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This paper summarizes the state of knowledge of the Cretaceous stratigraphy of the Mountainous Crimea and selected biostratigraphic groups and magnetostratigraphy. The first part of the paper discusses the Early Cretaceous, its stratigraphy, selected fossil groups and magnetostratigraphy of the Mountainous Crimea. The data on the figured reference sections were updated in terms of biostratigraphic zonation. Selected fossil groups represented in the paper include ammonites, organic-walled dinoflagellate cysts, ostracods, calpionellids and nannoplankton. The description of each group contains an information on the main publications, types of biostratigraphic units and their distribution, fossil assemplages, images of the most important fossils, and brief discussion on the correlation. Some of the ammonite index fossils are figured for the first time. The magnetostratigraphy summarizes latest data published mostly in Russian for the whole Early Cretaceous succession of the Mountainous Crimea. [ABSTRACT FROM AUTHOR]

The paper considers the possibility of determining the age and correlating peat sections by solving the inverse problem of magnetostratigraphy based on the findings of comprehensive (palaeomagnetic, petromagnetic, microprobe, and radiocarbon) studies on peats of the «Tyapka» and «Chlya» peat sections in the Lower Amur region. For this purpose, we used the values of relative paleointensity calculated following the technique described by Bagina-Petrova. There is no difference in the rate of magnetization fixation among studied peat samples, and the age of magnetization is comparable to the age of the peat deposits itself. The solution of the inverse problem of magnetostratigraphy using the values of relative paleointensity can be used to correlate peat sections among themselves and to estimate the rate of peat accumulation in different periods of the Holocene, even in the absence of radiocarbon dating for one of the correlated sections.

Abstract This paper contributes to an understanding of the tectono‐sedimentary evolution of the South Pyrenean foreland system by reviewing the chronostratigraphic framework of the basin infill in its eastern sector. Six sections are analysed and cross‐correlated to build a 6.5 km thick composite magnetostratigraphy that represents the complete record of the Cadí Nappe in the Ripoll Syncline. New and previous magnetostratigraphic sections are integrated with available biostratigraphy to provide a new age calibration of the sedimentary succession of the Cadí Nappe, encompassing from Palaeocene to Middle Lutetian age. The proposed correlation with the Geomagnetic Polarity Time Scale aims at best reconcile magnetostratigraphic data with the regional biochronology built on the marine Shallow Benthic Zonation (SBZ biozones), the continental mammalian biochronology (MP levels) and the newly collected charophyte data. A subsidence analysis was performed on the calibrated composite succession, resulting in two well‐defined intervals bounded by a hiatus. A Palaeocene to Early Eocene interval with low (11–21 cm/kyr) total subsidence rates, and an Early to Middle Eocene interval, characterised by high (70–75 cm/kyr) total subsidence rates. The detailed trends in both subsidence and sedimentation mark the development and evolution of the foreland depozones, from distal foreland depozones to foredeep and wedge‐top depozones, relative to the emplacement of the Pedraforca Nappe and Cadí Thrust Nappe. The most pronounced sedimentary shift in the Cadí Nappe occurred at 49 Ma, with the rapid drowning of the carbonate platforms and its transition into talus and deep basinal environments. Carbonate platforms collapsed and resedimented on the talus of the elongated trough, newly formed parallel to the orogenic front. This marked the onset of tectonic subsidence triggered by the submarine emplacement of the Lower Pedraforca Nappe. The emersion of the orogenic wedge drove the entry of siliciclastics, lagged by 1 Myr, into the Ripoll Trough. The foredeep filled rapidly (5.5 km thickness in less than 7 Myr) compared to other South Pyrenean regions, favoured by its semi‐enclosed palaeogeography. The emplacement of the Vallfogona Thrust as early as the Middle Lutetian (43 Ma) brought the Cadi Nappe into a wedge‐top setting. However, the Ripoll growth syncline continued acting as a temporary sink for alluvial sedimentation while a foredeep developed further south in the autochthonous Ebro Basin. The flexural response of the Iberian plate to the tectonic thickening of the Axial Zone counterbalanced for a period the local uplift of the Cadi Nappe, providing accommodation space for the top sediments filling the Ripoll Syncline.

Molasses of foredeeps are important indicators of the newest orogenic uplifts, as well as the source of data on climate and landscape changes. One of the fullest sections of Neogene–Quaternary deposits is studied in valleys of the Belaya, Pshekha, and Psekups rivers at the junction of the Western and Northwestern Caucasus with the Eastern Kuban and Western Kuban foredeeps. The formation of the deposits corresponds to the main evolution stages of the Great Caucasus orogen, as well as the foredeeps. A summary of extensive published and original tectonostratigraphic materials has shown that the lowland and then hilly relief in an axial zone of Western Caucasus existed at least from the Middle Miocene. At the same time, the northern flank of the present-day orogen and the foredeeps were located at sea level and were repeatedly flooded by the seas up to the Kuyalnikian (Piacenzian–Gelasian) time, and the Western Kuban Foredeep was flooded even later. The main data on stratigraphy of the upper molasses and Pliocene–Quaternary tectonic movements of the region are based on facies analysis and bio- and magnetostratigraphic studies of the Upper Pliocene–Lower Pleistocene Belorechensk Formation. Its sedimentation started at the beginning of the Kuyalnikian as a result of an increase in the energy of mountain rivers due to the uplift of the riverheads. It is stated that the minimum average rate of uplift of the Western Caucasus in the basin of the Belaya River is 0.8 mm/year over last 4 mln years with acceleration up to 1.7 mm/year from the beginning of the Calabrian. The Belorechensk Formation includes three subformations, which successively become coarser clastic and correspond to the main stages of the accumulation of upper molasses in the Late Pliocene and Early Pleistocene during the intensification of uplifts and landscape-climate changes of Western Caucasus and Ciscaucasia. [ABSTRACT FROM AUTHOR]

SUMMARY: The geocentric axial dipole (GAD) hypothesis is key to many palaeomagnetic applications, for example plate-tectonic reconstructions; however, the validity of this hypothesis at high latitudes is not fully resolved. To address this, in this paper we determined the palaeomagnetic directional data of 156 lava units in Eyjafjarðardalur, Iceland, with the aim of determining the validity of the GAD hypothesis at high latitudes using time-averaged field (TAF) analysis. In addition to the palaeomagnetic directional data, we constructed an age model for the sequences using new 40Ar/39Ar dates, magnetostratigraphy and field data. The sequence age range is 2.6–8.0 Ma. We show that the mean virtual geomagnetic pole (VGP) for our data does not agree with the GAD theory at 95 per cent confidence, when only the standard tilt and tectonic corrections are made; however, when inclination-shallowing processes are accounted for, for example thermoremanence (TRM) anisotropy and refraction effects, the mean VGP can align with GAD at 95 per cent confidence. These inclination-shallowing processes are shown to reduce the inclination by up to 14° for some of the basaltic units. Applying the inclination-shallowing correction also reduces VGP dispersion to levels that agree with global model predictions. We propose that much of the scatter within the palaeomagnetic directional databases are due to inclination-shallowing process effects, which become more important as the natural remanent magnetization (NRM) intensity is high, for example >2 A m−1. We propose that inclination-shallowing processes can be identified and corrected for by examining the NRM intensity and dispersion. [ABSTRACT FROM AUTHOR]

Abstract—We present the results of detailed paleomagnetic studies of six Permian–Triassic boundary sections in the central part of the East European Platform, which are located in the lower reaches of the Vetluga River: Astashikha, Voskresenskoe, Znamenskoe, Prudovka, Sosnovka, and Sukhoborka. The paleomagnetic data, which meet the modern quality standards for laboratory processing, together with the results of biostratigraphic studies, make it possible to develop and substantiate the magnetostratigraphic scales for each section, as well as to correlate them and to compile a composite magnetic polarity scale for the Permian–Triassic sedimentary complex of the Vetluga River. Rock-magnetic characteristics are determined for each of the studied sections, and paleomagnetic poles of the East European Platform are calculated for the Late Permian and Permian–Triassic boundary. [ABSTRACT FROM AUTHOR]

This paper contributes to an understanding of the tectono‐sedimentary evolution of the South Pyrenean foreland system by reviewing the chronostratigraphic framework of the basin infill in its eastern sector. Six sections are analysed and cross‐correlated to build a 6.5 km thick composite magnetostratigraphy that represents the complete record of the Cadí Nappe in the Ripoll Syncline. New and previous magnetostratigraphic sections are integrated with available biostratigraphy to provide a new age calibration of the sedimentary succession of the Cadí Nappe, encompassing from Palaeocene to Middle Lutetian age. The proposed correlation with the Geomagnetic Polarity Time Scale aims at best reconcile magnetostratigraphic data with the regional biochronology built on the marine Shallow Benthic Zonation (SBZ biozones), the continental mammalian biochronology (MP levels) and the newly collected charophyte data. A subsidence analysis was performed on the calibrated composite succession, resulting in two well‐defined intervals bounded by a hiatus. A Palaeocene to Early Eocene interval with low (11–21 cm/kyr) total subsidence rates, and an Early to Middle Eocene interval, characterised by high (70–75 cm/kyr) total subsidence rates. The detailed trends in both subsidence and sedimentation mark the development and evolution of the foreland depozones, from distal foreland depozones to foredeep and wedge‐top depozones, relative to the emplacement of the Pedraforca Nappe and Cadí Thrust Nappe. The most pronounced sedimentary shift in the Cadí Nappe occurred at 49 Ma, with the rapid drowning of the carbonate platforms and its transition into talus and deep basinal environments. Carbonate platforms collapsed and resedimented on the talus of the elongated trough, newly formed parallel to the orogenic front. This marked the onset of tectonic subsidence triggered by the submarine emplacement of the Lower Pedraforca Nappe. The emersion of the orogenic wedge drove the entry of siliciclastics, lagged by 1 Myr, into the Ripoll Trough. The foredeep filled rapidly (5.5 km thickness in less than 7 Myr) compared to other South Pyrenean regions, favoured by its semi‐enclosed palaeogeography. The emplacement of the Vallfogona Thrust as early as the Middle Lutetian (43 Ma) brought the Cadi Nappe into a wedge‐top setting. However, the Ripoll growth syncline continued acting as a temporary sink for alluvial sedimentation while a foredeep developed further south in the autochthonous Ebro Basin. The flexural response of the Iberian plate to the tectonic thickening of the Axial Zone counterbalanced for a period the local uplift of the Cadi Nappe, providing accommodation space for the top sediments filling the Ripoll Syncline. [ABSTRACT FROM AUTHOR]

Relevance. The confinement of hydrocarbon deposits to certain stratigraphic horizons, poor knowledge of the northeast of Western Siberia and adjacent territories, including the magnetostratigraphic method, with their oil and gas potential (over the past 10 years, four unique hydrocarbon deposits have been discovered here), the boreal nature of the deposits, and the need for remote magnetostratigraphic correlations. Aim. To create a magnetostratigraphic reference section of the northeast of Western Siberia. Objects. Sections of deep wells of the Pendomayakhskaya, Vostochno Suzunskaya, Vostochno Lodochnaya and Gorchinskaya areas of the Bolshekhetskaya structural terrace, which exposed the Lower Cretaceous and upper parts of the Upper Jurassic (Yanovstan Formation) deposits. Methods. Paleomagnetic studies were carried out according to standard methods and included sampling of core samples with an "up-down" orientation, sample preparation (kappametry, marking of samples, photographing, sawing), measurement of magnetic susceptibility, temporary cleaning (the samples were located along the field during a week, then a week-against the field with determination of residual magnetization), complete demagnetization by alternating magnetic field, plotting of complete demagnetization, mass cleaning, determination of components of natural residual magnetization, assessment of paleomagnetic stability, identification of forward and reverse polarity zones, construction of paleomagnetic sections. To construct the magnetostratigraphic sections given in this article, the paleomagnetic and biostratigraphic data are linked. For this purpose, magnetochrons were identified using biostratigraphic analysis. Results. The authors have compiled a composite magnetostratigraphic section of the boundary Jurassic-Cretaceous deposits of the Bolshekhetskaya structural terrace and identified four magnetozones with subzones of direct and reverse polarity, compared with the Berriasian ammonite scale. The high information content of the results of magnetostratigraphy research under boreal conditions was noted.

The buried Daxing Uplift connects the Beijing Sag and Dachang Sag, which is the critical tectonic unit for understanding the structural evolution of the Beijing Sub-plain and its linkages to regional tectonics. This study combines paleomagnetic, 26Al-10Be isochron dates and sedimentary analyses from a new borehole (Yx02) in the northeastern Beijing Sub-plain to shed fresh light on regional tectonic processes and the sedimentary history since the Pliocene. The main findings are as follows: (1) the Daxing Uplift had formed three depositional episodes: alluvial-fan, lacustrine-delta, and alluvial-fan sedimentation since the Cenozoic; (2) The borehole records the Brunhes, Gauss normal chron, and the Matuyama, Gilbert reversed chron in the Daxing Uplift, the corresponding depths are 0–148.9 m, 148.9–315.0 m, 315.0–520.5 m and 520.5–650 m; (3) An important tectonic event started in ~4.3 Ma, disintegrated NE-trending basin and range terrain, reactivated the NW-trending Nankou-Sunhe fault, and formed Shunyi fault in Beijing Sub-plain. Sedimentation occurs exclusively in the Beijing Sag and the northeastern Daxing Uplift during ~4.3–1.77 Ma; (4) During ~1.77–1.07 Ma, a transition from an extension to a strike-slip occurred, and is described not only in a progressively higher increase of the overall deposition rate, but also in a decrease of the relative deposition disparity between sags and uplifts. Since then, the Beijing Sub-plain has been shaped, associated with an overall subsidence depression in the Bohai Bay Basin. This work enhances our understanding of the formation and evolution of the Beijing Sub-plain, the division of tectonic episodes, and the initiation time of the latest tectonic movement in the break-up region, North China Craton, since the Neogene. [ABSTRACT FROM AUTHOR]

Stratigraphy of Campanian deposits in the stratotype of the Kudrinskaya Formation in the Southwestern Crimea is revised. For the first time, integrated sedimentological, biostratigraphic (ichnofossils, cephalopods, inoceramids, foraminifers, dinocysts, nannoplankton, gilianelles), isotope-geochemical, paleo- and petromagnetic characteristics of the section were obtained. The boundary of the lower and upper Campanian is substantiated and confirmed by U–Pb dating of zircons from the well-known bentonite (kil) clay bed in the interval of 77–80 Ma. It is proposed to accept the Campanian Substage boundary of the General Stratigraphic Chart (for bipartite stage subdivision) at the top of the Chron C33r, located near the δ13C isotopic excursion "MCaE" – Mid-Campanian Event, near the first occurrence of the benthic foraminifer Brotzenella monterelensis and a number of other traditional biomarkers. [ABSTRACT FROM AUTHOR]

Plain Language Summary: Nearly synchronous global changes in geomagnetic polarity give both a detailed irregular pacing to geological time and provide a glimpse into heat transfer processes across the core—mantle boundary which drives the Earth's geodynamo. Although the Late Carboniferous is characterized by some well‐studied reversals, details of the tempo of polarity changes in the Early Carboniferous are unknown. This work addresses this by providing a detailed record of polarity changes over a ∼2 million year interval at around 334.5–332.5 million years ago‐from the Trowbarrow Quarry section in NW England. We demonstrate that these limestones likely preserve magnetization from close to their time of formation and record at least 31 polarity reversals. These observations support the idea that the Earth's dynamo was in a hyperactive reversing state similar to those sustained for tens of Myr in the Late Jurassic, parts of the Cambrian and the Late Ediacaran. It further corroborates a ∼200 Myr cyclicity in paleomagnetic field behavior since the Precambrian, potentially linked to variable core heat flow forced by mantle convection. The pattern of geomagnetic polarity changes during the Early Carboniferous (Mississippian) is not known in detail. This information sparsity is addressed by determining a magnetostratigraphy from the late Asbian (late Visean at ∼333 Ma) in Trowbarrow Quarry, UK. This is the stratotype section of the late Asbian and has a detailed foraminiferal zonation based on the same set of paleomagnetic samples, establishing a detailed biostratigraphy. The 195 m‐thick section was sampled at an average spacing of 1.1 m, yielding a detailed magnetostratigraphy comprising nine major magnetozone couplets, and seven submagnetozones. The section dataset has a 78% bias to normal polarity determined from 177 sampling levels. The magnetization is carried by a mixture of hematite and detrital magnetite, with 68% of specimens dominated by hematite magnetizations. The primary magnetization passes a fold test showing its age was prior to the latest Carboniferous. The hematite is inferred to be largely of detrital, eolian origin, although some reddened levels are associated with emergent surfaces, suggesting that a small fraction of hematite is associated with platform emergence. The Mississippian age magnetization is partly overprinted with Kiaman Superchron‐age and Brunhes‐age magnetizations. Using the duration of the section based on astrochronology indicates a reversal frequency of 15.7 ± 0.75 Myr−1, indicating that the geodynamo was in a hyperactive reversing state between 335 and 333 Ma. Key Points: A 195 m section, representing ∼2 Myr, yields a magnetostratigraphy comprizing nine major magnetozone couplets and seven submagnetozonesPrimary magnetizations are predominantly carried by hematite with lesser important detrital magnetite. Data pass regional fold testsA reversal frequency of 15.7 ± 0.75 Myr−1 is calculated, suggesting that the geodynamo was in a hyperactive state at ∼333 Ma [ABSTRACT FROM AUTHOR]

In this article, the results of the rock-magnetic measurements (magnetic susceptibility and its anisotropy before and after the heating of rocks, magnetic saturation) and paleomagnetic studies of the Lower Syzran Subformation (Paleocene) in the Peschanyi Umyot section (Saratov, Russia) are discussed. The section is composed of weakly magnetic silicites and has the paleomagnetic parameters that are suitable for magnetostratigraphic purposes. The presence of a magnetic zone with predominantly reverse polarity, which is an analogue of either chron C27 or C26 or their combination, was found in the section. The results obtained, along with previously collected data from coeval sections in the south of the Saratov right bank and the city of Saratov, made it possible to draft a magnetostratigraphic chart for the Paleocene of the Volga region, provide a detailed correlation of the Syzran Formation, estimate the duration of the pre-Paleogene erosion, and more accurately date the age of deposits.

Abstract—In 394 samples characterizing 266 stratigraphic levels in four Turonian–Santonian sections of the Southwestern Crimea, characteristic remanent magnetization components (ChRM) acquired at the stage of diagenesis are identified. The obtained data fix the record of the paleosecular geomagnetic variation of high amplitude (root mean square deviation S = 25.9° with a fixed cut-off angle of 45°, which is about twice as high as the model S for this latitude) in the sediments formed during ~5–6 Myr and is interpreted as anomalous behavior of the geomagnetic field in the Turonian, Coniacian, and Santonian. [ABSTRACT FROM AUTHOR]

We studied the Pleistocene subsurface stratigraphy of an area in the northern Po Plain around the isolated tectonic hillocks of Castenedolo and Ciliverghe (Brescia, Italy) in order to estimate their long-term rates of tectonic deformation. Integrated stratigraphy of a new 100-m-long core (RL13) allowed better definition of the regional Y (0.45 Ma) and R (0.87 Ma) surfaces and the related magnetostratigraphically calibrated PS1, PS2, and PS3 depositional sequences. The Y surface in the RL13 core was placed at the base of the PS3 proximal braided river system that was deposited during middle Pleistocene within the Brunhes chron. The R surface is considered to be eroded within the PS2 braid-plain deposits at ca. 0.87 Ma between the top of Jaramillo subchron and the Bruhnes chron during the late Early Pleistocene. Based on different datasets, we evaluated the sedimentation rate, which has decreased from 0.09 mm/yr with deposition of PS2, to 0.06 mm/yr with deposition of PS3. The tectonic uplift, with an average rate of ~0.1 mm/yr in the last ca. 0.87 Ma, is interpreted to be associated with a fault and related fault-propagation folding. The Castenedolo and Ciliverghe hillocks then formed due to tectonic uplift during a change in the sedimentation regime since 0.45 Ma. [ABSTRACT FROM AUTHOR]

The age assignment to the Arctic Basin sediments is complicated by the insufficient microfauna in them. Under these conditions, the paleomagnetic method is the major method to determine age boundaries. This method was used to construct the first successful age model of Arctic sediments in the 1970s. In recent decades, a number of works made it possible to describe changes in natural remanent magnetization direction as a consequence of secondary geochemical processes, in fact, discrediting the possibility of applying paleomagnetism to the Arctic Basin sediments. Based on our research of natural remanent magnetization in sediment cores from the Central Arctic submarine elevations, the reference paleomagnetic horizons were determined reliably. The sedimentation rates at the Alpha and Mendeleev ridges was calculated to be low (<2 mm/kyr). Mean sedimentation rates increase toward the Lomonosov Ridge due to the influence of the Transpolar Drift and toward the shelf. Based on the comprehensive analysis of the paleomagnetic and seismoacoustic data, low sedimentation rates have been characteristic of the Mendeleev Ridge and Podvodnikov Basin since the Early Miocene. [ABSTRACT FROM AUTHOR]

The lithological, paleontological and biostratigraphic characteristics of the Turonian–Coniacian deposits of the Lower Bannovka section, the stratotype of the Bannovka Formation (Volga region, Turonian) are presented. Magnetostratigraphic characteristics of thе sediments have been supplemented and elaborated. Petromagnetic data contribute to more refined stratigraphy of the section and facilitate the revealing of depositional rhythmicity. Paleomagnetic data combined with benthic foraminifera data enable the most detailed correlation of the Turonian–Coniacian deposits in the Volga region. Results of a comprehensive study of this stratigraphic unit within the southeastern arch of the Ulyanovsk-Saratov trough revealed patterns in the distribution of the Gubkino Horizon, determined by regional tectonics and processes preceding deposition in the Coniacian and Santonian. [ABSTRACT FROM AUTHOR]

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Abstract The pattern of geomagnetic polarity changes during the Early Carboniferous (Mississippian) is not known in detail. This information sparsity is addressed by determining a magnetostratigraphy from the late Asbian (late Visean at ∼333 Ma) in Trowbarrow Quarry, UK. This is the stratotype section of the late Asbian and has a detailed foraminiferal zonation based on the same set of paleomagnetic samples, establishing a detailed biostratigraphy. The 195 m‐thick section was sampled at an average spacing of 1.1 m, yielding a detailed magnetostratigraphy comprising nine major magnetozone couplets, and seven submagnetozones. The section dataset has a 78% bias to normal polarity determined from 177 sampling levels. The magnetization is carried by a mixture of hematite and detrital magnetite, with 68% of specimens dominated by hematite magnetizations. The primary magnetization passes a fold test showing its age was prior to the latest Carboniferous. The hematite is inferred to be largely of detrital, eolian origin, although some reddened levels are associated with emergent surfaces, suggesting that a small fraction of hematite is associated with platform emergence. The Mississippian age magnetization is partly overprinted with Kiaman Superchron‐age and Brunhes‐age magnetizations. Using the duration of the section based on astrochronology indicates a reversal frequency of 15.7 ± 0.75 Myr−1, indicating that the geodynamo was in a hyperactive reversing state between 335 and 333 Ma.

The Yangtze River drains from the eastern Tibetan Plateau and provides insights into the evolution of the Asian monsoon and uplift of the Tibetan Plateau. The age and evolution of the Yangtze River have been investigated, yet consensus remains lacking. This study aimed to investigate the sediment source changes of the Yangtze Delta since approximately 3.6 Ma. A new sediment core (YZQK2, 300.36 m) was subjected to high-resolution magnetostratigraphic, zircon U–Pb age spectral, and heavy mineral assemblage analyses. Magnetostratigraphy showed that 79.65, 171.22, and 293.4 m reflected the Matuyama–Brunhes, Gaussian–Matuyama, and Gilbert–Gaussian boundaries, respectively. The bottom age of the core was approximately 3.60 Ma. Between 3.60 and 3.44 Ma, heavy mineral assemblies were characterized as high reductive heavy minerals, pyrite, and siderite with the dominant peak of the detrital zircon U–Pb ages being 400–450 Ma. The sediments were primarily fed by tributaries draining into the middle Yangtze River, which were the Han River oriented in the Tongbai-Dabieshan orogenic belt and Xiang River and Gan River oriented in the Cathaysia Block. Between 3.44 and 2.79 Ma, the reductive heavy minerals, pyrite, and siderite disappeared, while garnet, apatite, sphene, and ilmenite showed a sharp increase. The dominant peak of detrital zircon U–Pb ages exhibited an extremely narrow range of 100–150 Ma. The sediments originated from the rock basin in the lower Yangtze River, the dominant river system, and were sourced locally or regionally from the adjacent Cretaceous granite plutons and volcanic rocks. The zircon age spectrum similar to the mainstream of the Yangtze River, containing amphibole, pyroxene, and magnetite from the upper to the middle and lower reaches of Yangtze River, has formed the Yangtze drainage pattern since 2.79 Ma. The sediment in the middle Yangtze reached the Yangtze Delta no later than 3.6 Ma, while the integration of the upper Yangtze into the Yangtze Delta occurred no earlier than 2.79 Ma. Our results provide novel insights into the established timeline of the Yangtze River. [ABSTRACT FROM AUTHOR]

The Hawaiian Chain-Emperor Seamounts is known to be one of the most active regions influenced by mantle hotspot. However, previous studies have provided limited information on the growth process and metal enrichment of marine ferromanganese crusts as indicators of post-eruption history. In this study, we conducted a geochronological and major elemental study of a hydrogenetic ferromanganese crust, from the Detroit Seamount using high-resolution magnetic and geochemical scanning. Our findings are as follows: (1) A total of 39 magnetozones are recognized in the studied section of the crust, which can be preliminarily correlated to the geomagnetic polarity timescale from chrons C1n to C5Dn. This correlation yields growth rates of 1.48–2.18 mm/Myr over the past ∼18 Myr. (2) Columnar and lamellar growth structures are identified with distinct metal enrichment patterns. A significant transition from lamellar to columnar growth occurred at ∼11.6 Ma. (3) The quantified elements can be clustered into three groups, (Mn, Cu–Co–Ni, and Al–Si), (Fe and Ti), and Ca. A strong correlation between metal enrichment in the crust and the global benthic foraminifera δ13C record is then observed. Based on these results, we suggest a predominant role of deep-sea redox conditions in the growth history of ferromanganese deposits on the Detroit Seamount since the Early Miocene. [ABSTRACT FROM AUTHOR]

SUMMARY We study predictions of reversals of Earth’s axial magnetic dipole field that are based solely on the dipole’s intensity. The prediction strategy is, roughly, that once the dipole intensity drops below a threshold, then the field will continue to decrease and a reversal (or a major excursion) will occur. We first present a rigorous definition of an intensity threshold-based prediction strategy and then describe a mathematical and numerical framework to investigate its validity and robustness in view of the data being limited. We apply threshold-based predictions to a hierarchy of numerical models, ranging from simple scalar models to 3-D geodynamos. We find that the skill of threshold-based predictions varies across the model hierarchy. The differences in skill can be explained by differences in how reversals occur: if the field decreases towards a reversal slowly (in a sense made precise in this paper), the skill is high, and if the field decreases quickly, the skill is low. Such a property could be used as an additional criterion to identify which models qualify as Earth-like. Applying threshold-based predictions to Virtual Axial Dipole Moment palaeomagnetic reconstructions (PADM2M and Sint-2000) covering the last two million years, reveals a moderate skill of threshold-based predictions for Earth’s dynamo. Besides all of their limitations, threshold-based predictions suggests that no reversal is to be expected within the next 10 kyr. Most importantly, however, we show that considering an intensity threshold for identifying upcoming reversals is intrinsically limited by the dynamic behaviour of Earth’s magnetic field.

The Mt. Melbourne Volcanic Field is a quiescent volcanic complex located in Northern Victoria Land, Antarctica, mostly covered by ice. Its inner structure has remained largely unknown, due to the paucity of outcrops and the lack of detailed multi‐disciplinary investigations. Here we present a novel high‐resolution aeromagnetic dataset, revealing strong long‐wavelength negative anomalies superimposed by short‐wavelength positive ones forming characteristic radial patterns. Automatic lineament detection, through the Hough transform technique applied to the tilt derivative of our magnetic dataset, shows prevailing NW‐SE‐to NNE‐SSW‐trending structural features, which combined with the few structural field observations contribute to define the deformation pattern. Pre‐existing and novel magnetic property measurements, coupled with available geochronological data, are used to constrain a two‐step 3D magnetic inversion. A layer‐structured Oldenburg‐Parker's inversion was utilized to model the deep and long‐wavelength components of the magnetic field, whereas a linear inversion based on a set of shallower prisms was used to model the short‐wavelength components. The final 3D model shows widespread reversely‐polarized volcanics, which are locally intruded and superimposed, respectively by swarms of normally‐polarized dikes and radial lava flows along paleo‐valleys. These results support the onset of volcanic activity in the entire field at least in the Matuyama magnetic epoch, that is, between 2.58 and 0.78 Ma. Plain Language Summary: Airborne high‐resolution magnetic data play a crucial role in the understanding of the geological structure of ice‐buried volcanoes. In fact, an interesting property of magnetic minerals contained in volcanic rocks is that of retaining, after cooling below a certain characteristic temperature (i.e., Curie temperature), a permanent magnetization called remanent. Its direction (polarization) at the South Pole can be normal if rocks are cooled when the Earth's magnetic field presents negative inclination (as the current Brunhes epoch), whereas reverse in the case the Earth's magnetic field shows positive inclination (i.e., the Earth's magnetic field poles swap places). As a consequence, at polar latitudes, positive magnetic anomalies are associated with normally‐polarized rocks and, conversely, negative anomalies with reversely‐polarized rocks. Thanks to this property, in this study we have carried out the first reconstruction of the internal architecture of the Mt. Melbourne Volcanic Field. Our results, constrained by independent geological and geophysical information, suggest the volcanic complex is composed mainly by an older reversely‐polarized unit superimposed and intruded locally by younger normally‐polarized lava flows. Being the periods of magnetic polarity reversal well known, we have been able to estimate the beginning of a widespread volcanic activity before the last Brunhes‐Matuyama polarity reversal. Key Points: First detailed geophysical model of the internal structure of the Mt. Melbourne Volcanic FieldMagnetic anomalies and rock magnetism data suggest the field is predominantly built‐up by reversely‐polarized volcanicsOur results support an establishment of the Mt. Melbourne edifice at least at the reverse polarity Matuyama magnetic epoch [ABSTRACT FROM AUTHOR]

Multipolarity remanence in greigite‐bearing sediments has long been recognized, but the cause of this anomalous remanence behavior is not well understood. Here, we use electron microscopic and magnetic analyses to investigate the origin of such multipolarity in Miocene greigite‐bearing sediments from the Pannonian Basin (Hungary). We find a magnetic softening and partial transformation of iron sulfides to magnetite and pyrrhotite from "single‐polarity" to "multi‐polarity" samples. The inward alteration of sulfide grains is topotactic and is size‐dependent with higher alteration in smaller grains. We propose a multi‐phase self‐reversal chemical remanent magnetization (CRM) mechanism in altered greigite: the neoformed magnetite/pyrrhotite shell acquires a CRM coupled in the opposite direction to the primary CRM of the greigite core, likely through magnetostatic interactions or interfacial exchange interactions between the closely contacting core and shell. This new greigite self‐reversal model can explain the commonly observed antiparallel polarities and has broad geochronological, tectonic and paleoenvironmental implications. Plain Language Summary: Some magnetic minerals in nature can be magnetized opposite to the external geomagnetic and planetary magnetic fields—a peculiar phenomenon called "self‐reversal." A self‐reversal magnetization process is typically observed to occur in igneous rocks during cooling in an external field. Here, using magnetic and microscopic analyses we demonstrate that sediments containing authigenic ferrimagnetic iron sulfide mineral—greigite—can acquire a self‐reversed magnetization during progressive surface alteration of greigite nanoparticles. Surface alteration produces new "magnetic shells" that are magnetized opposite to the magnetization of the parent greigite core through magnetic interactions due to the close contact between the core and shell. Post‐depositional sedimentary processes, for example, percolation of fluids or oxygenation could trigger surface alteration that leads to "self‐reversal" and complicate the primary magnetization records. This self‐reversal mechanism can explain the commonly reported anomalous magnetization records of authigenic greigite; it is very useful for correct interpretations of tectonic and paleoenvironmental processes, and geological age frames of iron sulfide bearing sediment sequences. Key Points: Surface alteration of diagenetic greigite to magnetite and pyrrhotite causes magnetic softening and multipolarity remanenceThe original microtextures are preserved during iron sulfide alteration and the alteration extent is size‐dependentA new multi‐phase self‐reversal model of diagenetic greigite is proposed that has broad geochronological and geophysical implications [ABSTRACT FROM AUTHOR]

AbstractInternational Ocean Discovery Program Expedition 355 drilled Sites U1456 and U1457 in Laxmi Basin (eastern Arabian Sea) to document the impact of the South Asian monsoon on weathering and erosion of the Himalaya. We revised the chronostratigraphic framework for these sites using a combination of biostratigraphy, magnetostratigraphy and strontium isotope stratigraphy. The sedimentary section at the two sites is similar and we divided it into six units bounded by unconformities or emplaced as a mass-transport deposit (MTD). Unit 1 underlies the MTD, and is of early–middle Miocene age at Site U1456 and early Paleocene age at Site U1457. An unconformity (U1) created by emplacement of the MTD (unit 2) during the late Miocene Epoch (at c. 9.83–9.69 Ma) separates units 1 and 2 and is identified by a marked change in lithology. Unit 3 consists of hemipelagic sediment with thin interbeds of graded sandstone of late Miocene age, separated from unit 4 by a second unconformity (U2) of 0.5–0.9 Myr duration. Unit 4 consists of upper Miocene interbedded mudstone and sandstone and hemipelagic chalk deposited between c. 8 and 6 Ma. A c. 1.4–1.6 Myr hiatus (U3) encompasses the Miocene–Pliocene boundary and separates unit 4 from unit 5. Unit 5 includes upper Pliocene – lower Pleistocene siliciclastic sediment that is separated from unit 6 by a c. 0.45 Myr hiatus (U4) in the lower Pleistocene sediments. Unit 6 includes a thick package of rapidly deposited Pleistocene sand and mud overlain by predominantly hemipelagic sediment deposited since c. 1.2 Ma.

Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm. can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm. (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The important difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust.

The Ethiopia‐Yemen flood basalts are spatially zoned with progressively lower TiO2 lavas from near the Afar depression toward the margins. The timing and rate of emplacement of low TiO2 (LT) lavas are poorly known compared with the ultra‐high TiO2 (HT2) lavas. We measured two high‐precision 40Ar/39Ar ages of 29.63 ± 0.14 and 30.02 ± 0.22 Ma (2σ) from basalts of the 2‐km‐thick LT lava sequence at the Afar plume head margin. Using our eruption age model constructed from our and previous 40Ar/39Ar ages with the paleomagnetic directions, we estimate that the LT lava eruption continued over Chrons C12r‐C12n‐C11r. The eruption of the plume head margin started earlier than the plume head axis emplacement in C12n. Also, the eruption rate was low at the margin, high at the axis. We estimate that the LT lavas are induced by the edge‐driven convection, the result of a plume‐lithosphere interaction, not a plume head. Plain Language Summary: The Ethiopia‐Yemen Flood Basalts are thought to be the expression of a mantle plume erupting millions of km3 of basaltic lava in a geologically short period (1–3 million years [Myr]). Titanium concentrations in the flood basalts are zoned and named HT2, HT1, and LT basalts (from high to low Ti). The eruption timing and rate of the HT2 basalts are constrained with high precision, but those of the LT basalts remain ambiguous. Therefore, we measured two high‐precision 40Ar/39Ar ages from LT basalts in the 2‐km‐thick Lima‐Limo section, which erupted northwest of the Afar area. Based on our eruption age model constructed from 40Ar/39Ar ages and paleomagnetic directions, we estimate that the eruption of the LT basalts started earlier than the HT2 basalts that erupted in Chron C12n and lasted over at most ∼2 Myr. The eruptive rate of the LT basalts in the earliest interval was lower than that of the HT2 basalts. This feature of the eruption may be explained by edge‐driven convection caused by the interaction of a gradient of the lithospheric thickness with the Afar mantle plume. Key Points: We obtained two new 40Ar/39Ar ages for the low‐Ti basalt from the Lima‐Limo section of the Ethiopia–Yemen flood basaltsBased on our eruptive age model, we correlated the Lima‐Limo section to Chrons C12r to C11rWe concluded that the non‐plume low‐Ti basalts erupted before the Afar plume high‐Ti basalts because of the plume–lithosphere interaction [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of paleomagnetic, rock magnetic, and cyclostratigraphic studies of continental red beds that compose the Permian-Triassic boundary interval of the Staroe Slukino section in the Vladimir Region, Russia. Based on the directions of the characteristic components of the natural remanent magnetization of the studied rocks in the sampled stratum, the intervals of normal and reversed polarity related to the regional magnetozones r2RnP, r3RnP, and N3P-T were identified. Within the r3RnP zone, there is an interval of anomalous paleomagnetic directions, which has similar characteristics to those identified earlier in the coeval intervals of the Nedubrovo, Zhukov Ravine, and Okskiy Siyezd sections. Revising the biostratigraphy allows us to assume that the two zones of anomalous paleomagnetic directions in the composite magnetic polarity scale of the upper Permian of the Russian Platform are a reflection of the same epoch of an anomalous geomagnetic field configuration. It is estimated by the cyclostratigraphic method that the studied 16 m interval of the Staroe Slukino section took 900 ± 20 thousand years to accumulate, which limits the duration of the geomagnetic field anomalous state near the Permian-Triassic boundary to ~110 thousand years. A new Permian-Triassic (~252 Ma) paleomagnetic pole of the East European Platform is calculated: plat = 36.3°; plong = 155.0°; dp/dm = 2.8°/4.8°. [ABSTRACT FROM AUTHOR]

Paleolatitude evolution could provide a general paleo-location framework for explaining the paleoclimate change and tectonic deformation in geological time. Strengthening the paleolatitude study of the Tuotuohe Basin is important for understanding the history and mechanism of the tectonic uplift process in the north-central Tibetan Plateau. In this study, we introduced the magnetostratigraphy for the Tuotuohe-D (TTH-D) section in the Tuotuohe Basin, central-northern Tibetan Plateau, in order to constrain the chronology and to reconstruct the paleolatitude of the basin during the deposition of the Tuotuohe Formation. The results indicated that the Tuotuohe Formation in the TTH-D section was deposited between 38.5 and ~36.7 Ma. Combining this age with the results from the Tuotuohe section indicates that the age of the Tuotuohe Formation spans the interval from >38.5 Ma to ~33 Ma. Additionally, other paleomagnetic data of the Tuotuohe Formation from the Tuotuohe section, combined with the data from this study, indicate that the paleolatitude of the Tuotuohe Basin during the late Eocene was 25.9 ± 4.2°. That means that the Tuotuohe Basin was located in a subtropical anticyclonic zone and that the paleoenvironment during the late Eocene might be controlled by subtropical high pressure. Additionally, paleomagnetic results from the Qiangtang terrane and the bordering regions are combined with the results of our study, which suggest that the paleolatitude of the Tuotuohe Basin at ~26 Ma coincides well with the Eurasian apparent polar wander path for that interval, and that the N-S India–Asia convergence was reduced or ceased at ~26 Ma in the Tuotuohe Basin. [ABSTRACT FROM AUTHOR]

Under the influence of the far-field effect of the India-Asia convergence, the Tianshan Mountains have become a typical area of Cenozoic resurrection orogeny, a natural laboratory for continental geodynamics. However, the study of its uplift exhumation history is still controversial. Based on a detailed magnetostratigraphic study of sediments in a 501.29 m deep drill core, located in the Yili Basin that is sandwiched between the Northern and Southern Tianshan Mountains, a total of 202 samples were used to establish magnetostratigraphy. Characteristic remnant magnetization with both normal (N1–N7) and reversed (R1–R7) polarity was isolated by thermal demagnetization. The maximum age can be obtained at the bottom of the borehole profile is 1.95 Ma. Our results show that a significant increase in sedimentation rate as well as notable shift in depositional environment occurred at ~ 0.99–0.78 Ma, which represents the uplift of the northwest Tianshan Mountain and one subsequent rapid uplift event in early Pleistocene time. [ABSTRACT FROM AUTHOR]

Geomagnetic excursions are short‐lived episodes when Earth's magnetic field deviates into an intermediate polarity state. Understanding the origin, frequency, amplitude, duration, and field behaviour associated with excursions is a forefront research area within solid Earth geophysics. Excursion events typically last a few thousand to tens of thousands of years; unlike full reversals, excursions are generally not recorded around the globe. We present here a new palaeomagnetic record (Geomagnetic excursions) from a lacustrine sediment sequence (at times, punctuated by undersized horizons of the gravels) with extraordinarily stable signals. Palaeomagnetic and rock magnetic investigations were performed on a 17‐m‐thick profile of unconsolidated sediments from Bagwalipokar palaeolake (Lat. 29°43′18″; Long. 79°28′42″; altitude 4167 ft), Binta Basin in the Kumaun Lesser Himalaya, situated in the zone of the active North Almora Thrust (NAT). A total of 540 oriented palaeomagnetic samples from 108 horizons (five samples per horizon) were collected from the section. The extrapolation of the optically stimulated luminescence (OSL) date indicates that the whole section was deposited between 45 and 2.5 ka. Magnetic remanence is predominantly carried by magnetite alone. Virtual Geomagnetic Pole (VGP) latitudes were determined using mean declinations and inclinations. Two geomagnetic excursions were observed at younger levels [11.6–10.5 m (15.5–14.7 ka) and 15–11.7 m (8.0–2.85 ka)]. These geomagnetic excursions correlate with the recently reported younger Hawaiian lava flow excursions. The youngest excursion from 8 ka may be attributed to the climatic event beginning at 8.2 ka cooling event of an oxygen isotope record of biogenic carbonate from palaeolake Riwasa in north‐western India that provides a history of the Indian Summer Monsoon (ISM) from ∼11 to 6 ka BP and also the North Atlantic glacial outburst flood and the slowdown of Atlantic meridional overturning circulation. However, further work is needed to verify this interpretation. [ABSTRACT FROM AUTHOR]

As the northernmost locality yielding one of the most representative Early Pleistocene Gigantopithecus–Sinomastodon faunas in southern China, the Longgupo site has preserved valuable geological archives that have significantly improved our understanding of Pleistocene biostratigraphy and biogeography. A convincing chronological framework of this locality is therefore important to elaborate on the evolution of Quaternary faunas as well as paleoenvironment. To reconcile the existing geochronological results with new advances in geochronology and biochronology, we present here a revised magnetostratigraphic age model based on detailed rock magnetic and paleomagnetic data and strengthened by biochronology as well as recently published electron spin resonance and uranium series (ESR/U‐series) age data. Two geomagnetic polarities were identified from the Longgupo sequence: the upper one is thin and normal, corresponding to the Olduvai normal subchron; and the lower one is distinctly thick and reversed, corresponding to the pre‐Olduvai Matuyama Chron. The age of the Longgupo fauna constrained by this refined magnetochronological framework is therefore estimated to be about 2.5–2.0 Ma, consistent with the newly published ESR/U‐series age of 2.5–2.2 Ma. [ABSTRACT FROM AUTHOR]

Abstract Multipolarity remanence in greigite‐bearing sediments has long been recognized, but the cause of this anomalous remanence behavior is not well understood. Here, we use electron microscopic and magnetic analyses to investigate the origin of such multipolarity in Miocene greigite‐bearing sediments from the Pannonian Basin (Hungary). We find a magnetic softening and partial transformation of iron sulfides to magnetite and pyrrhotite from “single‐polarity” to “multi‐polarity” samples. The inward alteration of sulfide grains is topotactic and is size‐dependent with higher alteration in smaller grains. We propose a multi‐phase self‐reversal chemical remanent magnetization (CRM) mechanism in altered greigite: the neoformed magnetite/pyrrhotite shell acquires a CRM coupled in the opposite direction to the primary CRM of the greigite core, likely through magnetostatic interactions or interfacial exchange interactions between the closely contacting core and shell. This new greigite self‐reversal model can explain the commonly observed antiparallel polarities and has broad geochronological, tectonic and paleoenvironmental implications.

An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution. Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulites and Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12.

Hypogene caves in the Plavecký hradný vrch Hill (Western Slovakia, Central Europe) were formed by waters ascending along faults in fractured Triassic carbonates related to the horst-graben structure at the contact of the Malé Karpaty Mountains and the NE part of the Vienna Basin. The Plavecká jaskyňa and Pec caves mostly contain horizontal passages and chambers with flat corrosion bedrock floors, fissure discharge feeders, wall water-table notches, replacement pockets, as well as a few other speleogens associated with sulfuric acid speleogenesis. The low-temperature sulfuric acid development phases of the Plavecká Jaskyňa are also indicated by the presence of sulfate minerals (i.e., gypsum and jarosite).Subaerial calcite popcorn rims were precipitated from water condensation at the edges of feeding fissures that were still active as thermal vents when the water table dropped. Hydrogen sulfide involved in the sulfuric acid speleogenesis was likely derived from anhydrites and/or hydrocarbon reservoirs with sulfate-saline connate waters in the fill of the adjacent Vienna Basin. It ascended to the surface along deep-rooted sub-vertical fault zones at the contact of the Vienna Basin with neighboring mountains. Three cave levels at 295 to 283 m asl in the Pec Cave, and five levels at 225 to 214 m asl in the Plavecká jaskyňa corresponded to phases of stable local erosional base levels in the bordering part of the Vienna Basin, most likely during periods of strongly decelerated and/or interrupted subsidence. Cave levels separated by vertical differences of only a few meters may also be related to the Pleistocene climatic cycles. The subhorizontal parts of the Pec Cave are probably of late Early Pleistocene age (>0.99-1.07 Ma?). The two highest levels of the Plavecká jaskyňa developed during the early Middle Pleistocene (>600 ka). Fine-grained sediments in the passage at 225 m asl with normal magnetic polarity contain jarosite. The middle level of the Plavecká jaskyňa at 220 m asl was formed in the mid-Middle Pleistocene, while the lower and lowermost levels formed in the late Middle Pleistocene (>270 ka). The water table in the lowermost cave level probably dropped after the tectonic reactivation of the Podmalokarpatská zníženina Depression just in the front of a marginal horst structure of the Malé Karpaty Mountains.

A magnetostratigraphic study on four sections near Pinjor showed that the Tatrot stage falls in the Gauss magnetic epoch and the Pinjor corresponds to most of the Matuyama epoch. A significant faunal change, already observed by other authors in Pakistan, marks the Tatrot-Pinjor boundary and approximately coincides with the Gauss-Matuyama transition. Sedimentation becomes entirely conglomeratic in a positive episode tentatively interpreted as Jaramillo. The time interval represented by this event witnessed a deep climatic change in Europa and an extensive faunal turnover in all Eurasia, and seems also to correspond to the onset of a strong tectonic activity in the Himalayan belt.

Abstract The Ethiopia‐Yemen flood basalts are spatially zoned with progressively lower TiO2 lavas from near the Afar depression toward the margins. The timing and rate of emplacement of low TiO2 (LT) lavas are poorly known compared with the ultra‐high TiO2 (HT2) lavas. We measured two high‐precision 40Ar/39Ar ages of 29.63 ± 0.14 and 30.02 ± 0.22 Ma (2σ) from basalts of the 2‐km‐thick LT lava sequence at the Afar plume head margin. Using our eruption age model constructed from our and previous 40Ar/39Ar ages with the paleomagnetic directions, we estimate that the LT lava eruption continued over Chrons C12r‐C12n‐C11r. The eruption of the plume head margin started earlier than the plume head axis emplacement in C12n. Also, the eruption rate was low at the margin, high at the axis. We estimate that the LT lavas are induced by the edge‐driven convection, the result of a plume‐lithosphere interaction, not a plume head.

The Aïn Beni Mathar-Guefaït Basin, in the High Plateau Region (Morocco), is dissected by the Za River, the main eastern tributary of the Moulouya, which incises more than 150 m into Plio-Pleistocene sediments. The main goal of the present study is to provide an initial geochronologic framework for such basin infill based on a combination of magnetostratigraphy and electron spin resonance (ESR). The combined results have implications on the age of the paleontological record, the evolution of the Moulouya River, and the activity of the faults that delimit the basin. We have studied sedimentary rocks that are essentially flat-lying and of an alluvial and lacustrine/palustrine origin. An approximately 140 m-thick section has been sampled at an average of 2.5 m per site, allowing to build a local magnetic polarity stratigraphy that includes nine geomagnetic reversals. Although no fold test is available, the presence of dual polarities and rockmagnetic analysis give us confidence that magnetization directions are primary. We then anchored the obtained magnetozones to the Geomagnetic Polarity Timescale (GPTS) using the biostratigraphic data as well as local geological observations. Our proposed magnetostratigraphy-based chronology reveals a Plio-Pleistocene sedimentary infill spanning from Gauss to Olduvai Chrons. The lower, detrital formations mostly fall within the normal Gauss Chron, whereas the upper lacustrine and palustrine carbonates, which are almost widespread to the top of the sedimentary fill, are Olduvai in age. These results provide the first chronological constraints for the basin fill in one of the largest intermontane basins of the High Plateaus. The new magnetostratigraphy also reveals that the major environmental change that triggered a switch from alluvial to lacustrine-palustrine conditions in Northern Maghreb occurred near the Gauss-Matuyama reversal, ca. 2.6 Ma. In addition, it shows that the age of the paleontological site Guefaït-4 is approximately 1 myr older than the ESR ages obtained from the quartz grains. The possible sources for this underestimation are discussed. However, we also acknowledge and discuss other possible chronostratigraphic interpretations of the current data, although less likely. [ABSTRACT FROM AUTHOR]

A c. 31 m thick section straddling the fossil find of an Early Pliocene baleen whale ("Brunella", hereafter), made in 2007 in the sedimentary fill of the Middle Ombrone Basin of Tuscany, is investigated for depositional age and environment combining palaeomagnetic, micropalaeontological (Foraminifera and calcareous nannofossils) and sedimentary facies analyses. Resting unconformably onto Late Miocene continental deposits, the Early Pliocene marine deposits include, from bottom to top, a coarse-grained wave-winnowing lag, the few metres-thick fossiliferous sandstone bedset from which Brunella was unearthed, and several metres of clays. The stratigraphic organisation of these deposits indicate deposition in a deepening upward inner shelf environment. Successful isolation of characteristic remanent magnetisation and calcareous nannofossil content indicate the investigated marine section was deposited during the interval of polarity Chron C3n.2n corresponding to the basal part of the Mediterranean nannofossil zone MNN13 (between Helicosphaera sellii Base common and the Amaurolithus primus Top) and allow estimating the depositional age of Brunella to c. 4.6 Ma. Sedimentary facies, benthic Foraminifera association and anisotropy of magnetic susceptibility characterising the deposits that embedded Brunella suggest deposition above the fair-weather base level. [ABSTRACT FROM AUTHOR]

Knowledge of the history of the tectonic deformation of the eastern edge of Tibet is important for understanding the evolution of the entire Tibetan Plateau; however, the corresponding tectonic deformation process remains controversial. We conducted a detailed rock magnetic and magnetostratigraphic study of the Cretaceous Jiaguan and Guankou Formations (the Jinmenguan section) within the Longmenshan foreland basin on the eastern edge of Tibetan Plateau. The high‐temperature remanence components separated after thermal demagnetization passed the A‐class reversal test, Bootstrap Cartesian coordinate test, and fold test, at the 95% confidence level. The resulting magnetostratigraphy constrains the age range of the Jinmenguan section to 128.0–64.1 Ma, and that of the Jiaguan Formation to 128.0–83.6 Ma. The resulting chronology identifies two phases of rapid sedimentation (128.0–124.1, 68.8–64.1 Ma) that constrain two phases of tectonic uplift in the Longmenshan Fault Zone on the eastern margin of Tibet during the Cretaceous–early Cenozoic. Our findings suggest that the stress field generated by the subduction and closure of the Bangong‐Nujiang Ocean had already been transferred to the eastern edge of the Tibet in the Cretaceous (at ∼128 Ma). Plain Language Summary: Recent studies have suggested that a significant crustal thickness had already developed on the eastern edge of Tibet before the India‐Asia collision, and that the eastern extent of the Tibetan Plateau formed by the India‐Asia collision was controlled by the tectonic boundary (the Longmenshan Fault Zone [LMSFZ]) of the eastern edge of Tibet that had already formed during the Cretaceous. The tectonic deformation of the eastern edge of Tibet during the Cretaceous‐Early Cenozoic provides an important window for understanding the evolution of the entire Tibetan Plateau. The Longmenshan foreland basin is located on the eastern edge of the Tibet. The stratigraphy within the Longmenshan foreland basin can provide a detailed record of the tectonic deformation process of the eastern edge of Tibet. To further constrain the tectonic deformation process of the LMSFZ on the eastern boundary of Tibet, we conducted a detailed rock magnetic and magnetostratigraphic study within the Longmenshan foreland basin. Our results suggest the following. (a) The LMSFZ experienced two stages of uplift during the Cretaceous‐Early Cenozoic (at 128.0–124.1 and 68.8–64.1 Ma). (b) The stress field generated by the subduction and closure of the Bangong‐Nujiang Ocean had already affected the eastern edge of the Tibet in the Early Cretaceous. Key Points: The stratigraphic age of the Jiaguan Formation has the range of 128.0–83.6 MaThere were two stages of tectonic uplift in Longmen Mountain during the Cretaceous‐Early Paleogene (at 128.0–124.1 and 68.8–64.1 Ma)The stress field generated by the subduction and closure of the Bangong‐Nujiang Ocean had already affected to the eastern Tibet at ⁓128 Ma [ABSTRACT FROM AUTHOR]

Quaternary geology is important to the development of Quaternary resources and urban geological safety. The Quaternary geological borehole TB02 in Yongledian town, the southern Tongzhou district, Beijing was selected. Based on systematic core observation and cataloging, logging data analysis, the characteristics of grain size, together with AMS 14C and paleomagnetic dating, the chronostratigraphic division was carried out, and the sedimentary characteristics were discussed. The results show that the bottom of Quaternary is located at the depth of 276.21 m; the boundaries of Lower and Middle Pleistocene, and Middle and Upper Pleistocene are located at 97.75 and 39.32 m, respectively; the bottom of Holocene is located at the depth of 6.40 m. Grain size analysis shows that the sediments are mainly fine particle components, display good sorting properties, and present the characteristics of far-source deposition; the sedimentary hydrodynamic environment has changed significantly at 2 588, 1 539 and 781 ka for three times. Environmental evolution of the southeast margin of Beijing plain is as following: In the Early Pleistocene, the paleogeography sedimentary characteristics of the whole plain is dominated by stable lake sedimentary environment with weak hydrodynamic force; in the late stage of Early Pleistocene, the whole plain forms a braided river environment, and sufficient terrigenous detritus supply and strong construction capacity; since the Middle Pleistocene, the plain enters a peneplain process with weak hydrodynamic force and mainly fine-grained sediments, and the sedimentary geomorphology gradually finalizes, forming a broad plain area. [ABSTRACT FROM AUTHOR]

Abstract—We present the rock-magnetic and palaeomagnetic results of the Sarmatian-Maeotian (Upper Miocene) sediments of the key sections of Cape Popov Kamen and Cape Panagia from Taman Peninsula (Eastern Paratethys) and forming the flanks of a single synclinal fold. A three-component composition of magnetization has been detected. The first is the viscous component A, the second is the component B, which is intermediate between the components A and the third component C, which tends to zero in the Zijderveld diagram. The directions of component B are characterized by northern–northeastern–eastern declinations and positive inclinations in the stratigraphic coordinate system; the fold test for the Popov Kamen and Panagia results is negative, and the magnetization is post-folding. The directions of component C have negative inclinations and southern declinations in the stratigraphic coordinate system. Paleomagnetic results for two sections showed the test fold positive, magnetization preliminary and the magnetization is pre-folding. Components B and C, on the basis of which the polarity of the magnetozones is determined, are of different ages, and the palaeomagnetic record of component B is the result of complete or partial remagnetization, which makes it impossible to use magnetostratigraphy for section dating. Our work affects an important question about the reliability of palaeomagnetic data on the Miocene deposits of the Kerch-Taman region (Eastern Paratethys). [ABSTRACT FROM AUTHOR]

Dating volcanic eruptions, a central aspect of stratigraphic and geochronological studies, increasingly requires multiple techniques. Archaeomagnetic and paleomagnetic studies provide high resolution records, when referred to paleosecular variation and magnetic polarity time scales. Here, we review the use of archaeomagnetic and magnetic anomaly studies in dating a volcanic eruption. A case study in the Valsequillo Basin, in central Mexico, permits evaluation of different approaches. The paleomagnetic data on lavas and pyroclastics provide spot readings, whereas the volcanic conduit system covers a slightly longer temporal scale. The distinct cooling records provide additional constraints on the magnetization records for correlation and dating. [ABSTRACT FROM AUTHOR]

Abstract We report paleomagnetic records of Matuyama–Brunhes geomagnetic polarity reversal and associated key tephra layers from the Early–Middle Pleistocene marine sedimentary succession in the Boso Peninsula. The outcrop is in Terasaki, Chiba, Japan and ~ 25 km northeast of the Chiba section. The sediment succession consists of a massive siltstone layer of the Kokumoto Formation, Kazusa Group. A tephra layer was identified in the middle of the outcrop with chemical composition comparable to that of the Byk-E tephra layer from the Chiba section defining the base of the Chibanian Stage. Oriented paleomagnetic samples were collected at intervals of 1–10 cm from the siltstone. To identify the primary remanent magnetization, progressive alternating field demagnetization (PAFD) and progressive thermal demagnetization (PThD) were conducted on pilot samples. Identification of primary magnetization with PAFD was not successful, especially for reversely magnetized samples. In addition, magnetization during PThD showed sharp drops around 175 °C, which decreased gradually between 175 °C and ~ 300 °C, and became unstable above ~ 350 °C. To extract the primary remanent magnetization while avoiding laboratory alteration by heating, a PThD up to 175 °C followed by PAFD was conducted. Combined analysis of remagnetization circles enables extraction of primary magnetization with improved reliability. Rock magnetic experiments were conducted during stepwise heating to understand the magnetic minerals involved and to evaluate the influence of laboratory heating. During heating, FORC-PCA revealed significant changes of magnetic minerals at 200 °C, 400 °C, 450 °C and 550 °C. Rock magnetic analyses and electron microscopy indicate that titanomagnetite/magnetite are magnetic minerals contributing to primary remanent magnetization. Greigite was also identified preserving secondary magnetizations during sub-seafloor diagenesis. The presence of feroxyhyte is suggested as secondary magnetization through the weathering of pyrite by exposure to the air after the Boso Peninsula uplift. The correlation of relative paleointensity with the Chiba section provides an age model with sedimentation rates of 30 cm/kyr and 18 cm/kr for the intervals above and below the Byk-E tephra. VGP latitudes are highly consistent with those from the Chiba section based on the age model, which assigns the main directional swing from reversed to normal polarities as 772.8 ± 0.5 ka. Graphical Abstract

During the mid-late Pliocene to late Pleistocene, the Pampa Interserrana (i.e., the plains of central Argentina) experienced cycles of erosion and deposition on a Mio-Pliocene substrate generating the valleys of the main rivers of the region. These processes controlled the Quaternary sedimentary deposits that constitute their stratigraphy. The deposits of the Sauce Grande River Basin (SGRB) in Buenos Aires Province of Argentina are a useful case study to analyze in detail the sedimentary dynamics which took place during the late Cenozoic. Additionally, the development of river terraces and their fossiliferous content provide a temporal framework for such interpretations. The basin fill has been described sedimentologically and stratigraphically by several authors, but there is still much that is unknown about its evolution and sedimentary dynamics as well as the age of these deposits. Furthermore, the stratigraphy and age of the Saldungaray and La Toma formations remain largely unexplored, adding complexity to understanding the region's geological history. In this context, the objective of the present study is to characterize and determine the sedimentary evolution and paleoenvironmental dynamics of the SGRB during the Plio-Pleistocene. Additionally, we aim to establish an age model for the deposits and the vertebrate associations preserved in them. To achieve this, we conducted sedimentological, magnetostratigraphic, biostratigraphic, geomorphological, and paleontological studies in four localities in the Upper basin of the SGRB. This article is specifically reoriented towards understanding the age and environments of the Saldungaray and La Toma formations and their broader implications. For the first time, a detailed chronology of these two units will be provided. The Neogene substrate at our study sites comprises the Saldungaray and La Toma formation. These two formations characterized by sandy and silty clayey fluvial and facies with pedogenetic features, which are interpreted as channel fill and overbank floodplain deposits. The younger late Pleistocene to Holocene sequence ranges from a coarse gravelly facies interpreted as channel fill deposits grading into fine floodplain and aeolian facies near the surface. The latter constitutes a characteristic extensive mantle, which is distributed throughout the "Pampa Interserrana" and throughout almost the entire Buenos Aires Province. We described eight sedimentary facies and group them into three facies associations: channelized fluvial deposits; non-channelized deposits (floodplain/overbank deposits) and aeolian deposits. These facies and their associations are characteristic SGRB environments that responded to climatic and tectonic drivers. A key stratigraphic section (La Toma) proved to be critical for locating the boundary between the Pliocene and Pleistocene (the Marplatan Stage/Age, Vorohuean Substage/Subage) allowing us to link magnetically and biostratigraphically constrained ages and related them to the formation of two prominent fluvial terraces in the study area. • Sedimentological Succession: A detailed sedimentological description allowed for the identification of a fluvial, alluvial and aeolian succession for the Late Cenozoic of the Sauce Grande River basin. • Fluvial system interpretation : For the late Pliocene to the middle Pleistocene period, a low sinuosity fluvial system with gravelly and sandy channels and floodplain deposits with the development of paleosols was interpreted. • Chronostratigraphic sequence : stratigraphic and magnetostratigraphic studies allowed to place the substrate, (Saldungaray and La Toma Formations) in the late Pliocene to early Pleistocene period, and the incision and infilling of the valleys to the late Pleistocene-Holocene. • Age Model proposal : Based on palaeomagnetic, biostratigraphy, and geomorphological studies, an age model for the late Cenozoic deposits of the SGRB is proposed. A Late Pliocene age was assigned to the Saldungaray Formation and a Late Pliocene to Middle Pleistocene age to the La Toma Formation. [ABSTRACT FROM AUTHOR]

It is very important to distinguish the strata of different periods in the Quaternary period, especially the Middle Pleistocene and Late Pleistocene strata, for stratigraphic division, depositional environmental analysis and climate evolution analysis. In this study, the Shinaimiao (SNM) borehole sequence in Hebi City, Henan Province (China) was established by both electron spin resonance (ESR) and magnetostratigraphy methods. Both Al (eighteen samples) and Ti-Li (eight out of the eighteen samples) centers were measured using the Multiple Aliquots Additive Dose (MAAD) method. In addition, hundreds of magnetostratigraphic samples were measured to determine the precise position of the Matuyama/Brunhes (M/B) boundary. The results show that: (1) The equivalent dose (D E) values of the Al and Ti-Li centers are consistent within the error range, demonstrating that the Multiple Center (MC) approach has worked. (2) The ESR dating results are consistent with the order of sedimentation (the ages get older with depths) and with magnetostratigraphic results of the B/M boundary within the error range, indicating that the ESR ages obtained from the Al and Ti-Li centers are reliable in this study. (3) By comprehensive analysis of the dating results and lithology characteristics, the stratigraphic ages of the SNM borehole with a depth of 126.93 m spans from Neogene to Holocene, but part of the early Pleistocene strata are missing. [ABSTRACT FROM AUTHOR]

After a century of research, the chronology of the first arrival of hominins in Europe remains controversial. Four Spanish localities potentially record evidence of the oldest Europeans, yet arrival ages remain loosely constrained between 1.6 and 0.9 Ma. Here we provide a new Early Pleistocene magnetostratigraphy, recording four paleomagnetic boundaries within 80 m of a fluvio-lacustrine sedimentary succession in Orce, southeastern Spain. This Pleistocene succession incorporates for the first time in Europe five superposed paleontological localities between the Olduvai and Jaramillo magnetozones, including three hominin sites providing evidence of the presence of hominins older than 1.07 Ma in Europe. The specific age for each fossil quarry is estimated using a Bayesian age-stratigraphic model with 95% confidence intervals. The oldest sites, which lack evidence of hominin activity, are 1.60 ± 0.05 Ma and 1.35 ± 0.07 Ma, respectively. Three sites higher in the stratigraphy, which contain evidence of hominids, occur at 1.32 ± 0.07 Ma (Venta Micena), 1.28 ± 0.07 Ma (Barranco León-5), and 1.23 ± 0.06 Ma (Fuente Nueva-3). The magnetostratigraphy and paleontological content of the Orce hominin sites are compared with other European localities concluding that the new chronology for Orce represents Europe's oldest and most accurately dated early Pleistocene hominin records. These results indicate that African hominins with Oldowan technology reached Southwestern Europe >0.5 Ma after first leaving Africa. This diachronism is explained because Europe was limited by biogeographical barriers that hominins were able to surpass only in a later evolutionary/cultural stage. We propose that ∼1,3 Ma hominins first arrived in southern Europe by traversing the Strait of Gibraltar when in a similar time frame, crossed the Wallace Line and reached the island of Flores (Java) by navigating the wider Lombok Strait. Archaeological data shows that a second wave of hominins with Acheulian technology entered South Europe again via the Iberian Peninsula after the Jaramillo subchron (1.071–0.991 Ma) and before the Brunhes chron (0.77 Ma). • This study helps resolve when did early hominins arrive in Europe? • Hominin sites are dated between the Olduvai and Jaramillo magnetic subchrons for the first time in Europe. • A Bayesian age-stratigraphic model provides Europe's oldest and most accurate early Pleistocene hominin ages. • Hominins with Oldowan tools entered Europe for the first time ∼ 0.5 Ma after first leaving Africa. • This migration occurred ∼0.5 Ma before the arrival of Acheulian technology in Europe. • The Strait of Gibraltar was a permeable barrier for early Pleistocene hominins [ABSTRACT FROM AUTHOR]

The Upper Tithonian to Lower Berriasian carbonate sequence of the Getic Nappe system was studied near Golubac (eastern Serbia) using rock-magnetic and paleomagnetic methods to verify the age of the magnetization and to correlate magnetostratigraphy with biostratigraphy. A major part of the Dedina section shows the presence of authigenic goethite, hematite and magnetite as carriers of remagnetization. The youngest overprint, residing in goethite, sometimes carrying up to 90 % of natural remanent magnetization, was probably received after 18 Ma. The remagnetization residing in hematite and magnetite, attributed to the late Early Cretaceous collision, was obtained during long normal polarity Chron C34 (118–82 Ma). The mean direction implies a clockwise post-remagnetization rotation by about 57°. The normal (D n) and reverse (E r) polarity components, heavily affected by the chemo-remanent magnetization overprint, can be tentatively interpreted in terms of polarity zones. Thus, the obtained data enabled a preliminary identification of M17r to M19n.2n magnetochrons. The correlation of magnetostratigraphy with biostratigraphy of the Dedina section contributes to the stratigraphic framework necessary for the definition of the Berriasian Global Boundary Stratotype Section and Point. • Primary magnetization possibly heavily overprinted. • Tentative correlation to M17R to M19.2N magnetozones. • Large post-late Early Cretaceous clockwise rotation. [ABSTRACT FROM AUTHOR]