439 research outputs found
Quantitative Pleistocene calcareous nannofossil biostratigraphy of Leg 86 Site 577 (Shatsky Rise, Northwestern Pacific Ocean)
No full textLate Cenozoic silicoflagellate biostratigraphy, relative paleotemperature, and distribution of various genera and morphologic subgroups with remarks on noteworthy occurrences at DSDP Leg 86 Holes
No full textA quantitative study of late Cenozoic silicoflagellates from the northwestern Pacific sites of Deep Sea Drilling Project Leg 86 shows a relative paleotemperature (Ts) gradient with lowest values (Ts = 30) in the north. Some new ecostratigraphic relations for the region are indicated, such as the last common occurrence of Dictyocha brevispina at 2.6 - 3.0 m.y. ago during a cool interval. Elements of North Pacific and low-latitude biostratigraphic zonations can be identified, but the mixing of cool- and warm-indicator taxa prompted the definition of the new Miocene Mesocena hexalitha Subzone and Pliocene Distephanus jimlingii Subzone.
Scanning-electron microscope study of Leg 86 silicoflagellates was done to determine whether various types of skeletal surface texture are temperature dependent. To conduct the study we organized a new surface-texture descriptive code, which characterizes the apical structure/basal ring/spine sequence using new definitions of the terms crenulate (C), linear (L), nodular (N), reticulate (R), and smooth (S).
One new silicoflagellate genus, Caryocha Bukry et Monechi, n. gen., is described and several new combinations are made
The contribution of fossils to chronostratigraphy, 150 years after Albert Oppel
No full textThe 150th anniversary of the death of Albert Oppel (1831–65) provided the opportunity to celebrate this outstanding stratigrapher with a Thematic Issue dedicated to the importance of fossils for dating and correlating of sedimentary rocks. In this issue, we analyse Oppel’s significant contribution to modern chronostratigraphy, before exploring the Phanerozoic through all its major fossil groups, to verify if fossils are still able to make a significant contribution to chronostratigraphy. The extraordinary merit of Oppel’s work has been the demonstration that fossils can be used to sub-divide sedimentary sequences into zones, which in turn might be organized in higher chronostratigraphical units. The zone for Oppel is characterized by the distinctive fossil content, and his view strongly influenced the development of the standard chronostratigraphical scale for about one century, until the introduction, in the 1950s, of the log-based range chart as the common practice to study the fossil record of sedimentary successions. This approach forced the stratigraphers to shift the focus from the fossil content of the zones to their boundaries. This new view allowed for the introduction of new kind of zones with precisely defined boundaries based on bioevents and to the decline of the Oppel Zone. This turning point in the history of chronostratigraphy was fuelled by the International Commission on Stratigraphy programme of definition of the units of the International Chronostratigraphic Chart based on the boundary stratotype and point (GSSP) concept, which started in 1973
(Table T1) Distribution of selected calcareous nannofossils at the Paleocene/Eocene boundary, ODP Hole 208-1266C
No full textOcean Drilling Program Leg 208 Hole 1266C (28°32.55'S, 2°20.61'E) is located along the northwestern flank of Walvis Ridge (South Atlantic Ocean). The location of Site 1266, at 3.798 km water depth, corresponds to a mid-depth site of the Leg 208 transect. A stratigraphically continuous and expanded sequence of upper Paleocene and lower Eocene pelagic nannofossil ooze was recovered. Three holes were cored at Site 1266, and from Hole 1266C, an expanded and continuous Paleocene/Eocene (P/E) transition was recovered using the advanced piston corer system. The successful recovery and well-preserved nannofossil assemblages make Hole 1266C a reference section for improving the knowledge of the Paleocene/Eocene Thermal Maximum. The P/E transition is one of the most remarkable and intensively investigated time intervals. Significant and dramatic changes in climate and oceanography occurred at this transition. The P/E boundary is linked with an important turnover in benthic foraminifers and planktonic marine communities (Thomas and Shackleton, 1996, doi:10.1144/GSL.SP.1996.101.01.20; Kelly et al., 1998, doi:10.1016/S0031-0182(98)00017-0; Monechi et al., 2000, doi:10.2113/171.4.477; Bralower, 2002, doi:10.1029/2001PA000662). This report documents the calcareous nannofossil assemblage fluctuations at the P/E boundary in Hole 1266C based on semiquantitative and quantitative investigations
Contro i nemici della risata : Le stagioni teatrali di Umberto Simonetta al Teatro Gerolamo
No full textDirettore del Teatro Gerolamo fra il 1978 e il 1983, Umberto Simonetta è stato autore, regista e produttore di numerose pièce di successo, fra le quali Sta per venire la rivoluzione e non ho niente da mettermi (con Livia Cerini), Mi voleva Strehler (con Maurizio Micheli), che ha oltre mille repliche all’attivo, Ne ho mangiata troppa (con il figlio adottivo Luca Sandri).Head of the Teatro Gerolamo between 1978 and 1983, Umberto Simonetta was the author, director and producer of numerous successful plays, among which The revolution is about to come and I have nothing to wear (with Livia Cerini), I wanted Strehler (with Maurizio Micheli), who has over a thousand repeats to his credit, I ate too much (with his adopted son Luca Sandri)
(Fig. 5) Stratigraphic distribution of middle Paleogene calcareous nannofossils in the Bottaccione section, Italy
No full textPoint distance is the sample level (m). Species abundance: A = abundant (>10 %), C = common (1-10 %), F = few (0.1-1 %), R = rare (<0.1 %), - = not presen
The Scaglia Toscana Formation of the Monti del Chianti: new lithostratigraphic and biostratigraphic data
No full textThe Scaglia Toscana Formation (Scisti Policromi Auctt.) is one of the most investigated formations of the Tuscan Nappe. The formation is widely exposed in the Chianti Mounts and despite the number of studies in this area, some aspects remain poorly known and debated.In this paper new litho- and bio-stratigraphic data from eight key-sections distributed over the entire area are provided and discussed in order to clarify the stratigraphic relationships among different lithostratigraphic members, as well as the depositional ages of each member. The formation was deposited in the Cretaceous-Oligo-cene time interval and it can be subdivided into five lithostratigraphic members: i) the “Argilliti di Brolio” (wine-red shales with sporadic siliceous calcilutites and rare interbedded cherts); ii) the “Marne del Sugame” (red and pink marls, calcareous marls and marly limestones
with interbedded calcarenitic beds and ruditic lens-shaped bodies including calcareous-siliceous clasts); iii) the “Argilliti di Cintoia” (grey-green to black shales, locally with manganese-rich siliceous calcilutites and cherts); iv) the “Calcareniti di Montegrossi” (thin beds of calcilutites and calcarenites with varicoloured shaly-marly interbeds); and v) the “Argilliti e Calcareniti di Dudda” (alternating thin beds of calcilutites and calcarenites with varicoloured shaly-marly interbeds). These members were deposited in a marine environment and have been interpreted as deposited in a turbiditic system, in which shaly and calcareous turbiditic members have been attributed to a basin plain below the CCD, whereas the marls and marly limestones of the Marne del Sugame Member were deposited in a slope/ramp environment above or close to the CCD. Furthermore, the combination of these new
data with structural informations coming from the literature allowed a better paleogeographic reconstruction of the paleobasin. In order to better explain these data, the paper is accompanied by two geological maps realized in the past but never distributed. The two geological maps, at the scale of 1:25,000, cover the whole area from the Cintoia (south of Florence) to the San Gusmè (north of Siena) villages
(Table 5) Abundance of selected helicoliths at DSDP Site 82-563 in the North Atlantic
No full textRelative to a count of about 1500 coccoliths and plotted as number of specimens/1000 nannofossil
(Table 6) Abundance of selected discoasters at DSDP Site 82-563 in the North Atlantic
No full textRelative to a count on about 3000 coccoliths and plotted as number of specimens/1000 nannofossils. Abundance of D. deflandrei and D. signus are relative to 100 discoaster
(Table 2) Calcareous nannofossil distribution and relative abundance in ODP Hole 114-703A
No full textSpecies abundances: A = Abundant (1 specimen per field of view), C = common (1 specimen per 1 to 2 fields), F = few (1 specimen per 2 to 10 fields), R = rare (1 specimen per 10 to 100 fields), RR = very rare (1 specimen per >100 fields), - = not present
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