Middle Pleistocene
Encyclopedia
The Middle Pleistocene, more specifically referred to as the Ionian stage, is a period of geologic time from ca. 781 to 126 thousand years ago.
The base of the Ionian Stage succeeds the Calabrian Stage (the beginning of the Brunhes–Matuyama reversal) and precedes the Tyrrhenian Stage
or Upper Pleistocene, which in turn spans from the beginning of the last interglacial (Marine isotopic stage
5) to the base of the Holocene
(~10.5 ka).
Although experts are not yet in agreement on how to subdivide the stages of the Pleistocene
epoch, a possible international consensus on one subdivision of the Pleistocene
epoch called the Ionian Stage exists. The Ionian stage includes all of the European Sicilian Stage
and the first part of the Tyrrhenian Stage
.
margin was characterized by high sedimentation rates, in response to intense differential tectonic subsidence
and massive sedimentary yield. Specifically, candidate sections are the “Montalbano Jonico
” Section (Bradanic Trough, Basilicata
Region) and the “Valle di Manche Nord” Section (San Mauro Marchesato
, Crotone Basin, Calabria
Region). In the former, a spectacular succession of marls laid in the Apennine foredeep is exposed which, however, are unfortunately unsuitable for magnetostratigraphic
analyses. The latter, which is represented by a shallowing-upward succession that developed in an outer-shelf environment, has the bonus of a sharp biomagnetostratigraphic record, which provides tighter age control.
Besides these exposures, a number of ODP
cores drilled either in the Ionian Sea (Site 964) and in the Sicily Channel-Capo Rossello area (Site 963) are available, which correlate well with the on-land sections mentioned above based on a significant number of criteria (magnetostratigraphy, biostratigraphy
, sapropel
stratigraphy, stable isotopes, Tephrochronology
). The interval corresponding to the Ionian Stage is especially well represented in Site 963, where no turbidites and/or hiatuses are recognized. Presently, the Montalbano Ionico section is possibly the main candidate for defining the Lower - Middle Pleistocene boundary, when a reliable magnetostratigraphic record is found.
The base of the Ionian Stage succeeds the Calabrian Stage (the beginning of the Brunhes–Matuyama reversal) and precedes the Tyrrhenian Stage
Tyrrhenian Stage
The Tyrrhenian Stage is the last faunal stage of the Pleistocene in Italy. It runs from 0.26 million to 0.01143 million years ago. It overlaps with the end of the Middle Pleistocene and all of the Late Pleistocene...
or Upper Pleistocene, which in turn spans from the beginning of the last interglacial (Marine isotopic stage
Marine isotopic stage
Marine isotope stages , marine oxygen-isotope stages, or oxygen isotope stages , are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data reflecting changes in temperature derived from data from deep sea core samples...
5) to the base of the Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
(~10.5 ka).
Although experts are not yet in agreement on how to subdivide the stages of the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epoch, a possible international consensus on one subdivision of the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epoch called the Ionian Stage exists. The Ionian stage includes all of the European Sicilian Stage
Sicilian Stage
The Sicilian European Stage is a European faunal stage in the period of geological time between 0.781 ± 0.005 Ma and 0.26 Ma . It is considered to be in the middle of the Pleistocene epoch....
and the first part of the Tyrrhenian Stage
Tyrrhenian Stage
The Tyrrhenian Stage is the last faunal stage of the Pleistocene in Italy. It runs from 0.26 million to 0.01143 million years ago. It overlaps with the end of the Middle Pleistocene and all of the Late Pleistocene...
.
Origin
Suitable sections for defining the base of the Ionian Stage are located in southern Italy. During Lower and Middle Pleistocene the Adriatic-IonianIonian Sea
The Ionian Sea , is an arm of the Mediterranean Sea, south of the Adriatic Sea. It is bounded by southern Italy including Calabria, Sicily and the Salento peninsula to the west, southern Albania to the north, and a large number of Greek islands, including Corfu, Zante, Kephalonia, Ithaka, and...
margin was characterized by high sedimentation rates, in response to intense differential tectonic subsidence
Subsidence
Subsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation...
and massive sedimentary yield. Specifically, candidate sections are the “Montalbano Jonico
Montalbano Jonico
Montalbano Jonico is a town and comune in the province of Matera, in the Southern Italian region of Basilicata....
” Section (Bradanic Trough, Basilicata
Basilicata
Basilicata , also known as Lucania, is a region in the south of Italy, bordering on Campania to the west, Apulia to the north and east, and Calabria to the south, having one short southwestern coastline on the Tyrrhenian Sea between Campania in the northwest and Calabria in the southwest, and a...
Region) and the “Valle di Manche Nord” Section (San Mauro Marchesato
San Mauro Marchesato
San Mauro Marchesato is a comune and town with a population of 2002 people in the province of Crotone, in Calabria, Italy....
, Crotone Basin, Calabria
Calabria
Calabria , in antiquity known as Bruttium, is a region in southern Italy, south of Naples, located at the "toe" of the Italian Peninsula. The capital city of Calabria is Catanzaro....
Region). In the former, a spectacular succession of marls laid in the Apennine foredeep is exposed which, however, are unfortunately unsuitable for magnetostratigraphic
Magnetostratigraphy
Magnetostratigraphy is a geophysical correlation technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout the section. The samples are analyzed to determine their characteristic remanent magnetization , that is, the...
analyses. The latter, which is represented by a shallowing-upward succession that developed in an outer-shelf environment, has the bonus of a sharp biomagnetostratigraphic record, which provides tighter age control.
Besides these exposures, a number of ODP
Ocean Drilling Program
The Ocean Drilling Program was an international cooperative effort to explore and study the composition and structure of the Earth's ocean basins. ODP, which began in 1985, was the direct successor to the highly successful Deep Sea Drilling Project initiated in 1968 by the United States...
cores drilled either in the Ionian Sea (Site 964) and in the Sicily Channel-Capo Rossello area (Site 963) are available, which correlate well with the on-land sections mentioned above based on a significant number of criteria (magnetostratigraphy, biostratigraphy
Biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period...
, sapropel
Sapropel
Sapropel is a term used in marine geology to describe dark-coloured sediments that are rich in organic matter...
stratigraphy, stable isotopes, Tephrochronology
Tephrochronology
250px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at the height of the [[volcanologists]] hands is [[rhyolitic]] [[tephra]] from [[Hekla]]....
). The interval corresponding to the Ionian Stage is especially well represented in Site 963, where no turbidites and/or hiatuses are recognized. Presently, the Montalbano Ionico section is possibly the main candidate for defining the Lower - Middle Pleistocene boundary, when a reliable magnetostratigraphic record is found.
Faunal stages
- North American Land Mammal AgesNorth American Land Mammal AgesThe North American Mammal Ages establishes a geologic timescale for prehistoric North American fauna beginning 66.5 Ma during the Paleocene and continuing through to the Late Pleistocene...
within the Middle Pleistocene: - South American Land Mammal Ages within the Middle Pleistocene:
- Asian Land Mammal AgesAsian land mammal agesThe Asian Land Mammal Ages establishes a geologic timescale for prehistoric Asian fauna beginning 58.7 Mya during the Paleogene and continuing through to the Middle Pleistocene...
within the Middle Pleistocene: - European Land Mammal AgesEuropean Land Mammal AgesThe European Land Mammal Mega Zones are zones in rock layers that have a specific assemblage of fossils based on occurrences of fossil assemblages of European land mammals. These biozones cover most of the Neogene and Paleogene systems The European Land Mammal Mega Zones (abbreviation: ELMMZ,...
within the Middle Pleistocene: