ASTRONOMICAL CALIBRATION OF THE UPPER LANGHIAN/LOWERSERRAVALLIAN RECORD OF RAS IL PELLEGRIN SECTION (MALTA ISLAND, CENTRAL MEDITERRANEAN)

A high-resolution geochemical and micropaleontological data set has been obtained from the uppermost Langhian/lower Serravallian marly sediments of the Ras il Pellegrin section (Malta Island). A combination of the recorded stratal organization with the results of spectral analyses performed on CaCO3 data and faunal signals shows a dominance of the classic Milankovitch periodicities as modulating forcing of the studied succession. The application of band-pass filters allowed us to select the different Milankovitch frequencies (precession, obliquity and short- and long-eccentricity) from the original faunal and geochemical signals and to compare them with the same components of the astronomical curve. The reliability of the short-term astronomical tuning has been tested by using the larger-order cyclicity (100-400 kyr) as control. The good match of the different records with the selected insolation curve is consistent with the results of the cross-spectral analysis showing high coherency values in all the considered frequency bands. The calibration provided astronomical ages for the sedimentary cycles and consequently for all the bioevents recorded in the section. In particular, an age of 13.59 Ma has been obtained for the last occurrence (LO) of Sphenolitus heteromorphus, at present considered the best bioevent useful for recognizing the Langhian/Serravallian boundary. Moreover, an age of 12.62 Ma has been obtained for the first occurrence (FO) of Paragloborotalia partimlabiata.

Sand geochemistry on sediment core CRP-3 from the Ross Sea, Antarctica

A total of 167 samples distubuted throughout the CRP-3 drillhole from 5.77 to 787.68 mbsf and representing fine to coarse sandstones have been analysed by X-ray fluorescence spectrometry (XRF) Bulk sample geochemistry (major and trace elements) indicates a dominant provenance of detritus from the Ferrar Supergroup in the uppermost 200 mbsf of the core. A markedly increased contribution from the Beacon sandstones is recognized below 200 mbsf and down to 600 mbsf. In the lower part of CRP-3, down to 787.68 mbsf, geochemical evidence for influxes of Ferrar materials is again recorded. On the basis of preliminary magnetostratigraphic data reported for the lower 447 mbsf of the drillhole, we tentatively evaluated the main periodicities modulating the geochemical records. Our results identify a possible influence of the precession, obliquity and long-eccentricity astronomical components (21, 41, and 400 ky frequency bands) on the deposition mechanisms of the studied glaciomarine sediments

Major and trace element concentrations of sediment core CRP-2/2A (Table 1,2)

Bulk chemistry (major and trace elements) of sand-sized samples from the CRP-2/2A drillhole provides evidence for a multicomponent provenance with changes in the component proportions throughout the sedimentary succession. Geochemical data evaluated in terms of element association and distribution and by means of cluster analysis reveal a provenance dominated by the granitoid basement with a significant contribution of MVG debris above ~310 mbsf. Chemical fingerprints of both basic and evolved MVG materials are recognized at different depths. Below ~310 mbsf the influence of Beacon sandstones becomes more marked, but there is geochemical evidence for influxes of detritus derived from Jurassic Ferrar Dolerites and Kirkpatrick basalt lavas

Petrography and carbonate isotope stratigraphy from MIS AND-1B core, Antarctica: Evidence of the early Pliocene warming event

A large portion of ANDRILL (ANtarctic geological DRILLing) core AND-1B recovered in the Western Ross Sea and spanning the early Pliocene has been investigated in order to obtain a detailed carbonate isotope record from Antarctic margin sediments through the early Pliocene warming event. Petrographic observations and mineralogical analyses reveal the authigenic nature of the carbonate and small proportions of Fe and Mg incorporated within the calcite lattice. High productivity conditions testified by ~80 m-thick diatomite interval (383 to 460 mbsf) well fit with the composite nature of the authigenic carbonate generally characterizing organic matter-rich sediments. As is known, sediments from the Polar Region are generally poor in carbonate. Although in the investigated portion of AND-1B core the carbonate seldom exceeds 5% in content, an automated Carbonate Preparation Device was used to obtain a high-resolution stable isotope dataset. Paleoenvironmental conditions characterized by high organic matter flux are supported by negative δ13C values suggesting a contribution of isotopically light biogenic CO2 during the carbonate precipitation. As to δ18O, even if melting glaciers are thought to be responsible for depletion in 18O composition, the isotope record exhibits long- and short-term trends. Analysis of the long-term trend constrains the Pliocene warming climax in an interval between 400–450 mbsf highlighting that most of the event is not documented because of a 800 kyr hiatus. The short-term trend documents the influence of obliquity controlling the annual insolation, but also that of precession-linked cyclicity seldom documented at high latitude

Geochemical investigations of elements in sediment core CRP-1 from the Ross Sea, Antarctica

Geochemical data are presented for samples from strata, mainly of Miocene age, in the Cape Roberts-1 core (western McMurdo Sound, Antarctica) to assess the sediment provenance. Bulk (major and trace element) chemistry together with bulk mineralogy of fine-grained sandstones, siltstones, mudstones, and diamictites indicate that chemical alteration of source materials, fractionation due to sedimentary sorting, and diagenetic effects were not significant in the Cape Roberts sediment history. Relevant geochemical parameters are consistent with the Cape Roberts sediments being derived mainly from the crystalline basement and the Beacon Supergroup. On the basis of element distributions, an additional contribution from the Ferrar Dolerite and, mainly above about 60 m, influxes of detritus derived from basanitic to intermediate members of the McMurdo Volcanic Group are recognised