Annual Report 2009 of the Bartonian/Priabonian Boundary Stratotype Working Group

Tasks of the Italian scientific community were to search for GSSPs of the Middle-Upper Eocene and Lower-Upper Oligocene Transitions. Investigations on both transitions have been undertaken by a number of researchers from several Italian Universities (i.e. Padua, Ferrara, Florence, Urbino, Milan) and CNR Institutes as well as from some European and USA Universities and Institutions of the "ALANO NET" and by the numerous scientists of the OLIS Working Group coordinated by Rio (University of Padua) and Coccioni (University of Urbino), respectively. During the first half of 2009 the multidisciplinary studies on the Alano di Piave section (Veneto region, NE Italy), the potential candidate for defining the GSSP of the Middle/Upper Eocene, equated to the base of the Priabonian Stage, have been completed. An article, entitled "Integrated bio-magnetostratigraphy of the Alano section (NE Italy): a proposal for defining the Middle-Late Eocene boundary" co-authored by Agnini, Fornaciari, Giusberti, Grandesso, Rio & Stefani (Univ of Padua), Lanci (Univ. of Urbino), Luciani (Univ. of Ferrara), Muttoni (Univ. of Milan), Palike & Spofforth (Univ. of Southampton, UK), have been submitted for publication to the Geological Society of America Bulletin in August 2009; it was already reviewed and the revised version will be returned to the Editor before the end of October. The Alano section consists of ca. 120-130 m of bathyal gray marls interrupted in the lower part by 8 meters-thick package of laminated dark to black marlstones. Intercalated in the section there are prominent marker beds, six of which are crystal tuff layers, whereas the other two bioclastic rudites, useful for regional correlation. The section is easily accessible, crops out continuously, is unaffected by any structural deformation, is rich in calcareous plankton and contains an expanded record of the critical interval for defining the GSSP of the Priabonian. Integrated calcareous plankton quantitative biostratigraphy (nannofossils and foraminifera), and a detailed magnetostratigraphic analysis have been conducted in high resolution especially across the critical intervals for defining the Priabonian Stage. Moreover, the depositional paleodepth of the Alano section was estimated through the study of benthic foraminifera, whereas the detailed oxygen and carbon isotope curve for the entire section is included in another paper, submitted to Paleoceanography also in 2009, by Spofforth and co-authors entitled "Organic Carbon Burial following the Middle Eocene Climatic Optimum (MECO) in the central-western Tethys"

Report by Isabella Premoli Silva, Chairwoman

Annual Report 2008 of the Bartonian/Priabonian Boundary Stratotype Working Group

Tasks of the Italian scientific community were to search for GSSPs of the Middle-Upper Eocene and Lower-Upper Oligocene Transitions. Investigations on both transitions have been undertaken by a number of researchers from several Italian Universities (i.e. Padua, Ferrara, Florence, Urbino, Milan) and CNR Institutes as well as from some European and USA Universities and Institutions of the “ALANO NET” and by the numerous scientists of the OLIS Working Group coordinated by Rio (University of Padua) and Coccioni (University of Urbino), respectively.
During 2008 studies on the Alano di Piave section (Veneto region, NE Italy), the potential candidate for defining the GSSP of the Middle/Upper Eocene, equated to the base of the Priabonian Stage, are basically completed. Calcareous plankton (nannofossils and foraminifera) high-resolution quantitative biostratigraphies are now well correlated to magnetostratigraphy and to oxygen and carbon stable isotopes across the critical interval. Dinocyst biostratigraphical and benthic foraminiferal studies are close to completion. A paper on integrated multiple stratigraphies of the Alano di Piave section is in progress and should be submitted soon for publication.

Report by Isabella Premoli Silva, Chairwoman

Annual Report 2007 of the Bartonian/Priabonian Boundary Stratotype Working Group

Tasks of the Italian scientific community were to search for GSSPs of the Middle-Upper Eocene Transition. Investigations on both transitions have been undertaken by a number of researchers from several Italian Universities (i.e. Padua, Ferrara, Urbino, Milan) and CNR Institutes as well as from some European and USA Universities and Institutions of the “ALANO NET” and by the numerous scientists of the OLIS Working Group coordinated by Rio (University of Padua).
During 2007 studies on the Alano di Piave section (Veneto region, NE Italy), the potential candidate for defining the GSSP of the Middle/Upper Eocene, equated to the base of the Priabonian Stage, have progressed. Calcareous plankton (nannofossils and foraminifera) high-resolution quantitative biostratigraphies have been completed and correlated to magnetostratigraphy and to oxygen and carbon stable isotopes across the critical interval, while dinocyst biostratigraphical and benthic foraminiferal studies are close to completion. A paper on integrated multiple stratigraphies of the Alano di Piave section is expected to be submitted for publication early in 2008.

Report by Isabella Premoli Silva, Chairwoman.

Annual Report 2006 of the Bartonian/Priabonian Boundary Stratotype Working Group

Studies in 2006 focused on the Alano di Piave section (Veneto region, NE Italy), the potential candidate for defining the GSSP of Middle/Upper Eocene, equated to the base of the Priabonian Stage. The Alano section, continuously exposed along the banks of the Calcino Creek, consists of 120-130 m-thick gray marls of the Scaglia Cinerea Formation deposited at bathyal depth. It is easily accessible, is unaffected by structural deformation, is rich in calcareous plankton and contains the critical interval for defining the GSSP of the Priabonian. Calcareous plankton (nannofossils and foraminifera) high-resolution biostratigraphies have been completed and correlated to magnetostratigraphy across the critical interval.
The main bioevent in planktonic foraminifera, the extinction of the large acarininids (e.g. A. praetopilensis, A. rohri) and of Morozovelloides crassatus (formerly Morozovella crassata) just above, correlates with magnetic chron C17.3n falling in the same position as detected at ODP Site 1052 (Blake Nose, W Atlantic). This is supported by quantitative analysis on calcareous nannofossil distribution from both locations: across the studied interval at Alano and Site 1052 calcareous nannofossils show similar abundance patterns and in the same position with respect to the main planktonic foraminiferal event and magnetic chrons. Magnetic measurements of the Alano section have been extended below and above the critical interval and currently cover almost the whole section. Stable isotope analysis, dinocyst biostratigraphical and benthic foraminiferal studies are in progress. A paper on integrated calcareous plankton biostratigraphy calibrated to magnetostratigraphy is in preparation.
A synthesis of the available data was presented at the international meeting on “Climate and Biota of the early Paleogene” held in Bilbao in June 2006.
Reference
Rio D., Premoli Silva I., Agnini C., Brinkhuis H., Fornaciari E., Giusberti L., Grandesso P., Lanci L., Luciani V., Muttoni G., Stefani C., Villa I., The Alano di Piave section (Venetian Southern Alps, NE Italy). A potential GSSP of the Priabonian Stage (Upper Eocene). International Conference on “Climate and Biota of the early Paleogene”Abstract Volume, p. 109. ISBN 84-689-8939-8.

Report by Isabella Premoli Silva, Chairwoman.

Annual Report 2005 of the Bartonian/Priabonian Boundary Stratotype Working Group

A great wealth of data have been collected on the well-exposed Alano section (Veneto region, NE Italy), a potential candidate for the Upper Eocene GSSP. In particular, the >120 m-thick section is now completely sampled in high resolution for multiple biostratigraphies. The surveyed section spans the middle-upper Eocene transition from nannofossil Zone CP14 (NP16) through Zone CP15 (NP17 to NP19-NP20). Besides the main standard biohorizons that allowed to identify the named biozones, twelfe additional nannofossil bioevents have been recognized. Concerning planktonic foraminifera, the main extinction level of the muricate forms and the first and last occurrence of Globigerinatheka semiinvoluta have been detected within nannofossil Zone CP 15. A first set of samples from a ca. 30 m-thick segment straddling the critical interval for defining the GSSP, have been measured for magnetic properties. The magnetic signals obtained tourned out to be reliable allowing to recognize some reversals in a mainly positive polarity interval. After this pilot study, sampling for magnetostratigraphy was confidently extended ca. 45 m below and >30 m above the segment mentioned above in order to unequivocally interpret the magnetic chrons. Magnetic measurements of the new set of samples are in progress.
Two out of the six interbedded volcanoclastic layers, one at the base of the section (Mantegna bed) and one in the critical Bartonian-Priabonian transition, will be analysed for radiometric dating (Igor Villa).
Most of the missing data, including the detailed distribution charts of foraminifera, are being collected and will be ready confidently for mid 2006.
Tasks of the Italian scientific community were to search for GSSPs of the Middle-Upper Eocene and Lower-Upper Oligocene Transitions. Investigations on Middle-Upper Eocene and Lower-Upper Oligocene Transitions. tasks of the Italian scientific community, have been undertaken by a number of researchers from several Italian Universities and CNR Institutes (i.e. Padua, Ferrara, Urbino, Milan), as well as from some European and USA Universities and Institutions of the “ALANO NET” and by the numerous scientists of the OLIS Working Group coordinated by Rio (University of Padua) and Coccioni (University of Urbino), respectively.

Report by Isabella Premoli Silva, Chairwoman.

Annual Report 2004 of the Bartonian/Priabonian Boundary Stratotype Working Group

The Veneto region in the Southern Alps (NE Italy) is a classical area for the Paleogene Stratigraphy. In particular, the historical stratotype and the parastratotype of the Priabonian (Munier-Chalmas & De Lapparent, 1893) stage are located close to the Priabona and Possagno villages, respectively. However, in both areas, the transition from the middle to late Eocene is missing (Priabona) or poorly exposed (Possagno; Bolli, 1975). We report here preliminary results on the calcareous plankton biostratigraphy of an undescribed section (Alano Section) from the central-eastern Veneto region that contains an expanded record of the middle to late Eocene transition.

THE ALANO SECTION (pdf)
Location: On the left side of the Piave River Valley, in the Veneto Prealps (Belluno Province), some 8 km from the classical Possagno section, in the same region of the Priabonian historical stratotype.
Geologic setting: the section is exposed in continuity along a river cut within the northern limb of the Alano syncline; it belongs entirely to the "Scaglia Cinerea" Formation. It is easily accessible and shows a total thickness of 120-130 meters.
Lithology: grey marls and calcareous marls with numerous centimetric to decimetric silty to sandy intercalations some of which do represent useful marker beds in the field. The composition of these beds is variable (glauconitic, bioclastic and volcanoclastic). Noteworthy is the presence of a "black-shale" interval between 17 and 25 m level (upper part of the Bartonian).
Depositional setting: bathyal.
Fossil content: macrofossils have not been observed except for two badly preserved bivalves. Calcareous plankton is abundant. Planktonic foraminifera are fairly well preserved even if encrusted in the more calcareous lithologies. Calcareous nannofossils are well preserved. Benthic foraminifera are common, increasing in abundance in the upper part of the section. Dinoflagellate cysts.are also present and their detailed study is planned. Preliminary biostratigraphic data on calcareous plankton are reported in the attached Figure.
Sampling: 105 m of the section were sampled at high resolution every 20 cm; sampling of the uppermost 10-15 m is in progress. Some pilot samples for magnetic properties are now under examination.
Because of the excellent outcropping conditions, richness of planktonic fossils, easy access, amenability to radiometric dating, the Alano section might be a potential candidate for defining the middle/upper Eocene boundary. In addition, it is a key section for facing the climatic, biotic and chronologic problems associated with the middle to late Eocene transition.Investigations have been undertaken by researchers of the Universities of Padua, Ferrara, Urbino, Utrecht and Milan, and by the numerous scientists of the OLIS Working Group coordinated by Coccioni (University of Urbino), respectively.

Report by Isabella Premoli Silva, Chairwoman.