Pliocene and late Pleistocene (MIS 5e) decapod crustaceans from Santa Maria Island (Azores Archipelago: Central Atlantic): systematics, palaeoecology and palaeobiogeography

2020 ◽  
Vol 36 (1) ◽  
pp. 91-109
Author(s):  
Matúš Hyžný ◽  
Carlos S. Melo ◽  
Ricardo S. Ramalho ◽  
Ricardo Cordeiro ◽  
Patrícia Madeira ◽  
...  
2020 ◽  
Vol 8 (6) ◽  
pp. 386 ◽  
Author(s):  
Sérgio P. Ávila ◽  
Markes E. Johnson ◽  
Ana Cristina Rebelo ◽  
Lara Baptista ◽  
Carlos S. Melo

Modern and palaeo-shores from Pleistocene Marine Isotope Substage 5e (MIS 5e) featuring prominent cobble/boulder deposits from three locations, on the southern and eastern coast of Santa Maria Island in the Azores Archipelago, were compared, in order to test the idea of higher storminess during the Last Interglacial. A total of 175 basalt clasts from seven transects were measured manually in three dimensions perpendicular to one another. Boulders that exceeded the minimum definitional diameter of 25 cm contributed to 45% of the clasts, with the remainder falling into the category of large cobbles. These were sorted for variations in shape, size, and weight pertinent to the application of two mathematical formulas to estimate wave heights necessary for traction. Both equations were based on the “Nott-Approach”, one of them being sensitive to the longest axis, the other to the shortest axis. The preponderance of data derived from the Pleistocene deposits, which included an intertidal invertebrate fauna for accurate dating. The island’s east coast at Ponta do Cedro lacked a modern boulder beach due to steep rocky shores, whereas raised Pleistocene palaeo-shores along the same coast reflect surged from an average wave height of 5.6 m and 6.5 m. Direct comparison between modern and Pleistocene deposits at Ponta do Castelo to the southeast and Prainha on the island’s south shore produced contrasting results, with higher wave heights during MIS 5e at Ponta do Castelo and higher wave heights for the modern boulder beach at Prainha. Thus, our results did not yield a clear conclusion about higher storminess during the Last Interglacial compared to the present day. Historical meteorological records pit the seasonal activity of winter storms arriving from the WNW-NW against the scant record of hurricanes arriving from the ESE-SE. The disparity in the width of the marine shelf around Santa Maria Island with broad shelves to the north and narrow shelves to the south and east suggested that periodic winter storms had a more regular role in coastal erosion, whereas the rare episodic recurrence of hurricanes had a greater impact on southern and southeastern rocky shores, where the studied coastal boulder deposits were located.


2021 ◽  
Author(s):  
Svetlana Sycheva ◽  
Manfred Frechen ◽  
Birgit Terhorst ◽  
Sergey Sedov ◽  
Olga Khokhlova

<p>A detailed pedocryostratigraphic scheme of the Late Pleistocene periglacial region of the East European Plain has been developed on the basis of study of the paleorelief, sediments, paleosols, and cryogenic horizons. OSL and <sup>14</sup>C-dating of paleosols and sediments in Aleksandrov quarry and in other sections made it possible to substantiate this scheme and correlate it with analogous ones for different regions of Europe. The loess-paleosol sequence in Aleksandrov quarry (51º05'N, 36º08'E) does not have an analogous with respect to the completeness in the whole East European Plain. In the filling of paleobalka the Ryshkovo paleosol of the Mikulino interglacial (MIS 5e) is observed. Over this paleosol, the Valdai soil-sediment series (MIS 5d – MIS 2) is located. It includes four interstadial soils, two of them of the Early Valdai (Kukuevo and Streletsk ones), and two, sometimes three, of the Middle Valdai (Aleksandrov, Hydrouzel и Bryansk ones). The OSL date, 127 ± 8 ka BP, (beginning of MIS 5e) was obtained for a sample taken from the bottom of the Ryshkovo soil. The interglacial soil is overlain by the Seym layer formed mainly from destroyed and redeposited horizons of this soil. For the upper part of the Seym layer, OSL dates of 115 ± 7 ka BP and 112 ± 20 ka BP were obtained (MIS 5d). But the process of burial of Ryshkovo soil in the bottom of the paleobalka began at the end of the interglacial after a catastrophic forest fire. Large post-permafrost deformations - pseudomorphosis is confined to Selikhovodvor loess - MIS 4 (65 ± 8 ka BP). Two soils occurring between Seym and Selikhovodvor loesses: Kukuevo and Streletsk - Early Valdai (MIS 5c and MIS 5a). For Mlodat loess which separates those two soils (MIS 5b), OSL dates of 91 ± 1 and 89 ± 7 ka BP were obtained. For paleosols of Middle Valdai (MIS 3), <sup>14</sup>C-dates were obtained: Aleksandrov (53.742 - 2.124 ka cal BP) and Bryansk soils (37.618 ± 0.668 ka cal BP). For Tuskar loess, which separates Alexandrov and Bryansk soils, OSL dates of 50 ± 3 and 51 ± 3 ka BP were obtained. The new stratigraphic scheme of Late Pleistocene agrees with the ideas of researchers from Eastern, Central, and Western Europe , which allows the following correlations. The identified paleosols correspond to the following intervals: Ryshkovo – Eemian interglacial (127-117 ka BP); Kukuevo to Amersfoort + Brørup – Saint-Germain 1 (105-95 ka BP); Streletsk – Odderade to Saint-Germain 2 (about 85-75 ka BP); Aleksandrov to Oerel (56-53 ka BP); Hydrouzel to Moershoofd – Poperinge (44-45 ka BP) and Hengelo (40-38 ka BP); and Bryansk (33-27 ka BP) to Stillfried B, Denekamp or Grand Bois interstadials. The reconstructed Late Pleistocene loess-paleosol sequence has the most similar structure with loess-paleosol sequences of Ukraine, with sequence Dolní Věstonice in Moravia (Czech Republik), Stillfried in Austria and Mainz-Weisenau in the Rhenish area (Germany), and other archives. <strong>This work was supported by RFBR, grant N19-29-05024 mk. </strong></p>


2021 ◽  
pp. SP522-2021-69
Author(s):  
H. Allen Curran ◽  
Bosiljka Glumac

AbstractThe rosetted trace fossil Dactyloidites ottoi (Geinitz, 1849) is reported and described for the first time from late Pleistocene (MIS 5e) carbonates of the Bahama Archipelago in shallowing-upward, shelly calcarenites from Great Inagua and Great and Little Exuma islands. The distinctive, fan-shaped D. ottoi specimens from the Bahamas, while not preserved in fine detail and not revealing a shaft, compare favourably in shape and size with specimens from other localities around the world, including the oldest well-documented specimens from the Jurassic of Argentina. D. ottoi is interpreted as a fodinichnion formed by the activity of a deposit-feeding worm, probably a polychaete, consuming marine-plant remains within host sediment. The late Pleistocene palaeodepositional environment of these carbonate sediments is interpreted as within the lower foreshore-upper shoreface zone in full marine, tropical waters. This discovery of D. ottoi marks an addition to the Bahamian shallow-marine ichnocoenose within the Skolithos ichnofacies.


2020 ◽  
Vol 394 ◽  
pp. 106829 ◽  
Author(s):  
Ricardo S. Ramalho ◽  
Rui Quartau ◽  
Ármann Hóskuldsson ◽  
José Madeira ◽  
João Ventura da Cruz ◽  
...  

Radiocarbon ◽  
2021 ◽  
pp. 1-10
Author(s):  
Andrei V Shpansky ◽  
Yaroslav V Kuzmin

ABSTRACT We report a new series of radiocarbon (14C) dates on the MIS 3 megafauna for a previously poorly studied region of southeastern West Siberia. Some species, like woolly mammoth and woolly rhinoceros, and Pleistocene bison and horse, existed throughout the MIS 3 (ca. 29–59 ka cal BP); cave hyaena is dated to ca. 46,400 cal BP. The very late 14C dates on Khozarian steppe elephant (Mammuthus trogontherii chosaricus), ca. 45,100–45,400 cal BP, may indicate the survival of this species in Siberia up to MIS 3. More work is needed to confirm or reject this suggestion. Previously, Khozarian steppe elephant was known in Siberia only at the beginning of the Late Pleistocene (MIS 5e).


2013 ◽  
Vol 62 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Tobias Sprafke ◽  
Birgit Terhorst ◽  
Robert Peticzka ◽  
Christine Thiel

Abstract. Die über 12 m mächtige Löss-Paläoboden-Sequenz in Paudorf (Niederösterreich), ist seit Jahrzehnten bekannt als locus typicus für die „Paudorfer Bodenbildung“. Dieser 1 m mächtige Pedokomplex im obersten Profilabschnitt entwickelte sich eem- bis frühwürmzeitlich. Das differenzierte Lösssediment im Liegenden, mit einem über 2 m mächtigen Pedokomplex im basalen Bereich, stellt ein außergewöhnliches Archiv mittelpleistozäner Landschaftsentwicklung dar. Die paläopedologischen und sedimentologischen Untersuchungen sowie erste mikromorphologische Analysen widmen sich erstmals der Gesamtabfolge und den Prozessen, die zu ihrer Entstehung beitrugen. Farb- und Karbonatanalysen in hoher Auflösung sowie detaillierte Korngrößenanalysen dienen dabei als hilfreiche Datenbasis. Die Untersuchungen zeigen zum einen, dass die Lösssedimente einer komplexen Genese unter periglazialen Bedingungen unterlagen. Neben äolischer Akkumulation spielten (zumeist solifluidale) Umlagerungsprozesse unter Einmischung von lokalem Material ebenso wie in situ Prozesse eine Rolle. Morphodynamisch stabile Phasen sind insbesondere in den beiden Pedokomplexen nachweisbar. In Bereichen, in denen Datierungen vorliegen, können Entwicklungsphasen mit jenen anderer Sequenzen korreliert werden und als klimatische Signale interpretiert werden. Die „Paudorfer Bodenbildung“ ist vermutlich eine frühglaziale Humuszone (MIS 5c[–a?]), die sich in einer solifluidal umgelagerten (MIS 5d) eemzeitliche Braunerde (MIS 5e) gebildet hat. Im Lösssediment konnten Nassböden nachgewiesen werden, wie sie typisch für spätrisszeitliche (MIS 6) Sequenzen sind. Der untere Pedokomplex wurde offenbar über mehrere Warmphasen verschiedener Intensitäten hinweg gebildet und wiederholt von Umlagerungsprozessen und äolischer Sedimentation während Kaltphasen unterbrochen.


2015 ◽  
Vol 114 ◽  
pp. 126-148 ◽  
Author(s):  
Sérgio P. Ávila ◽  
Carlos Melo ◽  
Luís Silva ◽  
Ricardo S. Ramalho ◽  
Rui Quartau ◽  
...  
Keyword(s):  
Mis 5E ◽  

Zootaxa ◽  
2010 ◽  
Vol 2680 (1) ◽  
pp. 33 ◽  
Author(s):  
KAI WINKELMANN ◽  
JOHN S. BUCKERIDGE ◽  
ANA CRISTINA COSTA ◽  
MARIA ANA MANSO DIONÍSIO ◽  
ANDRÉ MEDEIROS ◽  
...  

A new species of Archaeobalanidae barnacle is described from the late Miocene and early Pliocene of Santa Maria Island (Azores). Samples were collected primarily from outcrops at Malbusca and “Pedra-que-Pica”. Zullobalanus santamariaensis sp. nov. is endemic to the Azores archipelago and until the discovery of this material, the genus was known only from the Southern Hemisphere. For such a long-range distribution we assume a combination of planktotrophic larval development, sea-surface oceanic currents and transport by cetaceans. This study endorses the elevation of the subgenus Zullobalanus to generic level.


2020 ◽  
Vol 221 (2) ◽  
pp. 1232-1247
Author(s):  
Ana M G Ferreira ◽  
Augustin Marignier ◽  
Januka Attanayake ◽  
Michael Frietsch ◽  
Andrea Berbellini

SUMMARY Determining the crustal structure of ocean island volcanoes is important to understand the formation and tectonic evolution of the oceanic lithosphere and tectonic swells in marine settings, and to assess seismic hazard in the islands. The Azores Archipelago is located near a triple junction system and is possibly under the influence of a mantle plume, being at the locus of a wide range of geodynamic processes. However, its crustal structure is still poorly constrained and debated due to the limited seismic coverage of the region and the peculiar linear geometry of the islands. To address these limitations, in this study we invert teleseismic Rayleigh wave ellipticity measurements for 1-D shear wave speed (VS) crustal models of the Azores Archipelago. Moreover, we test the reliability of these new models by using them in independent moment tensor inversions of local seismic data and demonstrate that our models improve the waveform fit compared to previous models. We find that data from the westernmost seismic stations used in this study require a shallower Moho depth (∼10 km) than data from stations in the eastern part of the archipelago (∼13–16 km). This apparent increase in the Moho depth with increasing distance from the mid-Atlantic ridge (MAR) is expected. However, the rate at which Moho deepens away from the MAR is greater than that predicted from a half-space cooling model, suggesting that local tectonic perturbations have modified crustal structure. The 1-D VS models obtained beneath the westernmost seismic stations also show higher wave speeds than for the easternmost stations, which correlates well with the ages of the islands except Santa Maria Island. We interpret the relatively low VS profile found beneath Santa Maria Island as resulting from underplating, which agrees with previous geological studies of the island. Compared to a recent receiver function study of the region, the shallow structure (top ∼2 km) in our models shows lower shear wave speed, which may have important implications for future hazard studies of the region. More generally, the new seismic crustal models we present in this study will be useful to better understand the tectonics, seismicity, moment tensors and strong ground motions in the region.


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