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  • 1
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Detailed magnetostratigraphic work at the Palaeocene/Eocene boundary interval in the Zumaia section has led to a precise delineation of the position of polarity Chron C25n from −35.0 m (or −35.7 m) to −25.2 m below the base of the Carbon Isotopic Excursion that marks the Palaeocene/Eocene boundary. This chronostratigraphic constraint suggests that the lithological carbonate–marl couplets making up most of the studied section are the expression of orbital precession cycles, and confirms the expanded and continuous nature of the section, with mean sediment accumulation rates of ∼ 2.5 cm kyr−1. The new data render Zumaia a unique land-based marine section with available magnetostratigraphic data coupled to cyclostratigraphy. The revised chronostratigraphic framework presented supports previous cyclostratigraphic calibration of the latest Palaeocene geomagnetic timescale; it should facilitate better assessment of the different chemobiostratigraphic events that span this critical interval as a consequence of past climate and oceanographic change. Consequently, the Zumaia section is proposed as a candidate Global Stratotype Section and Point (GSSP) for the Palaeocene/Eocene boundary.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1626
    Keywords: Magnetostratigraphy ; Bajo Segura Basin ; Olduwai ; AMS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary An integrated pilot paleomagnetic and sedimentological study has been conducted in the Neogene-Quaternary infilling materials of the Bajo Segura Basin (Eastern Betics, SE Spain). The studied sediments belong to the youngest (late Pliocene-Quaternary) lithostratigraphic unit of the basin (P-Q unit). The statistical analysis of tectonic striations and stylolitic dissolutions on the conglomerate limestone clasts indicates a NNW-SSE maximum compression direction. This is in accordance with the principal susceptibility axes, determined from the anisotropy of magnetic susceptibility measurements (AMS) of the interbedded siltstones where the Kmax axis group in a subhorizontal N 080° E direction. A total of 45 core samples have been collected from 16 stratigraphic siltstone levels encompassing the described section at Crevillente with the aim to establish a magnetochronology. Upwards in the section the NRM intensity and bulk susceptibility vary from 10−2 to 10−3 A/m and from 1550 to 100 × 10−6 SI, respectively. The mean characteristic remanent magnetization (ChRM) after bedding correction (Dec/Inc = 10°/60°, α95 = 8.7°, k = 15.9) is deviated slightly towards the E from the reference N direction, and could reflect a deflection related to the observed magnetic fabric although no clear correlation exists with AMS parameters. The derived magnetostratigraphy reveals only one reversal boundary within the upper third of the section, delimiting an upper reversal magnetozone which has been tentatively correlated with the Olduwai subchron close to the Plio-Pleistocene boundary. Pilot and preliminary rock-magnetic experiments and standard X-ray difraction (XRD) analysis have been performed on typical samples in order to establish the carriers of magnetization and characterize the sedimentological and magnetic-acquisition processes in these sediments. Magnetic carriers seem to be dominated by magnetite with a relative grain size within the PSD state (pseudo single-domain) threshold, but closer to the MD (multi domain) threshold, which favours the detrital origin for the magnetite.
    Type of Medium: Electronic Resource
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  • 3
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    In:  Supplement to: Dinarès-Turell, Jaume; Westerhold, Thomas; Pujalte, Victoriano; Röhl, Ursula; Kroon, Dick (2014): Astronomical calibration of the Danian stage (Early Paleocene) revisited: Settling chronologies of sedimentary records across the Atlantic and Pacific Oceans. Earth and Planetary Science Letters, 405, 119-131, https://doi.org/10.1016/j.epsl.2014.08.027
    Publication Date: 2023-03-03
    Description: Astronomical tuning of sedimentary records to precise orbital solutions has led to unprecedented resolution in the geological time scale. However, the construction of a consistent astronomical time scale for the Paleocene is controversial due to uncertainties in the recognition of the exact number of 405-kyr eccentricity cycles and accurate correlation between key records. Here, we present a new Danian integrated stratigraphic framework using the land-based Zumaia and Sopelana hemipelagic sections from the Basque Basin and deep-sea records drilled during Ocean Drilling Program (ODP) Legs 198 (Shatsky Rise, North Pacific) and 208 (Walvis Ridge, South Atlantic) that solves previous discrepancies. The new coherent stratigraphy utilises composite images from ODP cores, a new whole-rock d13C isotope record at Zumaia and new magnetostratigraphic data from Sopelana. We consistently observe 11 405-kyr eccentricity cycles in all studied Danian successions. We achieve a robust correlation of bioevents and stable isotope events between all studied sections at the ~100-kyr short-eccentricity level, a prerequisite for paleoclimatic interpretations. Comparison with and subsequent tuning of the records to the latest orbital solution La2011 provides astronomically calibrated ages of 66.022 ± 0.040 Ma and 61.607 ± 0.040 Ma for the Cretaceous-Paleogene (K-Pg) and Danian-Selandian 105 (D-S) boundaries respectively. Low sedimentation rates appear common in all records in the mid-Danian interval, including conspicuous condensed intervals in the oceanic records that in the past have hampered the proper identification of cycles. The comprehensive interbasinal approach applied here reveals pitfalls in time scale construction, filtering techniques in particular, and indicates that some caution and scrutiny has to be applied when building orbital chronologies. Finally, the Zumaia section, already hosting the Selandian Global Boundary Stratotype Section and Point (GSSP), could serve as the global Danian unit stratotype in the future.
    Keywords: AGE; Center for Marine Environmental Sciences; MARUM; Mass spectrometer Finnigan MAT 251; SECTION, height; Spain; ZUM; Zumaya_section; δ13C, carbonate; δ18O, carbonate
    Type: Dataset
    Format: text/tab-separated-values, 362 data points
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  • 4
    Publication Date: 2024-02-05
    Description: Here we present calcareus nannofossil and colour datasets from the hemipelagic lower Ypresian Arnakatxa section (Basque-Cantabrian basin, western Pyrenees). The Arnakatxa coastal cliffs, which constitute the present study area, are located approximately 15 km northwest of Bilbao (43°23'34.4N, 2°59'24.2W, altitude 0 m). The expanded hemiplegic succession offered a potentially valuable orbitally paced geological record. Sampling was carried out in 2015. For the study of calcareous nannofossils 65 hand samples were collected (average spacing of about 50 cm). For colour analysis, 635 rock-powder samples were collected (average resolution of ~5 cm) using a standard cordless drill with an 8 mm bit. Slides for nannofloral analysis were prepared according to Flores and Sierro (1997), avoiding any mechanical or physical disturbance of the samples that could modify the original fossil assemblages. A Zeiss Axioplan2 petrographic microscope at 1250× magnification was used to analyze the samples. Quantitative analysis was performed by counting at least 300 specimens per sample. Additionally, three random traverses (~9 mm2) were analyzed on each slide in order to detect rare but biostratigraphically significant species. The rock powder samples were stored in transparent antiglare prismatic plastic vials (3 ml) and scanned at high-resolution (600 dpi) using a desktop office scanner in a dark room. The average colour value of a homogeneous rectangular area covering 10-20% of the scanned image of each vial was measured using ImageJ software version 1.50i. Average colour value represents to the mean pixel RGB value of the selected area, which is equivalent to the brightness value. In order to perform a cyclostratigraphic analysis, the colour data series was linearly interpolated and the LOESS regression trend subtracted. The Astrochron code commands used to perform that spectral analysis are herein available.
    Keywords: Arnakatxa_coastal_cliffs; astronomical tuning; Basque-Cantabria basin; Biantholithus spp.; Biscutum spp.; Braarudosphaera spp.; Calcareous nannofossils; Chiasmolithus bidens; Chiasmolithus consuetus; Chiasmolithus solitus; Chiasmolithus spp.; Coccolithus pelagicus; colour; Cruciplacolithus spp.; Cyclostratigraphy; Discoaster barbadiensis; Discoaster diastypus; Discoaster mohleri; Discoaster multiradiatus; Discoaster nobilis; Discoaster salisburgensis; Discoaster spp.; Ellipsolithus spp.; Ericsonia spp.; Fasciculithus tympaniformis; Individuals; Light microscope; Markalius spp.; Rhomboaster bramlettei; Rhomboaster contortus; Sample code/label; SECTION, height; Sphenolithus anarrhopus; Sphenolithus moriformis; Sphenolithus radians; Thoracosphaera spp.; Toweius eminens; Toweius pertusus; Tribrachiatus orthostylus; Ypresian; Zygrhablithus bijugatus
    Type: Dataset
    Format: text/tab-separated-values, 2080 data points
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  • 5
    Publication Date: 2024-02-05
    Description: Here we present calcareus nannofossil and colour datasets from the hemipelagic lower Ypresian Arnakatxa section (Basque-Cantabrian basin, western Pyrenees). The Arnakatxa coastal cliffs, which constitute the present study area, are located approximately 15 km northwest of Bilbao (43°23'34.4N, 2°59'24.2W, altitude 0 m). The expanded hemiplegic succession offered a potentially valuable orbitally paced geological record. Sampling was carried out in 2015. For the study of calcareous nannofossils 65 hand samples were collected (average spacing of about 50 cm). For colour analysis, 635 rock-powder samples were collected (average resolution of ~5 cm) using a standard cordless drill with an 8 mm bit. Slides for nannofloral analysis were prepared according to Flores and Sierro (1997), avoiding any mechanical or physical disturbance of the samples that could modify the original fossil assemblages. A Zeiss Axioplan2 petrographic microscope at 1250× magnification was used to analyze the samples. Quantitative analysis was performed by counting at least 300 specimens per sample. Additionally, three random traverses (~9 mm2) were analyzed on each slide in order to detect rare but biostratigraphically significant species. The rock powder samples were stored in transparent antiglare prismatic plastic vials (3 ml) and scanned at high-resolution (600 dpi) using a desktop office scanner in a dark room. The average colour value of a homogeneous rectangular area covering 10-20% of the scanned image of each vial was measured using ImageJ software version 1.50i. Average colour value represents to the mean pixel RGB value of the selected area, which is equivalent to the brightness value. In order to perform a cyclostratigraphic analysis, the colour data series was linearly interpolated and the LOESS regression trend subtracted. The Astrochron code commands used to perform that spectral analysis are herein available.
    Keywords: Arnakatxa_coastal_cliffs; astronomical tuning; Basque-Cantabria basin; Calcareous nannofossils; Color, value; colour; Cyclostratigraphy; Height, relative; Measured using software ImageJ; Sample code/label; SECTION, height; Ypresian
    Type: Dataset
    Format: text/tab-separated-values, 1907 data points
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  • 6
    Publication Date: 2021-01-20
    Description: Multivariate analysis of the elemental composition of hemipelagic sedimentary successions has provided invaluable information about palaeoenvironmental evolution, including records of short-lived Eocene hyperthermal events. However, few studies have analyzed the sedimentary record of these climatic events in turbidite-rich continental margin successions. In order to test the usefulness of multivariate statistical techniques (factor and cluster analysis) in palaeonvironmental and palaeoclimatic research on turbiditic successions, the lowermost Eocene Solondota section, which accumulated on the North Iberian continental margin, was studied. A prominent negative carbon isotope excursion from Solondota was correlated with the Ypresian (early Eocene) hyperthermal event J, also known as C24n.2rH1. High-resolution sedimentological, geochemical (stable isotopes, major and trace elements) and mineralogical (bulk and clay mineralogy) data show that multivariate statistical analysis helps to manage large-sized quantitative datasets objectively, avoiding arbitrary choice of representative elements and identifying environmental factors (virtual variables) that may not be evident otherwise. Variations in major and minor elements from hemipelagic carbonates across the Solondota carbon isotope excursion suggest a temporarily more humid continental climate, which caused increased terrigenous material input into the marine environment. The finer grained fraction boosted hemipelagic carbonate dilution, whereas the coarser grained sediment was transported by temporarily more frequent and voluminous turbidity currents. Thus, the results from the Solondota carbon isotope excursion revealed similarities with deep marine records of other early Eocene minor hyperthermal events. This demonstrates the validity of deep-marine turbiditic successions for providing reliable sedimentological, mineralogical and geochemical records of global palaeoclimatic significance, complementing the information obtained from other sedimentary environments. Furthermore, the generally expanded nature of turbiditic successions can potentially provide palaeoclimatic information at very high resolution, enriching, and perhaps improving, the commonly condensed and sometimes discontinuous record of hemipelagic- only successions.
    Description: Published
    Description: 881-904
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2021-05-12
    Description: The most severe biotic crisis on Earth history occurred during the Permian–Triassic (PT) transition around 252 Ma. Whereas in the marine realm such extinction event is well-constrained, in terrestrial settings it is still poorly known, mainly due to the lack of suitable complete sections. This is utterly the case along the Western Tethys region, located at Pangaea's equator, where terrestrial successions are typically build-up of red beds often characterised by a significant erosive gap at the base of the Triassic strata. Henceforth, documenting potentially complete terrestrial successions along the PT transition becomes fundamental. Here, we document the exceptional Coll de Terrers area from the Catalan Pyrenees (NE Iberian Peninsula), for which a multidisciplinary research is conducted along the PT transition. The red-bed succession, located in a long E-W extended narrow rift system known as Pyrenean Basin, resulted from a continuous sedimentary deposition evolving from meandering (lower Upper Red Unit) to playa-lake/ephemeral lacustrine (upper Upper Red Unit) and again to meandering settings (Buntsandstein facies). Sedimentary continuity is suggested by preliminary cyclostratigraphic analysis that warrants further analysis. Our combined sedimentological, mineralogical and geochemical data infer a humid-semiarid-humid climatic trend across the studied succession. The uppermost Permian strata, deposited under an orbitally controlled monsoonal regime, yields a relatively diverse ichnoassemblage mainly composed of tetrapod footprints and arthropod trace fossils. Such fossils indicate appropriate life conditions and water presence in levels that also display desiccation structures. These levels alternate with barren intervals formed under dry conditions, being thus indicative of strong seasonality. All these features are correlated with those reported elsewhere in Gondwana and Laurasia, and suggest that the Permian–Triassic boundary might be recorded somewhere around the Buntsandstein base. Consequently, Coll de Terrers and the whole Catalan Pyrenees become key regions to investigate in detail the Permian extinction event and the Triassic ecosystems recovery.
    Description: Published
    Description: 46–60
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Keywords: 04.04. Geology ; 04.05. Geomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2021-06-30
    Description: composite stratigraphic section ranging from the Messinian to the Pliocene, recording the most important phases of the Messinian Salinity Crisis, is represented in the San Miguel de Salinas area (Bajo Segura basin, SE Spain). Detailed magnetostratigraphic and facies analyses and foraminifer and nannoplankton assemblage studies were carried out. Integration of the results has allowed the characterization of the pre-evaporitic (synthem Messinian I), syn-evaporitic (synthem Messinian II), and post-evaporitic phases (synthem Pliocene) from a paleoenvironmental and chronostratigraphic standpoint. The pre-evaporitic phase is late Messinian and records a shallowing-upward trend. The syn-evaporitic phase took place in chron C3r and is characterized by laminated marls with intercalated selenitic gypsum beds and sandstones. Variations in foraminifer and nannoplankton assemblages together with episodic gypsum precipitation record major changes in water salinity in a stressed marine environment. The pre- and syn-evaporitic phases are separated by the intra-Messinian unconformity, represented by an erosional surface related with a sea-level fall. After the evaporitic phase, a sea-level fall generates the end-Messinian unconformity, whose strongly erosional nature is evidenced by the deeply carved paleovalley of San Miguel de Salinas. The post-evaporitic phase begins in the earliest Pliocene and records the re-establishment of normal marine conditions in the basin. Since the San Miguel de Salinas composite section can be considered as a benchmark for the study of the evolution of marginal Mediterranean basins during the Messinian Salinity Crisis, the detailed characterization of these different phases is of great importance in understanding this event.
    Description: Published
    Description: 246-266
    Description: 4A. Oceanografia e clima
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2021-01-14
    Description: The Global Stratotype Section and Point (GSSP) for the base of the Bartonian, currently remains undefined. The Bartonian unit stratotype is located at the Barton coastal section in the Hampshire Basin, on the South Coast of the UK. The base of the “Barton beds” was originally placed at the lowest occurrence of Nummulites prestwichianus, and this is still the basis of the recognition of the unit Bartonian Stage as a formal chronostratigraphic unit of the Paleogene. However, this biostratigraphic marker is not widely applicable elsewhere. The base of the lithostratigraphic unit, the Barton Clay Formation, also extends below this level creating further complication. The parastratotype section is located at Alum Bay, 7 km away, on the Isle of Wight. Despite a number of studies carried out in 1970s and ‘80s on both sections, global correlation remains problematic. Here we present an integrated (micropalaeontological, stratigraphic, palaeomagnetic) study of the Lutetian-Bartonian transition at Alum Bay, and aim at improving the stratigraphy of this section to better define the base of the Bartonian and contribute towards a decision on the GSSP.
    Description: Published
    Description: 7–42
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2020-12-02
    Description: At Integrated Ocean Drilling Program (IODP) Expedition 317 Site U1352, east of the South Island New Zealand, we continuously cored a 1927-m-thick Holocene-to-Eocene section where we can uniquely document downhole changes in induration and lithification in siliciclastic to calcareous fine-grained sediment using a wide range of petrological, physical-property, and geochemical data sets. Porosity decreases from around 50% at the surface to 5–10% at the base of the deepest hole, with a corresponding increase in density from ∼ 2 to ∼ 2.5 g cm3. There are progressive bulk mineral changes with depth, including an increase in carbonate and decrease in quartz and clay content. Grain compaction is first seen in thin section at 347 m below sea floor and intensifies downhole. Pressure solution (chemical compaction) begins at 380 m and is common below 1440 m, with stylolite development below 1600 m, and sediment injection features below 1680 m. Porewater geochemistry and petrographic observations document two active zones of cementation, one shallow (eogenetic) down to ∼ 50 m, as evidenced by micritic nodules and pore-water geochemistry driven by methane oxidation by sulfate, and another burial-related cementation zone (mesogenetic) starting at ∼ 300 m. A transitional zone occurs between 50 and 300 m. Our results quantify downhole diagenetic changes and verify depth estimates for these processes inferred from outcrop studies, and provide an actualistic example of cementation and compaction trends in a slope setting.
    Description: Published
    Description: 272–287
    Description: 5A. Paleoclima e ricerche polari
    Description: JCR Journal
    Keywords: 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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