreen Fault segment of the Billefjorden Fault Zone. Field observations demonstrate that the fault most probably originated as a top-west Eurekan thrust fault in the early Cenozoic and that weak lithological units such a...

The Billefjorden Fault Zone is a major terrane boundary in the Norwegian Arctic. The fault separates basement rocks of Svalbard’s north-eastern and north-western terranes that recorded discrete Precambrian tectonothermal histories and were accreted, intensely deformed and metamorphosed during the Caledonian Orogeny. Although the fault represents a...

The Billefjorden Fault Zone is a major terrane boundary in the Norwegian Arctic. The fault separates basement rocks of Svalbard’s north-eastern and north-western terranes that recorded discrete Precambrian tectonothermal histories and were accreted, intensely deformed and metamorphosed during the Caledonian Orogeny. Although the fault represents a...

While the weather in Iceland is often cold, wet, and windy, a nearly endless supply of heat bubbles away below the surface. In fact, almost every building in the country is heated by geothermal energy in a process with virtually no carbon emissions. So how exactly does this renewable energy work? Jean-Baptiste P. Koehl explores the two primary mode...

The Svalbard Archipelago is composed of three basement terranes that record a complex Neoproterozoic-Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse-to rift-related extension (Devonian-Carboniferous and late Cenozoic). These three terranes are thought...

The present study of field, petrological, exploration well, and seismic data describes backward-dipping duplexes comprised of phyllitic coal and bedding-parallel décollements and thrusts localized along lithological transitions in tectonically thickened Lower Devonian to lowermost Upper Devonian; uppermost Devonian–Mississippian; and uppermost Penn...

The Billefjorden Trough, a well studied onshore analogue to Carboniferous rift basins in the Barents Sea, is bounded to the west by the Billefjorden Fault Zone. Structural field analysis of a megabreccia and adjacent strata of the Minkinfjellet Formation in the hanging wall of the Odellfjellet Fault segment of the Billefjorden Fault Zone suggest th...

Presentation of the ArcTec project to Lundin.

The Billefjorden Fault Zone is a major terrane boundary in the Norwegian Arctic. The fault separates basement rocks of Svalbard’s northeastern and northwestern terranes that recorded discrete Precambrian tectonothermal histories and were accreted, intensely deformed and metamorphosed during the Caledonian Orogeny. Although the fault represents a ma...

The Vestnesa Ridge is a 4–5 kilometers thick sedimentary drift of contourites deposited by NW-travelling bottom currents over young oceanic crust (< 24 Ma) between Svalbard and the Molloy Ridge. The ridge trends NW–SE and parallels major transform faults in the Fram Strait (Spitsbergen and Molloy fracture zones). Along the southeastern portion of t...

The Vestnesa Ridge is a 4–5 kilometers thick sedimentary drift of contourites deposited by NW-travelling bottom currents over young oceanic crust (< 24 Ma) between Svalbard and the Molloy Ridge. The ridge trends NW–SE and parallels major transform faults in the Fram Strait (Spitsbergen and Molloy fracture zones). Along the southeastern portion of t...

The Vestnesa Ridge is a 4–5 kilometers thick sedimentary drift of contourites deposited by NW-travelling bottom currents over young oceanic crust (< 24 Ma) between Svalbard and the Molloy Ridge. The ridge trends NW–SE and parallels major transform faults in the Fram Strait (Spitsbergen and Molloy fracture zones). Along the southeastern portion of t...

The Billefjorden area is located in central Spitsbergen where Lower-lowermost Upper Devonian deposits of the southeastern part of the northern Spitsbergen Devonian collapse basin presumably affected by Late Devonian Ellesmerian folds and thrusts are juxtaposed against Proterozoic basement rocks overlain by uppermost Devonian-early Permian rift depo...

The present study of field, petrological, exploration well and seismic data shows that backward-dipping duplexes comprised of phyllitic coal and bedding-parallel décollements and thrusts, which 15 localized along lithological transitions in tectonically thickened Lower-lowermost Upper Devonian, uppermost Devonian-Mississippian and uppermost Pennsyl...

ArcTec proposes to study (1) the westward extent, kinematics and timing of formation, and (2) reactivation–overprint of Timanian (i.e., ca. 600 million years old) faults during subsequent tectonic events in the Arctic, and to (3) insert these faults into a detailed tectonic evolution model for Svalbard, the northwestern Barents Sea and the Fram Str...

Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronological ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three terranes of rocks formed...

Abstract. In the Late Devonian, Svalbard was affected by a short-lived episode of contraction called the Ellesmerian (Svalbardian) Orogeny, which resulted in top-west thrusting of Proterozoic basement rocks onto Devonian sedimentary strata along the Balliolbreen Fault, a major fault segment of the east-dipping Billefjorden Fault Zone, and juxtaposi...

Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronologic ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three-four terranes of rocks form...

Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronological ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three terranes of rocks formed...

Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronological ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three terranes of rocks formed...

Despite more than a century of investigation, the relationship between basement rocks throughout the Svalbard Archipelago is still a mystery. Though these rocks display similar geochronological ages, they show significantly different metamorphic grades and structures. Thus far, Svalbard was believed to be composed of three terranes of rocks formed...

In the SW Barents Sea, Devonian–Carboniferous collapse led to the formation of major basins and faults, e.g., the Hammerfest Basin bounded by the Troms–Finnmark Fault Complex, and rhomboid- to sigma-shaped (half-)grabens on the Finnmark Platform. High-resolution aeromagnetic and bathymetry data from the shallow shelf show that analogue fault system...

The presentation reviews the impact of inherited, WNW-ESE-striking, Timanian thrust systems on the Phanerozoic tectonic history of Spitsbergen and the possible link of Devonian-Mississippian dykes with diamond-bearing intrusions in northwestern Russia.

In 132 CE, Zhang Heng presented his latest invention: a large vase he claimed could tell them whenever an earthquake occurred for hundreds of miles. Today, we no longer rely on pots as warning systems, but earthquakes still offer challenges to those trying to track them. Why are earthquakes so hard to anticipate, and how could we get better at pred...

In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippi...

Alternative tectonic mechanisms to explain why folded Devonian strata are covered by relatively undeformed Carboniferous strata and angular unconformities within Devonian and Carboniferous sedimentary successions in Spitsbergen.

In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesme...

Research proposal for a Post-doctoral fellowship to the VISTA grant.

Well-preserved fault gouge along brittle faults in Paleoproterozoic, volcano-sedimentary rocks of the Raipas Supergroup exposed in the Alta–Kvænangen tectonic window in northern Norway yielded latest Mesoproterozoic (approximately 1050 ± 15 Ma) to mid-Neoproterozoic (approximately 825–810 ± 18 Ma) K–Ar ages. Pressure–temperature estimates from micr...

In northern Norway, late/post-Caledonian extension initiated along inverted, brittle-ductile thrusts, e.g., Sørøya-Ingøya shear zone, which truncated existing, margin-oblique, late Neoproterozoic, Timanian faults and margin-parallel, latest Mesoproterozoic-mid Neoproterozoic faults related to the opening of the Asgard Sea and Iapetus Ocean. Inverte...

Video recording of the following Ph.D. trial lecture: The Caledonides and their role in North Atlantic–Arctic opening.

Video recording of the following Ph.D. defense presentation: Mid/Late Devonian–Carboniferous extensional faulting in Finnmark and the SW Barents Sea margin.

Research proposal to the Transition Grant of the University of Tromsø.

Research proposal to the mobility grant of the Research Council of Norway, April 2018.

The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i) the...

Well-preserved fault gouge along brittle faults in Paleoproterozoic, volcano-sedimentary rocks of the Raipas Group exposed in the Alta-Kvænangen tectonic window in northern Norway yielded latest Mesoproterozoic (ca. 1050 ± 15 Ma) to mid Neoproterozoic (ca. 825–810 ± 18 Ma) K/Ar ages. Pressure-temperature estimates from microtextural and mineralogy...

Background The Caledonian Orogeny was followed by a phase of late/post extensional collapse that resulted in the formation of thick, Middle Devonian sedimentary basins preserved onshore western Norway and Spitsbergen in Svalbard (Figure 1) and exhumation of Precambrian basement rocks as core complexes, e.g. the Lofoten Ridge in Lofoten-Vesterålen (...

Research proposal for a Post-doctoral fellowship to the VISTA grant, January 2018.

The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle-Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, i) the M...

Video of the presentation "Faults" at the Forsker Grand Prix 2017 - region nord, in Tromsø, Norway.

The southwesternmost Nordkapp basin accommodated the deposition of thick, Upper Carboniferous evaporites that are significantly thicker than Asselian (early Permian) evaporites. Three minor salt diapirs most likely sourced from the Upper Carboniferous evaporite layer align along an ENE-WSW trending axis that strikes parallel to the N-bounding fault...

This essay deals with the degree of subjectivity involved in the interpretation of seismic data in geoscience, and with associated ethical issues. The essay includes a case study from northern Norway.

Bjørnøya (Bear Island) is a 178 km 2 large isle emerging in the western Barents Sea about half way between Northern Norway and Spitsbergen. The island appears as a massive block with a coastline of mostly vertical cliffs at least a few tens of meters high.. Above the cliffs, thetopography is predominantly characterized by a large flat plain extendi...

The bedrock geology of NW Finnmark is dominated by Caledonian thrust nappes that include the Magerøy Nappe and the Kalak Nappe Complex, and Precambrian basement rocks exposed in tectonic windows. Recent K/Ar radiometric age dating of onshore brittle fault gouge in NW Finnmark, adjacent to the offshore Finnmark Platform, suggests a long-term and com...

This study is part of the onshore-offshore correlation project that aims at getting a better link between onshore and offshore post-Caledonian brittle structures on the SW Barents Sea Margin, and more specifically in the western part of Troms and Finnmark and the coastal onshore areas adjacent to the Finnmark Platform. Our focus is to explore the t...

The present study focuses on the onshore-offshore correlation of brittle faults along the SW Barents Sea Margin, northern Norway. Several studies indicate that the SW Barents Sea Margin experienced a pulse of extensional deformation in the Late Devonian?-early Carboniferous, shortly after the Caledonian contractional deformation ended. The formatio...

The present study focuses on the onshore-offshore correlation of brittle faults along the SW Barents Sea Margin, northern Norway. Several studies indicate that the SW Barents Sea Margin experienced a pulse of extensional deformation in the Late Devonian?-early Carboniferous, shortly after the Caledonian contractional deformation ended. The formatio...

The Billefjorden Trough is a N-S to NNW-SSE trending rift basin that developed in the Carboniferous during the early stages of the NorthEast Atlantic rifting. The basin displays an asymmetric, half-graben geometry with major down to the East displacements along the N-S trending, right-stepping fault segments of the Billefjorden Fault Zone (BFZ). Th...