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The methods and result of scientific studies are often difficult to understand for non-specialists due to their esoteric nature. Such lack of understanding means that such work is removed from our normal life experience, and thus, the applicability, interest and use of such work can be minimal. The communication of geoscience finds a natural conduit through geoheritage. A good example of an inaccessible technique far removed from everyday experience is anisotropy of magnetic susceptibility (AMS), an extremely useful geoscience technique with many applications, including finding strain and flow directions in rocks. We explored here how to make “AMS” understandable, using three different volcanic sites where the flow of molten rock is an important aspect, each situated in different types of geoheritage visitation context (wild trekkers, beach visitors, and walkers). The method we developed and tested follows the production of simple and adapted explanations, and is coupled with geoheritage inventorying and communication. We utilized the tangible geological features of outcrops, as well as intangible elements such as rock magnetic data, and conducted a geoheritage inventory using the modified geosite assessment model (M-GAM) to create narratives for popular comprehension. The M-GAM analysis has identified the geosites of the San Bartolo lava flow of the Stromboli volcano for the communication of AMS. Later, a simple and comprehensible definition of AMS and thus of the flow processes was created using a step-by-step process. This method could be useful for scientific studies to allow them to reach out to a wider public, using their input in the simple explanation stage to con-construct a narrative. This would provide a way for science to be more widely appreciated, useful and applicable.

The methods and result of scientific studies are often difficult to understand for non-specialists due to their esoteric nature. Such lack of understanding means that such work is removed from our normal life experience, and thus, the applicability, interest and use of such work can be minimal. The communication of geoscience finds a natural conduit through geoheritage. A good example of an inaccessible technique far removed from everyday experience is anisotropy of magnetic susceptibility (AMS), an extremely useful geoscience technique with many applications, including finding strain and flow directions in rocks. We explored here how to make "AMS" understandable, using three different volcanic sites where the flow of molten rock is an important aspect, each situated in different types of geoheritage visitation context (wild trekkers, beach visitors, and walkers). The method we developed and tested follows the production of simple and adapted explanations, and is coupled with geoheritage inventorying and communication. We utilized the tangible geological features of outcrops, as well as intangible elements such as rock magnetic data, and conducted a geoheritage inventory using the modified geosite assessment model (M-GAM) to create narratives for popular comprehension. The M-GAM analysis has identified the geosites of the San Bartolo lava flow of the Stromboli volcano for the communication of AMS. Later, a simple and comprehensible definition of AMS and thus of the flow processes was created using a step-by-step process. This method could be useful for scientific studies to allow them to reach out to a wider public, using their input in the simple explanation stage to con-construct a narrative. This would provide a way for science to be more widely appreciated, useful and applicable. [ABSTRACT FROM AUTHOR]

Dykes are one of the primary subvolcanic bodies that transport magma from the shallow magma chamber or from the deep-seated magma reservoir. The mechanism of magma transport and emplacement in dyke swarms can contribute precious details on source and how magma has associated with crustal rocks. Here we are presenting the results obtained from the Anisotropy of magnetic susceptibility (AMS) on their mode of emplacement and to understand magma flow direction. AMS and rock magnetic studies were performed on 33 dykes located on the West coast of Maharashtra, (India) to determine the magma flow direction using magnetic fabric. Thermomagnetic curves and hysteresis loop measurement indicates that titanomagnetite of associated pseudo-single-domain/multi-domain grain sizes are responsible for the magnetic fabrics. Based on the clustering of the principal AMS axes, three types of AMS fabrics were recognized, (i) Normal fabric, interpreted as due to magma flow characterised by clustering of K1–K2 axes on the dyke plane and K3 axes are nearly perpendicular to it, (ii) Inverse fabric with K2–K3 plane parallel to the dyke plane and K3 is perpendicular to it and (iii) Intermediate fabric, with K1–K3 axes clustering close to dyke plane. The inclination of the K1 axis (IK1) of Normal fabric is the most important to determine the flow of magma for the studied dyke swarm. The IK1 of the studied dykes were fed dominantly by horizontal (IK1 < 30°), inclined (30° < IK1 < 60°) up to vertical fluxes (IK1 > 60°). These results suggest that the dykes may be closer to the magma source and horizontal magma flow inferred from the dykes reveals source is located further away. The present AMS study along with geophysical, geochemical and petrological study supports the evidence of feeder fed mechanism. [ABSTRACT FROM AUTHOR]

Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post‐depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post‐depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low‐pressure systems passing through the English Channel during that period. [ABSTRACT FROM AUTHOR]

Abstract Palaeocurrent analysis is vital for basin analysis and helps in the interpretation of depositional environments (along‐slope or downslope). For that, it is crucial to have multiple measuring methods at hand to apply palaeocurrent analysis with a wide range of different datasets (outcrops, cores and photographs). Here, two relatively underexploited palaeocurrent measurement techniques are assessed when applied to trough cross‐stratification observed in the Arenazzolo Formation at Eraclea Minoa (Sicily). The first technique is a novel design of a qualitative approach to infer palaeocurrent directions from photographs of two‐dimensional sedimentary structures. The second technique involves measurements of the anisotropy of magnetic susceptibility from drilled samples. A broad agreement, with overlapping uncertainty boundaries, is observed between results from both techniques. This agreement validates the use of trough cross‐strata to infer palaeocurrent directions. Moreover, the addition of photographs improves reproducibility and prevents a bias towards the best‐exposed troughs. The application of both techniques to outcrops and sedimentary cores provides new opportunities for palaeocurrent analysis in any type of sedimentary environment.

Palaeocurrent analysis is vital for basin analysis and helps in the interpretation of depositional environments (along‐slope or downslope). For that, it is crucial to have multiple measuring methods at hand to apply palaeocurrent analysis with a wide range of different datasets (outcrops, cores and photographs). Here, two relatively underexploited palaeocurrent measurement techniques are assessed when applied to trough cross‐stratification observed in the Arenazzolo Formation at Eraclea Minoa (Sicily). The first technique is a novel design of a qualitative approach to infer palaeocurrent directions from photographs of two‐dimensional sedimentary structures. The second technique involves measurements of the anisotropy of magnetic susceptibility from drilled samples. A broad agreement, with overlapping uncertainty boundaries, is observed between results from both techniques. This agreement validates the use of trough cross‐strata to infer palaeocurrent directions. Moreover, the addition of photographs improves reproducibility and prevents a bias towards the best‐exposed troughs. The application of both techniques to outcrops and sedimentary cores provides new opportunities for palaeocurrent analysis in any type of sedimentary environment. [ABSTRACT FROM AUTHOR]

One of the major challenges facing geochemistry, petrology, and volcanology researchers is the difficulty in determining the origin and paleo-flow directions of igneous and volcanic rocks. It is not possible to clearly determine origins and paleo-flow directions in areas with numerous volcanic centers. Anisotropy of magnetic susceptibility (AMS) is a valuable method that provides insights into the origins and paleo-flow directions of lavas that are complex to study. The presence of volcanic materials with thicknesses up to 1 km, coming from different sources at varied time intervals in the north of Lake Van, makes this area an ideal setting for implementing AMS in establishing paleo-flow directions. This study presents the magnetic mineralogy and AMS analysis of volcanic rocks from the Miocene to the Quaternary in the Lake Van region. We conducted isothermal remanent magnetization (IRM) and high-temperature susceptibility (HTS) studies to determine the magnetic mineralogy. IRM studies revealed that (titano)magnetite is responsible for the magnetization in most samples, while both (titano)magnetite and hematite are responsible for the rest. Alteration degrees and Curie temperatures of the rock samples were also determined through HTS measurements. There is good agreement between the anticipated directions of lava flow and our findings for nearly all volcanic rocks.

In this paper, we have synthesized the information derived from more than 20 papers and PhD theses on the anisotropy of the magnetic susceptibility (AMS) of 19 Variscan granite plutons, spanning the period between 320 Ma and 296 Ma. The AMS data are obtained from 876 sampling sites with more than 7080 AMS measurements and a re-interpretation is proposed. The studied granites exhibit a magnetic susceptibility (Km) ranging from 30 to 10,436 × 10−6 SI units. Most granites typically exhibit Km values below 1000 × 10−6 SI, indicative of paramagnetic behavior. Biotite serves as the main carrier of iron (Fe), emphasizing the reduced conditions prevalent during the formation of granite melts in the Variscan orogeny. The AMS fabrics of the studied granite plutons record the magma strain, expressing the chronologic evolution of the stress field during the orogeny. This chronologic approach highlights the magmatic events between around 330 and 315 Ma, occurring in an extensional regime, in which the Borralha pluton is an example of a suite that recorded this extensional AMS fabric. Plutons with ages between 315 and 305 Ma show AMS fabrics, pointing out their emplacement in a compressional tectonic regime related to the Variscan collision. The plutons, younger than 305 Ma, record AMS fabrics indicating that the tectonic setting for emplacement changes from a wrench regime to an extensional one at the end of the collision stage. This is evident as there is a chronological overlap between the granites that exhibit AMS fabrics indicating extension and the ones that have AMS fabrics indicating a wrench regime. [ABSTRACT FROM AUTHOR]

Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene. Plain Language Summary: Understanding the effects and responses of atmospheric mineral dust to climate changes in the geologic past is crucial for predicting future scenarios. Analysis of the source of dust deposited 35–27 million years ago in Ulantatal, Inner Mongolia, China reveals that the Central‐East Asian atmospheric circulation during this time interval was similar to that of today. Specifically, dust transport was dominated by northwesterly and westerly winds despite a significantly warmer global climate. We also propose that Arctic Oscillation (AO)‐type conditions, stemming from the temperature difference between the high and low latitudes, modulated planetary westerly winds during this period. Our results suggest that during warmer phases, a negative AO type dominated and resulted in wave‐like westerly wind patterns and a northwesterly dust transport pathway to Ulantatal. During cooler phases, the westerly circulation became stronger and more zonal. The Siberian High pressure system was possibly strengthened during increased Northern Hemisphere (NH) ice volume and further affected northwesterly dust transport. Our findings suggest that NH ice volume increase was possibly also responsible for the formation of the Ulantatal dust sequence itself. Our results imply that even under significantly warmer conditions than today, polar ice affects the long‐term dustiness in this highly populated region. Key Points: The provenance of a Paleogene (35–27 Ma) eolian dust sequence in Ulantatal, Inner Mongolia, China, reveals a modern‐type eolian regimeGlobal cooling and possibly expansion of Northern Hemisphere ice volume modulated the dust provenance by strengthening the Siberian HighLong‐term negative (positive) phase of Arctic Oscillation‐like conditions were favored in the warmhouse Eocene (coolhouse Oligocene) [ABSTRACT FROM AUTHOR]

Abstract The southwestern Ryukyu Trench is an ideal place for investigating sediment transport from the Taiwan mountain belt to the Ryukyu Trench floor. To study the characteristics of trench turbidites and sediment transport along the trench, we utilize two piston cores: KR1518-PC04/PL04 at the southwestern end of Ryukyu Trench and YK1501-PC14/PL14 in the trench floor. We also collect two push cores, YK1611-6K1467MG and 6K1467MR, from undisturbed seabed surface to observe lithology. Our analysis reveals that the lithology of the cores shows homogeneous gray mud layers intercalated with very-thin fine sand layers, which we interpret as hemipelagites intercalated with very-thin turbidites. We identify 60 turbidites (0.3–4.0 cm thick) from YK1501-PC14 and 36 turbidites (0.9–4.2 cm thick) from KR1518-PC04. Based on observation from YK1501-PC14, most turbidites, which were less than 1 cm in thickness, displayed planar and sharp bottom contacts. The turbidite thickness of YK1501-PC14 (6448 m water depth) is thinner than that of KR1518-PC04 (6147 m water depth) in general. Through X-ray fluorescence core scans (ITRAX), we distinguished trench turbidites by elemental patterns and accurately determined the depths of every very-thin turbidite. Most hemipelagites from YK1501-PC14 and KR1518-PC04 show similar ITRAX profiles, indicating a similar source of the sediments. ITRAX analysis also revealed five intervals in high-Ca mud in YK1501-PC14, suggesting another potential source from the Ryukyu forearc. Anisotropy of Magnetic Susceptibility (AMS) results show that both YK1501-PC14/PL14 and KR1518-PC04/PL04 exhibit an oblate fabric indicating a normal sedimentary condition. Magnetic signatures showed the presence of pyrrhotite, supporting evidence that Taiwan-sourced sediments can be transported up to ~ 250 km by turbidity currents and spread from the Taiwan Island to the Ryukyu Trench floor. This study improves our understanding of Ryukyu Trench turbidites and provides valuable insights into active sediment transport along the southwestern Ryukyu Trench.

Abstract Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene.

Growth strata are important for understanding regional tectonic evolution. However, it is difficult to identify growth strata in the field, because of subsequent intensive modification and erosion. To address this problem, we studied two paleomagnetic sections at the stable deposition setting and the growth end of the Miocene growth strata of the Gengma Basin. Average inclinations of the two sections show a systematic deviation of 4.7° ± 5.2°. The anisotropy of magnetic susceptibility results for the growth end of the section A demonstrate a sedimentary fabric. However, the tilt‐corrected K3 axis deviates to the southwest from the normal direction of the bedding by 5.4° ± 3.8°, the magnetic foliation deviates to the equatorial plane by 5.3° ± 4.7°. The K3 axis is perpendicular to the bedding at the stable deposition setting. The deviation of the K3 axis from the normal direction of bedding is interpreted as the growth angle, which can be used to correct the paleomagnetic inclination data. Plain Language Summary: Growth strata are linked with tectonic deformation, and so they are often used as an indicator for analyzing regional tectonics. However, it is difficult to directly identify growth strata in the field, due to typically strong structural deformation. Additionally, unidentified growth strata often lead to the inaccurate correction of the paleomagnetic data, which is a source of uncertainty in estimating for the paleolatitudes of blocks. The Gengma Basin in the north of the Shan‐Tai Block is a typical graben basin. Paleomagnetic and anisotropy of magnetic susceptibility (AMS) data of Miocene growth strata show that the paleo‐inclination of the growth end deviates from that of the stable depositional setting. Moreover, the tilt‐corrected K3 axis of the sedimentary fabric at the growth end deviates from the normal to bedding by 5.4° ± 3.8°, and the magnetic foliation deviates from the equatorial plane by 5.3° ± 4.7°. However, the tilt‐corrected K3 axis at the stable deposition setting is consistent with the normal to bedding. The differences in the paleo‐inclinations and AMS results between the growth end and the stable depositional setting can be used to identify the growth strata, and to correct the paleo‐inclination. Key Points: The paleo‐inclination and anisotropy of magnetic susceptibility data at the growth end of the growth strata were over‐correctedOffset angle of the K3 axis of sedimentary fabric deviating from the normal direction of the bedding is the growth angle of growth strataThe offset angle of the K3 axis of the sedimentary fabric can be used to identify growth strata and precisely correct paleo‐inclination [ABSTRACT FROM AUTHOR]

The southwestern Ryukyu Trench is an ideal place for investigating sediment transport from the Taiwan mountain belt to the Ryukyu Trench floor. To study the characteristics of trench turbidites and sediment transport along the trench, we utilize two piston cores: KR1518-PC04/PL04 at the southwestern end of Ryukyu Trench and YK1501-PC14/PL14 in the trench floor. We also collect two push cores, YK1611-6K1467MG and 6K1467MR, from undisturbed seabed surface to observe lithology. Our analysis reveals that the lithology of the cores shows homogeneous gray mud layers intercalated with very-thin fine sand layers, which we interpret as hemipelagites intercalated with very-thin turbidites. We identify 60 turbidites (0.3–4.0 cm thick) from YK1501-PC14 and 36 turbidites (0.9–4.2 cm thick) from KR1518-PC04. Based on observation from YK1501-PC14, most turbidites, which were less than 1 cm in thickness, displayed planar and sharp bottom contacts. The turbidite thickness of YK1501-PC14 (6448 m water depth) is thinner than that of KR1518-PC04 (6147 m water depth) in general. Through X-ray fluorescence core scans (ITRAX), we distinguished trench turbidites by elemental patterns and accurately determined the depths of every very-thin turbidite. Most hemipelagites from YK1501-PC14 and KR1518-PC04 show similar ITRAX profiles, indicating a similar source of the sediments. ITRAX analysis also revealed five intervals in high-Ca mud in YK1501-PC14, suggesting another potential source from the Ryukyu forearc. Anisotropy of Magnetic Susceptibility (AMS) results show that both YK1501-PC14/PL14 and KR1518-PC04/PL04 exhibit an oblate fabric indicating a normal sedimentary condition. Magnetic signatures showed the presence of pyrrhotite, supporting evidence that Taiwan-sourced sediments can be transported up to ~ 250 km by turbidity currents and spread from the Taiwan Island to the Ryukyu Trench floor. This study improves our understanding of Ryukyu Trench turbidites and provides valuable insights into active sediment transport along the southwestern Ryukyu Trench. [ABSTRACT FROM AUTHOR]

Abstract—The magnetic fabric of the reference Khonako-II (south Tajikistan), Beglitsa, and Chumbur-Kosa (Azov region) loess-paleosol sections was studied to reconstruct the paleowind directions during the Middle and Upper Pleistocene. The paleosols and loesses of the Khonako-II section represent a promising object for study of paleowinds. Our data indicate a prevailing ~ northwestward or ~northeastward wind directions during accumulation of the upper 40.8 m of the section. Thereby, a change from warm (pedocomplex 2) to cold (loess 2) epochs during the accumulation of the lower half of the studied sequence (end of the Middle Pleistocene) was accompanied by "switching" the predominant winds (from northwestern to northeastern ones), whereas accumulation of the upper part of the sequence was mainly controlled by winds of intermediate directions. The latter can be considered as evidence for the lesser contrast of wind rose during later epochs that were responsible for the formation of the upper part of the sequence. The study revealed that the magnetic fabric of loess and paleosol horizons of the Azov region sequences was deformed and cannot be used for paleowind reconstruction. It was demonstrated that sampling using plastic container technique widely applied in studying loess–paleosol deposits could led to the significant deformation of primary magnetic fabric. [ABSTRACT FROM AUTHOR]

The Banyo Syenitic Pluton (BSP) is located on the south western extension of the Mayo Nolti Shear Zone (MNSZ). It is a NNE-SSW elliptical pluton. On the petrographic view, the BSP displays two rock types namely: hornblende-pyroxene-quartz syenite (HPQS) and hornblende-biotite granite (HBG), intruded in a plutono-metamorphic basement rock consists of biotite granite (BG) and hornblende-biotite gneiss (HBGn). Structural investigations indicate that the study area recorded three deformation phases: D1, D2 and D3. D1 is a flattening phase characterized by WNW-ESE to NNW-SSE (N110°E to N160°E) trending metamorphic foliation (S1) with moderate (50°–60°) dips toward NNE to ENE. D2 trends N–S and is characterized by crenulation cleavages (S2), N–S sinistral shear and coeval S2 foliation in hornblende-biotite gneiss. The emplacement of the HPQS and (HBG) took place during this phase considering the N–S global trend of the entire pluton and the NNE-SSW shape of the HPQS in the one hand and sinistral shear deformation microstructures display by plagioclase and K-feldspar crystals in HPQS. D3 displays NE–SW (N30E to N45E) trend in HBGn and HPQS. Magnetic data indicate an inward-dipping NNE-SSW concentric pattern around station N32. The NNE-SSW elliptic shape and concentric magnetic foliation trajectories displayed by the BSP indicate its synkinematic emplacement during the D2 N–S sinistral activation of the MNSZ with the feeder zone (station N32) located on the north eastern border. The sinistral activation is related to the Saharan Metacraton convergence over the Cameroon northern margin. This emplacement was disturbed by an overprinting E–W to NNW-SSE dextral syn-D3 shear phase probably due to the dominant convergence (during its late stage) of the West African Craton over the Cameroon western border. Structural field data and magnetic fabrics infer that the Banyo syenitic pluton was emplaced in a N–S to NNE-SSW oriented fracture initiated during the transcurrent strike-slip MNSZ. The BSP is intruded in HBGn basement rock whose deformation ages are bracketed between 600 Ma (for the early syn-D1 deformation structures) and 550 (for the late syn-D3 deformation structures). The location of the BSP on the N–S to NNE-SSW sinistral MNSZ, between the GGSZ to the north and the RLSZ to the south, displaying similar structural features and N–S syn-to late kinematic syenitic plutons respectively dated at 593 Ma and 590 Ma help in dating the BSP pluton at 593 - 590 Ma. This age range dates several synkinematic emplacements of Pan-African younger syenite and granitoids along N–S and NE–SW shear zones during the western Gondwana post-collisional history.

Abstract Growth strata are important for understanding regional tectonic evolution. However, it is difficult to identify growth strata in the field, because of subsequent intensive modification and erosion. To address this problem, we studied two paleomagnetic sections at the stable deposition setting and the growth end of the Miocene growth strata of the Gengma Basin. Average inclinations of the two sections show a systematic deviation of 4.7° ± 5.2°. The anisotropy of magnetic susceptibility results for the growth end of the section A demonstrate a sedimentary fabric. However, the tilt‐corrected K3 axis deviates to the southwest from the normal direction of the bedding by 5.4° ± 3.8°, the magnetic foliation deviates to the equatorial plane by 5.3° ± 4.7°. The K3 axis is perpendicular to the bedding at the stable deposition setting. The deviation of the K3 axis from the normal direction of bedding is interpreted as the growth angle, which can be used to correct the paleomagnetic inclination data.

Geological evidence indicates that the deformation along the southwest Gondwana margin began during the Middle-to-Late Devonian (the Acadian-Cháñica orogenic phase in Argentina). It has been interpreted that this deformation occurred as a consequence of the collision of Chilenia from the west and Patagonia from the south-southwest with Gondwana. As both Chilenia and Patagonia collided at the same time, in this study, we proposed that these continental blocks conform to the same allochthonous drift terrain, named here as CHIPA. The geological evolution of this margin is still under debate. Field work, paleomagnetic studies, and anisotropy of magnetic susceptibility (AMS) studies were integrated from different localities along this paleomargin in Argentina. In Permian rocks, all the geological indicators show a clear regional NW-SE elongation signature and NE-SW shortening direction. The middle Devonian to Permian patterns are more complex as the result of stress interference and the overlapping of orogenic activities with different intensities and ages. The deformation that started as the product of the CHIPA collision with Gondwana during the Middle Devonian continued through the Permian (the Hercinian-San Rafael orogenic phase in Argentina) as post-collisional compressive deformation, consequence of the paleogeographic re-organization of Gondwana and Laurentia, which moved toward the Equator from the south and the north, respectively, to form the Pangea supercontinent during the Triassic.

The Fenwei Graben located in the conjoint region between the Neo-Tethys tectonic domain and the western Pacific tectonic domain is key to understanding the tectonic evolution of the East Asian interior. Extensive Late Cretaceous–Paleogene fluvial and lacustrine deposits within the southeastern Fenwei Graben, provide ideal archives of early tectono-sedimentary evolution in Fenwei Graben. Recently, we find two complete Late Cretaceous–Cenozoic sections in the Lingbao Basin. These unique sections provide an excellent opportunity to investigate regional tectono-sedimentary evolution and its potential dynamic mechanisms in Fenwei Graben. The anisotropy of magnetic susceptibility (AMS) is an effective and economic method to obtain information about tectonic and/or sedimentary evolution recorded in deposits. To this end, we present an integrated rock magnetism and AMS study of 36 sampling sites from these two sections that span the interval from the Late Cretaceous to the Early Eocene. Our rock magnetism results suggest that hematite and magnetite are the main magnetic carriers of remanence, and paramagnetic minerals and hematite are major contributors to AMS in the Lingbao Basin. In addition, the reverse, intermediate and anomalous magnetic fabrics are found in these two sections, which may result from the contribution of iron-bearing carbonates in deposits. The AMS of the Lingbao Basin is a primary sedimentary fabric with the K1 direction antiparallel to the preferential paleocurrent direction. During the Paleocene, the clockwise rotation of the paleocurrent directions in both sections is more likely to be caused by the rotation of the Lingbao basin or the relatively rapid uplift of western provenance under the influence of the India–Eurasia convergence. Moreover, the inferred early evolution of the Fenwei Graben is likely controlled by both the western Pacific plate subduction and India–Eurasia convergence. [ABSTRACT FROM AUTHOR]

Information about birth and early eruptions of composite volcanoes is scarce, but erosion has revealed very early deposits of the Dunedin Volcano, and we apply anisotropy of magnetic susceptibility (AMS) techniques to retrieve information about the earliest known, submarine, eruptive centre. Although AMS has been used to recover information from subaerial eruptions, and to examine turbidites, this is its first use in investigating depositional processes and the source location for submarine volcaniclastic deposits. AMS fabrics of the deposits, emplaced by submarine eruption‐fed density currents, show basal portions of the currents were decoupled from more‐buoyant upper parts. Triangulation of AMS vectors and orientations yields a vent site location, with some imprecision reflecting the chaotic nature of deposits rapidly aggraded within 500 m of the source vent. This method elucidates depositional processes of subaqueous volcanic currents as well as subaerial ones, while still yielding sufficient consistency for triangulation of flow source sites. Plain Language Summary: The early histories of volcanoes are difficult to reconstruct, as rocks from the earliest eruptions are buried by later eruptions. The Dunedin Volcano (active 16–11 million years ago), has been eroded back so that deposits from early eruptions are exposed along the coasts. We used a rock‐magnetic technique, anisotropy of magnetic susceptibility (AMS) on a submarine eruption deposit, to locate the vent of origin active early in the life of the Dunedin Volcano. This is the first time this technique has been applied to rocks formed by submarine eruptions. AMS fabrics suggest that the source vent was located <500 m southwest of the present‐day coastline. AMS results show that parts of the deposit were formed by chaotic eruption‐fed currents, while other parts were formed as the eruption‐fed current separated into a denser base layer and a more dilute top layer. Key Points: We apply anisotropy of magnetic susceptibility (AMS) to submarine eruption deposits from the early life of the Dunedin Volcano, active 16–11 MaThis is the first time this rock‐magnetic technique is used on submarine eruption deposits to investigate flow processesTriangulation of AMS vectors indicates the source submarine vent was located within 500 m southwest of the present day coastline [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data from Quaternary basalt outcrops along the Hantangang River, Korea. A total of 554 samples were collected from 20 sites, representing three distinct units, Unit I, Unit II, and Unit III. Paleomagnetic data reveal a difference in the timing of eruptions between Units I and II, suggesting distinct periods by volcanic episodes. The mineral magnetic analysis identified titanomagnetite as the dominant magnetic carrier in the samples. AMS results indicated weak anisotropy and scattered AMS directions, indicating a low degree of preferred orientation of grains within the basalt rocks. The inverse AMS fabrics observed at specific sites are attributed to single-domain (SD) grains. Comparing the AMS data with the anisotropy of anhysteretic remanent magnetization (AARM) data, three distinct types of magnetic fabrics (normal, intermediate, and inverse) were discerned. The magnetic fabric was utilized to ascertain the flow direction based on the findings obtained from the AMS results. The findings suggest that the Quaternary basalts in this study's area were primarily confined to the Hantangang River channel and its immediate vicinity during lava flow. However, distinct flow patterns are observed in the southwestern region, implying the presence of unknown volcanic sources. [ABSTRACT FROM AUTHOR]

Mechanisms of northern Tibet crustal thickening are strongly debated. Here we present a high‐resolution and continuous record (24–4.8 Ma) of anisotropy of magnetic susceptibility and paleomagnetic declination from the Dahonggou section in the northern Qaidam Basin, northern Tibet. Our results reveal two major clockwise rotations of the regional paleostress field at ∼15 Ma (∼20°) and ∼8.4 Ma (∼15°), coeval with episodes of mountain building and basin deformation in northern Tibet. We suggest that simultaneous stress field rotation and uplift observed in the study area are related to progressively slowing lateral‐extrusion tectonics along boundary‐parallel strike‐slip faults (Altyn Tagh and Haiyuan faults). The 15 Ma event can be explained by the transition from northeastward to eastward extrusion of northern Tibet materials due to the obstruction of the rigid Alxa block. As deformation keeps migrating toward the east, the 8 Ma event is possibly related to a change from eastward to southeastward extrusion of northeastern Tibet materials as a result of the resistance of the rigid Ordos block. We conclude that Tibetan deformation evolved through successive stages of slowing extrusion tectonics since the mid‐Miocene. Deformation was initially localized along pre‐existing lithospheric structures, and subsequently more distributed under confining boundary conditions, leading to crustal thickening and uniform uplift of northern Tibet during the late stage of plateau development. Plain Language Summary: How northern Tibet evolved as a far‐field response to the India‐Asian collision remains an open question. Here we present high‐resolution and continuous record (24–4.8 Ma) of anisotropy of magnetic susceptibility and paleomagnetic declination from a well‐exposed sedimentary section in the northern Qaidam Basin, northern Tibet. The results indicate two significant clockwise rotations (∼20° and ∼15°) of the regional paleostress field at 15 and 8.4 Ma. Interestingly, these two ages are characterized by large‐scale mountain building, basin deformation and initiation or slowdown of major strike‐slip faulting in northern Tibet. Given that the relatively weak northern Tibet crust is surrounded by several rigid blocks on its northern and eastern sides, we suggest that Tibetan deformation patterns since the mid‐Miocene was associated with successive stages of a weakening extrusion process (from NE‐ to E‐directed extrusion at 15 Ma and from E‐ to SE‐directed extrusion at ∼8 Ma) that exploits pre‐existing lithospheric weak zones. This study lend support to the dominant role of strain transfer from localized strike‐slip faulting to distributed thickening deformation under confining boundary conditions in raising the crust of northern Tibet uniformly during the late stage of plateau development. Key Points: We present high‐resolution anisotropy of magnetic susceptibility and paleomagnetic data from the Neogene sediments in the Qaidam BasinOur results indicate two major clockwise rotations (∼20° and ∼15°) of the regional paleostress field at 15 and 8.4 Ma, respectivelyWe propose a slowing extrusion tectonics and accelerated uplift model to explain the uplift mechanism of northern Tibet in the Neogene [ABSTRACT FROM AUTHOR]

Abstract Previous studies of sediments recovered from the Japan Trench between 37° 25′ N and 38° 30′ N document distinctive turbidite beds induced by huge earthquakes. We studied two sediment cores at 39°N to investigate the depositional record further north along the Japan Trench. These investigations spatially extend our knowledge of the depositional record of earthquakes in the Japan Trench. We examined specifically the precise stratigraphy of turbidite beds using paleomagnetic secular variation, and a tephra correlation. Additionally, anisotropy of magnetic susceptibility (AMS) was investigated to understand the depositional conditions of each turbidite bed. The inferred ages of turbidite beds in this study closely approximate their previously reported ages, which are correlated with the historical and prehistorical huge earthquakes off Tohoku, northeastern Japan. The paleo current directions during deposition of turbidite are inferred from their grain alignment based on AMS data. The directions of basal part reveal northeastward in the slope-side basin and north-northeast in oceanward basin. The directions of basal and upper thick muddy part of a turbidite bed are not always consistent, which suggests the hydraulic condition in the narrow elongated deep-sea basin. This fact could be essential information to elucidate a unique hydraulic condition during the turbidite deposition in the confined basin in the Japan Trench.

The eastern Qinling orogenic belt, located in the conjoint region between the Neo-Tethys tectonic domain and the western Pacific tectonic domain, is key to understanding the tectono-sedimentary evolution of the East Asian interior. Extensive Late Cretaceous–Cenozoic fluvial and lacustrine deposits within the eastern Qinling orogen provide ideal archives of tectono-sedimentary evolution in Fenwei, the eastern Qinling orogen. We present an integrated rock magnetism and anisotropy of magnetic susceptibility (AMS) study of a Middle Eocene–Early Oligocene succession in the Lushi Basin, eastern Qinling region. Our rock magnetic results suggest that hematite and magnetite are the main magnetic carriers of remanence, while χ−T curves, hysteresis loops, and low values of bulk susceptibility indicate that paramagnetic minerals are major contributors to AMS in the Lushi Basin. Nevertheless, the anomalous magnetic fabrics in the Zhangjiacun and Lushi Formations may result from the contribution of the iron-bearing carbonates in deposits. The clustering of the minimum principal axes nearly vertical to the bedding plane and the well-defined NW–SE magnetic lineation almost parallel to the dip of the bounding fault suggest that the AMS of the Dayu Formation is not a sedimentary fabric but an incipient deformation magnetic fabric. The pronounced NW–SE magnetic lineation indicates the NW–SE stretching of the Lushi Basin during the Late Eocene–Earliest Oligocene, which may have been caused by the combined effects of the India–Eurasia collision and the subduction of the western Pacific plate.

The structure of granular materials is one of the most important influential factors in mechanical behaviors. A few inevitable limitations exist in current optical measuring techniques, such as structure disturbance, operational complexity, and high cost. This study attempts to take a new application of the anisotropy of magnetic susceptibility (AMS) technique to investigate the structure of granular materials. To illustrate the feasibility of the AMS in detecting the structure, each of five different kinds of sand, including beach sand, river sand, aeolian sand, and calcareous sand, was reconstituted by moist tamping method and air pluviation method, respectively. Based on the structural features obtained from the optical and the AMS techniques, the validity and applicability of the AMS technique on granular materials with different magnetic mineral compositions were discussed systematically. It is found that the AMS technique is a feasible and efficient method to investigate the structure of granular materials both in laboratory tests and field sampling tests. [ABSTRACT FROM AUTHOR]

Subglacial till can deform when overriding ice exerts shear traction at the ice–till interface. This deformation leaves a strain signature in the till, aligning grains in the direction of ice flow and producing a range of diagnostic microstructures. Constraining the conditions that produce these kinematic indicators is key to interpreting the myriad of features found in basal till deposits. Here, we used a cryogenic ring shear device with transparent sample chamber walls to slip a ring of temperate ice over a till bed from which we examined the strain signature in the till. We used cameras mounted to the side of the ring shear and bead strings inserted in the till to estimate the strain distribution within the till layer. Following the completion of the experiment, we extracted and analyzed anisotropy of magnetic susceptibility (AMS) samples and created thin sections of the till bed for microstructure analysis. We then compared the AMS and microstructures with the observed strain history to examine the relationship between kinematic indicators and strain in a setting where shear traction is supplied by ice. We found that AMS fabrics show a high degree of clustering in regions of high strain near the ice–till interface. In the uppermost zone of till, k1 eigenvector azimuths are generally aligned with ice flow, and S1 eigenvalues are high. However, S1 eigenvalues and the alignment of the k1 eigenvector with ice flow decrease nonlinearly with distance from the ice–till interface. There is a high occurrence of microshears in the zone of increased deformation. [ABSTRACT FROM AUTHOR]

In this article we present the first data on the anisotropy of magnetic susceptibility (AMS) for the rocks of the Early Carboniferous Nepluyevka polyphase pluton, which is situated in the southern part of the East Urals megazone. We consider the properties of magnetic mineralogy of all phases of the batholith, and show that the leading role in determining the magnetic properties of the rocks belongs to an isotropic grain population of MD magnetite and multiple populations of SD magnetite, which are the chief contributors to AMS. We consider the characteristic parameters of AMS for each phase, and show that the AMS is magmatic (non-deformational) in nature. An emplacement mechanism of "magmatic duplex" developing in a kinematic setting of sinistral transtension is proposed for the batholith, based on the analysis of the characteristic magnetic fabrics. [ABSTRACT FROM AUTHOR]

Previous studies of sediments recovered from the Japan Trench between 37° 25′ N and 38° 30′ N document distinctive turbidite beds induced by huge earthquakes. We studied two sediment cores at 39°N to investigate the depositional record further north along the Japan Trench. These investigations spatially extend our knowledge of the depositional record of earthquakes in the Japan Trench. We examined specifically the precise stratigraphy of turbidite beds using paleomagnetic secular variation, and a tephra correlation. Additionally, anisotropy of magnetic susceptibility (AMS) was investigated to understand the depositional conditions of each turbidite bed. The inferred ages of turbidite beds in this study closely approximate their previously reported ages, which are correlated with the historical and prehistorical huge earthquakes off Tohoku, northeastern Japan. The paleo current directions during deposition of turbidite are inferred from their grain alignment based on AMS data. The directions of basal part reveal northeastward in the slope-side basin and north-northeast in oceanward basin. The directions of basal and upper thick muddy part of a turbidite bed are not always consistent, which suggests the hydraulic condition in the narrow elongated deep-sea basin. This fact could be essential information to elucidate a unique hydraulic condition during the turbidite deposition in the confined basin in the Japan Trench. [ABSTRACT FROM AUTHOR]

Patterns of magma transport during the emplacement of Large Igneous Provinces (LIPs) are extremely important for the understanding of their formation. The Permian-Triassic Siberian Traps LIP is considered to be one of the largest in the Phanerozoic; however, mechanisms of magma transfer within and under the crust are still poorly studied. This problem is vital for the reconstruction of the dynamics of magmatic activity and eruption styles, ascertaining the position of magmatic centers and feeding zones, and conception of ore deposits genesis. Here, we present the detailed results of anisotropy of magnetic susceptibility measurements for lava flows and intrusions from the Noril'sk and Kulumbe regions (the northwestern Siberian platform). We reconstructed patterns of magma flow based on the magnetic fabric analysis of more than 100 sites. Distribution of the magnetic lineation in the studied intrusions and flows points out that the lateral magma flow of NW-SE directions was predominant. Our results support the idea of a magma-controlling role of Noril'sk-Kharaelakh and Imangda-Letninskiy regional fault zones. Furthermore, the reconstructed geometry of magma transport in intrusions is contrasting with that in the Angara-Taseeva depression (the southern part of the LIP) due to the presence of the long-lived mobile zones in the northwestern Siberian platform. [ABSTRACT FROM AUTHOR]

This paper presents new structural, anisotropy of magnetic susceptibility (AMS), and petrological data in tandem with existing geochronological data to determine a polyphase Variscan tectonometamorphic event in the southwestern Moldanubian Zone of the Bohemian Massif. The high-grade metamorphic rocks of this Zone underwent the successive tectonometamorphic evolution (from ca. 360 to 310 Ma) that portrays three main geodynamic episodes: (a) The collisional to exhumation episode (ca. 360–335 Ma) recorded by the relict, steeply dipping, and ~ N(NNE) to S(SSW) striking foliation planes (S1) developed at temperatures of 720–754 °C and pressures of ca. 790 MPa (M1) and superimposed flat-lying foliation planes (S2) under temperatures of 674 ± 27 °C and pressures of 680 ± 110 MPa (M2). (b) The late-orogenic ~ N–S oriented shortening (ca. 335–325 Ma) controlled by convergence of a crustal segment derived from the Gondwana continent (newly named as the "Salzburgia Block) and the mostly consolidated Bohemian Massif. These collisional processes resulted in superimposition of the foliation planes (S3) dipping steeply to moderately to the ~ N to ~ NNE(NE), re-heating and metamorphic overprint at temperatures of 770–830 °C and pressures of 450–530 MPa (M3) and syn-tectonic emplacement of the numerous late-orogenic granitoids. (c) Subsequently, the switch in the paleostress regime from ~ N–S shortening to that of late-orogenic ~ ENE–WSW extension (ca. 325–310 Ma) led to the activation of regional right-lateral transtension and exhumation of the deep-seated rocks. Associated re-equilibration proceeded under temperatures of 662–701 °C and pressures of 362–437 MPa (M4 event). In the latter stages of this episode, the synchronous reactivation of the regional ~ NW–SE striking right-lateral shear zones (Pfahl and Danube) and the almost perpendicular ~ NNE(NE)–SSW(SW) striking left-lateral shear zones took place. [ABSTRACT FROM AUTHOR]

Oriented samples were collected in the southern Mongolia Plateau and north‐eastern Tibetan Plateau to detect links between microstructural features, which are inferred from magnetic fabrics, and outcrop‐scale sedimentary structures that include slender fossil orientations. Palaeocurrent imprints in particles and their recognition in magnetic fabrics depend on the kinetics of current and any post‐depositional reworking. Here, we restored the flooding palaeocurrent direction through the statistical orientation of slender fossils and imprints indicated by magnetic fabric patterns in the sediments. We found that the tilt response of the minimum susceptibility axes preserves more links to the dynamic orientation of fossil deposits, while the maximum susceptibility axes may be easily reworked by a weak but long‐term tectonic compression. Comparing the two methods reveals the correlation between fossil distribution and magnetic fabric. The dynamic identification of anisotropy of magnetic susceptibility on large quantitative samples contributes to provide an alternative way for further statistics of fine‐grained sediments and fabric arrangement. [ABSTRACT FROM AUTHOR]

The majority of the strain in Earth crust and upper mantle is localized to the high strain zones developed at ductile‐to‐brittle condition at kilometer‐to‐micrometer scale. Therefore, they represent the key to understanding the deformation evolution of the lithosphere. The finite strain pattern recorded within these zones has been therefore a subject of research in geology. The methods studying rock magnetism such as the anisotropy of magnetic susceptibility (AMS) are frequently used techniques to characterize and quantify deformation and flow record in rocks. Numerous sedimentary, subsolidus and submagmatic deformation zones exhibit typical evolution of the AMS ellipsoid across the strain gradient suggesting indirect not straightforward correlation between AMS and strain ellipsoids. To document spatiotemporal and internal fabric evolution during strain localization, pure shear, simple shear, and shear zone (SZ) analog experiments were performed using shear‐thinning thixotropic material of plaster of Paris. The experimental results closely resemble the record from natural SZs in sedimentary rock systems but also in subsolidus SZs and submagmatic mushy systems. The magnetic fabric evolution across deformation zones is interpreted to be associated with the intersection and transposition of preexisting primary fabric with shear fabrics and evolution of synkinematic subfabrics. Their development is attributed to localization of deformation at microscale due to the self‐organized slip of anisometric particles forming microshear planes reflecting the symmetry of deformation. The experimental results when confronted with the natural examples implies that the localization and partitioning of deformation is one of the most important factors for the interpretation of AMS in deformation zones. Plain Language Summary: The tectonic stresses acting in the Earth's lithosphere are often concentrated in narrow zones of strong deformation called shear zones (SZs) that originated by rock blocks slipping over each other. Therefore, the SZs represent the key to understanding the evolution of the lithosphere and an important subject of scientific interest in geology. The aim of this research was to document the evolution of SZs using examples of physical experiments in the laboratory. We have performed series of experiments with liquid plaster of Paris containing dispersed magnetite particles. When the experiments solidified, we have analyzed the images and measured the preferred orientation of magnetic particles by applying number of frequently used magnetic methods. The experimental results closely resemble the typical record from natural SZs in varied rock systems. The evolution in rocks as well as in experiments is explained in terms of localization and partitioning of deformation at microscale. The research provides a detailed view of the complex structures preserved in the Earth's SZs, their corresponding rock magnetic record and their interpretation. Key Points: Spatiotemporal and internal fabric evolution during strain localization is documented by magnetic fabric analysis in analog experimentsExperimental results closely resemble the record from natural deformation zones in sedimentary, subsolidus and submagmatic mushy systemsLocalization and partitioning of deformation are essential factors for interpretation of magnetic fabric in deformation zones [ABSTRACT FROM AUTHOR]

Structurally, the North Almora Thrust (NAT), is placed in the northern proximity of the Almora Nappe (AN) in the Kumaun Lesser Himalaya. The NAT is characterized by the presence of a zone of mylonitic rocks of basal Saryu Formation (1800 ± 100 Ma) in the hanging wall and the metasedimentaries of Inner Lesser Himalayan rocks as the footwall block. The NAT has been dextrally offset by two estabilished major faults i.e. Saryu River Fault (SRF) in Saryu Valley and Dwarahat-Chaukhutia Fault (DCF) in Ramganga valley. In present study, we identified four new faults, based on field study, geomorphic landform and magnetic fabric analysis. These faults are N–S trending Pancheshwar Fault, NE–SW Rameshwer Fault, NNE-SSW trending Kosi Fault, and NNE-SSW trending Gagas Fault (GF). Our results show that the zone is bound by cross cutting relation with NAT and these fault zones are comparatively more active than other regions. Furthermore, we suggest that the steep and NW–SE orientation of magnetic foliation within the NAT zone is a result of NE–SW oriented progressive regional compression. The magnetic foliations represent the unseen internal foliations in the rocks developed due to preferred alignment of magnetic minerals and can be found through the Anisotropy of magnetic susceptibility (AMS) study. Variation in the alignment of the field and magnetic foliations are developed due to superimposed brittle deformation along the faults over the pre-existing field foliations. Magnetic foliations represent the impact of last stage deformation and significant to find brittle deformation and finite strain in the rocks of the study area. The lowering of anisotropy (Pj) away from the fault zone represents distribution of strain across the NAT zone. AMS fabric confirms the presence of faults developed across the NAT zone and also explains the deformation pattern along these faults. The geomorphic anomalies and steepness changes across the NAT zone are correlated with active deformation along the NAT and associated transverse faults.

The Capo di Bove (CDB) lava flow was emplaced at ∼277 ka during the Faete eruptive Phase of Colli Albani volcanic district near the city of Rome. The CDB lava has a historical significance as it provided the slabs used in the paving of the ancient Appian Way, built in the 4th century BCE. Puzzlingly beyond the seventh milestone, the ancient Appian Way deviates briefly from an otherwise straight SE-NW direction, abandoning the top of the lava flow and resuming its elevation and the SE-NW trend within less than 1 km. This peculiarity raised a question as to whether the deviation could have been the result of a tectonic deformation caused by a (buried) fault. To test this hypothesis, we sampled the CDB lava flow at four locations over a ∼ 10 km transect near the ancient Appian Way around the bend and performed a detailed rock magnetic, paleomagnetic, and petrographic study. Rock magnetic data indicate that pseudo-single-domain magnetite and low-Ti titanomagnetite particles are the main magnetic carriers for three sampling locations, located in freshly cut quarries, which reliably recorded the paleomagnetic field at the time of emplacement. Conversely, the samples collected in the upper part of the lava flow, within the bent segment of the ancient Appian Way, show multi-domain low- and moderate-Ti titanomagnetites as main magnetic carriers which fail to record a paleomagnetic direction. Anisotropy of magnetic susceptibility data are consistent with an overall CDB lava flow direction from SE to NW and the paleomagnetic directional data from the three reliable sampling sites are statistically indistinguishable. Hence, data from this study show no evidence of post-emplacement tectonic rotations. We suggest that the origin of the bend could be identified in the pre-existing morphology (for the lava flow path) and in historical reasons (for the ancient Appian Way). • Near its VII mile the ancient Appian Way built on top of the Capo di Bove (CDB) lava flow deviates briefly from an otherwise straight SE-NW direction. • We investigate a possible reason for such deviation withpetrographic, rock magnetic and paleomagnetic data from the CDB. • Paleomagnetic data indicate no post-emplacement rotation, thus ruling out previously undetected tectonic activity. • The origin of the deviation could be identified in pre-existing morphology (for the lava flow) and in historical reasons (for the Appian Way). [ABSTRACT FROM AUTHOR]

Abstract The majority of the strain in Earth crust and upper mantle is localized to the high strain zones developed at ductile‐to‐brittle condition at kilometer‐to‐micrometer scale. Therefore, they represent the key to understanding the deformation evolution of the lithosphere. The finite strain pattern recorded within these zones has been therefore a subject of research in geology. The methods studying rock magnetism such as the anisotropy of magnetic susceptibility (AMS) are frequently used techniques to characterize and quantify deformation and flow record in rocks. Numerous sedimentary, subsolidus and submagmatic deformation zones exhibit typical evolution of the AMS ellipsoid across the strain gradient suggesting indirect not straightforward correlation between AMS and strain ellipsoids. To document spatiotemporal and internal fabric evolution during strain localization, pure shear, simple shear, and shear zone (SZ) analog experiments were performed using shear‐thinning thixotropic material of plaster of Paris. The experimental results closely resemble the record from natural SZs in sedimentary rock systems but also in subsolidus SZs and submagmatic mushy systems. The magnetic fabric evolution across deformation zones is interpreted to be associated with the intersection and transposition of preexisting primary fabric with shear fabrics and evolution of synkinematic subfabrics. Their development is attributed to localization of deformation at microscale due to the self‐organized slip of anisometric particles forming microshear planes reflecting the symmetry of deformation. The experimental results when confronted with the natural examples implies that the localization and partitioning of deformation is one of the most important factors for the interpretation of AMS in deformation zones.

Knowing the rotation and paleo-stress history in Qaidam Basin is a fundamental parameter to quantify the mechanism of intracontinental deformation in Tibetan Plateau. However, few studies have been conducted on tectonic rotation and stress evolution over long timescales in the Qaidam Basin. Here, we report new magnetic declination and the anisotropy of magnetic susceptibility (AMS) from a ∼52–7 Ma sequence of fluvial and lacustrine sediments in the Dahonggou (DHG) section in the northern Qaidam Basin. The magnetic declination revealed that the northern Qaidam Basin underwent a clockwise rotation 25.1° ±8.6° during ∼33–17 Ma, followed by a counterclockwise rotation 16.9°±6.8° during ∼17–13.5 Ma. The AMS results showed that the "earliest deformation" fabrics were interrupted by the "pencil structure" fabrics in the intervals of ∼52–45 and ∼21–15 Ma. The interruption, synchronous with the marked deceleration of the India-Asia convergence rate, indicates pulse of strong tectonic compressive stress. In addition, the AMS results documented a transition in stress direction from S-N to SW-NE at ∼15 Ma, suggesting a kinematic shift in the northeastern TP. Our constraints on the rotation and stress from the northern Qaidam Basin support the two-stage evolution of the Altyn Tagh Fault (ATF). The fast-rate slip motion on the ATF during the early Oligocene caused the clockwise rotation in the northern Qaidam Basin; the second stage with enhanced thrusting since the middle Miocene caused extensive crustal shortening and dispersive NW-trending folds and faults in the Qaidam Basin and the northeastern TP. [ABSTRACT FROM AUTHOR]

[Display omitted] • The magnetic mineral fabrics of the Lassiter Coast Intrusive suite, Chile, and Sierra Nevada record tectonic strain. • Magmatic pulses coincide with increased tectonic compression, recorded by AMS fabric. • Increased tectonic compression and convergence rate both influence flare-up events. This paper applies magnetic fabric analyses to plutons of the East Pacific continental arc. Continental arc magmatism is strongly episodic, with voluminous granitic magma addition occurring during discrete high-flux events ('flare-ups'). The cause of these flare-ups is debated, variously invoking tectonic, mantle, or crustal controls. To understand how the syn-magmatic strain history changes during a flare-up, we compare granitic magnetic fabric (Anisotropy of Magnetic Susceptibility, AMS) and geochronological data from the Antarctic Peninsula (Lassiter Coast), Sierra Nevada, and Chile. This comparison indicates a common pattern in orientation and magnitude of syn-magmatic deformation, showing flare-up events occur during increased tectonic compression driven by enhanced interplate coupling and fast subduction. Flare-ups terminate as tectonic compression reduces or the regime becomes extensional, even if convergence rates remain high. As with enhanced seismicity, magmatic flare-ups result from high tectonic compression, during discrete periods of enhanced interplate coupling within broader periods of increased subduction rates. The enhanced magmatic flux results either from crustal thickening leading to partial melting of a newly accreted, hydrous mafic underplate, enhanced melt segregation in the source, or in response to high tectonic compression rendering lithostatic compression the weakest compressive force, enhancing magma extraction and ascent from the mantle. [ABSTRACT FROM AUTHOR]

The Chočské vrchy Mts. are a part of the Tatra--Fatra Belt located in the Central Western Carpathians (Slovakia). We characterize the main Late Cretaceous--Cenozoic deformation events and the changing strain that formed the geological setting of the Chočské vrchy Mts. by applying the Anisotropy of Magnetic Susceptibility coupled with the Anisotropy of Anhysteretic Remanent Magnetization and complemented by petromagnetic analyses. We analyse Lower Cretaceous marly limestones of the Mraznica Formation (Fm.), which is a part of the Krížna nappe, and the "post-thrusting" Eocene--Oligocene Huty Fm. Petromagnetic experiments reveal that paramagnetic minerals control the magnetic susceptibility, although a distinct contribution of ferromagnetics (magnetite, hematite and likely pyrrhotite) is also documented. The magnetic fabric in both the Mraznica and Huty fms. is generally sedimentary with minor tectonic imprint. The NNE--SSW orientation of the magnetic lineation in most of the Mraznica Fm. sites corresponds well with the local bedding strike as well as the calculated regional statistical fold axis for the Krížna nappe, but it deflects from the expected orientation considering the regional Cretaceous thrusting direction. Similarly oriented magnetic lineation is also documented in some Huty Fm. sites. Magnetic and structural results reveal the dip of the post-trusting Paleogene strata covering the Chočské vrchy Mts. horst block differs from both the dip of magnetic lineation and the dip of statistical fold axis from the Krížna nappe within this uplifted block, suggesting complex uplift-related deformations. We conclude that Krížna nappe folds together with AMS lineation, both formed during Late Cretaceous thrusting, have been later rotated by an angle of 20° as an effect of Neogene transpression, which also affected the magnetic fabric of the postthrusting cover. [ABSTRACT FROM AUTHOR]

Anisotropy of magnetic susceptibility (AMS) is commonly used to assess sedimentation, deformation, tectonics, rock fabric, and texture. Using focused‐ion beam nanotomography, we develop a micromagnetic method to investigate the AMS of individual magnetite inclusions in silicates across the transition between single‐domain (SD) to multidomain behavior. We calculate individual AMS tensors by modeling the magnetization response of a particle to weak applied fields in three orthogonal directions. The main AMS mode of elongated SD particles is not a homogeneous magnetization rotation, but focused alignment of spins at their edges and tips. In single‐vortex particles, vortex displacement is the dominant AMS mode, which focuses the largest magnetization changes in a planar region containing the vortex core, and perpendicular to the direction of vortex motion. In multi‐vortex structures a combined motion of all vortex centers can lead to high degrees of anisotropy when some motion patterns are energetically much easier to achieve than others. Plain Language Summary: Many rocks have physical properties that vary according to the direction in which these are measured. Such rocks are called anisotropic. A fast and simple measurement which can uncover such anisotropy is the magnetization response to applied fields in different directions. This anisotropy of magnetic susceptibility (AMS), or AMS, is used in numerous applications to detect hidden information about geological processes. However, the interpretation of AMS data requires additional knowledge about the small magnetic mineral grains in the rock, because very small grains behave exactly opposite (inverse) to very large grains (normal). Here, we use hundreds of slices of electron microscopy images to reconstruct the exact shape of hundreds of such tiny magnetite grains. Then we run computer models to predict how these grains respond to applied magnetic fields. These data reveal how magnetic grains react to magnetic fields, and help us to understand better why small and large grains behave differently. Now we have a much better insight into the physical processes that are measured during AMS determinations made in laboratories all over the world. Key Points: Micromagnetics and nanotomography elucidate the physical anisotropy of magnetic susceptibility (AMS) modes of natural magnetite particlesThe data explain the transition from inverse to normal AMS fabric with increasing grain sizeA systematic characterization of AMS modes in single‐domain and pseudo‐single domain magnetite particles is established [ABSTRACT FROM AUTHOR]

In this study, we report results from three analog models with a similar initial setup and different amounts of bulk shortening, to simulate the development of a thrust imbricate in fold‐and‐thrust belts at different stages. Samples are taken at the back‐ and forethrusts, in the complex forekink zones, and at random distances to thrusts for analysis using anisotropy of magnetic susceptibility as strain indicator. This analysis shows that three distinct types of magnetic fabric can be identified throughout the models: (a) a compactional oblate fabric that changes as a function of distance toward a localized deformation zone (e.g., thrust or kinkzone), (b) a thrust‐induced fabric with magnetic foliation parallel to the thrust surface depicting its geometry, and (c) a complex forekink zone fabric with broad girdle distributions of principal axes and magnetic lineation perpendicular to the shortening direction. The latter indicates an interplay between folding and thrusting of the shortened sand layers. Additionally, a decrease in the degree of anisotropy with appearance of a quantitatively more prolate fabric can be observed toward the thrusts and kinkzones. Moreover, a thrust‐induced fabric is inherited by the variation of strain, depicted by changes in magnetic fabrics. In conclusion, our analysis of model results shows that strain changes as a function of distance toward localized deformation zones with characteristic magnetic fabrics that develop as deformation continues. Plain Language Summary: Deformation within fold‐and‐thrust belts occurs as thrusting (displacement along fracture zones), folding (bending of rock units), and internal deformation. The internal deformation, like compaction and grain realignment, is hard to analyze by the naked eye. Fortunately, the magnetic properties of grains can be measured and provide information on grain realignment within an imbricate structure. In this study, we combine analog modeling with magnetic analysis to track the internal deformation of imbricates in detail. We modeled thrust imbricates and analyzed the magnetic fabric within the models. Our observations show a gradual change in magnetic fabric within an imbricate toward thrusts and kinkzones, which bound the imbricate, showing increasing deformation. At the thrusts, the magnetic fabric becomes parallel to the thrust surface and depicts the geometry of the thrust, whereas in the kinkzone a complex interplay between folding and thrusting is revealed. Our results can be compared to natural examples, as observations from models and published natural analogies are comparable. Our study provides insights into the strain distribution and gradients within thrust imbricates. Key Points: Anisotropy of magnetic susceptibility as strain indicator within three analog models simulating thrust imbricate developmentCharacteristic sets of magnetic fabric are developed for each structure in the models, revealing deformation in detailGradients in changes in magnetic fabric are recognized as function of distance toward a thrust or kinkzone [ABSTRACT FROM AUTHOR]

The Qinghai Lake is located near the junction of the East Asian summer monsoon (EASM), East Asian winter monsoon (EAWM), and Westerlies. The aeolian deposits around Qinghai Lake hold significant value in tracking the paleowind direction, which is crucial to reconstruct paleo-atmospheric circulations. In this paper, a systematic study of anisotropy of magnetic susceptibility (AMS), rock and environmental magnetism, grain size distribution, and X-ray diffraction was conducted on a loess sequence (named Heimahe) in the Qinghai Lake area. The AMS results of the Heimahe section reveal two prevailing winds of NE-SW and NW-SE orientations during the last deglacial in the Qinghai Lake area. Grain size distribution and mineral composition analyses suggest that the NE-SW and NW-SE winds are respectively associated with the winter monsoon and the Westerlies. Moreover, the variations in magnetic lineation as well as other AMS parameters indicate that the dominant paleowind direction in the Qinghai Lake region during the last deglacial changed periodically with a ∼ 300 yr frequency. It appears that magnetic fabric is capable of recording rapid changes in paleowind direction. • Heimahe section recorded two groups of magnetic lineations in NW-SE and NE-SW. • NW-SE and NE-SW lineations respectively correspond to Westerlies and Winter monsoon. • Westerlies and Winter monsoon alternately prevailed in Qinghai Lake area in 13–11 ka. • The dominant paleowind direction changed periodically with a ∼ 300 yr frequency. • Magnetic fabric is capable of recording rapid changes in paleowind direction. [ABSTRACT FROM AUTHOR]

• Comparative geochemical and AMS study of three subswarms of 2.08 Ga dyke swarm. • Multiple magma pulses from a common source generating the 3 subswarms. • Revealing spatial variation in geochemistry and emplacement in a radiating swarm. • Inferences towards multiple concentric magma chamber around a central domal uplift. • Emplacement of 2.08 Ga dyke swarm to be the precursor to Proterozoic Cuddapah Basin. The ca. 2.08 Ga Devarabanda mafic dyke swarm in the eastern Dharwar craton exhibits a spectacular radiating geometry spanning 167˚. This study focuses on unravelling the intra-swarm variability in geochemistry and emplacement systematics across its three distinct sub-swarms designated as SS-1, SS-2 and SS-3, trending N, NW, and NE, respectively. Through an integrated study that includes whole rock geochemistry, anisotropy of magnetic susceptibility (AMS), and available geochronology and gravity data, we identify shared differentiation trends across all the sub-swarms, suggesting a common genetic linkage. While crustal influence is evident, the SS-3 displays relatively primitive geochemical signatures, the other two sub-swarms signify more highly differentiated pulses, indicating multiple magma pulses in the ca. 2.08 Ga dyke swarm. AMS analyses reveal lateral magma flow for SS-3, while vertical injection feeds the other two sub-swarms. Based on this study, we propose the role of a mantle plume for the formation of the three sub-swarms; SS-3 formed from a shallow crustal magma chamber during the pre-rift phase, due to a central domal uplift. Subsequently, SS-1 and SS-2 were emplaced at a later rift phase, where SS-2 was emplaced along a pre-existing NW-trending rift, and SS-1 formed during active rifting and crustal thinning. Evidence supporting an older NW-trending rifting event in the region corresponding to the SS-2 exposures was observed from available gravity data. The presence of discrete crustal magma reservoirs, separate for each sub-swarm, surrounding the domal uplift, explains the intervening dyke-poor areas, and suggests the formation of an apical graben as a precursor to the Proterozoic Cuddapah basin. [ABSTRACT FROM AUTHOR]

The anisotropy of magnetic susceptibility (AMS) record generated from 112 levels in 1248 m long KBH 07 borehole up to the basement in Deccan Volcanic Province of Koyna region depicts episodic variation in the magnetic fabrics. Anomalies in the AMS parameters: volume susceptibility (K), degree of anisotropy (Pj), shape factor (T), degree of lineation/foliation (L/F), inclinations of principle susceptibility axes (Kmax and Kmin) are inferred along with previously published rock magnetic data for the KBH 07. A major change observed at ~600 m level based on magnetic mineralogy and fabrics, density and lava thickness pattern is attributed to shift in magmatic compositional trends in agreement with the high-Mg to low-Mg magma reported previously in the same core (Banerjee and Mondal 2021). Further, the higher-order anomalies depict smaller episodes influencing the fabrics possibly due to differential dynamic viscosities governed by composition in addition to cooling trends. Whereas the major trends can be assigned to compositionally controlled viscosities and hence can be correlated to larger stratigraphic intervals based on the AMS studies. [ABSTRACT FROM AUTHOR]

In anisotropic materials such as minerals and rocks, the AC magnetic susceptibility is also anisotropic, and consists of two components, one in-phase with the applied field (ipMS) and the other out-of-phase (opMS). Correspondingly, anisotropies of these components, in-phase magnetic anisotropy (ipAMS) and out-of-phase anisotropy (opAMS), can be defined. In non-conductive dia- and paramagnetic materials, and in pure multi-domain magnetite, the opMS is effectively zero and only ipAMS can be measured. In some ferromagnetic minerals, such as pyrrhotite, hematite, titanomagnetite, or small magnetically viscous grains of magnetite, the opMS is clearly non-zero, and not only ipAMS but also opAMS can be determined. The opAMS can then be used as a tool for the direct determination of the magnetic sub-fabrics of the minerals with non-zero opMS. The precision in measurement of opMS decreases non-linearly with decreasing opMS/ipMS ratio, which may result in imprecise determination of the opAMS if the ratio is very low. It is highly recommended to inspect the results of the statistical tests of each specimen and to exclude the specimens with statistically insignificant opAMS from further processing. In rocks with a mono-mineral magnetic fraction represented by the mineral with non-zero opMS, the principal directions of the opAMS and ipAMS are virtually coaxial, while the degree of opAMS is higher than that of ipAMS. In some cases, the opAMS provides similar results to those provided by anisotropies of low-field-dependent susceptibility and frequency-dependent susceptibility. The advantage of the opAMS is in its simultaneous measurement with the ipAMS during one measuring process, whereas the other two methods require measurement in several fields or operating frequencies. [ABSTRACT FROM AUTHOR]

In many modern deep‐water slope environments, deposits formed by bottom currents (contourites) are rather common. However, reports on ancient contourites in deep‐water environments are scarce and most of them remain contentious. Based on the study of high‐resolution sedimentological, sedimentary geological and magnetic fabric characteristics, this study presents the key evidence of bottom current activity in the Middle Ordovician Kelimoli Formation from the western margin of the North China craton, and reconstructs the deep‐sea circulation pattern and the direction of deep‐water bottom currents in the middle and low latitudes during the Middle Ordovician. Six typical carbonate microfacies are identified in the Kelimoli Formation, which can be grouped into three sedimentary facies types related to the main interpreted depositional processes (bottom current, undifferentiated bottom current and hemipelagic settling, and hemipelagic settling). The evidence of bottom current deposits are five‐fold. Firstly, it is possible to observe a variety of traction current structures, which mainly represent bed‐load‐dominated transport of sediments. Secondly, there are multi‐scale inverse grading and bi‐grading, as well as inversely‐graded and normally‐graded sedimentary sequences, which reflect the periodic change of bottom current activity. Thirdly, gradual or sharp contact boundaries and small internal erosional surfaces indicate omission surfaces caused by the oscillating variation of bottom current velocity. Fourthly, the continuous rhythmic change of sedimentary fabrics on the microscopic scale reflects sustained, waxing and waning current intensities. Fifthly, the anisotropy of magnetic susceptibility reveals the microscopic fabric characteristics of imbricated magnetic grains, which represent the continuous action of directional current, and the restored palaeocurrent direction indicates that the current is mainly parallel to the slope strike. After the palaeo‐north correction of the North China craton clockwise rotation of 120° to 150° since the Ordovician, anisotropy of magnetic susceptibility shows that the direction of bottom current in the study area is towards the north‐east/east. Therefore, it is speculated that there was a clockwise deep‐water circulation in the middle and low latitudes of the southern hemisphere during the Ordovician. This study not only provides sedimentological evidence for the Ordovician bottom current activity, but also contributes to a better understanding of the Ordovician palaeoceanographical environment, especially the Middle Ordovician deep‐sea circulation pattern. [ABSTRACT FROM AUTHOR]

The steps of the southeastward stepwise‐descending topography of the Chuandian Fragment (CDF) in the southeastern edge of the Tibetan Plateau coincide with N‐S and NE‐SW trending faults that changed from thrusting to normal activity, indicating that since the Middle‐Late Miocene the CDF maintained an E‐W oriented extensional tectonic environment. However, the anisotropy of magnetic susceptibility (AMS) data sets presented herein, from the Cretaceous and Cenozoic sedimentary strata of the southeastern Tibetan Plateau and its edge, show that since ∼28.0 Ma the CDF remained within a stabilized compressional stress field, oriented NEE‐SWW. A comprehensive analysis of the AMS results, topography, fault systems, and geophysical observations indicate that the northward‐advancing eastern Himalaya syntaxis impeded the southeastward‐flowing viscous lower crust and correspondingly decreased its flux, which could have reduced the thickness of the lower crustal channel beneath the CDF. The original low‐gradient topography of the CDF formed by the viscous lower crustal flow could no longer be supported by the thinned lower crustal channel, and thus gravity drove the collapse of the uplifted CDF. This process reconstructed the topography and remodeled the preexisting fault systems of the CDF, resulting in the coexistence of the E‐W oriented extensional tectonic environment and the stabilized NEE‐SWW oriented compressional stress field of the western part of the CDF, since the Middle‐Late Miocene. Thus, the change in the status of the lower crustal channel related to block interactions provided a major geodynamic setting for shaping the topography of the southeastern edge of the Tibetan Plateau. Plain Language Summary: The present work conducted anisotropy of magnetic susceptibility studies in the Cretaceous and Cenozoic fluvio‐lacustrine strata in the southeastern Tibetan Plateau and the Chuandian Fragment (CDF). The results confirm the coincidence of the geomorphologic steps and N‐S trending normal faults within the stabilized NEE‐SWW oriented compressional stress field in the western part of the CDF, since the Middle‐Late Miocene. This seeming paradox can be perfectly resolved by the crustal collapse of the western part of the CDF. The northward advance of the eastern Himalayan syntaxis since ∼28.0 Ma impeded the southeastward flow of the viscous lower crust and reduced the volume of lower crust flowing into the southeastern edge of the Tibetan Plateau, inducing the collapse of the uplifted CDF along the preexisting strike‐slip fault system, which in turn reconstructed the topography and remodeled the preexisting fault systems of the CDF. Key Points: The Chuandian Fragment (CDF) remained within a NEE‐SWW oriented compressional stress field, since the Middle‐Late MioceneThe northward advance of the eastern Himalayan syntaxis reduced the thickness of the lower crustal channel beneath the CDFThe collapse of the uplifted CDF reconstructed its topography and remodeled the preexisting fault systems [ABSTRACT FROM AUTHOR]