Haakon Fossen

Haakon Fossen
University of Bergen | UiB · Natural History Collections/Department of Earth Science

BSc, Cand Scient, PhD

About

318
Publications
125,004
Reads
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11,655
Citations
Citations since 2016
112 Research Items
6929 Citations
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201620172018201920202021202202004006008001,0001,200
201620172018201920202021202202004006008001,0001,200
201620172018201920202021202202004006008001,0001,200
Introduction
Haakon Fossen, professor at the University of Bergen, Norway, has a passion for Structural geology and Tectonics. He is the author of the textbook "Structural Geology" (Cambridge University Press) and works on orogeny and orogenic collapse, rifting, shear zones, transpression, fault growth, deformation bands and other subseismic structures. Currently focusing on the North Sea rift, Scandinavian Caledonides, and the Brasiliano orogenic evolution (Brazil).
Additional affiliations
January 2005 - December 2012
Uni Research
Position
  • Principal Investigator
Description
  • Structural geology
April 1996 - present
University of Bergen
Position
  • Professor (Full)
June 1986 - April 1996
Statoil ASA
Position
  • Geophysicist, Senior geologist, structural geologist
Description
  • Seismic and structural interpretation, structural analysis, well planning, exploration

Publications

Publications (318)
Preprint
Full-text available
Understanding where normal faults are is critical to an accurate assessment of seismic hazard, the successful exploration for and production of natural (including low-carbon) resources, and for the safe subsurface storage of CO2. Our current knowledge of normal fault systems is largely derived from seismic reflection data imaging intra-continental...
Article
Full-text available
Our understanding of continental rifting is, in large parts, derived from the stratigraphic record. This record is, however, incomplete as it does not often capture the geomorphic and erosional signal of rifting. New 3D seismic reflection data reveals a Late Permian‐Early Triassic landscape incised into the pre‐rift basement of the northern North S...
Article
The concepts of progressive and polyphase deformation have been widely applied by structural geologists to explain complexly deformed rocks, particularly for ductile conditions. Interpreting complex structural patterns as the result of progressive deformation is mainly based on structural and kinematic evidence, applying the Ockham's razor principl...
Preprint
Full-text available
An impressively extensive shore platform, the strandflat, is cut 20-50 km into hard crystalline bedrock along most of the Norwegian coastline. Its age and origin have been debated for more than a century, including a model that it represents a weathered, buried and re-exposed Triassic surface. Resolving this issue requires integrated examination of...
Article
We combine quartz textural analysis with Titanium-in-quartz (TitaniQ) geothermometry to investigate the late stages of deformation in mylonitic rocks from the Sucuru dike swarm in the Borborema Province. The wide range in TitaniQ temperatures (>340 to 740 °C) closely related to grain sizes are attributed to inefficient Ti resetting during bulging (...
Article
Full-text available
The Rio do Peixe Basin is part of a series of aborted Cretaceous rifts formed within the Proterozoic Borborema Province, onshore NE Brazil in response to rifting between Africa and South America. The basin is remarkably well‐imaged and comprises fault‐bounded depocentres, the main ones being the NE‐oriented Brejo das Freiras and the E‐W‐oriented So...
Preprint
Full-text available
Understanding where normal faults are is critical to an accurate assessment of seismic hazard, the successful exploration for and production of natural (including low-carbon) resources, and for the safe subsurface storage of CO2. Our current knowledge of normal fault systems is largely derived from seismic reflection data imaging intra-continental...
Article
Full-text available
Hidden, blind faults have a strong seismic hazard potential. Consequently, there is a great demand for a robust geological indicator of neotectonic activity on such faults. Here, we conduct field measurements of disaggregation bands above known underlying blind faults at several locations in Central Europe. We observe that the disaggregation bands...
Article
A relationship between crystallographic preferred orientation (CPO) and strain geometry (strain-ellipsoid shape) is often assumed, but not well documented. In this work, we use the EBSD method to study quartz CPO and microstructure in relation to strain geometry in a folded conglomerate in the SW Scandinavian Caledonides, where strain varies from s...
Preprint
Full-text available
This study presents K-Ar geochronology ages of illite from fault gouge in the crystalline basement in central-western Sweden. Samples of fault gouge were taken from two faults localizing brittle deformation along and within mafic dikes that intrude Paleoproterozoic granites. K-Ar ages from the ten dated fractions span from 823 Ma to 392 Ma. The old...
Article
Full-text available
The Neoproterozoic-Cambrian (Brasiliano) intracontinental Patos-Pernambuco shear system is developed in Archean to Neoproterozoic crust, reactivating rift margins N of the São Francisco Craton. We here use enhanced aeromagnetic images to reveal internal details of the broad E-W dextral Patos and Pernambuco shear zones, the intervening Central (Tran...
Chapter
Full-text available
For 400–500 millioner år siden reiste det seg en mektig fjellkjede langs landet vårt. Den hadde flere likhetstrekk med dagens Himalayafjellkjede, og ingen hendelse har preget den norske berggrunnen mer enn denne langsomme, men bestemte kollisjonen mellom Laurentia og Baltika. Grønnsteinsbeltene med kisforekomstene våre ble dannet. “Halve Norge” ble...
Chapter
Full-text available
Så lenge kontinentene kolliderer og fjellmassene presses opp, holdes fjellene ved like. Men når kreftene svinner hen, får vind og vær fritt spillerom. Da oppfylles Skriftens ord om at "hvert fjell og hver haug skal jevnes. Bakket land skal bli til slette og kollene til flat mark". Slik var det også med den kaledonske fjellkjeden. Etter at kollisjon...
Article
Full-text available
The Måløy Slope is a key area for studying the connection between onshore and offshore geology of South Norway. It has functioned as an area of bypass, erosion and deposition between the Norwegian mainland source area and the offshore northern North Sea sink area since the Permian. The slope was faulted into N–S-trending rift fault-blocks through f...
Article
Full-text available
Our understanding of folds and folding builds on detailed geometrical analysis. Proper description of folds and their relation to other structures such as fractures, cleavage and lineations form, together with physical and numerical modelling, the foundation for linking folds to stress, strain, kinematics, mechanics, and underlying tectonic process...
Article
Understanding the internal structure of our planet is a fundamental goal of the earth sciences. As direct observations are restricted to surface outcrops and borehole cores, we rely on geophysical data to study the earth's interior. In particular, seismic reflection data showing acoustic images of the subsurface provide us with critical insights in...
Preprint
Full-text available
Our understanding of continental rifting is largely derived from the stratigraphic record. This archive is, however, incomplete as it does not capture the geomorphic and erosional record of rifting. New 3D seismic reflection data reveals a Late Permian-Early Triassic landscape incised into the pre-rift basement of the northern North Sea. This lands...
Article
Full-text available
While seismic and stratigraphic well information put tight constraints on rift basin evolution, eroded rift shoulders commonly expose polydeformed prerift basement whose deformation history may be difficult to constrain. In this work we apply K‐Ar dating of fault gouge samples from 18 faults to explore the brittle deformation of the well‐exposed ea...
Article
The (ultra)high-pressure Western Gneiss Region (WGR) of the Norwegian Caledonides represents an archetypical orogenic infrastructure of a continent-continent collision zone. To test established exhumation models, we synthesize the geochronology and structures of major basement windows and provide new ages from poorly dated areas. Migmatite U-Pb zir...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Chapter
This market-leading textbook has been fully updated in response to extensive user feedback. It includes a new chapter on joints and veins, additional examples from around the world, stunning new field photos, and extended online resources with new animations and exercises. The book's practical emphasis, hugely popular in the first edition, features...
Preprint
Understanding the internal structure of our planet is a fundamental goal of the Earth Sciences. As direct observations are restricted to surface outcrops and borehole cores, we rely on geophysical data to study the Earth’s interior. Especially, seismic reflection data showing acoustic images of the subsurface, provide us with critical insights into...
Article
Full-text available
In regions experiencing multiple phases of extension, rift‐related strain can vary along and across the basin during and between each phase, and the location of maximum extension can differ between rift phase. Despite having a general understanding of multiphase rift kinematics, it remains unclear why the rift axis migrates between extension episod...
Article
Full-text available
Extensional systems evolve through different stages due to changes in the rheological state of the lithosphere. It is crucial to distinguish ductile structures formed before and during rifting, as both cases have important but contrasting bearings on the structural evolution. To address this issue, we present the illustrative ductile‐to‐brittle str...
Preprint
Seismic facies analyses are fundamental to the study of sedimentary, tectonic and magmatic systems using seismic reflection data. These analyses generally assume that seismic facies are: (1) well defined, (2) distinct and (3) prevalent patterns in the data. Here, we examine these assumptions critically. First, we demonstrate how to extract the main...
Article
Full-text available
The formation of low-angle detachments involves exhumation of previously ductile material and fault zone weakening. To better understand this relationship, we studied a deeply eroded metamorphic core complex, which formed in the core of the Bergen Arcs (W Norway) during Caledonian post-orogenic collapse. Multi-scale structural mapping in the Øygard...
Article
Strain localization and influence of grain-size reduction processes were investigated from field and microstructural observations, and from quartz textural analysis using EBSD, in rocks deformed along an anastomosing network of shear zones in the Ribeira belt in Brazil. Rocks deformed along the Lancinha shear zone (LSZ) display high percentage of r...
Preprint
Full-text available
In multirifted regions, rift-related strain varies along and across the basin during and between each extensional event, and the location of maximum extension often differs between rift phases. Despite having a general understanding of multiphase rift kinematics, it remains unclear why some parts of the rift are abandoned, with strain accumulating...
Article
Full-text available
Shear zones are common strain localization structures in the middle and lower crust and play a major role during orogeny, transcurrent movements and rifting alike. Our understanding of crustal deformation depends on our ability to recognize and map shear zones in the subsurface, yet the exact signatures of shear zones in seismic reflection data are...
Article
Full-text available
Existing models of tectonic evolution of the Neoproterozoic orogenic system rimming the shores of the South Atlantic Ocean (the Araçuaí–Ribeira–Congo and Dom Feliciano–Kaoko–Gariep belts) interpret the belts as subduction-related orogens and emphasize the role of the “Adamastor Ocean” in their pre-collisional evolution. A critical problem in such a...
Article
Full-text available
The Neoproterozoic Araçuaí-West Congo orogen in Brazil and Congo represents a branch of the Brasiliano/Pan-African orogenic system that is considered to terminate northward into a confined cratonic environment defined by the horseshoe-shaped pre-Atlantic São Francisco-Congo craton. The prevailing interpretation is that this orogen formed as a resul...
Article
Full-text available
The objective of this short paper was to provide some advice on how to write a geoscience paper of international standard and to warn against some common pitfalls. It is focused on how to structure a paper and stresses the importance of building its contents around a well-defined problem. Furthermore, the importance of moving away from outdated and...
Chapter
In this chapter, we consider the evolution of faults from their initial stages of formation to large faults and fault populations. In essence, initiation can occur by the formation and linkage of minor oblique structures such as Riedel shears and tension gashes or, if available, by reactivation of preexisting structures such as joints and dikes. As...
Article
Full-text available
The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn‐rift depocenters during this multiphase evolution and the mechanisms and extent to which they were influenced by preexisting structural heterogeneities remain elusive, particularly at the regional sc...
Article
Full-text available
Viscous crustal flow can exhume once deeply buried rocks in postorogenic metamorphic core complexes (MCCs). While migmatite domes record the flow dynamics of anatectic crust, the mechanics and kinematics of solid‐state flow in the deep crust are poorly constrained. To address this issue, we studied a deeply eroded and particularly well‐exposed MCC...
Article
Full-text available
Shear zones typically interact to form connected systems or networks to accommodate crustal deformation, but our knowledge of how this happens is fragmentary. Understanding branching and interacting shear zones requires knowledge of timing, deformation kinematics, and rheology. The Senador Pompeu, Tauá, and Cococi strike‐slip shear zones of the Bor...
Article
Full-text available
Asymmetric porphyroclast systems have long been used as independent shear-sense indicators based on their clast-tail asymmetry and/or stair-stepping tail geometry. Over the last two decades, advances in exploring the mechanical behavior of rigid clasts in a viscous flow has shed new light on understanding the formation of porphyroclast systems embe...
Preprint
Full-text available
The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn-rift depocentres during this multiphase evolution, and the mechanisms and extent to which they were influenced by pre-existing structural heterogeneities remain elusive, particularly at the regional...
Poster
Full-text available
The last pulse of the Brasiliano deformation in the Borborema Province is being investigated through textural analysis of the Sucuru Diques, dated at 540 Ma. The Quartz CPO is being measured via SEM-EBSD technique in order to understand how deformation localizes along anastomosing shear zones.
Article
Full-text available
When continents rift, magmatism can produce large volumes of melt that migrate upwards from deep below the Earth’s surface. To understand how magmatism impacts rifting, it is critical to understand how much melt is generated and how it transits the crust. Estimating melt volumes and pathways is difficult, however, particularly in the lower crust wh...
Article
Microstructural analysis and characterization of quartz veins hosted in rocks from the Brusque Metamorphic Complex in the region of Brusque, State of Santa Catarina, have been performed to establish the relations between fluid regimes, tectonic styles and deformation/recrystallization mechanisms. The analysis was based on observations of structural...
Conference Paper
Full-text available
Post-orogenic extension exhumed large terranes of deeply subducted continental crust in the southern Scandi-navian Caledonides and overprinted large parts of the orogen. Hence, this last stage of the orogenic evolution is particularly important to understand in order to unravel earlier phases of the Wilson cycle. We compare two basement windows in...
Conference Paper
Full-text available
Existing models of tectonic evolution of the Neoproterozoic orogenic system rimming the shores of the southern Atlantic Ocean (the Araçuaí-Ribeira-Congo and Dom Feliciano-Kaoko-Gariep belts) interpret the belts as subduction-related orogens and stress out the role of the "Adamastor Ocean" in their pre-collisional evolution. A critical problem in su...
Conference Paper
Full-text available
Shear zones play an important role in localizing crustal deformation during rifting, continental break up and passive margin formation. Because shear zones change physical rock properties relative to the surrounding undeformed rocks, we can image them in seismic reflection data. The exact seismic signature of shear zones is however still largely un...
Conference Paper
Full-text available
Understanding the Earth's internal structure is one of the key challenges of geophysics. Advanced geophysical techniques, such as 3-D seismic technology, produce increasingly large datasets of the Earth's subsurface, which require significant amounts of time, experience and expertise to analyze. On the other hand, there have recently been great adv...
Preprint
Full-text available
Numerous studies have investigated the geodynamic history and lithological composition of the Proterozoic basement, Caledonian nappes, and Devonian extensional basins and shear zones onshore west Norway. However, the offshore continuation of these structures, into the northern North Sea, where they are suspected to have influenced the structural ev...
Article
Full-text available
Numerous studies have investigated the geodynamic history and lithological composition of the Proterozoic basement, Caledonian nappes, and Devonian extensional basins and shear zones onshore west Norway. However, the offshore continuation of these structures, into the northern North Sea, where they are suspected to have influenced the structural ev...
Article
Palinspastic reconstructions suggest that the late Proterozoic–Cambrian Brasiliano/Pan-African orogenic belt in southeast Brazil and west Congo terminated northwards into an embayment within the São Francisco-Congo cratonic unit. The orogenic shortening that created the Araçuaí-West Congo orogen in this embayment has been explained by tightening of...
Chapter
Full-text available
Mafic dike swarms and sills intruding, respectively, the Precambrian Borborema and Paleozoic Parnaíba provinces (NE Brazil) constitute two major magmatic events related to the continental break-up that formed the Equatorial Atlantic. Available whole rock K–Ar determinations and a few plagioclase ⁴⁰Ar/³⁹Ar ages suggest that these events occurred app...
Article
The parallelism between older collisional belts and younger rift systems is widely known and particularly well portrayed along the Atlantic Ocean. How tectonic inherited and new‐formed shear zones control rift nucleation and the final architecture of rifted conjugate passive margins is still poorly understood. Here we present lithospheric scale the...