Eurekan faults on northern Ellesmere Island, Arctic Canada: from Cenozoic strike-slip tectonics to recent seismicity

The Eurekan deformation is a partially contractional Cenozoic tectonic event that affected large parts of the Arctic region. In the study area on northern Ellesmere Island, major NE-SW trending strike-slip faults occur, which are related to the Eurekan deformation. The outcrop data show that left-lateral strike-slip kinematics slightly dominate, but also right-lateral kinematics were documented. Cross-cutting relationships of the individual faults give evidence for multiple fault reactivations within major strike-slip zones. The reconstructed paleostress fields show two phases. The first phase started with a N-S compression and shifted over a NNE-SSW compression into a NNW-SSE compression. The second phase was a WNW-ESE compression. The paleostress field evolution reflects the movements of Greenland. During the Eurekan phase 1, Greenland moved northward and during Eurekan phase 2 it moved to the WNW. These motions likely controlled the stress field on northern Ellesmere Island. From the paleostress field analyses and the orientation of the strike-slip faults in the study area, it can be derived that the Eurekan phase 1 deformation is characterized by left-lateral strike-slip faults, whereas most-likely during Eurekan phase 2 the majority of right-lateral strike-slip faults formed. The paleostress field analysis implies that many Eurekan faults are reactivated Ellesmerian faults. Recent seismic events indicate ongoing tectonic activity at some of the major strike-slip faults. This sheds new light on the geodynamics of northern Ellesmere Island, which was mechanically coupled to the Greenland plate, and implies that under the recent stress field, earthquakes at strike-slip faults are still possible and some of these faults were active in at least three phases over the last 350 Myr

The Mesozoic-Cenozoic tectonic evolution of the New Siberian Islands, NE Russia

On the New Siberian Islands the rocks of the east Russian Arctic shelf are exposed and allow an assessment of the structural evolution of the region. Tectonic fabrics provide evidence of three palaeo-shortening directions (NE–SW, WNW–ESE and NNW–SSE to NNE–SSW) and one set of palaeo-extension directions revealed a NE–SW to NNE–SSW direction. The contractional deformation is most likely the expression of the Cretaceous formation of the South Anyui fold–thrust belt. The NE–SW shortening is the most prominent tectonic phase in the study area. The WNW–ESE and NNW–SSE to NNE–SSW-oriented palaeo-shortening directions are also most likely related to fold belt formation; the latter might also have resulted from a bend in the suture zone. The younger Cenozoic NE–SW to NNE–SSW extensional direction is interpreted as a consequence of rifting in the Laptev Sea

World ocean review: Mit den Meeren leben 6: Arktis und Antarktis – extrem, klimarelevant, gefährdet

Die sechste Ausgabe des „World Ocean Review“ (WOR) widmet sich der Arktis und Antarktis, diesen zwei extremen und ausgesprochen gegensätzlichen Regionen der Erde. Mit profunden Informationen zur Entstehungs- und Entdeckungsgeschichte bietet der WOR 6 ein tiefes Verständnis der Bedeutung der Pole für das Leben auf unserer Erde. Er zeigt zudem die zu beobachtenden Veränderungen in der Tier-und Pflanzenwelt und analysiert die zum Teil schon dramatischen Folgen, die der Klimawandel in diesen äußerst gefährdeten Regionen bewirkt

Stratigraphy of the uppermost Old Red Sandstone of Svalbard (Mimerdalen Subgroup)

Between the fjords Dicksonfjorden and Billefjorden in central Spitsbergen, Svalbard’s youngest deposits (Early Givetian to Famennian in age) of the Old Red Sandstone—the Mimerdalen Subgroup—are exposed. They form a narrow outcrop area parallel to the Billefjorden Fault Zone and overlie unconformably the multicoloured sandstones of the Lower Devonian Wood Bay Formation. Stratigraphic rank and subdivision of the succession were changed repeatedly since its first mention in 1910. Based on student work in 1996, as well as regional mapping by the authors in 1993 and 2003, the present work formalizes the stratigraphic framework of the succession. This framework has already been applied in recent geological maps. At the same time it is a continuation of the lithostratigraphic standardization carried out by the Committee on the Stratigraphy of Svalbard (1999), where only post-Devonian rocks were considered. Except for some small-pebble conglomerate layers in the Wood Bay Formation, the upper part of the Mimerdalen Subgroup contains the first coarse-grained deposits in Svalbard’s Old Red since the lowermost Devonian Red Bay Group. Faulting between its formations as well as conglomerate pebbles derived from the Lower Devonian Wood Bay Formation indicate the onset of the Svalbardian Event after the tectonic stability during the deposition of the Wood Bay Formation. The Mimerdalen Subgroup is probably the detrital fill of a small foreland basin derived from erosion during the uplift of the Ny-Friesland Block to the east of the Billefjorden Fault Zone. It was later affected by compressional tectonic movements during the Svalbardian Event.Keywords: Svalbard; geology; stratigraphy; Mimerdalen Subgroup; Devonian; Old Red.To access the supplementary material for this article, please see supplementary files under Article Tools online.(Published: 30 October 2014)Citation: Polar Research 2014, 33, 19998, http://dx.doi.org/10.3402/polar.v33.1999

The Lomfjorden Fault Zone in eastern Spitsbergen (Svalbard)

The Lomfjorden Fault Zone in the eastern part of Spitsbergen is one of the prominent structures in Svalbard oriented parallel to the continental margin of the Barents Shelf. It consists of a network of three N–S-striking major faults (Veteranen, Lomfjorden, and Agardhbukta faults), two N–S-striking reverse faults (Lomfjella and Bjørnfjellet reverse faults), and a number of NE–SW- and NNW–SSE-striking normal, reverse, and strike-slip faults. Structural data collected during fieldwork in the northern and central segments of the fault zone, in combination with published data from the southernmost segment, indicate that N–S-striking reverse faults in the Lomfjorden Fault Zone were caused by convergence transferred from the West Spitsbergen Fold-and-Thrust Belt eastward along detachments during an initial phase of the Eurekan deformation in the early Eocene. The W–E contraction was followed by sinistral and dextral strike-slip tectonics along the Lomfjorden Fault Zone during a later phase of the Eurekan deformation in the late Eocene. The NNW–SSE-striking reverse and normal faults are oriented obliquely between the N–S-striking, en-échelon Lomfjorden and Agardhbukta faults. Shortening and extension across these, respectively, can be explained by left-stepping contractional overstep or left-stepping wrench faults in an overall dextral and left-stepping extensional overstep or left-stepping wrench faults in an overall sinistral, N–S-trending strike-slip system. It was not possible to determine if the sinistral phase pre-dated the dextral one or vice versa. The presence of a large granite massif, the Newtontoppen Granite, is suspected to influence or even control the course of the faults and their transfer systems. The involvement and reactivation of preexisting Carboniferous and even older structures and the superimposition of convergent and lateral movements along the Lomfjorden Fault Zone is similar to large fault zones in North Greenland and on Ellesmere Island, indicating that it represents an important element of the Eurekan Orogeny during the final break-up of Laurasia

Geology of the Millen thrust system, northern Victoria Land, Antarctica

Rocks of the Millen Schists were analysed during GANOVEX X (2009/10) to evaluate the nature of the contact between the Ross-age Bowers and Robertson Bay Terranes in northern Victoria Land. The majority of this work was carried out in proximity to the Millen Thrust System, a major structure that separates the whole Millen Shear Belt into two overlying tec tonic units. The Millen Shear Belt has been widely acknowledged to repre sent the tectonic contact between the two terranes. Lithological similarities between the rocks in the hanging wall and footwall of the Millen Thrust Sys tem and those located in the Bowers and Robertson Bay Terranes support this suggestion. The structural history of the Millen Schists can be divided into three stages: (i) formation of isoclinal folds and pervasive S1 foliation that largely parallels bedding S0; (ii) upright D2 folding along northwest-south east axes and (iii) localised D3 high-strain that was dominantly related to reverse transport along the Millen Thrust System. Interpretations based on field observations and the available geochronological data supports a model where: (i) sub-horizontal northeast-southwest directed pure shear shortened the juxtaposed (by the late Cambrian) Bowers and Robertson Bay terranes; (ii) strain localisation along the Millen Thrust System resulted in the devel opment of a complex finite strain pattern in the Millen Schists, which records evidence of dominant northeast directed reverse transport with minor lateral displacement

Structural transect through Ellesmere Island (Canadian Arctic): superimposed Palaeozoic Ellesmerian and Cenozoic Eurekan deformation

The complete transect (Segment 1 to 5) through Ellesmere Island between the Arctic Ocean in the NNW and Kane Basin in the SSE