For 30 years the Deep Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP) have been drilling the ocean floors and retrieving sediment cores. This study presents a relational micropaleontological and stratigraphic database, Neptune, where a selection of the published studies made on these sediments is available. The selected sites and their stratigraphic extent represent a statistically reproducible subset of the whole DSDP and ODP data set as of 1995 (up to Leg 135). Cenozoic sediments from 165 globally distributed holes were dated with age/depth plots using biochronology of four marine plankton groups (diatoms, nannofossils, foraminifera, and radiolarians). Each hole's location is available with paleogeographic coordinates. A taxonomic revision of the 8000+ reported species names was also made. The database is searchable and a variety of routines are available. Data can be exported to produce age range charts, geographic distribution maps, and occurrence charts. A rigorous evaluation of the database potentials and limitations is presented together with a summary of the published studies that have been carried on with the data. These include stratigraphic studies (diachrony of Neogene plankton, hiati distribution in Cenozoic sediments) and evolution studies (cladogenesis and evolution of one foraminiferal lineage). Unpublished data on macroevolutionary patterns (species longevity and richness, speciation and extinction rates) are presented as example of Neptune's potential for paleobiological research. Finally, some suggestions are presented as to how Neptune can be more fully exploited through the addition of sedimentologic and isotopic data. A variety of critical sedimentologic and paleoceanographic questions could be addressed with this extended database.

Speciation processes are only rarely studied with fossil materials, even though in principle hypotheses of speciation patterns are most directly testable in the fossil record. We quantitatively document in two widely separated South Pacific DSDP holes the mid-Pliocene speciation of the planktonic foraminifer Globorotalia truncatulinoides. Speciation, with continuous geographic co-occurrence of ancestor and descendant forms, occurred simultaneously at both localities over a period of ~500,000 years. This suggests a sympatric speciation process that involved a large, geographically extensive population. Globorotalia truncatulinoides underwent its most rapid and extensive evolutionary change between ~2.8 and 2.5 Ma. This time interval corresponds to the development of northern hemisphere glaciation, suggesting that climate-controlled paleoceanographic change may have played a significant role in the evolution of G. truncatulinoides.

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An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer‐Cervato, H. R. Thierstein, D. B. Lazarus, andJ‐P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order. We analyzed the synchrony and diachrony of commonly used Neogene biostratigraphic events from data published in the Initial Reports of the Deep Sea Drilling Project (DSDP) and in the Proceedings of the Ocean Drilling Program (ODP). On the basis of the combined biostratigraphic and magnetostratigraphic evidence, new Neogene age models were constructed for 35 globally distributed DSDP and ODP holes. Biostratigraphic events from the four major plankton groups (calcareous nannofossils, diatoms, planktonic foraminifera, and radiolarians) were compiled from DSDP and ODP reports. After the elimination of possible sources of error such as stratigraphic hiatuses and reworking of specimens, 124 biostratigraphic events that occurred in at least four holes were analyzed in detail: for each event a biochronologic age estimate was derived by projection of the depth of the event onto the line of correlation of each hole, and from these a global mean age for each event was calculated, together with its standard deviation. Average standard deviations for event ages by fossil group are: calcareous nannofossil first appearance datums (FADs): 0.57 m.y. (21 events), calcareous nannofossil last appearance datums (LADs): 0.60 m.y. (25 events), diatom FADs: 0.57 m.y. (7 events), diatom LADs: 0.85 m.y. (14 events), planktonic foraminifera FADs: 0.88 m.y. (22 events), foraminifera LADs: 0.68 m.y. (16 events), radiolarian FADs: 0.30 m.y. (9 events), radiolarian LADs: 0.31 m.y. (10 events). Since the average sample spacing in the sites used for this analysis is only 0.185 m.y., we have examined the data for true patterns of diachrony and for other biases. Diachrony is more frequent among cosmopolitan than among endemic taxa, thus there is a general trade‐off between the obtainable age precision and the geographic extent of a bioevent. Precision of age calibrations also decreases with increasing age. Although some of these features may be due to investigator bias, they appear in part to be real phenomena, and thus could also provide opportunities for further exploration of important paleobiological processes, such as change in environmental gradients through time, evolutionary adaptation of species populations and migration due to water mass changes.

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ZusammenfassungIn den zentralen Sfidalpen (Feltre, VeronaItalien) findet sich eine etwa 750 m dicke Abfolge jurassischer und kretazischer pelagischer Kalke, die nach der Ablagerung zum Teil breckziert und dolomitisiert wurde, w/ihrend die darfiberliegenden 500 m mfichtigen tertiriren Sedimente keine Dolomitisierung zeigen. Im Pal/iogen ist im Gebiet ein marlscher, fiberwiegend mariner Vulkanismus dokumentiert. Kleinmagstribliche listrische Brfiche in Kalken am Kontakt mit der dolomitisierten Breckzie entsprechen geometrisch einem grogr/iumigen extensiven Regime im Palfiogen. Sie beweisen die Gleichzeitigkeit der vulkanischen Aktivit/it und der Breckzierung. Die Verteilung und petrographischen Eigenschaften der Basalte, mit der Geometrie der Extensionsstrukturen, erlauben eine palriotektonische Rekonstruktion. Diese tektonische Situation entspricht einem Back-arc-basin und stellt die 6stliche Verlfingerung des ligurisch-balearischen Beckens dar, das Sfidfrankreich vom Sardisch-Korsisch-Kalabrischen-Block im spriten Oligoz/in getrennt hat.Die 613C Werte der Dolomite sind weniger als 1%0 negativer als die entsprechender nicht dolomitisierter Kalke. Die 6180-Werte (relativ zum PDB Standard) variieren zwischen -5 %o und -13 %o, das ist 2 bis 11%o negativer als die nicht dolomitisierter Kalke. Dies wird auf erh6hte Bildungstemperaturen zurfickgeftihrt. Ein Anstieg der 87Sr/86Sr-Signaturen spond to the tectonic framework of the area and give evidence for the contemporaneousness of the volcanic activity and the brecciation. The distribution and petrologic characteristics of the basalts, combined with the orientation of the extensional features observed in the field, allow a paleotectonic reconstruction. This tectonic scenario can be viewed as a back-arc extension, an eastward prolongation of the spreading that divided Southern France from the Sardinia-Corsica-Calabria block, generating the Ligurian-balearic basin in the Late Oligocene.The dolomite is fine-grained to sucrosic, with a microamygdaloidal porosity, partially filled with ankerite and calcite. The matrix shows a homogeneous, orange-red cathodoluminescence, indicating a single phase of iron-poor dolomite. The carbonate fraction consists of more than 90 % dolomite. The dolomite is almost stoichiometric (Ca0.6Mg0.4 to Ca0.sMg0.s). The 613C values of the dolomite are less than 1%o more negative than the unaffected limestone. The 6180 values are between -5 %0 to -13 %0, with a depletion of 2-11%o relative to the undolomitized limestone. The depleted oxygen isotope ratios in the dolomitized rock can be derived either from fluids impoverished in the heavy isotopes (e.g. meteoric water) or high temperatures. The unvaried carbon isotopic ratios make the second interpretation the most acceptable. As the 87Sr/86Sr values increase from a mean of 0.7077 in the unaffected limestones to 0.7085 in the dolomitized limestones, a derivation of the dolomitizing fluids from the volcanic rocks can be excluded. Comparing the obtained data with the Phanerozoic seawater isotope curve,...