Latitudinal migration of calcareous nannofossil Micula murus in the Maastrichtian: implications for global climate change
Thibault, N., Gardin, S. and Galbrun, B., "published in 'Geology, 2010, v. 38, p. 203-206'"
Micula murus is one of the main calcareous nannofossil b iostratigrapic markers of Tethyan and Intermediate provinces... more Micula murus is one of the main calcareous nannofossil b iostratigrapic markers of Tethyan and Intermediate provinces in the upper Maastrichtian (uppermost Cretaceous). A review of its first occurrence at 14 deep-sea sites and sections shows that it is time transgressive from the Tropical Realm of the Atlantic and Pacific Oceans to the intermediate latitudes of the North Atlantic, South Atlantic, Indian Ocean and the northern Tethys. M. murus remained confined to the Tropical Realm for ~1.2 m.y. in the early late Maastrichtian, thus supporting high-latitudinal thermal gradients. It subsequently spread out in the late Maastrichtian to temperate latitudes and to the Tethys in coincidence with the onset of a thermohaline circulation change at ~67.5 Ma, suggesting a major change in surface-water circulation and interocean communications.
Download (.pdf) The cyclic Rørdal Member - a new lithostratigraphic unit of chronostratigraphic and palaeoclimatic importance in the upper Maastrichtian of Denmark
Surlyk et al., 2010, published in Bulletin of the Geological Society of Denmark, Vol. 58, pp. 89-98.
The Maastrichtian chalk of the Danish Basin has been referred to the Tor Formation of the North Sea, but this may not... more
The Maastrichtian chalk of the Danish Basin has been referred to the Tor Formation of the North Sea, but this may not be tenable because this formation in its type area shows a much higher degree of redeposition than the Maastrichtian chalk of the Danish Basin. The onshore succession has not been lithostratigraphically subdivided due to its rather monotonous nature and the widely scattered outcrops. An exception is the uppermost Maastrichtian exposed at Stevns Klint which is been referred to the Sigerslev Member, comprising rather benthos-poor, deep-water pure chalk, and the overlying mound-bedded, bryozoan-rich chalk which is placed in the Højerup Member. In addition, a thin marly chalk bed, the Kjølby Gaard Marl Member, containing Tethyan planktonic foraminifers is known from localities in northern Jylland and from water wells around Køge, eastern Sjælland. The new Rørdal Member is a cyclic chalk-marl unit, about 10 m thick, sandwiched between pure white chalks. It is well exposed in the large Rørdal quarry in Aalborg, and is recognised in boreholes south of Aalborg and in the Stevns-1 and Karlslunde-1 boreholes south of Copenhagen. Coccolith and brachiopod data show that it belongs to the UC20b-cBP nannofossil zone of the North Sea scheme for the Upper Cretaceous Boreal province, and the semiglobularis-humboldtii brachiopod zone, both indicating the lower upper Maastrichtian. Isotope data show that it represents a distinct early late Maastrichtian cooling event. The member thus has a basinwide distribution and is an important isochronous marker because it represents a significant change in sea-water temperature and not a progradational event.
Upper Campanian - Maastrichtian nannofossil biostratigraphy and high-resolution carbon-isotope stratigraphy of the Danish Basin: towards a standard <delta>13C curve for the Boreal Realm
Thibault, N. et al., in press in Cretaceous Research, doi:10.1016/j.cretres.2011.09.001
High-resolution carbon isotope stratigraphy of the upper Campanian – Maastrichtian is recorded in the Boreal Realm... more High-resolution carbon isotope stratigraphy of the upper Campanian – Maastrichtian is recorded in the Boreal Realm from a total of 1968 bulk chalk samples of the Stevns-1 core, eastern Denmark. Isotopic trends are calibrated by calcareous nannofossil bio-events and are correlated with a lower-resolution δ13C profile from Rørdal, northwestern Denmark. A quantitative approach is used to test the reliability of Upper Cretaceous nannofossil bio-events and provides accurate biohorizons for the correlation of δ13C profiles. The Campanian–Maastrichtian boundary (CMB) is identified through the correlation of dinoflagellate biostratigraphy and δ13C stratigraphy between Stevns-1 and the Global boundary Standard Stratotype-section and Point at Tercis les Bains (SW France), allowing the identification of new chemical and biostratigraphic markers that provide a precise placement of the stage boundary on a regional scale. The boundary interval corresponds to the third phase of a stepwise 0.8‰ negative δ13C excursion, lies in calcareous nannofossil subzone UC16dBP, and encompasses the last occurrence of nannofossil Tranolithus stemmerikii and first occurrence of nannofossil Prediscosphaera mgayae. Fifteen δ13C events are defined and correlated to sixteen reliable nannofossil biohorizons, thus providing a well-calibrated standard high-resolution δ13C curve for the Boreal Realm.
Bio-magnetochronology for the upper Campanian - Maastrichtian from the Gubbio area, Italy: new results from the Contessa Highway and Bottaccione sections
Gardin, S., Galbrun, B., Thibault, N., Coccioni, R., Premoli Silva, I., Newsletter on Stratigraphy. In press. http://www.ingentaconnect.com/content/schweiz/nis/pre-prints/0014
A new bio-chronostratigraphic framework is presented for the upper Campanian-Maastrichtian pelagic sediments of the... more A new bio-chronostratigraphic framework is presented for the upper Campanian-Maastrichtian pelagic sediments of the Gubbio area (Bottaccione and Contessa Highway sections, Italy). New planktonic foraminiferal (FO of P. hantkeninoides), calcareous nannofossil (FO of M. prinsii, base acme of M. murus) and magnetostratigraphic data are provided and integrated to construct an age-depth curve based on the recent astronomical calibration of the late Campanian-Maastrichtian magnetic polarity time scale (Husson, D., Galbrun, B., Laskar, J., Hinnov, L.A., Thibault, N., Gardin, S., Locklair, R.E., 2011. Astronomical calibration of the Maastrichtian, Late Cretaceous. Earth and Planetary Science Letters 305, 328-340). All bio-horizons recorded in both sections fall on or are very close to the Line of Correlation (LOC), which testifies to the reliability of biochronologic studies in the Umbria-Marche basin. The proposed age model allows to estimate the sedimentation rates and the ages of calcareous nannofossil and planktonic foraminiferal bio-horizons in both sections. Also, it provides an excellent late Campanian–Maastrichtian reference for sections in the Umbria-Marche area and the entire southern Tethys. Due to the presence of a ~425 kyr-long hiatus in Chron C31n of the Bottaccione section, the Contessa Highway section constitutes a more complete late Campanian–Maastrichtian reference for bio-magnetochronology in the Tethyan realm.
Astronomical calibration of upper Campanian-Maastrichtian carbon isotope events and calcareous plankton biostratigraphy in the Indian Ocean (ODP Hole 762C): implication for the age of the Campanian-Maastrichtian boundary
Thibault, N., Husson, D., Harlou, R., Gardin, S., Galbrun, B., Huret, E., Minoletti, F., Palaeo3. in press. http://www.sciencedirect.com/science/article/pii/S0031018212001769?v=s
An integrated framework of magnetostratigraphy, calcareous microfossil bio-events, cyclostratigraphy and δ13C... more An integrated framework of magnetostratigraphy, calcareous microfossil bio-events, cyclostratigraphy and δ13C stratigraphy is established for the upper Campanian-Maastrichtian of ODP Hole 762C (Exmouth Plateau, Northwestern Australian margin). Bulk-carbonate δ13C events and nannofossil bio-events have been recorded and plotted against magnetostratigraphy, and provided absolute ages using the results of the cyclostratigraphic study and the recent astronomical calibration of the Maastrichtian. Fifteen carbon-isotope events and 40 nannofossil bio-events are recognized and calibrated with cyclostratigraphy, as well as 14 previously published foraminifer events, thus constituting a solid basis for large-scale correlations. Results show that this site is characterized by a nearly continuous sedimentation from the upper Campanian to the K-Pg boundary, except for a 500 kyr gap in magnetochron C31n. Correlation of the age-calibrated δ13C profile of ODP Hole 762C to the δ13C profile of the Tercis les Bains section, Global Stratotype Section and Point of the Campanian-Maastrichtian boundary (CMB), allowed a precise recognition and dating of this stage boundary at 72.15 Ma. Correlation of this boundary with the Lägerdorf - Kronsmoor - Hemmoor section shows that the CMB as defined at the GSSP is ~800 kyr younger than the CMB as defined by Belemnite zonation in the Boreal realm. ODP Hole 762C is the first section to bear at the same time an excellent recovery of sediments throughout the upper Campanian-Maastrichtian, a precise and well-defined magnetostratigraphy, a high-resolution record of carbon isotope events and calcareous plankton biostratigraphy, and a cyclostratigraphic study tied to the La2010 astronomical solution. This section is thus proposed as an excellent reference for the upper Campanian-Maastrichtian in the Indian Ocean.
STRATIGRAPHY AND TECTONIC AND METAMORPHIC EVOLUTION OF THE PORTO AZZURRO UNIT IN THE MONTE CALAMITA PROMONTORY (SOUTHEASTERN ELBA ISLAND, TUSCANY)
Francesca Garfagnoli, Francesco Menna, Enrico Pandeli, Gianfranco Principi
The Elba Island has a key role in the reconstructions of the stratigraphic, tectonic, metamorphic and magmatic... more The Elba Island has a key role in the reconstructions of the stratigraphic, tectonic, metamorphic and magmatic evolution of the Northern Tyrrhenian Sea and of the inner part of the Northern Apennines chain. The Porto Azzurro Unit, cropping out in the SE part of the Island, is the deepest tectonic unit of the central-eastern Elba structural pile of Tuscan, Ligurian and Ligurian-Piedmontese Nappes, which were intruded by Late Tortonian-Lower Pliocene granitoids and mainly acidic dikes. Moreover, in this part of the Island, the relationships between the uplift of the plutonic bodies and the final deformations of the tectonic stack are well exposed. To improve the geological knowledge of SE Elba, the authors carried out a 1:10.000 geological survey of the Calamita Promontory (mostly made up of the Porto Azzurro Unit) and performed petrographic and meso-/micro-structural studies on its rocks. The Porto Azzurro Unit consists of a Paleozoic, likely pre-Carboniferous basement (Mt. Calamita Fm.), which is unconformably overlain by the ?Triassic Verrucano metasiliciclastics (Barabarca Quartzites) and ?Upper Triassic-?Hettangian metacarbonates. In the Mt.Calamita Fm., five main lithofacies were recognized and mapped. In particular, garnet-bearing, albite micaschist (lithofacies a) geometrically underlie a phyllitic-quartzitic unit (lithofacies b); Porphyroids-like rocks (lithofacies e), metabasite bodies (lithofacies d) and graphite-rich siliciclastics (lithofacies c) are also present. The rocks of the lithofacies a are similar to those of the ?pre-Paleozoic-?Paleozoic Micaschist Complex of the Larderello Geothermal Field, whereas the other lithofacies can be probably correletable with the ?Ordovician formations of the Tuscan Metamorphic Units. The complex deformation-metamorphic evolution of the Porto Azzurro Unit consists of the following events: a) a Variscan tectono-metamorphic event (Dx), recognized in the Mt.Calamita Fm., which is defined by pre- Alpine schistosity and mineralogic relics (garnet); b) two Alpine tectono-metamorphic folding events (D1 and D2) in the Greenschists facies, which deformed also the Mesozoic covers; c) a following folding event (D3) which probably occurred during or immediately after the strong thermometamorphic imprint (including the magnetite-rich skarn bodies), due to the Neogene magmatic intrusions; d) Subsequently, the uplift of the magmatic bodies caused low-angle detachments within the Porto Azzurro Unit (between the Mt.Calamita Fm. and the Mesozoic cover) and between the latter and the overlying tectonic Units (e.g. Zuccale Fault between the Porto Azzurro Unit and the Cretaceous Flysch). A final weak antiformal folding (D4) of the whole promontory took place before the development of NW-SE and N-S trending high –angle normal fault systems, locally sealed by hydrothermal, sometimes Fe-rich mineralizations. The lithostratigraphic, tectonic, metamorphic and magmatic evolution of the Porto Azzurro Unit is similar to that defined for the Larderello geothermal region. Thus, the Mt.Calamita area can be considered as a little older, but similar geological model for all the future interpretations of the deep structure of southern Tuscany crossed by the Crop 18 profile.
Tephro- and chemo-stratigraphy of the Vulcanello Peninsula (Vulcano, Aeolian Islands)
New stratigraphic studies of the Vulcanello Peninsula have been used to better define the small-scale evolution of... more New stratigraphic studies of the Vulcanello Peninsula have been used to better define the small-scale evolution of this young (1000 AD and 325±100 BP) volcanic center and to re-investigate the last 1000 years of volcanic history for the Island of Vulcano (Aeolian Islands, Southern Italy). Vulcanello Peninsula is the northern-most part of the Island of Vulcano. It comprises a shoshonitic lava platform and a volcanic edifice made up of three overlying cones, which are shoshonitic to trachytic in composition. Volcanic activity in this area was coeval with the recent eruptions of the La Fossa Cone, the present-day active center of the island. Our goal is to constrain the recent volcanic development of this mafic volcano and to focus on the historic eruptive activity of the two other recent or active centres in the southern Aeolian Islands, Mt. Pilato (Island of Lipari) and La Fossa Cone. In order to do so, we reconstructed the stratigraphical setting of the proximal deposits of the three Vulcanello cones, through the investigation of 25 outcrops. We analyzed the stratigraphy of the tephra blankets deposited on the lava platform, studying 10 trenches. Our intention is to integrate morphological, textural and chemical data in order to correlate these deposits with the Vulcanello, La Fossa Cone or Mt Pilato. LA-MC-ICPMS (RHUL) analysis of juvenile clasts is underway in order to investigate the evolution of the Vulcanello juvenile clasts. In addition 14C dating is planned on selected organic matter from the volcanostratigraphic sections. Our preliminary data for the Vulcanello proximal deposits suggest that each of the three cones experienced several eruptions, with a wide spectrum of eruptive styles and a diversity of chemistry. The oldest cone (Vulcanello I) is characterised by four different eruptions separated by minor unconformities or reworking material indicative of little or not time breaks in the eruptive cycle. The eruptions shift from Violent Strombolian to Hawaiian in style, testifying to a reduction in fragmentation and dispersal. The second cone (Vulcanello II), contains volcanic deposits from Strombolian eruptions only. The third cone (Vulcanello III), displays a complex evolution with an initial effusive episode of a trachytic lava flow, followed by phreatic explosions, evident as altered fine ash layers. These deposits are interbedded with scoriaceous fall deposits, attesting the occurrence of some mild explosive activity during this eruptive phase. This detailed study of the effusive and explosive products from Vulcanello reveals rapid evolution of Vulcanello during the initial phases (1000 AD to 1200 AD) with voluminous mafic eruptions, both effusive and explosive. A progressive reduction in emitted volume is apparent. The presence of abundant explosive deposits related to phreatic explosions during the Vulcanello III phase, is related to the presence of water, a reduction in magma volume and the presence of intense hydrothermal activity in the latter stage of the evolution of Vulcanello evolution until 1878. This may indicate the presence of a stable shallow thermal anomaly.
Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)
Andrea Ciampalini, Ilaria Consoloni, Giovanni Sarti
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.
BURIAL DATING OF LATE-CENOZOIC DEPOSITS USING IN-SITU PRODUCED COSMOGENIC NUCLIDES
Andrea Ciampalini, Cristina Persano, Derek Fabel, Marco Firpo
Dating the Miocene to Pleistocene deposition of fluvial and deltaic sediments is often difficult because of the... more
Dating the Miocene to Pleistocene deposition of fluvial and deltaic sediments is often difficult because of the absence of suitable biostratigraphic markers. Temporal limits on sediment deposition, however, are fundamental constraints in many geological, geomorphological, stratigraphical and archeological studies. In particular a dated stratigraphy of sedimentary basins provides information about timing of evolution of the sediment source and routing system due to tectonics, sea-level and/or climate changes. Traditional techniques, such as luminescence, radiocarbon dating of organic material, etc. only permit us to date sediments that are no older than ~250,000 years. Recently a method for dating sediment burial using the radioactive decay of cosmogenic nuclides 26Al and 10Be has been developed. 26Al and 10Be are produced by the continuous bombarding by high-energy cosmic rays of the Earth surface where they penetrate into rocks and sediments at a depth that varies, depending on rock density, between 2 and 3 m. The long half-life of the 26Al (7.05X105 yr) and 10Be (1.5X106 yr) make them optimal for dating sediments that were deposited over the past five million years, as long as the sediments were at the surface and exposed to cosmic rays before sedimentation and burial. The sediments that can be dated using the cosmogenic isotopes technique need to have the following characteristics: (1) quartz needs to be present and have been exposed at the surface for a time necessary to accumulate measurable cosmogenic radionuclides concentration (i.e., depending
on latitude and altitude, at least ~ 200 years); (2) transport time needs to have been negligible (3) burial was rapid and deep (>10 m) to avoid cosmogenic nuclides production after deposition, otherwise a correction needs to be introduced. This method is useful in many Italian areas where deltaic or fluvial Miocene to Pleistocene deposits crop out.
Late Dinantian (Lower Carboniferous) platform carbonate stratigraphy of the Buttevant area North Co. Cork, Ireland
A thick sequence of late Dinantian (Asbian±Brigantian) carbonates crop out in the Buttevant area, North Co. Cork,
Ireland. A mud-mound unit of early Asbian age (the Hazelwood Formation) is the oldest unit described in this work.
This formation is partly laterally equivalent to, and is overlain by, over 500 m of bedded platform carbonates which
belong to the Ballyclogh and Liscarroll Limestone Formations. Four new lithostratigraphic units are described within
the platform carbonates: (i) the early Asbian Cecilstown Member and (ii) the late Asbian Dromdowney Member in
the Ballyclogh Limestone Formation; (iii) the Brigantian Templemary Member and (iv) the Coolbane Member in the
Liscarroll Limestone Formation.
The Cecilstown Member consists of cherty packstones and wackestones that are inferred to have been deposited below
fair-weather wavebase. This unit overlies and is laterally equivalent to the mud-mound build-up facies of the Hazelwood
Formation. The Dromdowney Member is typi®ed by cyclic-bedded kamaenid-rich limestones possessing shell bands,
capped by palaeokarst surfaces, with alveolar textures below and shales above these surfaces. The carbonates of this unit
were deposited at or just below fair-weather wavebase, the top of each cycle culminated in subaerial emergence. The
Templemary Member consists of cyclic alternations of subtidal crinoidal limestones capped by subtidal lagoonal crinoid-
poor, peloidal limestones possessing coral thickets. Intraclastic cherty packstones and wackestones characterize the
Coolbane Member, which is inferred to have been deposited below fair-weather wavebase but above storm wavebase.
The early Asbian Cecilstown Member has a relatively sparse micro- and macrofauna, typi®ed by scattered Siphono-
dendron thickets, archaediscids at angulatus stage and common Vissariotaxis. Conversely, macro- and microfauna is
abundant in the late Asbian Dromdowney Member. Typical late Asbian macrofossils include the coral Dibunophyllum
bipartitum and the brachiopod Davidsonina septosa. The base of the late Asbian (Cf6g Subzone) is recognized by the ®rst
appearance of the foraminifers Cribrostomum lecompteii, Koskinobigenerina and the alga Ungdarella. The Cf6g Subzone
can be subdivided into two biostratigraphic divisions, Cf6g1 and Cf6g2, that can be correlated throughout Ireland.
Relatively common gigantoproductid brachiopods and the coral Lonsdaleia duplicata occur in the Brigantian units. The
base of the Brigantian stage (Cf6d Subzone) is marked by an increase in the abundance of stellate archaediscids,
the presence of Saccamminopsis-rich horizons, Loeblichia paraammonoides, Howchinia bradyana and the rarity of
Koninckopora species.
Changes in facies at the Cecilstown/Dromdowney Member and the Ballyclogh/Liscarroll Formation boundaries
coincide closely with the changes in fossil assemblages that correspond to the early/late Asbian and the Asbian/Brigantian
boundaries. These facies changes are believed to re¯ect major changes in relative sea-level on the Irish platforms. The sea-
level variations that are inferred to have caused the facies changes at lithostratigraphic boundaries also brought in the new
taxa that de®ne biostratigraphic boundaries. Moreover, many of the Dinantian stage boundaries that are de®ned bio-
stratigraphically in Great Britain, Belgium and the Russian Platform also coincide with major facies boundaries caused
by regressive and transgressive episodes. The integration of detailed biostratigraphic analyses with facies studies will lead
to better stratigraphic correlations of Dinantian rocks in northwest Europe.
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