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Simplified geologic map of Central Fjord region of East Greenland showing structural relations between high-grade Proterozoic gneisses in west and overlying Caledonian supracrustal rocks in east. Patterns: 1-highg r a d e m e t a m o r p h i c rocks; 2-Late Proterozoic (Eleonore Bay Group) to Ordovician sedimentary rocks; 3-Devonian deposits; 4-Caledonian granites; 5-Post-Devonian deposits. SL-Strindb e r g L a n d ; O R L-O l e Rømer Land; KF-Kempes fjord; MF-Moskusokse fjord; KFJF-Kejser Franz Joseph fjord; FFF o r s b l a d f j o r d ; A FAlpefjord; WFZ-Western fault zone. Boxes mark areas where detailed mapping has been conducted.
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Structural observations of the basement-cover contact in the Central Fjord region of the East Greenland Caledonides suggest Silurian to Devonian crustal thinning with top-to-the-east displacement of the cover sequence. The east-dipping, low-angle shear zone separating the Late Proterozoic (Eleonore Bay Group) to Lower Ordovician cover sequence from...
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Fault interaction in the Hold With Hope region of NE Greenland occurs between basin-margin faults that have a separation of about 100 km, with the relay ramp covering an area of about 25 000 km2. This structure is therefore much larger than previously described relay ramps, showing that interaction between normal faults can occur over large areas a...
Citations
... In the western Norwegian Caledonides, a suite of transtensional supradetachment basins developed during extensional 'collapse' of the orogen in Devonian time (Figure 2a,b;Andersen & Jamtveit, 1990;Krabbendam & Dewey, 1998;Osmundsen & Andersen, 2001) as part of a system that now fringes the North Atlantic (e.g. Braathen et al., 2018;Hartz & Andresen, 1995;Fossen, 2010). In southwest Norway, remnants of such basins are variably juxtaposed with the eclogite-bearing rocks of the Western Gneiss Region (WGR) across the regional top-to-the-west Nordfjord-Sogn Detachment Zone (NSDZ, Figure 2; Hossack, 1984;Norton, 1986;Séranne & Seguret, 1987). ...
For basins that evolve adjacent to large‐magnitude normal faults, tectonic controls on sedimentation involve isostatic back‐rotation of an exhuming footwall and, commonly, the evolution of kilometre‐scale extension‐parallel folds. Based on observations from classic localities in western Norway, we propose a three‐stage evolution scenario for transtensional supradetachment basins where the basins become progressively re‐arranged because of core complex exhumation and subsequent orthogonal shortening. Extension‐parallel transverse synclines initially form due to a normal displacement gradient, but when displacements accumulate beyond a certain magnitude, the hanging wall increasingly responds to core complex exhumation and the original depocenter, formed close to the original area of maximum displacement, will become inverted and dismembered above the core complex. Two new synclinal depocenters will develop along the flanks. Because these synclines form by extensional fault growth rather than by shortening, they will be associated with widening of the basin, and onlap onto basement at high angles to the maximum elongation trend with overall grain size decrease and retrogradational stacking patterns. Further, because these synclines grow away from the evolving core complex, sedimentary units will become asymmetrically distributed inside each syncline in such a way that the oldest deposits in the syncline will be preserved on the flank most proximal to the core complex. In transtensional environments, a third evolutionary stage may involve constrictional strain where extension‐parallel folds and reverse faults produced by orthogonal shortening enhance or interact with other structures. Ultimately, initial extensional subbasins may become warped across extension‐parallell folds. Hanging wall deformation will be manifested in shifting accommodation patterns, with depocentres that generally migrate in the direction of the detachment fault. Accommodation patterns initially related to megafault growth may conceptually evolve into depocentres controlled by orthogonal shortening.
... The collapse is suggested to have initiated the formation of a series of large Devonian half-graben basins along major faults inherited from the Caledonian orogenic belt. These basins, which are deeper on the Greenland than the Norwegian side, were subsequently filled with thick successions of mainly intra-continental molasse deposits (e.g., Braathen et al., 2002;Hartz and Andresen, 1995;Osmundsen et al., 2002). The extent of gravitational collapse and syn-orogenic extension remain speculative since the mid-Permian-Devonian crustal thickness is difficult to assess with the current available data. ...
The formation of the NE Atlantic conjugate margins is the result of multiple rifting phases spanning from the Late Paleozoic and culminating in the early Eocene when breakup was accompanied with intense magmatic activity. The pre‐breakup configuration of the NE Atlantic continental margins is controlled by crustal extension, magmatism, and sub‐lithospheric processes, all of which need to be quantified for the pre‐breakup architecture to be restored. Key parameters that need to be extracted from the analysis of crustal structures and sediment record include stretching factors, timing of rifting phases, and nature of the deep crustal structures. The aim of this study is to quantify the pre‐drift extension of the NE Atlantic conjugate margins using interpreted crustal structure and forward basin modeling. We use a set of eight 2D conjugate crustal transects and corresponding stratigraphic models, constrained from an integrated analysis of 2D and 3D seismic and well data. The geometry and thickness of the present‐day crust is compared to a reference thickness which has experienced limited or no crustal extension since Permian time allowing the quantification of crustal stretching. Based on the eight conjugate crustal transects, the total pre‐drift extension is estimated to range between 181 and 390 km with an average of 270–295 km. These estimates are supported by the results of forward basin modeling, which predict total extension between 173 and 325 km, averaging 264 km. The cumulative pre‐drift extension estimates derived from basin modeling are in turn used to calculate the incremental crustal stretching factors at each of the three main rifting phases between the conjugate Greenland‐Norwegian margins. The mid‐Permian early Triassic rifting phase represents 32% of the total extension, while the equivalent values are 41% for the mid‐Jurassic to mid‐Cretaceous and 27% for the Late Cretaceous‐Paleocene rifting phases. These values are used to establish and present at first, a full‐fit palinspastic plate kinematic model for the NE Atlantic since the mid‐Permian and will be the base for future work on more elaborated models in order to build accurate paleogeographic and tectonic maps.
... As at the Atlantic margins of Norway and Britain, rifting and basin formation in central East and NE Greenland was initiated during the Devonian, an event attributed to orogenic collapse and left-lateral transtension during the final stages of the Caledonian Orogeny (Larsen and Bengaard 1991;Hartz and Andresen 1995;Hartz et al. 2000Hartz et al. , 2001. Basin development continued after the Early -Middle Devonian cessation of the Caledonian Orogeny but transtension shifted to east to west extension and rifting during the latest Devonian. ...
... The East Greenland basins are progressively downfaulted towards the east by roughly north-south-striking faults that mimic the Caledonian structural trends and subordinate more NE-SW-striking faults (Fig. 1). Middle-Late Devonian basin formation was probably governed by extension across the Fjord Zone Fault located several kilometres west of the present-day outcrops of Devonian and younger strata, and possibly also the Nunatak Zone Fault located further to the west (Larsen and Bengaard 1991;Hartz and Andresen 1995;Hartz et al. 2000Hartz et al. , 2001. The Western Fault Zone located further east probably accommodated Devonian and Carboniferous left-lateral transtension (Larsen and Bengaard 1991). ...
The Devonian to lower Eocene Central-East and NE Greenland Composite Tectono-Sedimentary Element CTSE) is a part of the North-East Atlantic rift system. East and NE Greenland geology is therefore analogues to that of the prolific basins on the conjugate Atlantic margin and in the North Sea in many respects. None the less, hydrocarbon discoveries remain. The presence of world-class source rocks, reservoirs and seals, together with large structures, may suggest an East and NE Greenland petroleum potential, however. The TSE was established through Devonian - Carboniferous, Permian - Triassic and Jurassic - Cretaceous rifting interspersed by periods of uplift and post-rift sagging. Subsequently, Paleocene - Eocene magma-rich rifting accompanied the North-East Atlantic break-up. Depositional environments through time varied in response to the changing tectonism and climate. None-marine deposition dominated until the end of the Triassic, only interrupted by marine sedimentation during Late Permian - Early Triassic times. Subsequently, marine conditions prevailed during the Jurassic and Cretaceous. Volumetric series of basalt erupted over most of the CTSE during the latest Paleocene - early Eocene following a significant latest Cretaceous - Paleocene regression, uplift and erosion event. Since the Eocene, denudation pulses have removed much of these basalts uniquely exposing the up to 17 km strata of the CTSE.
... The deformation events described as the Hudson Land and Ymer Ø phases (Bütler, 1935) were caused by left-lateral strikeslip movements along the eastern basin margin. Hartz and Andresen (1995) and Andresen et al. (1998) interpreted the N-S trending regional detachments as the main extensional features in the region. (Rittmann, 1940). ...
In East Greenland sedimentation during the Middle Devonian-earliest Carboniferous interval, was characterized by the Old Red Sandstone Molasse Basin deposits. The continental succession recorded folding and intra-basinal unconformities associated with activation of extensional detachments and core complex formation which post-dated high-pressure granulite facies metamorphism at ca. 403 Ma. The extensional collapse responsible for the initiation of the Devonian basin and associated bi-modal magmatism must be understood in the context of continued continental convergence during the early Carboniferous, required by ultrahigh-pressure metamorphism in North-East Greenland at ca. 355 Ma. Along a small nunatak within the Wordie Gletscher in Payer Land, NE Greenland (Lat. 74°N), Precambrian gneisses recording Devonian granulite-facies metamorphism are in tectonic contact with the molasse deposits along an ESE-ward dipping thrust fault: the Scotstounhill Thrust. This paper will discuss the role of Devonian contractional structures and contemporaneous extensional faulting and present a new tectonic model which accounts for the exhumation of deep crustal rocks by these coupled mechanisms.
... Late Devonian-Early Carboniferous shear zones formed during Caledonian collapse (Surlyk 1990;Price et al. 1997;Parsons et al. 2017;Rotevatn et al. 2018), accompanied and possibly facilitated by major strike-slip deformation (Dewey and Strachan 2003), which may have reactivated older, pre-Caledonian shear zones related to the opening of the Iapetus Ocean (Soper and Higgins 1993). Faulting in the Triassic-Cretaceous East Greenland rift system was episodic, with multiple stages of reactivation culminating in the final separation of the JMMC (Surlyk 1990;Stemmerik et al. 1991;Hartz and Andresen 1995;Seidler et al. 2004;Parsons et al. 2017;Rotevatn et al. 2018). The East Greenland rift system is segmented by right-stepping NW-SE transfer zones Rotevatn et al. 2018). ...
The North Atlantic, extending from the Charlie Gibbs Fracture Zone to the north Norway-Greenland-Svalbard margins, is regarded as both a classic case of structural inheritance and an exemplar for the Wilson-cycle concept. This paper examines different aspects of structural inheritance in the Circum-North Atlantic region: 1) as a function of rejuvenation from lithospheric to crustal scales, and 2) in terms of sequential rifting and opening of the ocean and its margins, including a series of failed rift systems. We summarise and evaluate the role of fundamental lithospheric structures such as mantle fabric and composition, lower crustal inhomogeneities, orogenic belts, and major strike-slip faults during breakup. We relate these to the development and shaping of the NE Atlantic rifted margins, localisation of magmatism, and microcontinent release. We show that, although inheritance is common on multiple scales, the Wilson Cycle is at best an imperfect model for the Circum-North Atlantic region. Observations from the NE Atlantic suggest depth dependency in inheritance (surface, crust, mantle) with selective rejuvenation depending on time-scales, stress field orientations and thermal regime. Specifically, post-Caledonian reactivation to form the North Atlantic rift systems essentially followed pre-existing orogenic crustal structures, while eventual breakup reflected a change in stress field and exploitation of a deeper-seated, lithospheric-scale shear fabrics. We infer that, although collapse of an orogenic belt and eventual transition to a new ocean does occur, it is by no means inevitable.
... Refraction data suggest that 2-3 km thick succession of Devonian may potentially exist over the Trøndleag Platform and the Halten terrace (Breivik et al., 2011). The NE Greenland margin and the Barents Sea basins initially formed by orogenic collapse or extension around Late Devonian -Early Carboniferous time (Hartz and Andresen, 1995;Fossen, 2010;Gernigon et al., 2018: Klitzke et al., 2019. Late Carboniferous to mid-Permian faulting events also occurred onshore East Greenland (Peacock et al., 2000). ...
The Norwegian-Greenland Sea (NGS) in the NE Atlantic comprises diverse tectonic regimes and structural features including sub-oceanic basins of different ages, microcontinents and conjugate volcanic passive margins, between the Greenland-Iceland-Faroe Ridge in the south and the Arctic Ocean in the north. We summarize the tectonic evolution of the area and highlight the complexity of the conjugate volcanic and rifted margins up to lithospheric rupture in the NGS. The highly magmatic breakup in the NGS was diachronous and initiated as isolated and segmented seafloor spreading centres. The early seafloor spreading system, initiating in the Early Eocene, gradually developed into atypical propagating systems with subsequent breakup(s) following a step-by-step thinning and rupture of the lithosphere. Newly-formed spreading axes propagated initially towards local Euler poles, died out, migrated or jumped laterally, changed their propagating orientation or eventually bifurcated. With the Palaeocene onset of volcanic rifting, breakup-related intrusions may have localized deformation and guided the final axis of breakup along distal regions already affected by pre-magmatic Late Cretaceous-Palaeocene and older extensional phases. The final line of lithospheric breakup may have been controlled by highly oblique extension, associated plate shearing and/or melt intrusions before and during Seaward Dipping Reflectors (SDRs) formation. The Inner SDRs and accompanying volcanics formed preferentially either on thick continental ribbons and/or moderately thinned continental crust. The segmented and diachronic evolution of the NGS spreading activity is also reflected by a time delay of 1–2 Myrs expected between the emplacement of the SDRs imaged at the Møre and Vøring margins. This complex evolution was followed by several prominent changes in spreading kinematics, the first occurring in the Middle Eocene at 47 Ma–magnetic chron C21r. Inheritance and magmatism likely influenced the complex rift reorganization resulting in the final dislocation of the Jan Mayen Microplate Complex from Greenland, in the Late Oligocene/Early Miocene.
... As at the Atlantic margins of Norway and Britain, rifting and basin formation in central East and NE Greenland was initiated during the Devonian, an event attributed to orogenic collapse and leftlateral transtension during the final stages of the Caledonian Orogeny (Larsen & Bengaard 1991;Hartz & Andresen 1995;Hartz et al. 2000;. Basin development continued after the Early -Middle Devonian cessation of the Caledonian Orogeny, but transtension shifted to east to west extension and rifting during the latest Devonian. ...
... The East Greenland basins is progressively down-faulted towards the east by roughly northsouth striking faults that mimic the Caledonian structural trends and subordinate more NE -SW striking faults (Fig. 1). Middle-Late Devonian basin formation was probably governed by extension across the Fjord Zone Fault located several kilometres west of the present-day outcrops of Devonian and younger strata and possibly also the Nunatak Zone Fault located farther to the west (Larsen & Bengaard 1991;Hartz & Andresen 1995;Hartz et al. 2000;. The Western Fault Zone located farther east probably accommodated Devonian and Carboniferous left-lateral transtension (Larsen & Bengaard 1991). ...
The Devonian to lower Eocene NE and central East Greenland Rifted Tectono-Sedimentary Element (TSE) is part of the North Atlantic rift system. East and NE Greenland geology is therefore analogues to that of the prolific basins on the conjugated Atlantic margin and in the North Sea in many respects. None the less, hydrocarbon discoveries remain. The presence of world-class source rocks, reservoirs and seals, together with large structures, may suggest a significant East and NE Greenland petroleum potential, however. The TSE was established through Devonian-Carboniferous, Permian-Triassic and Jurassic-Cretaceous rifting interspersed by periods of uplift and post-rift sagging. Subsequently, Paleocene-Eocene magma-rich rifting accompanied the North Atlantic break-up. Depositional environments through time varied in response to the changing tectonism and climate. None-marine deposition dominated until the end of the Triassic, only interrupted by marine sedimentation during Late Permian-Early Triassic times. Subsequently, marine conditions prevailed during the Jurassic and Cretaceous. Volumetric series of basalt erupted over most of the TSE during the late Paleocene-early Eocene following a significant latest Cretaceous-Paleocene uplift and erosion event. Since the Eocene, denudation pulses have removed much of these basalts uniquely exposing the up to 17 km strata of the TSE.
... Although strike-slip reactivation is reported in the literature (e.g. Aris, Coiffait, & Guiraud, 1998;Balaguru, Nichols, & Hall, 2003;Ducea, Kidder, Chesley, & Saleeby, 2009;Faure, Tremblay, Malo, & Angelier, 2006;Firth et al., 2015;Hartz & Andresen, 1995;Jankowski & Probulski, 2011;Kim, 1996;Turner, Liu, & Cosgrove, 2011), detailed descriptions of the strike-slip reactivation of normal faults (Van Noten et al., 2013) and the associated effects of reactivation on along-strike transfer zones (Barton, Evans, Bristow, Freshney, & Kirby, 1998;Kelly, McGurk, Peacock, & Sanderson, 1999 Massironi, 2007) are scarce. Thus, an understanding of key features and typical structures produced during strike-slip reactivation of normal faults is currently lacking. ...
Reverse reactivation of normal faults, also termed ‘inversion’, has been extensively studied, whereas little is known about the strike-slip reactivation of normal faults. At the same time, recognizing strike-slip reactivation of normal faults in sedimentary basins is critical, as it may alter and impact basin physiography, accommodation and sediment supply and dispersal. Motivated by this, we present a study of a reactivated normal fault zone in the Liassic limestones and shales of Somerset, UK, to elucidate the effects of strike-slip reactivation of normal faults, and the inherent deformation of relay zones that separate the original normal fault segments. The fault zone, initially extensional, exhibits a series of relay zones between right-stepping segments, with the steps between the segments having subsequently become contractional due to sinistral strike-slip movement. The relay zones have therefore been steepened and are cut by a series of connecting faults with reverse and strike-slip components. The studied fault zone, and comparison with larger-scale natural examples, lead us to conclude that the relays-turned-contractional-steps are associated with (i) complex fault and fracture networks that accommodate shortening, (ii) anomalously high numbers of fractures and faults, (iii) layer parallel slip and (iv) folding and uplift. Comparison with published statistics from global relay zones shows that whereas the reactivated relay zones feature aspect ratios similar to those of unreactivated relay zones, bed dips within reactivated relay zones are significantly steeper than unreactivated relay zones. Given the potential of reactivated relay zones to form areas of local uplift, they may affect basin structure and may also form potential traps for hydrocarbon or other fluids. The elevated faulting and fracturing, on the other hand, means reactivated relays are also likely loci for enhanced up-fault flow.
... During the late stages of the Caledonian orogeny, several top-to-theeast extensional shear zones developed in East Greenland. The most extensive of these is the N-trending, E-dipping Fjord Region Detachment Zone (FRDZ; Hartz & Andresen, 1995;Hartz et al., 2001;Andresen et al., 2007; Figure 1), a low-angle extensional detachment characterized by an up to 1-km-thick mylonite zone (Andresen et al., 1998). The FRDZ originated at more than 25 km depth and developed during progressively lower P-T conditions (Fossen, 2010;Gilotti & McClelland, 2008). ...
... The FRDZ originated at more than 25 km depth and developed during progressively lower P-T conditions (Fossen, 2010;Gilotti & McClelland, 2008). At higher crustal levels, strain is largely localized in a 10-50 m wide, slightly steeper, brittle fault within the FRDZ (Andresen et al., 1998;Hartz & Andresen, 1995). A metamorphic break from greenschist-to amphibolite-facies across the shear zone suggests that it is associated with at least several tens of kilometers of extensional displacement (Fossen, 2010). ...
We investigate (i) margin-scale structural inheritance in rifts and (ii) the time scales of rift propagation and rift length establishment, using the East Greenland rift system (EGR) as an example. To investigate the controls of the underlying Caledonian structural grain on the development of the EGR, we juxtapose new age constraints on rift faulting with existing geochronological and structural evidence. Results from K-Ar illite fault dating and syn-rift growth strata in hangingwall basins suggest initial faulting in Mississippian times and episodes of fault activity in Middle-Late Pennsylvanian, Middle Permian, and Middle Jurassic to Early Cretaceous times. Several lines of evidence indicate a close relationship between low-angle late-to-post-Caledonian extensional shear zones (CESZs) and younger rift structure: (i) reorientation of rift fault strike to conform with CESZs, (ii) spatial coincidence of rift-scale transfer zones with CESZs, and (iii) close temporal coincidence between the latest activity (late Devonian) on the preexisting network of CESZs and the earliest rift faulting (latest Devonian to earliest Carboniferous). Late- to post-Caledonian extensional detachments therefore likely acted as a template for the establishment of the EGR. We also conclude that the EGR established its near-full length rapidly, i.e., within 4–20% of rift life. The “constant-length model” for normal fault growth may therefore be applicable at rift scale, but tip propagation, relay breaching, and linkage may dominate border fault systems during rapid lengthening.
... Orogenic collapse initiated in the Devonian, affecting supracrustal rocks of the Eleonore Bay Supergroup found in the inner fjord region, west of Traill Ø (Surlyk, 1990;Bengaard, 1991). Faulting was restricted to a region bound to the west by the Fjord region detachment (FRD) (Hartz and Andresen, 1995;Voss and Jokat, 2009). Continued crustal thinning driven by orogenic collapse during the Devonian subsequently led to the formation of the Western fault zone (WFZ), east of the FRD (Larsen and Bengaard, 1991;Voss and Jokat, 2009). ...
... Between the Late Devonian and Carboniferous, extensional faulting and syn-rift deposition migrated eastward of the FRD, leaving the Eleonore Bay Supergroup close to its present-day configuration between the FRD and WFZ (Hartz and Andresen, 1995;Voss and Jokat, 2009). At that time, extensional deformation concentrated on the WFZ and GHF (Fig. 13B), and produced ~80-100-km-wide fault blocks (Bütler, 1955;Larsen and Bengaard, 1991;Stemmerik et al., 1991;. ...
... At that time, extensional deformation concentrated on the WFZ and GHF (Fig. 13B), and produced ~80-100-km-wide fault blocks (Bütler, 1955;Larsen and Bengaard, 1991;Stemmerik et al., 1991;. In the subsurface, this eastward migration of deformation preserved an upwarped Moho underlying the Eleonore Supergroup at 30 km depth (Fig. 14B) (Hartz and Andresen, 1995;Voss and Jokat, 2009). Extensional faulting in the Traill Ø region during this time is recorded on the GHF (Fig. 13A) (Bütler, 1955;Stemmerik et al., 1991) and may have also occurred during Permian-Triassic time (Fig. 13B) (Surlyk et al., 1986;Seidler, 2000). ...
Fault block basins exposed along NE Greenland provide insights into the tectonic evolution of East Greenland and the Norwegian-Greenland Sea. We present a new geological map and cross sections of the Traill Ø region, NE Greenland, which formed the western margin of the Vøring Basin prior to Ceno zoic seafloor spreading. Observations support a polyphase rift evolution with three rift phases during Devonian–Triassic, Jurassic–Cretaceous, and Cenozoic time. The greatest amounts of faulting and block rotation occurred during Cenozoic rifting, which we correlate with development of the continent ocean transition after ca. 56 Ma and the Jan Mayen microcontinent after ca. 36 Ma. A newly devised macrofaunal-based stratigraphic framework for the Cretaceous sandy mudstone succession provides insights into Jurassic– Cretaceous rifting. We identify a reduction in sedimentation rates during the Late Cretaceous; this corresponds to a transition from structurally confined to unconfined sedimentation that coincides with increased clastic sedimenta-tion to the Vøring and Møre Basins derived from East Greenland. With each rift phase we record an increase in the number of active faults and a decrease in the spacing between them. We attribute this to fault block rotation that leads to an excess build-up of stress that can only be released by the creation of new steep faults. In addition, we observe a stepwise migration of deformation toward the rift axis that we attribute to preexisting lithospheric heterogeneity that was modified during subsequent rift and post-rift phases. Such observations are not readily conformable to classic rift evolution models and highlight the importance of post-rift lithospheric processes that occur during polyphase rift evolution.
