Matuyama-Brunhes Boundary Research Articles

Magnetic stratigraphy constraints on the Matuyama–Brunhes boundary recorded in a loess section at the southern margin of Chinese Loess Plateau

Although the Matuyama-Brunhes boundary (MBB) in the Chinese Loess Plateau (CLP) is very important in reliably correlating Quaternary loess with other sediments in the world, particularly with marine and polar ice cores, its exact stratigraphic position remains controversial. Previous investigations usually placed the MBB between paleosol unit S8 and loess unit L8 in various locations. To better understand the spatial differences in the MBB position, a high-resolution paleomagnetic study was conducted in a loess section of the Lantian Basin at the southern margin of the CLP. The results show that the MBB is situated in the middle of the relatively weak paleosol unit S7, consistent with a recent report on the MBB based on a Be-10 study from the Xifeng and Luochuan loess sections of the central CLP. However, the regional anomalously low magnetic susceptibility in paleosols S7 and S8 indicates that it is more reliable to determine the paleoclimate boundaries between loess and paleosol horizons of this segment with median grain size. Then, the MBB in the Yushan section can be correlated with the bottom of paleosol S7, corresponding to the older part of interglacial marine isotope stage 19. This result temporally reconciles the striking discrepancy of the position of the MBB recorded in between loess and other typical sedimentary sequences, and further confirms that the stratigraphic position of the MBB could spatially vary to a certain extent due to regional sedimentary or paleoclimatic conditions in the marginal areas of the CLP. In the Yushan section, the high-frequency variations of paleomagnetic directions during a long period of similar to 31 ka before the MBB, however, could not be attributed to a genuine response to the true geomagnetic behaviour. Moreover, the climate offset defined by the magnetic susceptibility and median grain size of the section can be preliminarily attributed to the regional geology and paleoenvironment background. A multiproxy-based stratigraphic division is considered very necessary when paleomagnetic and climatic boundaries are defined exactly in a specific area of the southern CLP.

Faunas from Atapuerca at the Early–Middle Pleistocene limit: The ungulates from level TD8 in the context of climatic change

Abstract An extraordinary sequence of fossiliferous levels at the locality of Gran Dolina in the Atapuerca Hills (Burgos, Spain) records the Early–Middle Pleistocene transition. These levels are well dated by a variety of methods, including palaeomagnetism, which locates Lower–Middle Pleistocene boundary at the top of level TD7. Level TD6 is the type site of the species Homo antecessor and yielded over 90% of the European Early Pleistocene human record, while other levels have an archaeological record. The present paper deals with the earliest Middle Pleistocene ungulates of TD8, but we plan to describe the faunas, or at least the ungulates, of levels TD4 to TD8 in the context of the faunal changes that took place around the Early–Middle Pleistocene transition. About 600 fossils could be assigned to a taxon and on this basis the following ungulates are described from TD8: horse Equus altidens , rhinoceros Stephanorhinus aff. etruscus , wild boar Sus scrofa , hippopotamus Hippopotamus sp., red deer Cervus elaphus , giant deer Eucladoceros aff. giulii , giant deer Megaceroides solilhacus , fallow deer Dama vallonnetensis , and bison Bison voigtstedtensis . The evolution of these taxa is discussed. The fauna from level TD8 dates to the earliest Middle Pleistocene (stage 19) and differs from later faunas in the retention of a small rhinoceros ( Stephanorhinus aff. etruscus ) and the latest representative of the genus Eucladoceros . It differs from earlier faunas in having the striped hyaena. Together with the fauna from TD7, in which the Brunhes–Matuyama boundary is recorded, TD8 will provide the most precise criterions for correlation of the Early–Middle Pleistocene boundary on the basis of fossils of large mammals. Profound changes in the global climate system started to take place during the late Early Pleistocene, leading to intensive environmental and faunal change and to human dispersal into Europe. These events mark the beginning of a new time and the Early–Middle Pleistocene boundary is taken somewhere in the middle of this drawn out process. It is taken at a palaeomagnetic change, which is convenient, but this does not appear to be close to an important climatic or faunal change. Ten faunal events are recognized in the period from about 1.2 to 0.5 Ma. The event closest to the Early–Middle Pleistocene boundary is one of the minor events and up to now it is recorded in only few localities, principally in TD8.

Sarykul paleosol in Southern Urals sediments (Russia)

Sarykul paleosols in the Southern Urals (Russia) with a stable position in geological sediments are considered. The Brunhes-Matuyama boundary was found in these paleosols and they were used as a source of information on the environment. Data were obtained during the study of the Sarykul paleosols in four sections located in the mountain part of the Southern Urals on the Miass River erosion-accumulation terrace and at the eastern edge on the trans-Uralian peneplain. Saykul paleosols have a relatively thick and compact humic horizon with a tongued lower boundary. The paleosols are dark grey with high TOC content that is not usual for the Early Pleistocene paleosols. The materials showed that Sarykul paleosols formed on different parent rocks may have various characteristics of the mineral part (texture, pH, magnetic susceptibility, carbonate content, ratio of exchangeable cations), while their humic substances characteristics (humic and fulvic acid ratio, humic acid characteristics of elemental composition and structure) are very similar. Climate conditions during Sarykul paleosol formation changed from relatively warm and humid to less warm and more humid. The study of Southern Urals Sarykul paleosols has shown that they can serve as a reliable marker of the final Early Pleistocene due to their specific characteristics, not analogous to the modern soils.

Chronology for the Cueva Victoria fossil site (SE Spain): Evidence for Early Pleistocene Afro-Iberian dispersals

Cueva Victoria has provided remains of more than 90 species of fossil vertebrates, including a hominin phalanx, and the only specimens of the African cercopithecid Theropithecus oswaldi in Europe. To constrain the age of the vertebrate remains we used paleomagnetism, vertebrate biostratigraphy and 230Th/U dating. Normal polarity was identified in the non-fossiliferous lowest and highest stratigraphic units (red clay and capping flowstones) while reverse polarity was found in the intermediate stratigraphic unit (fossiliferous breccia). A lower polarity change occurred during the deposition of the decalcification clay, when the cave was closed and karstification was active. A second polarity change occurred during the capping flowstone formation, when the upper galleries were filled with breccia. The mammal association indicates a post-Jaramillo age, which allows us to correlate this upper reversal with the Brunhes–Matuyama boundary (0.78 Ma). Consequently, the lower reversal (N-R) is interpreted as the end of the Jaramillo magnetochron (0.99 Ma). These ages bracket the age of the fossiliferous breccia between 0.99 and 0.78 Ma, suggesting that the capping flowstone was formed during the wet Marine Isotopic Stage 19, which includes the Brunhes–Matuyama boundary. Fossil remains of Theropithecus have been only found in situ ∼1 m below the B/M boundary, which allows us to place the arrival of Theropithecus to Cueva Victoria at ∼0.9–0.85 Ma. The fauna of Cueva Victoria lived during a period of important climatic change, known as the Early-Middle Pleistocene Climatic Transition. The occurrence of the oldest European Acheulean tools at the contemporaneous nearby site of Cueva Negra suggest an African dispersal into SE Iberia through the Strait of Gibraltar during MIS 22, when sea-level was ∼100 m below its present position, allowing the passage into Europe of, at least, Theropithecus and Homo bearing Acheulean technology.

Age of Mammuthus trogontherii from Kostolac, Serbia, and the entry of megaherbivores into Europe during the Late Matuyama climate revolution

At the Drmno open-pit coal mine near Kostolac in Serbia, a nearly complete skeleton of Mammuthus trogontherii (nicknamed Vika) was discovered in a fluvial deposit overlain by a loess–paleosol sequence where a second paleontological level named Nosak with remains of M. trogontherii was found. We studied the magnetostratigraphy of the Kostolac sedimentary sequence and found that the Vika layer dates to ~0.8Ma, shortly before the Brunhes–Matuyama boundary. In addition, according to our age model and previously reported optically stimulated luminescence and electron spin resonance dates, the Nosak fossils have an estimated age of 0.19Ma and lived during the earliest part of Marine Isotope Stage 6. It appears therefore that at Kostolac, M. trogontherii is preserved both at its earliest occurrence at ~0.8Ma and close to its latest occurrence at 0.19Ma, and may well have been present in between, albeit not yet found. We speculate that megaherbivores such as M. trogontherii entered Europe along a conjunct Danube–Po River migration conduit connecting western Asia-Levant with central-southern Europe where vast and exploitable ecosystems, particularly suited for steppe- or savanna-adapted megaherbivores from Asia and Africa, developed during the late early Pleistocene climate revolution at around 0.8Ma.

Age of Matuyama-Brunhes boundary constrained by U-Pb zircon dating of a widespread tephra

ABSTRACTThe youngest geomagnetic polarity reversal, the Matuyama-Brunhes boundary (MBB), provides an important datum plane for sediments, ice cores, and lavas. Its frequently cited age of 780 ka is based on orbital tuning of marine sedimentary records, and is supported by 40 Ar/ 39 Ar dating of Hawaiian lavas using recent age calibrations. Challenging this age, how-ever, are reports of younger astrochronological ages based on oxygen isotope stratigraphy of high-sedimentation-rate marine records, and cosmogenic nuclides in marine sediments and an Antarctic ice core. Here, we present a U-Pb zircon age of 772.7 ± 7.2 ka from a marine-deposited tephra just below the MBB in a forearc basin in Japan. U-Pb dating has a distinct advantage over 40 Ar/ 39 Ar dating in that it is relatively free from assumptions regarding stan-dardization and decay constants. This U-Pb zircon age, coupled with a newly obtained oxygen isotope chronology, yields an MBB age of 770.2 ± 7.3 ka. Our MBB age is consistent with those based on the latest orbitally tuned marine sediment records and on an Antarctic ice core. We provide the first direct comparison between orbital tuning, U-Pb dating, and magnetostratig-raphy for the MBB, fulfilling a key requirement in calibrating the geological time scale.INTRODUCTION

Stratigraphy of the Kazusa Group, Boso Peninsula: An expanded and highly-resolved marine sedimentary record from the Lower and Middle Pleistocene of central Japan

Major climatic reorganizations, including changes in the nature of glacial–interglacial cycles through the Pleistocene, are a key issue for improving the understanding of Earth's climate system. Highly resolved marine sedimentary records are essential to reconstruct the details of these past climatic changes and investigate the mechanisms responsible for them. The Kazusa Group, located in the central part of the Japanese island chain, is well-exposed and contains a remarkably continuous and thick, deep- and shallow-water marine sedimentary succession. This group also contains well-preserved marine microfossils, pollen, paleomagnetic reversal events, geochemical signatures, and a large number of tephra beds. These features allow us to establish a robust chronological and stratigraphic framework for the Kazusa Group, and provide a rare opportunity to study oceanic and terrestrial climatic and environmental changes at high resolution especially through the Lower and lower Middle Pleistocene. In the Boso Peninsula, Chiba Prefecture, the Kazusa Group is deeply incised, yielding spectacular river-cut exposures. The Matuyama–Brunhes paleomagnetic reversal is observed immediately above the widespread Byakubi-E (Byk-E) tephra in the Chiba composite section within the Kokumoto Formation (Kazusa Group). Because the Matuyama–Brunhes boundary customarily serves as the primary guide for the Lower–Middle Pleistocene Subseries boundary, the Chiba composite section is considered an excellent candidate for its global boundary stratotype section and point (GSSP). This study reviews the published data for the Kazusa Group (hitherto almost exclusively in Japanese) in order to place the Chiba composite section within its broader depositional and chronostratigraphic context.

A paleomagnetic record of the Matuyama-Brunhes boundary at the lower-middle Pleistocene GSSP candidate section of the Kazusa Group, Boso Peninsula, Japan

A paleomagnetic record of the Matuyama-Brunhes boundary at the lower-middle Pleistocene GSSP candidate section of the Kazusa Group, Boso Peninsula, Japan

Timing of the Matuyama–Brunhes geomagnetic reversal: Decoupled thermal maximum and sea-level highstand during Marine Isotope Stage 19

Recent high-resolution magnetic and microfossil data from a long core penetrating the Osaka Group, Japan are astronomically tuned and reassessed to reveal detailed stratigraphic features across the Matuyama–Brunhes (MB) polarity transition during Marine Isotope Stage (MIS) 19. The sediments have a uniform and high average accumulation rate of 63 cm/ky. Astronomical tuning based on six calibration points, including a clear MIS 19.2 sea-level lowstand, dates the main MB boundary (MBB) to 777.6 ka, the sea-level peak of the MIS 19.3 highstand to 780.7 ka, and the climatic thermal maximum (TM) to 776.4 ka. The MB transition began with a short-lived normal polarity episode that occurred before the highstand at MIS 19.3, and terminated with multiple rapid reversals that occurred between highstand MIS 19.3 and lowstand 19.2. The TM just postdates the termination of the MB transition, and occurs about 4000 years after the sea-level peak. The delayed TM is also observed at Gesher Benot Ya'aqov, Israel and on the Mediterranean coast, and possibly at Lake Baikal. In high-resolution records from Chinese loess–paleosols and deep-sea sediments, the rapid reversal zone of the MBB has a very similar climatostratigraphic character. These magneto-climatostratigraphic features in MIS 19 are useful for correlating between terrestrial and marine sediments. The delay in warming relative to the sea-level highstand seems to have been due to a cloud-albedo effect induced by an increase in galactic cosmic ray flux during an extremely low magnetic field intensity interval.

Magnetostratigraphy of the loess-palaeosol key Palaeolithic section at Korolevo (Transcarpathia, W Ukraine)

A total of 213 oriented samples were taken for palaeomagnetic investigations from 11 m of loess-palaeosol sediments cropping out in the Korolevo new section (W Ukraine). As the background of our palaeomagnetic investigations we present the results of granulometric, chemical (content of humus and iron oxides), mineralogical (heavy minerals) and structural analyses of loess and soil deposits. The Matuyama–Brunhes boundary was found at a depth of 8.7 m, in the upper part of the illuvial horizon of the soil S7, the second well developed soil from the bottom. The bottom part of the oldest sediment studied here (relict palaeosol of Cambisol type?) was magnetized by the normal polarity geomagnetic field that can be correlated with the top of the Jaramillo subchron. The oldest cultural-chronological assemblages VII and VIII from the Korolevo site can be dated at the period between the B/M boundary (780ka) and the top of the Jaramillo subchron (986ka) but this conclusion must be supported by further, more extensive palaoemagnetic investigations of the bottom part of Quaternary deposits in different places in the Korolevo site. Three zones of the Korolevo section containing anomalous directions inside the normal polarity record of the Brunhes chron can be interpreted as possible places with destructed record of palaeomagnetic excursions.

Lower–Middle Pleistocene ostracod assemblages from the Montalbano Jonico section (Basilicata, Southern Italy)

The Montalbano Jonico section is a Pleistocene sequence, about 450 m thick, comprising silty clays and silty sands deposited during the upper part of the Calabrian Stage and lower part of the “Ionian” Stage. It is a candidate global boundary stratotype section and point for the Middle Pleistocene Subseries. Ostracod assemblage analyses were carried out on 40 samples from the uppermost levels of the Lower Pleistocene and the lowermost part of the Middle Pleistocene, with the aim of reconstructing the paleoenvironmental evolution around the Matuyama–Brunhes boundary. Taxonomic investigations, quantitative distribution data and statistical analysis (Q-mode cluster analysis) define four intervals, correlated with sea-level changes linked to Marine Isotope Stages (MIS) 21–18. The lower part of the section, ranging from 864.00 to 820.00ka, was deposited in an outer shelf paleoenvironment during a period of high sea level associated with MIS 21. The transition to the second interval (815.42–785.62ka) is marked by a shallowing trend, reflecting the MIS 20 decrease in sea level. The overlying part of the section (783.54–749.91ka) yielded assemblages indicating a return to deeper-water conditions corresponding to the warm phase MIS 19. The uppermost interval was deposited during 746.60–740.54ka, when cooling in MIS 18 produced a sea level drop. Here, some levels (164.20 m, 745.51ka; 170.10 m, 743.05ka; 176.10 m, 740.54ka) show the presence of both “deep” and “shallow” autochthonous taxa, suggesting the occurrence of upwelling episodes during this cold phase. In some layers, deposited during warm stages, the ostracod assemblages indicate the presence of kenoxic bottom waters. The lowest paleo-oxygen levels are correlated with Marine Isotope Substages 21.3 and 19.1.

Apparent timing and duration of the Matuyama‐Brunhes geomagnetic reversal in Chinese loess

AbstractThe Matuyama‐Brunhes (MB) geomagnetic reversal in Chinese loess has been studied extensively as an important boundary for land‐ocean stratigraphic and paleoclimatic correlations. However, the apparent timing and duration of the MB boundary remain controversial in Chinese loess deposits due to its inconsistent stratigraphic position and the uncertain chronologies. Here we synthesized high‐resolution paleomagnetic records from four loess sequences in the central Chinese Loess Plateau and synchronized the loess‐paleosol chronology by matching the grain‐size variations to orbitally tuned grain‐size time series. The synthesized paleomagnetic results reveal consistent features of the MB transition in Chinese loess, including the stratigraphic position (L8/S8 transition), timing (∼808–826 ka), duration (∼14–16 ka), and rapid directional oscillations. Compared with the MB transition in marine records (770–775 ka), the timing of the MB transition is relatively older and longer in Chinese loess, due to a complex interplay between different remanence acquisition mechanisms which occurred during the course of postdepositional physical and chemical processes.

Определение границы Матуяма–Брюнес по результатам палеомагнитных исследований разреза Роксоланы (западное Причерноморье)

Определение границы Матуяма–Брюнес по результатам палеомагнитных исследований разреза Роксоланы (западное Причерноморье)

The Matuyama–Brunhes polarity reversal in four Chinese loess records: high-fidelity recording of geomagnetic field behavior or a less than reliable chronostratigraphic marker?

The paleomagnetic recording fidelity of Chinese loess has been a matter of long-term dispute. To help shed light on the acquisition/retention mechanisms of natural remanent magnetization in loess, we report on high-sampling-resolution paleomagnetic constraints on the position of the Matuyama–Brunhes Boundary (MBB) in four typical loess sections in different marginal areas of the Chinese Loess Plateau (CLP), each of which has experienced different East Asian winter/summer monsoon strengths and pedogenic intensities. Detailed thermal demagnetization experiments for 1850 specimens reveal that none of the high-accumulation-rate loess with the weakest pedogenesis at Caotan (western CLP), the massive Pedogenesis loess characterized by extensive development of thick calcareous nodule layers at Jixian (SE CLP), and the moderately pedogenized loess at Fanshan (NE CLP) have preserved high-fidelity geomagnetic records across the MBBs. Jiuzhoutai (western CLP), one of the thickest loess profiles in the world, contains the thickest, and hitherto the most complex MBB that is too extensive to be regarded as rapid fluctuations of geomagnetic field during the M/B reversal. At Jixian, a predominance of pedogenesis-induced chemical remanent magnetization overprinting has heavily obscured the original remanence. The significant downward displacement of the MBB at Fanshan and even its total absence at Caotan, together with extensive remagnetization of the coarse-grained ‘upper sandy loess layer’ (L9) in both sections, further suggest that the processes of remanence acquisition/retention of Chinese loess in the marginal areas of the CLP are rather complicated. Thus, interpretations of the fine structure of geomagnetic transitional field behavior and ‘excursions’, especially in the Matuyama Chron, should be regarded with caution.

NEW DATA ABOUT MATUYAMA-BRUNHES BOUNDARY IN ROXOLANY SECTION

From new palaeomagnetic data of 55-meter key section of Quaternary loess-soil sediments on the Dniester estuary near Roxsolany village the position of Matuyama-Brunhes boundary have been determined. Earlier this section had been studied by different research groups [Третяк, 1983; Третяк и др., 1987; Третяк и др., 1989; Tsatskin et al., 1998; Tsatskin et al., 2001; Dodonov et al., 2006; Gendler et al., 2006] and the position and ages of individual soil horizons caused much discussion. The primary component of natural remanent magnetization and their polarity was identifying both in loess and soil horizons due to detail measurements on the modern equipments. Position of Matuyama-Brunhes boundary has been identified at a depth of 46.6 m between Martonosha and Lubny soil horizons. This is agree with modern knowledge of Ukrainian scientists about Quaternary records in south Ukraine and is not consistent with the results which identified this boundary at a depth of 34 m in loesses above the level of РК7.

Human occupation of Iberia prior to the Jaramillo magnetochron (>1.07 Myr)

The first migration out of Africa undertaken by the genus Homo is documented in Georgia at 1.8 Myr (Dmanisi) and some 0.4 Myr afterwards in the Middle East (’Ubeidiya). However, the debate on when the European continent was populated for the first time remains open. The first human presence in Europe prior to the Jaramillo subchron (1.07–0.99 Myr) is evidenced at Fuente Nueva 3 and Barranco León D (Orce) and at Sima del Elefante (Atapuerca), an occupation that seems to have continued through the Jaramillo at Gran Dolina TD3–4 and TD5 (Atapuerca), at Vallparadís (Barcelona), and up to the Matuyama–Brunhes boundary at Gran Dolina TD6. Even so, those who still defend a ‘short chronology’ espouse an intermittent early population limited to the Mediterranean area, delaying the first occupation until after the Jaramillo. These hypotheses fail to explain what factors were behind the absence of population in Europe prior to this period, bearing in mind that there were populations of hominins at the gates of Europe between 1 and 0.5 Myr before the first archaeological record documented in Western Europe. Paleomagnetic analyses of the archaeological sites are rarely able to detect the Jaramillo subchron due to its short duration, while the radiometric dating methods (U-series/ESR) usually applied are limited in the accuracy they can achieve for the chronologies in question. These limitations make it necessary to depend on the biostratigraphy of small and large mammals to ascertain with precision the time of the first colonization of the continent. Accordingly, in the present article we discuss the chronological data from the older Iberian archaeological sites using biostratigraphic data to establish an archaeological sequence that demonstrates the expansion of the first hominin occupation of Southern Europe prior to Jaramillo.

Morphology, sedimentary infill and depositional environments of the Early Quaternary North Sea Basin (56°–62°N)

The North Sea Basin has been subsiding during the Quaternary and contains hundreds of metres of fill. Seismic surveys (170 000 km2) provide new evidence on Early Quaternary sedimentation, from about 2.75 Ma to around the Brunhes-Matuyama boundary (0.78 Ma). We present an informal seismic stratigraphy for the Early Quaternary of the North Sea, and calculate sediment volumes for major units. Early Quaternary sediment thickness is > 1000 m in the northern basin and >700 m in the central basin (total about 40 000 km3). Northern North Sea basin-fill comprises several clinoform units, prograding westward over 60 000 km2. Architecture of the central basin also comprises clinoforms, building from the southeast. To the west, an acoustically layered and mounded unit (Unit Z) was deposited. Remaining accommodation space was filled with fine-grained sediments of two Central Basin units. Above these units, an Upper Regional Unconformity-equivalent (URU) records a conformable surface with flat-lying units that indicate stronger direct glacial influence than on the sediments below. On the North Sea Plateau north of 59°N, the Upper Regional Unconformity (URU) is defined by a shift from westward to eastward dipping seismic reflectors, recording a major change in sedimentation, with the Shetland Platform becoming a significant source. A model of Early Quaternary sediment delivery to the North Sea shows sources from the Scandinavian ice sheet and major European rivers. Clinoforms prograding west in the northern North Sea Basin, representing glacigenic debris flows, indicate an ice sheet on the western Scandinavian margin. In the central basin, sediments are generally fine-grained, suggesting a distal fluvial or glacifluvial origin from European rivers. Ploughmarks also demonstrate that icebergs, derived from an ice sheet to the north, drifted into the central North Sea Basin. By contrast, sediments and glacial landforms above the URU provide evidence for the later presence of a grounded ice sheet.

Early human occupation of Iberia: the chronological and palaeoclimatic inferences from Vallparadís (Barcelona, Spain)

Vallparadís is one of the best calibrated and most accurately dated archaeological sites from the European Early Pleistocene. Chronological analyses combined with palaeomagnetism, ESR-U/series and OSL, and the biochronology of macro- and micromammals are fully consistent and situate the site just above the upper limit of the Jaramillo subchron. In this article we compare the mandibular first molar (m1) of individual adult specimens of Mimomys savini recovered from level 10 (EVT7) at Vallparadís with specimens from the stratigraphic sequence at Gran Dolina (Atapuerca), Fuente Nueva 3 and Barranco León D (Orce). This comparison allows us to chronostratigraphically relate level 10 at Vallparadís with level TD5 at Gran Dolina and to fix the former's chronology to around 0.98–0.95 Ma (MIS 27) and, therefore, prior to level TD6 in which fossil remains of Homo antecessor were recovered. The chronology of Vallparadís and the set of contemporary palaeoclimatic proxies regarding the Iberian Peninsula strengthen the hypothesis that hominins continuously populated Europe, at least in Iberia, throughout the late Early Pleistocene between the Jaramillo subchron and the Matuyama–Brunhes boundary by overcoming the climatic fluctuations and changes to the landscape that occurred during this period.

Paleomagnetic data on the sedimentation rate near the Mendeleev Rise (Arctic Ocean)

Seven cores of bottom sediments were collected during the cruise of R/V Akademik Fedorov in 2000 along the latitudinal profile crossing the Mendeleev Rise near 82° N, and then studied. The length of cores varies from 240 to 334 cm. In all cores, the boundary of the changing remanent magnetization vector corresponding to the Brunhes-Matuyama boundary was established reliably. In five cores, this boundary is at a depth of 86–102 cm; in two cores, collected to the west of the Mendeleev Rise, at depth levels of 188 and 208 cm. The correlation of paleomagnetic and lithological data demonstrates that the upper boundary of a bench of speckled pelites, overlapped by a bench of variegated pelites, is confined to the Olduvai episode or horizons lying slightly below. The average sedimentation rate of sediments from the Mendeleev Rise during the last 2–2.5 Ma have not exceeded 1–1.3 mm/ka, increasing towards the shelf seas of northeast Russia.

Reassessing the age of Atapuerca-TD6 (Spain): new paleomagnetic results

We carry out a new paleomagnetic study across stratigraphic layer TD7 of Gran Dolina Site, Atapuerca, and reassess the existing absolute ages (thermoluminescence, electron spin resonance) obtained at this site. The new and more detailed magnetostratigraphic record of the Matuyama-Brunhes boundary, combined with absolute ages, enables further constraint on the age of the underlying human-bearing level or Aurora Stratum. Paleomagnetism of the studied silts and sandstones reveals stable, dual polarity Characteristic Remanent Magnetization directions. A new normal magnetic polarity short interval is found at several consecutive sampling localities in the upper part of TD7, providing a new ante quem date for the human-bearing sediments of 0.9 Ma, possibly formed during MIS 25.