共查询到20条相似文献,搜索用时 0 毫秒
1.
Calcareous nannofossils from the Brendola section permit recognition of the NP 19–20 zone. The calcareous nannofossil assemblages of this area indicate an inner shelf marine environment and the scarcity of discoasters and sphenoliths during late Priabonian time in this area is attributed to the very shallow nature of the association and not to the temperature dependence of this group. Systematic details concerningOrthozygus aureus and its relations withHolodiscolithus macroporus, Clathrolithus minutus andZygolithus fiscus are given. 相似文献
2.
Two 305 m cored sections from the northwest Florida continental shelf contain a nearly complete record of late Neogene hemipelagic sedimentation. One of the sites, south and east of De Soto Canyon, is isolated from terrigenous sediment except for sediment transported in suspension. This site contains a continuous record from the late Miocene to the Recent. The second site, on the western rim of De Soto Canyon, is more expanded and continuous from the late Pliocene to the Recent. A hiatus separates the late Pliocene from the middle Miocene. Six prominent nannofossil biohorizons were recognized within the Pleistocene, seven within the Pliocene, and three within the Miocene; in addition one biohorizon marks the base of the Pleistocene and another the base of the Pliocene.Nearly all carbonate in the sediment is pelagic. Terrigenous detrital sedimentation was controlled by glacioeustatic sea level fluctuations during the Pleistocene, and sea level changes are probably responsible for fluctuations in the ratio of pelagic carbonate to clayey detritus in pre-Pleistocene sediments also. Carbonate content, coarse fraction percent, and relative abundances of environmentally sensitive nannoplankton species suggest important paleoceanographic changes in the northeastern Gulf of Mexico and adjacent areas. Fluctuations in the relative abundance of the solution-resistant coccoliths of the genusCyclococcolithus indicate that waters at a depth of 600–1000 m were more corrosive during the late Miocene than they are today. The decrease in carbonate dissolution during the late Miocene probably was a response to gradual constriction of the Central American passage and the consequent restriction of flow of corrosive water from the Pacific. Short term fluctuations in dissolution during the Pliocene and Pleistocene are related to climatic cycles.Productivity variations in the surface waters, recorded mainly by the relative abundance of small and large morphotypes of closely related coccolith species, indicate that productivity increased during the Pliocene, but the most dramatic change — a major oceanwide increase in productivity — occurred during the Pleistocene, during and just prior to the Jaramillo magnetic event about 0.9 m.y. ago. Surprisingly the late Miocene Messinian event did not leave a significant imprint in the northeastern Gulf of Mexico. 相似文献
3.
J. R. DODSON 《Austral ecology》1979,4(4):419-427
The stratigraphy and pollen analysis of the basal 5.73 m of an 11.73 m core from the centre of Victoria's deepest lake is described. The hypothesis is advanced that at 16 100 B.P. a cool semi-arid environment supporting a sparse or scattered Eucalyptus–Callitris woodland with an understorey of grasses, Asteraceae and Chenopodiaceae dominated the region. From this time the lake level fell and was at its lowest between 15 000 B.P. and 10 000 B.P. At about the same time Casuarina migrated into the region as Callitris, Asteraceae and Chenopodiaceae declined. There was a period from 9600 B.P. to 9200 B.P. when Acacia and Dodonaea were common around Lake Bullenmerri, but these declined and were replaced by the Eucalyptus-Casuarina woodland with a herbaceous understorey which persisted through the Holocene period in western Victoria until it was cleared by European settlers. 相似文献
4.
Rook L 《Journal of human evolution》1999,36(5):535-547
This paper reports on new finds and re-discovered old collections of the latest Miocene colobine Mesopithecus from Italian localities. New finds are reported from the Baccinello V3 faunal assemblage and from the Monticino gypsum quarry (Brisighella) and newly rediscovered teeth from the Casino basin are herein described. The latter two samples are attributed to the species Mesopithecus pentelicus, while the allocation of the Baccinello V3 sample is unclear and for the moment is attributed to Mesopithecus sp. indet. A fourth Italian locality that yielded Mesopithecus remains is Gravitelli. Unfortunately the latter specimens are lost, and from the literature it is impossible to furnish an accurate specific attribution. The taxonomic allocation of latest Miocene Mesopithecus species is briefly discussed. 相似文献
5.
A new pollen record from Lago di Vico (core V1) provides fundamental new information towards reconstruction of flora and vegetation history in central Italy during the last 90 000 years. The chronological framework is secured by seventeen AMS14C dates, one40Ar/39Ar date and tephra analyses. At the base of the pollen record, i.e. shortly after the40Ar/39Ar date 87 000±7000 B.P., three phases with significant expansion of trees are recorded in close succession. These forest phases, which stratigraphically correspond to St Germain II (and Ognon?) and precede pleniglacial steppe vegetation, are designated by the local names Etruria I, Etruria II and Etruria III. During the pleniglacial, a number of fluctuations of angiosperm mesophilous trees suggest the presence of tree refugia in the area. The lowest pollen concentration values are recorded at ca. 22 000 B.P. which corresponds with other pollen records from the region. The late-glacial is characterized by an expansion in the arboreal pollen curves that is less pronounced, however, than in other pollen profiles from Italy. The Holocene part of the profile is consistently dominated by deciduous oak pollen. No major changes in arboreal pollen composition are recorded but several marked and sudden declines of the tree pollen concentration suggest that the forest cover underwent dramatic changes. Clear evidence for human impact is recorded only when cultivated crops became important which dates to ca. 2630±95 B.P. 相似文献
6.
The Radiolarian biotic response during OAE2. A high-resolution study across the Bonarelli level at Bottaccione (Gubbio, Italy) 总被引:1,自引:0,他引:1
Benjamin Musavu-Moussavou Taniel Danelian Rodolfo Coccioni 《Revue de Micropaléontologie》2007,50(3):253
In order to improve our understanding of the radiolarian biotic response and the palaeoceanographic changes associated with the Late Cenomanian oceanic anoxic event (OAE2), a high-resolution radiolarian study was carried out across the Bonarelli level at its typical locality (Bottaccione section, central Italy). Our results confirm that a drastic radiolarian faunal change took place during the OAE2. The radiolarian turnover took place within the median part of the Bonarelli level, associated with an interval of high organic matter preservation, but relatively low values of silica. Therefore, this part constitutes a critical period in the evolutionary history of Radiolaria. A synthesis of all data available in the Umbria-Marche basin suggests that the lower part of the Bonarelli level (and underlying limestones) records mainly radiolarian extinctions (ca. 41%), while its upper part (and overlying limestones) records mainly first occurrences (ca. 35%). Our results improve understanding of the paleoecology of the family Saturnalidae, which would seem to prefer oligotrophic environments. 相似文献
7.
Marco Giardini 《Vegetation History and Archaeobotany》2007,16(4):301-316
The pollen diagram from Stracciacappa (Sabatini volcanic complex, Rome) provides a record of vegetational and climatic change
spanning the last 60000 years, which is the time since when volcanic activity in the crater came to an end. The chronological
framework of the sediment core is set by five AMS and three conventional radiocarbon dates; the mean sedimentation rate obtained
by radiocarbon measurements was used to extrapolate the age of the record beyond the reach of 14C dating. The sequence from Stracciacappa provides results of fundamental importance for the understanding of the vegetational
changes which occurred during the last pleniglacial period in central Italy, and it can be considered as a reference pollen
record for the regional biostratigraphic characterization of this period. The site shows a high climatic sensitivity, particularly
highlighted by the development of some pleniglacial oscillations with woodland, which interrupted the succession of steppe
and grassland vegetational formations typical of the glacial periods. Unfortunately, due to sedimentation problems and alteration
of the top level sediments, the Holocene is only recorded in part. Only for one millennium, from ca. 8300 to 7200 uncalb.p., was a real forest expansion characterized by over 90% arboreal pollen found. 相似文献
8.
We describe the new agglutinated foraminiferal genus and species Rectogerochammina eugubina nov. gen., nov. sp. from the Upper Cretaceous Scaglia Rossa Formation of the Umbria-Marche Basin in Italy. The genus differs from Gerochammina (Neagu, 1990) in the presence of a terminal uniserial part. 相似文献
9.
《Comptes Rendus Palevol》2016,15(5):515-526
Squirrel remains are rare in the fossil record, which hampers a properly documented interpretation of their evolutionary history. The Late Miocene sciurids from Moncucco Torinese (NW Italy) are described based on a diverse tooth assemblage. The data presented herein confirm the presence of Sciurus warthae and Pliopetaurista pliocaenica, and also include the first unquestionable occurrence of Hylopetes hungaricus plus an indeterminate Sciurinae. The report of Sciurus warthae from Moncucco Torinese represents the earliest record of the genus Sciurus in Europe. Moreover, Moncucco Torinese is the first European locality recording the co-occurrence of Sciurini and Pteromyini in the Late Miocene. Comparative analyses support a close relationship between S. warthae and Sciurus vulgaris corroborating the hypothesis of an earliest divergence of the “Sciurus vulgaris clade” in the Late Miocene. Biochronological, paleobiogeographical and paleoecological implications are also discussed. 相似文献
10.
Vertebrate microremains from the Late Devonian-Early Carboniferous of the Carnic Alps are predominantly chondrichthyan, with minor placoderm and actinopterygian remains. The faunas are sparse and, with very few exceptions, occur only in conodont-rich pelagic limestones (Pramosio Limestone) representative of the palmatolepid-bispathodid conodont biofacies. Phoebodont and jalodont chondrichthyans, also reflecting open-ocean environments, predominated during the Famennian, and eventually symmoriids seem to predominate during the Early Carboniferous. The presence of Siamodus in this assemblage gives a new locality for this genus known from few regions in the world and allows confirming its stratigraphical range (limpidus Zone) and its relation to deep-water environments. The Late Devonian vertebrate faunas are tropical and cosmopolitan, having much in common with coeval taxa from the North-Gondwanan margins and Asian terranes. Composition of the vertebrate faunas is consistent with the Carnic Alps terrane having occupied a position intermediate between Gondwana and Laurussia, as hypothesized by various authors, but because of sparsity of the taxa represented and the pronounced cosmopolitan nature of both the conodont and vertebrate faunas, the data are not compelling. 相似文献
11.
A multidisciplinary approach to stratigraphy based on magnetostratigraphy, stable isotopes, percent CaCO3 and microfossils provides a framework for paleoclimatic and paleoceanographic reconstruction of the equatorial and North Pacific. A high-resolution biochronologic time scale has been achieved through integration of diatom, radiolaria, coccolith and planktic foraminifer datum levels with direct or indirect correlations to the paleomagnetic time scale. Over 70 datum levels have been identified between 12.5 and 5 Ma from low and middle latitudes resulting in an unprecedented time control. This high-resolution biostratigraphic control combined with stable-isotopic and percent CaCO3 analyses permits identification of regional as well as global paleoceanographic events. 相似文献
12.
13.
Simone Colombero Edmondo Bonelli Tassos Kotsakis Giulio Pavia Marco Pavia Giorgio Carnevale 《Geobios》2013,46(1-2):111-125
The stratigraphic and paleoenvironmental context of the Verduno fossil vertebrate locality is discussed herein based on its rodent record. The Verduno section crops out in the southern part of the Tertiary Piedmont Basin (TPB), and can be included in the Messinian post-evaporitic Cassano Spinola Fm., chronologically corresponding to the so-called Lago-Mare event. Rodents are represented by a relatively rich assemblage. Murids are by far the most diverse and abundant, with at least four taxa, including the common Centralomys benericettii and Paraethomys meini, and the rare Apodemus gudrunae and Occitanomys sp. Cricetids are represented by a single species, Apocricetus cf. A. barrierei. Muscardinus aff. M. vireti appears to be the only glirid present at Verduno. The Verduno rodent assemblage shares some taxa with other Messinian post-evaporitic localities from Italy bearing continental vertebrate remains, such as Brisighella (central Italy) and Moncucco Torinese (NW Italy) (e.g., C. benericettii, P. meini) and, possibly, with Ciabòt Cagna (NW Italy). However, the general structure of these four Messinian assemblages displays substantial differences, which may reflect different palaeoenvironmental conditions. 相似文献
14.
15.
Dr. Francesca R. Bosellini 《Facies》1998,39(1):203-225
Summary During the Late Eocene, shelf-edge patch reefs developed on the western margin of the Lessini Shelf. The coral fauna, studied
in the Nago Limestone type locality, is described and interpreted for the first time, and provides further data for better
understanding of the generally poorly known Eocene reef communities.
Facies analysis was carried out across the shallowing upward succession that characterizes the well exposed type-section of
the Nago Limestone. Four distinct facies are identified and a detailed qualitative-quantitative investigation has been applied
to the coral-bearing facies in particular, in order to describe and quantify the distribution and palaeoecological zonation
of corals.
By a comparison of sedimentological and palaeoecological data, it is possible to reconstruct a depositional model of the Nago
Limestone at its type locality. In particular, the palaeoecological study clearly reveals that corals change with depth in
taxonomic composition, in percentage and proportion within the framework and in growth form, allowing the definition of a
relative depth coral zonation.
Three coral associations are recognized from the base to the top of the shallowing upward sequence. These differ from each
other in the relative abundance of main reefbuilders, in the growth form exhibited by corals in growth position and in the
density of the reef framework. These variations are interpreted as responses to major environmental controls which prevailed
during the deposition of the different facies (mainly light intensity and hydrodynamic energy).
The coral speciesActinacis rollei
Reuss is the most abundant and ubiquitous coral of the Nago Limestone. Its adaptation to low-light levels is described here for
the first time, confirming the high plasticity of this important Paleogene reef-builder.
The results of the present study are finally compared with data from other Middle-Late Eocene European reef sites and some
common features are inferred. 相似文献
16.
Haitham M. Ayyad 《Revue de Micropaléontologie》2018,61(1):37-54
This study is a preliminary quantitative analysis of Paleocene calcareous nannofossil assemblages of the Tenida area (Egypt) in order to establish a detailed biostratigraphic framework as well as to reconstruct the paleoclimatic trends. A total of 48 samples with an average sample spacing of 1.5 m allowed the identification of 63 calcareous nannofossil species belonging to 19 different genera. The preservation of the studied samples varies from poor to moderate and is characterized by the frequent presence of small frangible placoliths, and nannoliths. This study recognizes three calcareous nannofossil biozones in the Danian-Thanetian time interval; Chiasmolithus danicus (NP3) Zone, Ellipsolithus macellus (NP4) Zone, and Heliolithus kleinpellii (NP6) Zone. Moreover, the multivariate statistical analysis of the calcareous nannofossil communities reveals a relationship between the distribution of these nannofossil assemblages and variations in paleoclimatic trends. Accordingly, the relative abundances of Coccolithus pelagicus in addition to nine calcareous nannofossil genera along with the diversity and preservation indices of calcareous nannofossil elements have been used to elucidate changes in paleoclimatic trends. Based on the cyclic change from cold to warm climates, it was possible to subdivide the Paleocene Period recorded in the Tenida section into four paleoclimatic intervals. The oldest is a global cooling trend spanning 2.01 Myr long, starting in the early Paleocene (Danian) during the deposition of the lower part of the Kharga Shale Member. This cooling trend is followed by a ~ 0.56 Myr warming trend during deposition of the middle part of the Kharga Shale Member that was followed by a return to a cooling mode, with an estimated duration of roughly 1.67 Myr. The last interval includes a 0.39 Myr long period at the Selandian/Thanetian boundary interval, which is dominated by a global warming trend during deposition of the upper part of the Upper Kharga Shale Member. 相似文献
17.
The Castel di Guido site, with an estimated age of approximately 300,000 years, has yielded abundant animal remains, Acheulian stone and bone bifaces, and small tools. On the surface of the original deposit, turned over by agricultural activities, fragments of human remains were discovered between 1980 and 1986, including a temporal bone described here. 相似文献
18.
Excavations at hearth levels at the Molare Shelter in 1985 yielded the mandible of a 3-4-year-old child. The associated lithic artifacts recovered with it are Mousterian. Its features, although quite archaic, are within the known range of variation of Neandertals. Four deciduous molars are still preserved in the mandible. They were compared with other known specimens, which date to the Middle and Upper Pleistocene. The metrical characteristics are surprisingly primitive, within the range of variation of Homo erectus, or at least within that of European Pre-Neandertals, more so than within the variability of typical Neandertal specimens. On the other hand, the morphological characteristics, except for a few that are decidedly plesiomorph, are predominantly Neandertal. 相似文献
19.
20.
Maurizio Gatta Tassos Kotsakis Luca Pandolfi Carmelo Petronio Leonardo Salari Katia Francesca Achino Letizia Silvestri Mario Federico Rolfo 《Comptes Rendus Palevol》2019,18(1):51-71
Palaeoenvironmental information on Marine Isotope Stage 3 (MIS 3) coastal Latium is sparse, mainly based on studies of isolated faunal assemblages or long pollen records from lake sediments, often of insufficient resolution to aid in palaeoenvironmental reconstruction. This study describes in detail the Late Pleistocene faunal assemblage from layers SU11 and SU12 of Cava Muracci (Cisterna di Latina, central Italy), the first of which is a partially-preserved hyena den. The first multi-disciplinary palaeoenvironmental reconstruction of coastal Latium between 34–44 ka BP, a critical time span for the presence of the latest Neanderthals and the arrival of Anatomically Modern Humans (AMH), is provided combining palaeoecological inferences from a previous pollen study of hyena coprolites with the palaeontological study described here. The results indicate a temperate climate and a landscape characterised by the coexistence of at least three habitats within a short distance between the coastline and the inland mountains, suitable for a wide variety of species. 相似文献