High-resolution mineralogical and rock magnetic study of ferromagnetic phases in metabasites from Oscar II Land, Western Spitsbergen—towards reliable model linking mineralogical and palaeomagnetic data

Mariusz, Burzyński; Michalski, Krzysztof; Nejbert, Krzysztof; Domańska−Siuda, Justyna; Manby, Geoffrey

doi:10.1093/gji/ggx157

Cited by 7 publications

(7 citation statements)

References 18 publications

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“…The presence of magnetite within the examined samples has also been confirmed by rock-magnetic experiments. The presence of the above ferromagnetic Fe-oxides has proven to be common in the metamorphic basement of western Spitsbergen [13][14][15]49,50]. In many thin sections, small amounts of anataze were also found ( Figure 4C).…”

Section: Mineralogical Methodsmentioning

confidence: 95%

“…This contribution follows on from previous studies of the metabasites by the authors in the St. Jonsfjorden, Venernbreen, Kinnefjellet, Ommafjellet areas of Western OIIL [14,15]. The metadolerite host rocks of western OIIL have been found, from in situ 40 Ar/ 39 Ar data using a 1059 nm CSI fibre laser and MAP215-50 mass spectrometer, to have been subjected to three thermal events in the 426-380 Ma (Caledonian (sensu lato) metamorphism?…”

Section: Introductionmentioning

confidence: 89%

“…All of the listed events could potentially have reset and/or overprinted the palaeomagnetic record. While the pre-metamorphic palaeomagnetic record of the metadolerites of western OIIL can, potentially, survive the Caledonian greenschist-facies metamorphism the rock-magnetic and mineralogical data reported by Michalski et al [14] and Burzyński et al [15] demonstrate that there are no relicts of any pre-Caledonian ferromagnetic carriers. Several palaeogeographic and tectonic models have been tested to explain inconsistency of the calculated palaeopoles with reference to the Apparent Polar Wander Path of Laurussia [14].…”

Section: Introductionmentioning

confidence: 95%

“…Torrelian deformations also affected two Early and Late Neoproterozoic metasedimentary succession from northern Wedel-Jarlsberg Land causing a regional-scale angular unconformity [22,23]. In those Neoproterozoic metasediments and others occurring across western Spitsbergen a further magmatic episode has been reported as a mafic dyke swarm and their extrusive equivalents (e.g., [14,15,24,25]). All those rocks were folded and affected by greenshist facies metamorphism during Caledonian (sensu lato) orogeny (for the numerous relevant references, see for example, [10,26]).…”

Section: Geological Settingmentioning

confidence: 99%

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Mineralogical, Rock-Magnetic and Palaeomagnetic Properties of Metadolerites from Central Western Svalbard

et al. 2018

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A combination of mineralogical, rock-magnetic and palaeomagnetic methods were employed in an attempt to shed a new light on the tectonism and paleogeography of Central Western Svalbard. The focus is on six metadolerite sites from the metamorphic Proterozoic-Lower Palaeozoic complex of southwestern Oscar II Land (Western Spitsbergen). The primary mineral compositions of the metadolerites were strongly remineralized during Caledonian (sensu lato) greenschist-facies metamorphism although some younger tectonothermal modification is also apparent from the rock-magnetic studies. Rock-magnetic experiments supported by thin-section mineral identification and separation of Fe-containing fractions indicate that the main ferromagnetic carriers of the Natural Remanent Magnetization are represented by low-coercivity pyrrhotite and magnetite/maghemite. The investigated metadolerites are characterized by complex pattern of magnetization. The low-temperature palaeomagnetic components which demagnetized up to 250 • C, are characterized by high inclinations (~70-80 •) potentially representing Mesozoic-Cenozoic remagnetization. The most stable middle-high temperature directions which demagnetized from 250 • C, were obtained from only two of six sites. Two Virtual Geomagnetic Poles calculated from two of the middle-high temperature site means do not correlate with the Laurussia reference path for synto post-Caledonian time. Two possible explanations of observed inconsistency are discussed. These are a modification of the Oscar II Land Caledonian basement geometry by listric faulting and/or tectonic rotations related to Daudmannsdalen-Protectorbreen high-strain (shear) zone. The results presented here suggest that post-Caledonian tectonic modification of the palaeomagnetic directions may be more a widespread feature of Western Svalbard.

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Section: Mineralogical Methodsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 95%

Section: Geological Settingmentioning

confidence: 99%

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Mineralogical, Rock-Magnetic and Palaeomagnetic Properties of Metadolerites from Central Western Svalbard

et al. 2018

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“…A corresponding lack of increase in magnetization suggested that no new ferro/ferri-magnetic minerals were grown during metamorphism up to greenschist facies (Hattori & Hirooka, 1979). Burzyński et al (2017) demonstrated growth of metamorphic magnetite in greenschist facies metabasites. These phases were coarse-grained, euhedral and intergrown with albite-chlorite-actinolite.…”

Section: Chemical Remanent Magnetization Of Mafic Metamorphic Rocksmentioning

confidence: 99%

Using paleomagnetism to test rolling hinge behaviour of an active low angle normal fault, Papua New Guinea

Watson¹

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<p>Metamorphic core complexes (MCC) are widespread in extensional tectonic environments. Despite their significant contribution to extension in rifts, little is known about the origin and evolution of metamorphic core complexes. Particular controversy regards the origin of the typically shallowly dipping (<30°) detachment fault that bounds the footwall core of metamorphic rocks. According to Andersonian faulting theory, normal faults should initiate at a dip of ~60° and frictionally lock up and stop slipping at dips of <30°. One possible solution to this problem is a rolling hinge evolution for the fault. In this scenario the fault initiates at a steep dip of ~60° and evolves to a shallower dip during slip due to the rebound of the footwall in response to progressive unloading as the hangingwall is removed (Wernicke & Axen, 1988; Buck, 1988; Hamilton, 1988). Large rotations of the footwall, indicative of rolling hinge style deformation, may conceivably be measured by comparing the remanent paleomagnetic vector of the footwall rocks with the expected direction of the geomagnetic field at the site where the remanent magnetization was acquired. Using these techniques, large rotations of footwall rocks consistent with rolling hinge style deformation have been demonstrated for the footwalls of oceanic core complexes (Garcés & Gee, 2006; Zhao & Tominaga, 2009; Morris et al., 2009; MacLeod et al., 2011), but not for continental MCCs. In this study we attempt to test, using the remanent magnetization of the footwall rocks, whether rolling hinge style rotations have affected the footwall of the Mai’iu fault, Papua New Guinea. The Mai’iu fault, located in the continental Woodlark Rift, is a rapidly slipping (~1 cm/yr) (Wallace et al., 2014; Webber et al., 2018), shallowly-dipping (<22° at the surface) normal fault (Spencer, 2010; Little et al., 2019) responsible for the Pliocene-Recent exhumation of the domed Suckling-Dayman MCC, which is comprised mostly of Goropu Metabasalt. The remanent magnetization of forty-four samples of footwall Goropu Metabasalt were measured for this study. Close to the fault trace (<1.5 km) a moderately inclined, northerly trending, normal component of magnetic remanence is preserved (Dec: 351.1°, Inc: -35.7°, α₉₅: 6.8°, N= 18 sites). Farther to the south, and up-dip of the fault trace (>1.5 km to 10 km from the fault trace) a normal component is observed in the lower blocking temperature range (Dec: 347.2°, Inc: -41.7°, α₉₅: 9.4°, N= 7 sites) (up to 300-400°C) that we interpret to be equivalent to the normal component present in samples closer to the fault trace. The maximum (un)blocking temperature to which the normal component is carried decreases with increasing distance up-dip and away from the fault trace. In the higher blocking temperature range a southerly trending, reversed component of magnetization is preserved that is more steeply inclined than the component mentioned above (Dec: 177.2°, Inc: 57.1°, α₉₅: 7.3°, N= 8 sites). We interpret the moderately-inclined normal component in both regions to be a recent component of magnetization to have been acquired during the exhumation of the Goropu Metabasalt over the last 780,000 years (Brunhes chron). The origin of the older, reversed component is less clear; however, we prefer the interpretation that this component is also an exhumational overprint that was acquired between 2,600,000-780,000 years ago during the Matuyama chron. Comparison of the direction of the average normal component of both Group 1 and Group 2 samples (Dec: 350.6°, Inc: -37.1°, α₉₅: 5.4°, N= 25 sites) with the expected direction of the geomagnetic field at the paleomagnetic sampling locality indicates that 23.9 ± 2.6° (1σ) of back-rotation about a sub-horizontal axis sub-parallel to fault strike has affected the footwall of the Mai’iu fault. Taking into account the known dip of the fault at the surface of <20-22°, this rotation value implies an original fault dip at depth of 41.3-48.5° that is inherited from a paleo-subduction zone. This result is remarkably consistent with other estimates of the original fault dip: for example, geologically observed fault-bedding cut-off angles on an upper plate imbricate (rider) block imply an original fault dip of ~40-49° (Little et al., 2019). Also, microseismicity between 10-25 km depth implies a modern dip there of 30-40° (Eilon et al., 2015; Abers et al., 2016). This study is the first of its kind to use paleomagnetism to demonstrate that substantial rolling hinge style rotations have affected the footwall of a continental MCC.</p>

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Caught between two continents: First identification of the Ediacaran Central Iapetus Magmatic Province in Western Svalbard with palaeogeographic implications during final Rodinia breakup

Gumsley

Manby

Domańska−Siuda

et al. 2020

Precambrian Research

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High-resolution mineralogical and rock magnetic study of ferromagnetic phases in metabasites from Oscar II Land, Western Spitsbergen—towards reliable model linking mineralogical and palaeomagnetic data

Cited by 7 publications

References 18 publications

Mineralogical, Rock-Magnetic and Palaeomagnetic Properties of Metadolerites from Central Western Svalbard

Mineralogical, Rock-Magnetic and Palaeomagnetic Properties of Metadolerites from Central Western Svalbard

Using paleomagnetism to test rolling hinge behaviour of an active low angle normal fault, Papua New Guinea

Caught between two continents: First identification of the Ediacaran Central Iapetus Magmatic Province in Western Svalbard with palaeogeographic implications during final Rodinia breakup

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