Magnetostratigraphic dating of the middle and late Pliocene sequence in the marchean apennines, Central Italy.

Il Quaternario Italian Journal of Quaternary Scienz

The lower and middle Pleistocene geological record of the San Lorenzo lacustrine sequence in Sant’Arcangelo Basin (Southern Apennines, Italy)

A facies analysis and preliminary palaeoclimate and biochronology investigation, are presented for the San Lorenzo lacustrine deposits, outcropping in the Pliocene to Pleistocene satellite Sant'Arcangelo Basin (Southern Apennines). Facies analysis shows that sedimentation developed in the inner zone of a terrigenous-dominated fresh water lake. The pollen record shows repeated alternations between two distinct vegetational assemblages, one dominated by steppe taxa, and the other one by forest taxa. The faunal assemblage is indicative of a late Biharian mammal age. The palaeomagnetic survey yielded three polarity intervals throughout the succession; the middle one is of reversed polarity (and is associated with a volcaniclastic layer radiometrically dated at approximately 1 Ma), and thus the two normal polarity intervals are identified as the Jaramillo subchron and the base of the Brunhes chron. The detailed geological and paleontological analyses as well as the preliminary results from the palynological and magnetostratigraphical investigation, indicates that these deposits may contain a continuous record of both climatic changes and tectonic activity within the Sant'Arcangelo Basin during the early and middle Pleistocene. © 2004 Elsevier Ltd and INQUA. All rights reserved

The lower and middle Pleistocene geological record of the San Lorenzo lacustrine succession in the Sant'Arcangelo Basin (Southern Apennines, Italy)

The Sant’Arcangelo Basin is located in the southern part of the Apennine chain (Basilicata). It is filled by a siliciclastic sequence 3500m thick, dated to the Late Pliocene–Middle Pleistocene time interval. In this basin an Early Middle Pleistocene fluvio-lacustrine sequence, known as San Lorenzo Cycle, has been recognised. In the upper part of the sequence, in Rifreddo, a fairly diversified small vertebrate assemblage has been recovered. The occurrence of Mimomys savini allows to the fauna to be considered as Biharian. The presence of some faunal elements such as Microtus (Terricola) arvalidens, Microtus (Iberomys) ex gr. huescarensis-brecciensis, and Macroneomys cf. brachygnathus restricts the age of the Rifreddo assemblage to the latest part of this Mammal Age. In several European localities, sediments containing such late Biharian faunas are correlated with the lower part of Brunhes magnetochrone (e.g. the normally magnetised sections at West Runton in the United Kingdom, Voigtstedt in Germany and Prˇezletice in the Czech Republic) or just below this boundary (e.g. the negatively magnetised part of the Atapuerca section—levels TD4-6 in Spain). Taking into account the faunal composition and the positive magnetisation of the sediments outcropping at the Rifreddo locality, the chronological referral of the mammal assemblage can be restricted to the early Brunhes and therefore to the early middle part of Middle Pleistocene

The Colle Curti Mammal Site in the Colfiorito area Umbria-Marchean Apennine, Italy): geomorphology, stratigraphy, paleomagnetism and palynology

An approximately90 mthicksequencehasbeenstudiedinthe ColleCurtibasin(Colfioritoarea,Umbria-MarcheanApennine).Itwasdepositedin adrainagesystemcharacterizedbya‘mature’landscapewithouta clearwatershedseparatingtheAdriaticandTyrrheniansides.Closetotheendof the Early Pleistocene this landscape was dismembered by the activation of extensional faults, linked to an uplifting of the chain that reached its greatest magnitude at the beginning of the Middle Pleistocene. From a sedimentological point of view the sequence can be roughly divided into threeparts,withgraveldepositionin abraidplainenvironmentdominatingthelowerandupperparts,and aphaseof claydepositionina lacustrine environmentseparatingthese.AnAr/Aranalysisonthesanidinecontainedinavertisolintheupperpartofthesequencegaveanagenotolderthan 427 ka. An early Galerian fauna was collected in clay layers where the Jaramillo palaeomagnetic event was recognized. Cold periods are documented in the lower and upper part of the sequence, although in the latter the intense weathering caused by the development of a soil with tropical features precludes further investigations. The palynological data supported by sedimentological and palaeomagnetic evidence indicate that the sequence can be related to a large part of the Bavelian and part of the Menapian. In the middle part, where clay layers outcrop, two cool and humid phases are followed by colder and drier periods. Biological and geological evidence suggests that around 1My the basin of Colle Curti was probably located at an elevation of about 600 m

Climatic control on deposition of upper Pliocene deepwater gravity-driven strata in the Apennines foredeep (central Italy): correlations to the marine oxygen sea isotope record.

The thick upper Pliocene to lower Pleistocene succession of hemipelagic mudstones of the Marche Apennines foredeep (central Italy) is punctuated by several mostly coarse-grained, cyclic turbidite systems. Integrated and detailed analyses of sedimentary facies, physical stratigraphy, biostratigraphy, and magnetostratigraphy have provided a high-resolution sequence stratigraphic framework for sediments of two of these coarse-grained systems, each resulting from the stack of five deepwater, high-frequency depositional sequences backfilling the mouth and lower reaches of a long-lived submarine canyon. The tight chronostratigraphic control available on these two turbidite systems and encasing hemipelagic sediments allows a precise correlation of the component high-frequency sequences with the Pliocene marine oxygen isotope curve. This reveals that the cyclic arrangement occurred near the Gauss–Matuyama polarity transition and the onset of the Olduvai subchron in response to recurring, obliquity-driven global changes in sea level. Each depositional sequence, 20 to 65 m thick, includes sediments that were deposited by a range of gravity-driven processes, resulting in sedimentary motifs that contain a deep marine record of both glacial and interglacial stages. A typical depositional sequence comprises: (1) a lowstand systems tract composed of cohesionless-debris-flow conglomerates (braided submarine channel complex), which passes down-dip into turbidite sandstones (frontal-splay complex); (2) an overlying transgressive to early falling-stage systems tract composed of a mud-rich masstransport complex of slumped horizons and cohesive-mud-flow pebbly mudstones eventually overlain by a thin interval of hemipelagic mudstones. This stacking pattern records variations in depositional style, and hence, variations in canyon activity during eustatic changes in sea level