Magnetic anisotropy, rock fabrics and finite strain in deformed sediments of SW Sardinia (Italy)

Luneburg, Catalina; Lampert, S.A.; Lebit, Hermann; Hirt, Ann M.; Casey, Martin; Lowrie, William

doi:10.1016/s0040-1951(99)00118-3

Cited by 110 publications

(84 citation statements)

References 51 publications

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“…Higher anisotropies (Pj = 1.15 and 1.25) are more typical for slaty cleavage with strong preferred orientation of phyllosilicates (e.g. schists in SE Sardinia, Lüneburg et al 1999;Culm basin in SW England, de Wall and Warr 2004). K min and K max are very sensitive for small tectonic perturbations (Borradaile and Henry 1997 and references therein), but in the present study we observe changes in the K int as well.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

Magnetic fabrics indicating Late Quaternary seismicity in the Himalayan foothills

Jayangondaperumal

Dubey

Kumar³

et al. 2009

Int J Earth Sci (Geol Rundsch)

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The anisotropy of magnetic susceptibility (AMS) study was performed on soft sediment samples from a trenched fault zone across the Himalayan frontal thrust (HFT), western Himalaya. AMS orientation of K min axes in the trench sediments is consistent with lateral shortening revealed by geometry of deformed regional structures and recent earthquakes. Well-defined vertical magnetic foliation parallel to the flexure cleavage in which a vertical magnetic lineation is developed, high anisotropy, and triaxial ellipsoids suggest large overprinting of earthquake-related fabrics. The AMS data suggest a gradual variation from layer parallel shortening (LPS) at a distance from the fault trace to a simple shear fabric close to the fault trace. An abrupt change in the shortening direction (K min ) from NE-SW to E-W suggests a juxtaposition of pre-existing layer parallel shortening fabric, and bendingrelated flexure associated with an earthquake. Hence the orientation pattern of magnetic susceptibility axes helps in identifying co-seismic structures in Late Holocene surface sediments.

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Section: Discussion and Interpretationmentioning

confidence: 99%

Magnetic fabrics indicating Late Quaternary seismicity in the Himalayan foothills

Jayangondaperumal

Dubey

Kumar³

et al. 2009

Int J Earth Sci (Geol Rundsch)

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“…Although these values are lower than the expected 3.8 for a unique and purely paramagnetic phase, the considerable increase of bulk susceptibilities at low temperature demonstrates a predominant presence of paramagnetic minerals (e.g. Lüneburg et al 1999). When we compare ellipsoid orientations from both techniques (Fig.…”

Section: Ams Resultsmentioning

confidence: 60%

“…Samples are cooled to 77 K by using liquid nitrogen (e.g. Hirt & Gehring 1991;Lüneburg et al 1999) and measured in the KLY-3S Kappabridge susceptometer. This technique gives repeatable results (Oliva-Urcia et al 2010a,b, 2013García-Lasanta et al 2014).…”

Section: Amsmentioning

confidence: 99%

Tethyan versus Iberian extension during the Cretaceous period in the eastern Iberian Peninsula: insights from magnetic fabrics

García‐Lasanta

Román‐Berdiel

Oliva‐Urcia

et al. 2015

JGS

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This work investigates how anisotropy of magnetic susceptibility (AMS) recorded the strain related to the Early Cretaceous extensional processes in synrift sediments of the Maestrat basin (eastern Spain). Forty-two sites, distributed throughout the Lower Cretaceous sequence with dominant gentle dips, were sampled. Minerals contributing to the AMS are mainly phyllosilicates. The parallelism between magnetic and sedimentary foliation seems to indicate that a primary (synsedimentary and early diagenetic) magnetic fabric was preserved at 84% of sites. Consequently, preferred orientations of magnetic lineations are interpreted to record the effect of extensional processes coeval with sedimentation and diagenesis during this period. At these 35 sites, two main magnetic lineation orientations are found, delimiting two large domains: a NE-SW orientation prevailing in the NW sector of the basin (parallel to the extension direction of the Iberian basin), and NW-SE to NNW-SSE orientations to the SE (parallel to the extension direction controlling the western Tethys margin). Directional variability demonstrates that the Maestrat basin is located at the boundary between two domains (Iberian and Tethyan) undergoing different plate-scale extensional processes. The subsequent Cenozoic tectonic inversion affected the synsedimentary magnetic fabrics at only a few sites at the borders of the basin, where compressive features are more developed. Received

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“…Assuming an ideal paramagnetic phase with a paramagnetic Curie temperature (Tc) around 0 K, its expected magnetic susceptibility at low temperature (77 K) would be approximately 3.8 times higher than at room temperature (i.e., the ratio of temperatures, 292/77, Ritcher and van der Pluijm 1994; Lüneburg et al 1999). The presence of ferromagnetic s.l.…”

Section: Magnetic Techniques: Rt-ams Lt-ams Aarm and Paleomagnetismmentioning

confidence: 99%

“…The analyzed specimens were immersed for 30-40 min in a Dewar filled with liquid nitrogen before measurement (in order to acquire a homogeneous temperature of −195 °C/77 K), and again for 10 more min between each of the three spinner positions required by the measurement procedure. This technique gives reproducible results (Hirt and Gehring 1991;Lüneburg et al 1999;Oliva-Urcia et al 2010a, b). When the magnetic fabric results from the contribution of ferro-and paramagnetic phases, AARM (anisotropy of the anhysteretic remanent magnetization) is useful to separate the ferromagnetic s.l.…”

Section: Magnetic Techniques: Rt-ams Lt-ams Aarm and Paleomagnetismmentioning

confidence: 99%

Multidisciplinary approach to constrain kinematics of fault zones at shallow depths: a case study from the Cameros–Demanda thrust (North Spain)

Sáinz

Román‐Berdiel

Oliva‐Urcia

et al. 2016

Int J Earth Sci (Geol Rundsch)

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Thrusting at shallow depths often precludes analysis by means of structural indicators effective in other geological contexts (e.g., mylonites, sheath folds, shear bands). In this paper, a combination of techniques (including structural analysis, magnetic methods, as anisotropy of magnetic susceptibility and paleomagnetism, and paleothermometry) is used to define thrusting conditions, deformation, and transport directions in the Cameros–Demanda thrust (North Spain). Three outcrops were analyzed along this intraplate, large-scale major structure having 150 km of outcropping length, 30 km of maximum horizontal displacement, and 5 km of vertical throw. Results obtained by means of the different techniques are compared with data derived from cross sections and stratigraphic analysis. Mixed-layer illite–smectite and vitrinite reflectance indicating deep diagenetic conditions and mature stage of hydrocarbon generation suggests shallow depths during deformation, thus confirming that the protolith for most of the fault rocks is the footwall of the main thrust. Kinematic indicators (foliation, S/C structures, and slickenside striations) indicate altogether a dominant NNW movement of the hanging wall in the western zone and NE in the eastern zone of the thrust, thus implying strain partitioning between different branches of the main thrust. The study of AMS in fault rocks (nearly 400 samples of fault gouge, breccia, and microbreccia) indicates that the strike of magnetic foliation is oblique to the transport direction and that the magnetic lineation parallelizes the projection of the transport direction onto the kmax/kint plane in sites with strong shear deformation. Paleomagnetism applied to fault rocks indicates the existence of remagnetizations linked to thrusting, in spite of the shallow depth for deformation, and a strong deformation or scattering of the magnetic remanence vectors in the fault zone. The application of the described techniques and consistency of results indicate that the proposed multidisciplinary approach is useful when dealing with thrusts at shallow crustal levels

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Magnetic anisotropy, rock fabrics and finite strain in deformed sediments of SW Sardinia (Italy)

Cited by 110 publications

References 51 publications

Magnetic fabrics indicating Late Quaternary seismicity in the Himalayan foothills

Magnetic fabrics indicating Late Quaternary seismicity in the Himalayan foothills

Tethyan versus Iberian extension during the Cretaceous period in the eastern Iberian Peninsula: insights from magnetic fabrics

Multidisciplinary approach to constrain kinematics of fault zones at shallow depths: a case study from the Cameros–Demanda thrust (North Spain)

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