Unilocular calcareous Foraminifera of the middle-upper Eocene and lower Oligocene from Tierra del Fuego Island and adjacent continental platform, Argentina

A different basin evolution is suggested between the northern and southern parts of the Pindos basin, based on biostratigraphic dating results. Characteristic nannofossils showed that flysch sedimentation in the whole basin started in the Paleocene and generally finished during the Eocene, with the exception of the Konitsa and Milia areas where sedimentation lasted until Early Oligocene. Although, basin depth increased southwards, Kastaniotikos and Sperchios faults affected the geometry of Pindos basin, creating ridges and troughs within the basin. Due to this segmentation of the basin, the continuity of the sedimentation in the northern part of the study area until Oligocene is suggested. Calcareous nannofossils recovered from this northern part indicate a Paleocene NP5 to early Cligocene (NP20-21) age. On the other hand, in the southern part, sedimentation of flysch was lasted until middle Eocene. According this model, sedimentation in the southern part, stopped during the middle Eocene, was followed by subaerial exposure and the migration of clastic sedimentation to the western part of Pindos zones (Pindos foreland basin of Ionian zone). At this time, in the northern part, a small-restricted basin was continuously active as a piggyback basin from upper Eocene to lower Oligocene and shallow deposits (slope and submarine canyon deposits, delta fan deposits) accumulated.

Download Full-text

Insectivores (Mammalia) from the earliest Oligocene (MP 21) of Belgium

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s0016774600023489 ◽

2004 ◽

Vol 83 (3) ◽

pp. 187-192

Author(s):

R. Smith

Keyword(s):

Late Eocene ◽

Upper Eocene ◽

Faunal Turnover ◽

Early Oligocene ◽

New Immigrants ◽

Lower Oligocene ◽

Primitive Species ◽

Grande Coupure ◽

Important Progress

AbstractInsectivore remains are not common in the Lower Oligocene of Europe. For this reason, the study of the earliest Oligocene insectivore fauna (MP 21) from Boutersem and Hoogbutsel, all together yielding nine species, representing five families, constitutes an important progress in the knowledge of the Late Eocene and Early Oligocene insectivore evolution. Some of the genera discovered in Belgium are known from upper Eocene sites (Saturninia, Amphidozotherium, Euronyctia, Eotalpa), whereas others are not known before the Oligocene (Butselia, Tetracus, Heterosoricinae ind.). The co-occurrence of primitive species of Nyctitheriidae with modern forms belonging to the Plesiosoricidae, Talpidae and Erinaceidae at the Eocene-Oligocene boundary suggests a transition fauna. Between the Priabonian (Late Eocene) and the Rupelian (Early Oligocene), the endemic European insectivores were in competition with the new immigrants. This faunal turnover is generally accepted as the ‘Grande Coupure’ event (the MP 21 event).

Download Full-text

Coralgal facies of the Upper Eocene-Lower Oligocene limestones in Letca-Rastoci area

Studia Universitatis Babes-Bolyai Geologia ◽

10.5038/1937-8602.46.2.4 ◽

2001 ◽

Vol 46 (2) ◽

pp. 53-61 ◽

Cited By ~ 4

Author(s):

Ioana Prica

Keyword(s):

Upper Eocene ◽

Lower Oligocene

Download Full-text

The western termination of the South Pyrenean Triangle Zone; a structural and geophysical characterization.

10.5194/egusphere-egu21-3417 ◽

2021 ◽

Author(s):

Pablo Santolaria ◽

Concepción Ayala ◽

Emilio L. Pueyo ◽

Félix M. Rubio ◽

Ruth Soto ◽

...

Keyword(s):

Upper Eocene ◽

The South ◽

The North ◽

Triangle Zone ◽

Structural Style ◽

Lower Oligocene ◽

Thrust Belts ◽

Stratigraphic Model ◽

Structural Architecture ◽

Surface Geology

<p>The presence of multiple evaporite levels strongly influence the structural style and kinematics of fold-and-thrust belts. Particularly (but not exclusively) in their fronts, it is common for these d&#233;collements to favor the formation of triangle zones. In the central portion of the Pyrenees, the South Pyrenean Triangle Zone represents the frontal part of this chain, that involves the Oligocene-Miocene Ebro Basin foreland deposits. We have focused on its western termination, characterized by a salt-cored anticline that laterally passes to a backthrust which dies out to the west. These structures are detached on the Upper Eocene-Lower Oligocene syntectonic evaporite Barbastro Formation (and lateral equivalents) that acted as a multidetachment unit. To the north, the south-directed Pyrenean thrust unit detached on Middle-Upper Triassic evaporites to finally glide along the Upper Eocene-Lower Oligocene d&#233;collement horizons.</p><p>In this contribution, we present a detailed structural and stratigraphic model of this triangle zone termination, constructed accordingly to two major approaches (1) constraining the geometry and structural architecture based on surface geology, interpretation of seismic lines (>900 km) and wells and, (2) obtaining the 3D density distribution of the detachment level (Barbastro Fm. and lateral equivalents as well as deeper, Triassic evaporites) using gravity stochastic inversion by means of more than 7000 gravity stations and 1500 actual density data from surface rocks. All in all, this multidisciplinary approach allows us to characterize the western termination of the South Pyrenean Triangle zone as the transition from a ramp-dominated and multiple triangle zone to a detachment-dominated one whose geometry, kinematics, and location were controlled by the distribution and heterogeneity of the Upper Eocene-Lower Oligocene syntectonic d&#233;collements and the southern pinch-out of the basal detachment of this unit.</p>

Download Full-text