New late Miocene and Pliocene occurrences of Globorotalia species from the North Atlantic; and a paleogeographic review

1979 ◽  
Vol 9 (3) ◽  
pp. 210-227 ◽  
Author(s):  
R. Cifelli ◽  
G. Glacon
Keyword(s):  
North Atlantic ◽  
Late Miocene ◽  
The North ◽  
The North Atlantic

scholarly journals Reinforcing the North Atlantic backbone: revision and extension of the composite splice at ODP Site 982

2017 ◽  
Author(s):  
Anna Joy Drury ◽  
Thomas Westerhold ◽  
David Hodell ◽  
Ursula Röhl
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
North Atlantic ◽  
Late Miocene ◽  
Deep Sea ◽  
Equatorial Atlantic ◽  
The North ◽  
Isotope Stratigraphy ◽  
Stable Isotope Stratigraphy ◽  
The North Atlantic

Abstract. Ocean Drilling Programme (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To resolve this uncertainty, we verify and extend the early Pliocene to late Miocene shipboard composite splice at Site 982 using high-resolution XRF core scanning data and establish a robust high-resolution stable isotope stratigraphy and astrochronology between 4.5 and 8.0 Ma. Splice revisions and verifications resulted in ~ 11 m of gaps in the original Site 982 isotope stratigraphy. Our new stratigraphy reveals previously unseen benthic δ18O excursions, particularly prior to 6.65 Ma. The benthic δ18O record displays distinct, asymmetric cycles between 7.7 and 6.65 Ma, confirming that high-latitude climate is a prevalent forcing during this interval. An intensification of the 41-kyr beat in both the benthic δ13C and δ18O is also observed ~ 6.4 Ma, marking a strengthening in the cryosphere-carbon cycle coupling. A large ~ 0.7 ‰ double excursion is revealed ~ 6.4–6.3 Ma, which also marks the onset an interval of average higher δ18O and large precession and obliquity-dominated δ18O excursions between 6.4–5.4 Ma, coincident with the culmination of the late Miocene cooling. The two largest benthic δ18O excursions ~ 6.4–6.3 Ma and TG20/22 coincide with the coolest alkenone-derived SST estimates from Site 982, suggesting a strong connection between the late Miocene global cooling and deep-sea cooling and dynamic ice sheet expansion. The splice revisions and revised astrochronology resolve key stratigraphic issues that have hampered correlation between Site 982, the equatorial Atlantic and the Mediterranean. Comparisons of the revised Site 982 stratigraphy to high-resolution astronomically tuned benthic δ18O stratigraphies from ODP Site 926 (equatorial Atlantic) and Ain el Beida (north western Morocco) show that prior inconsistencies in short-term excursions are now resolved. Our new integrated deep-sea benthic stable isotope stratigraphy and astrochronology from Site 982 will facilitate future high-resolution late Miocene to early Pliocene climate research.

scholarly journals Effect of vegetation on the Late Miocene ocean circulation

2006 ◽  
Vol 2 (4) ◽  
pp. 605-631 ◽  
Author(s):  
G. Lohmann ◽  
M. Butzin ◽  
A. Micheels ◽  
T. Bickert ◽  
V. Mosbrugger
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Late Miocene ◽  
Land Surface ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
The North ◽  
The North Atlantic

Abstract. A weak and shallow thermohaline circulation in the North Atlantic Ocean is related to an open Central American gateway and exchange with fresh Pacific waters. We estimate the effect of vegetation on the ocean general circulation using the atmospheric circulation model simulations for the Late Miocene climate. Caused by an increase in net evaporation in the Miocene North Atlantic, the North Atlantic water becomes more saline which enhances the overturning circulation and thus the northward heat transport. This effect reveals a potentially important feedback between the ocean circulation, the hydrological cycle and the land surface cover for Cenozoic climate evolution.

scholarly journals Reinforcing the North Atlantic backbone: revision and extension of the composite splice at ODP Site 982

2018 ◽  
Vol 14 (3) ◽  
pp. 321-338 ◽  
Author(s):  
Anna Joy Drury ◽  
Thomas Westerhold ◽  
David Hodell ◽  
Ursula Röhl
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
North Atlantic ◽  
Late Miocene ◽  
Deep Sea ◽  
Equatorial Atlantic ◽  
The North ◽  
Isotope Stratigraphy ◽  
Stable Isotope Stratigraphy ◽  
The North Atlantic

Abstract. Ocean Drilling Program (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To resolve this uncertainty, we verify and extend the early Pliocene to late Miocene shipboard composite splice at Site 982 using high-resolution XRF core scanning data and establish a robust high-resolution benthic foraminiferal stable isotope stratigraphy and astrochronology between 8.0 and 4.5 Ma. Splice revisions and verifications resulted in  ∼  11 m of gaps in the original Site 982 isotope stratigraphy, which were filled with 263 new isotope analyses. This new stratigraphy reveals previously unseen benthic δ18O excursions, particularly prior to 6.65 Ma. The benthic δ18O record displays distinct, asymmetric cycles between 7.7 and 6.65 Ma, confirming that high-latitude climate is a prevalent forcing during this interval. An intensification of the 41 kyr beat in both the benthic δ13C and δ18O is also observed  ∼  6.4 Ma, marking a strengthening in the cryosphere–carbon cycle coupling. A large  ∼  0.7 ‰ double excursion is revealed  ∼  6.4–6.3 Ma, which also marks the onset of an interval of average higher δ18O and large precession and obliquity-dominated δ18O excursions between 6.4 and 5.4 Ma, coincident with the culmination of the late Miocene cooling. The two largest benthic δ18O excursions  ∼  6.4–6.3 Ma and TG20/22 coincide with the coolest alkenone-derived sea surface temperature (SST) estimates from Site 982, suggesting a strong connection between the late Miocene global cooling, and deep-sea cooling and dynamic ice sheet expansion. The splice revisions and revised astrochronology resolve key stratigraphic issues that have hampered correlation between Site 982, the equatorial Atlantic and the Mediterranean. Comparisons of the revised Site 982 stratigraphy to high-resolution astronomically tuned benthic δ18O stratigraphies from ODP Site 926 (equatorial Atlantic) and Ain el Beida (north-western Morocco) show that prior inconsistencies in short-term excursions are now resolved. The identification of key new cycles at Site 982 further highlights the requirement for the current scheme for late Miocene marine isotope stages to be redefined. Our new integrated deep-sea benthic stable isotope stratigraphy and astrochronology from Site 982 will facilitate future high-resolution late Miocene to early Pliocene climate research.

scholarly journals Diversity of late Neogene Monachinae (Carnivora, Phocidae) from the North Atlantic, with the description of two new species

2018 ◽  
Vol 5 (3) ◽  
pp. 172437 ◽  
Author(s):  
Leonard Dewaele ◽  
Carlos Mauricio Peredo ◽  
Pjotr Meyvisch ◽  
Stephen Louwye
Keyword(s):  
North America ◽  
North Atlantic ◽  
Late Miocene ◽  
East Coast ◽  
Type Specimens ◽  
The North ◽  
Late Neogene ◽  
New Material ◽  
The North Sea ◽  
The North Atlantic

While the diversity of ‘southern seals’, or Monachinae, in the North Atlantic realm is currently limited to the Mediterranean monk seal, Monachus monachus , their diversity was much higher during the late Miocene and Pliocene. Although the fossil record of Monachinae from the North Atlantic is mainly composed of isolated specimens, many taxa have been erected on the basis of fragmentary and incomparable specimens. The humerus is commonly considered the most diagnostic postcranial bone. The research presented in this study limits the selection of type specimens for different fossil Monachinae to humeri and questions fossil taxa that have other types of bones as type specimens, such as for Terranectes parvus . In addition, it is essential that the humeri selected as type specimens are (almost) complete. This questions the validity of partial humeri selected as type specimens, such as for Terranectes magnus . This study revises Callophoca obscura , Homiphoca capensis and Pliophoca etrusca , all purportedly known from the Lee Creek Mine, Aurora, North Carolina, in addition to their respective type localities in Belgium, South Africa and Italy, respectively. C. obscura is retained as a monachine seal taxon that lived both on the east coast of North America and in the North Sea Basin. However, H. capensis from North America cannot be identified beyond the genus level, and specimens previously assigned to Pl. etrusca from North America clearly belong to different taxa. Indeed, we also present new material and describe two new genera of late Miocene and Pliocene Monachinae from the east coast of North America: Auroraphoca atlantica nov. gen. et nov. sp., and Virginiaphoca magurai nov. gen. et nov. sp. This suggests less faunal interchange of late Neogene Monachinae between the east and west coasts of the North Atlantic than previously expected.

scholarly journals Late Miocene-Early Pliocene Planktonic Foraminifera and Palaeoceanography of the North Atlantic

1991 ◽  
Vol 9 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Peter W. P. Hooper ◽  
Brian M. Funnell ◽  
Philip P. E. Weaver
Keyword(s):  
North Atlantic ◽  
Late Miocene ◽  
Planktonic Foraminifera ◽  
Time Interval ◽  
Messinian Salinity Crisis ◽  
Dominant Form ◽  
Early Pliocene ◽  
North East ◽  
The North ◽  
The North Atlantic

Abstract. Relative abundance variations of planktonic Foraminifera have been studied for the Late Miocene to Early Pliocene time interval of 7.0 to 3.5 Ma from three sites in the North East Atlantic; DSDP607 (41°N), DSDP609 (50°N) and DSDP611 (53°N), Particular attention has been given to the percentage of benthic Foraminifera of total (benthic + planktonic) Foraminifera as an index of dissolution by aggressive bottom waters, and to the percentage of dextral Neogloboquadrina pachyderma of total (dextral + sinistral) N. pachyderma as an index of “Sub-Polar” or warmer waters.Strong dissolution, probably associated with the northward penetration of aggressive Antarctic Bottom Water, is observed at two of the sites up to and during the initiation of the Messinian “Salinity Crisis” in the adjoining Mediterranean Sea at about 5.8 Ma. All three sites exhibit strong cyclic fluctuations of the percentage of dextral N. pachyderma during the Messinian “Salinity Crisis” interval, from approximately 5.8 Ma to 4.8 Ma. These are interpreted as indicating wide-ranging oscillations of a water mass boundary, analogous to the present-day Polar Front, in the North Atlantic during the “Salinity Crisis”. Following the re-filling of the Mediterranean with normal marine waters at about 4.8 Ma, the dextral form of N. pachyderma, which is more characteristic of warmer waters than the sinistral form, becomes the dominant form and shows less quantitative variation at all three sites throughout the Early Pliocene.

scholarly journals Scaldiporia vandokkumi, a new pontoporiid (Mammalia, Cetacea, Odontoceti) from the Late Miocene to earliest Pliocene of the Westerschelde estuary (The Netherlands)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3991 ◽  
Author(s):  
Klaas Post ◽  
Stephen Louwye ◽  
Olivier Lambert
Keyword(s):  
The Netherlands ◽  
North Atlantic ◽  
Late Miocene ◽  
New Genus ◽  
South Atlantic ◽  
New Genus And Species ◽  
The North ◽  
Westerschelde Estuary ◽  
The Family ◽  
The North Atlantic

Background The family Pontoporiidae (Cetacea, Odontoceti, Inioidea) is currently represented in our oceans by just one species of diminutive dolphin (Pontoporia blainvillei, franciscana). Although P. blainvillei is limited to coastal waters of the South Atlantic along Brazil, Uruguay and Argentina, multiple Miocene and Pliocene fossils indicate the past presence of members of the family in the South Atlantic, South Paciifc and North Atlantic oceans. Our comprehension of the origin and diversity of this clade and of the relationships of its members with other inioids is hampered by the fact that part of the described fossil specimens, especially from the North Atlantic realm, are cranial fragments often associated to limited stratigraphic information. Methods Based on an almost complete fossil cranium of pontoporiid from the Westerschelde estuary, The Netherlands, whose preservation allows for detailed morphological observations, we describe a new genus and species. The latter is compared to other pontoporiids, as well as a few non-pontoporiid inioids. A phylogenetic analysis is performed to investigate the relationship of S. vandokkumi with the best-known extinct and extant inioids. Palynological analysis of the sediment associated to the holotype is used to assess its geological age. Results and discussion The new genus and species Scaldiporia vandokkumi is characterized among others by greatly thickened premaxillary eminences reaching the level of the antorbital notch. Palynologically dated from the late Tortonian—earliest Zanclean (7.6–5 Ma, Late Miocene—earliest Pliocene), this new pontoporiid confirms the surprising past diversity of marine inioids in the North Atlantic area. Finally the content of the pontoporiid subfamily Brachydelphininae is briefly discussed.

scholarly journals A new species of rorqual whale (Cetacea, Mysticeti, Balaenopteridae) from the Late Miocene of the Southern North Sea Basin and the role of the North Atlantic in the paleobiogeography of Archaebalaenoptera

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8315 ◽  
Author(s):  
Michelangelo Bisconti ◽  
Dirk K. Munsterman ◽  
René H.B. Fraaije ◽  
Mark E.J. Bosselaers ◽  
Klaas Post
Keyword(s):  
New Species ◽  
The Netherlands ◽  
North Sea ◽  
North Atlantic ◽  
Late Miocene ◽  
North Atlantic Ocean ◽  
Center Of Origin ◽  
Southern North Sea ◽  
The North ◽  
The North Atlantic

Background The rich fossil record of rorqual and humpback whales (Cetacea, Mysticeti, Balaenopteridae) is mainly characterized by monotypic genera since genera including more than one species are extremely rare. The discovery of new species belonging to known genera would be of great importance in order to better understand ancestor-descendant relationships and paleobiogeographic patterns in this diverse group. Recent discoveries in the southern North Sea Basin yielded a number of reasonably well preserved fossil balaenopterids from the Late Miocene; this sample includes a balaenopterid skull from Liessel, The Netherlands, which shares key characters with Archaebalaenoptera castriarquati from the Pliocene of Mediterranean. This skull is permanently held by Oertijdmuseum, Boxtel, The Netherlands, with the number MAB002286 and is investigated here. Methods A detailed comparative anatomical analysis of the skull MAB002286 is performed in order to understand its relationships. The age of the skull is determined by dinocyst analysis of the associated sediment. A paleobiogeographic analysis is performed to understand paleobiogeographic patterns within the balaenopterid clade the new skull belongs to. Results Our work resulted in the description of Archaebalaenoptera liesselensis new species. The geological age of the holotype skull is between 8.1 and 7.5 Ma. The phylogenetic relationships of this species reveals that it is monophyletic with Archaebalaenoptera castriarquati from the Italian Pliocene. Moreover, in combination with a more basal species of Archaebalaenoptera from the late Miocene of Peru, our paleobiogeographic analysis suggests that the North Atlantic ocean played a major role as a center of origin of a number of balaenopterid clades including Protororqualus, Archaebalaenoptera and more advanced balaenopterid taxa. From a North Atlantic center of origin, two dispersal events are inferred that led to the origins of Archaebalaenoptera species in the South Pacific and Mediterranean. The distribution of Archaebalaenoptera was antitropical in the late Miocene. The role played by the Mediterranean salinity crisis is also investigated and discussed.

Geonettia waltonensis, a new goniodomacean dinoflagellate from the Pliocene of the North Atlantic region, and its evolutionary implications

2000 ◽  
Vol 74 (5) ◽  
pp. 812-827 ◽  
Author(s):  
Martin J. Head
Keyword(s):  
New Species ◽  
North Atlantic ◽  
Late Miocene ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
Closely Related Species ◽  
Dinoflagellate Cyst ◽  
The North ◽  
The North Atlantic ◽  
A New Species

A new species of the unusual dinoflagellate cyst genus Geonettia de Verteuil and Norris, 1996a is here described from the Pliocene of the western North Atlantic and eastern England. Geonettia waltonensis new species is only the second species to be formally described for this genus, whose type, G. clineae de Verteuil and Norris, 1996a, has a range of Miocene through Pliocene. Geonettia is a gonyaulacalean, goniodomacean genus of the subfamily Pyrodinioideae and is closely related to Eocladopyxis Morgenroth, 1966 and Capisocysta Warny and Wrenn, 1997, also found in the Cenozoic. However, Geonettia is the only known dinoflagellate cyst genus to have plates that dissociate extensively on both epi- and hypocyst during excystment. Geonettia waltonensis has this style of excystment, but its hypocystal tabulation is more akin to Capisocysta lata Head, 1998a than to G. clineae. Comparison of tabulation and other morphological features suggests that during the late Miocene, Capisocysta lata evolved from Geonettia waltonensis or a closely related species through failure of its epicystal plates to dissociate. Geonettia waltonensis probably did not evolve directly from G. clineae but may represent a separate lineage within Geonettia that arose during the Miocene.

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