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Firm stratigraphic correlations are needed to evaluate the global significance of unconformity bounded units (sequences). We correlate the well-developed uppermost Campanian and Maestrichtian sequences of the New Jersey Coastal Plain to the geomagnetic polarity time scale (GPTS) by integrating Sr-isotopic stratigraphy and biostratigraphy. To do this, we developed a Maestrichtian (ca. 73–65 Ma) Sr-isotopic reference section at Deep Sea Drilling Project Hole 525A in the southeastern Atlantic Ocean. Maestrichtian strata can then be dated by measuring their 87 Sr/ 86 Sr composition, calibrating to the GPTS of S. C. Cande and D. V. Kent (1993, personal commun.), and using the equation Age (Ma) = 37 326.894–52 639.89 ( 87 Sr/ 86 Sr). Sr-stratigraphic resolution for the Maestrichtian is estimated as ±1.2 to ±2 m.y. At least two unconformity-bounded units comprise the uppermost Campanian to Maestrichtian strata in New Jersey. The lower one, the Marshalltown sequence, is assigned to calcareous nannofossil Zones CC20/21 (∼NC19) and CC22b (∼NC20). It ranges in age from ∼74.1 to 69.9 Ma based on Sr-isotope age estimates. The overlying Navesink sequence is assigned to calcareous nannoplankton Zones CC25–26 (∼NC21–23); it ranges in age from 69.3 to 65 Ma based on Sr-isotope age estimates. The upper part of this sequence, the Tinton Formation, has no calcareous planktonic control; Sr-isotopes provide an age estimate of 66 ± 1.2 Ma (latest Maestrichtian). Sequence boundaries at the base and the top of the Marshalltown sequence match boundaries elsewhere in the Atlantic Coastal Plain (Owens and Gohn, 1985) and the inferred global sea-level record of Haq et al. (1987); they support eustatic changes as the mechanism controlling depositional history of this sequence. However, the latest Maestrichtian record in New Jersey does not agree with Haq et al. (1987); we attribute this to correlation and time-scale differences near the Cretaceous/Paleogene boundary. High sedimentation rates in the latest Maestrichtian of New Jersey (Shrewsbury Member of the Red Bank Formation and the Tinton Formation) suggest tectonic uplift and/or rapid progradation during deposition of the highstand systems tract.

Recent onshore New Jersey drilling (Ocean Drilling Program Leg 150X) provided excellent recovery of lower to middle Miocene sequences that we dated with Sr isotopic stratigraphy. Sequence boundaries correlate with deep-sea δ 18 O increases (inferred glacioeustatic lowerings), indicating a primary control by global sea-level change. Maryland Miocene outcrops appear to correlate with New Jersey sequences and the δ 18 O record, although diagenesis and intense bioturbation limit Sr isotopic age resolution in Maryland. The early Miocene is not well represented in Maryland due to regional tectonics; in contrast, early Miocene accommodation in New Jersey was provided by flexural effects due to sediment loading.

Stephen J. Gould [1987] argued that one of the greatest scientific realizations was the concept of “deep time,” a phrase coined by John McPhee to encompass the breadth of geological time. We rely on measurements of geological time to provide rates of geological and geophysical processes and a chronology for the evolution of the Earth. Geological measurements of deep time rely on a limited number of radiometric ages that provide the only true clocks. Our chronometer is the geological time scale, and it is based on these ages and interpolations between them. The most precise ruler for these interpolations is provided by minor variations in the Earth's orbit, which control solar insolation and global climate changes; this “astronomical pacemaker” has provided a precise chronology (one with 5,000-year resolution) for the past few million years. It has proven difficult to extend this astronomical time scale to the geological record older than about 5 m.y. However, for the Late Cretaceous to Pleistocene (approximately the last 150 m.y.), another ruler is available: reversals of the Earth's magnetic field provide a Geomagnetic Polarity Time Scale (GPTS) that serves as a framework for a limited number of radiometric ages.

We examined uppermost Oligocene to lowermost Pliocene sections from four northeastern Gulf of Mexico boreholes for quantitative benthic foraminiferal faunal changes, stratigraphic ranges, paleobathymetry, organic carbon content, and planktonic foraminiferal relative abundances. The Eureka boreholes provide a depth transect in the De Soto Canyon area from the upper to lower bathyal zone: E68-136 (557m present depth, -600m paleodepth), E66-73 (857m present depth, 860-lOOOm paleodepth), E68-151A (1326m present depth, -1300m paleodepth), and E68-14 1A (1599m present depth, -1600m paleodepth). A number of taxa last appeared in the late Oligocene to early Miocene (Biochrons P22-N5) at E68-136; several of these disappearances constitute global last occurrences. A global benthic foraminiferal taxonomic turnover that began in the latest early Miocene in other parts of the ocean was restricted to the middle Miocene at E68-136 (Biochrons N9-N12), although faunal abundance changes began in late early Miocene Biochron N8. At middle bathyal borehole E66-73, ten taxa last occurred in Biochrons N8-N10, which is consistent with the timing of the taxonomic turnover in the Pacific and Atlantic. Depth-related faunal trends are examined and compared with previously published distributional data, resulting in revised paleobathymetric ranges of 12 taxa. Detailed age-paleodepth reconstructions reveal several stratigraphically and bathymetrically significant predominance biofacies in the northeast Gulf of Mexico: 1) Uvigerina pigmea dominated the middle-upper bathyal late Neogene; 2) Lenticulina spp. dominated the late Oligocenemiddle Miocene bathyal zone; 3) Oridorsalis spp., Gyroidinoides spp., and Globocassidulina subglobosa dominated the late Neogene lower bathyal zone; and 4) Uvigerina proboscidea was important in the late Neogene in the middle to upper bathyal zones. Four distinct bathymetric migrations are mapped, and 34 additional taxa are shown to have distinct paleobathymetric distributions. Planktonic foraminiferal biostratigraphic control allows us to evaluate the stratigraphic usefulness of benthic foraminiferal ranges. We revise the stratigraphic ranges of 12 bathyal benthic foraminiferal taxa, requiring re-correlation of the benthic foraminiferal zonal boundaries of Berggren and Miller (1989). INTRODUCTION Previous studies have shown that one of the largest benthic foraminiferal faunal changes of the Cenozoic occurred throughout the deep sea (>200m) in the late early to middle Miocene (Berggren 1972; Schnitker 1979, 1986; Woodruff and Douglas 1981; Boersma 1986; Thomas 1985, 1986a, 1886b, 1989, 1992; Woodruff 1985; Kurihara and Kennett 1986; Miller and Katz 1987; Thomas and Vincent 1987; Woodruff and Savin 1989; Miller et al. 1992; Thomas 1992; for an alternative view, see Boltovskoy and Boltovskoy 1988; Boltovskoy et al. 1992). These authors documented that major changes in taxonomic composition, percentages, and absolute abundances of benthic foraminifera began in the late early Miocene and culminated in the middle Miocene. Although this event has been well documented at open ocean locations, it remains poorly documented in marginal seas such as the Gulf of Mexico. The Eureka boreholes examined in this study (northeast Gulf of Mexico) yield faunal abundance changes and stratigraphic ranges that reflect this global middle Miocene benthic foraminiferal event. Benthic foraminiferal faunas have been recognized for their potential to assess paleobathymetry (e.g. Natland 1933; Bandy 1960). While Bandy (1960) promoted the concept that benthic foraminifera have distinct upper and lower depth limits, Streeter (1973) and Schnitker (1974) established that deep-water (>200m; bathyal-abyssal) benthic foraminifera are correlated to water mass properties that may vary independently of depth. Numerous subsequent studies have documented that deep-water benthic foraminiferal distributions are associated with physiochemical properties other than depth, and that depth alone does not control the vertical distribution of benthic foraminifera. For example, vertical distributions are correlated with water masses (e.g. Lohmann 1978; Corliss 1979; Schnitker 1979; Murray 1984; for Gulf of Mexico examples, see Pflum and 88? 86? 84? TEXT-FIGURE 1 Eureka bo ehole location map in the Gulf of Mexico. Contours are in meters. micropaleontology, vol. 39, no. 4, pp.367-403, plates 1-6, text-figures 1-32, tables 1-5, 1993 367 This content downloaded from 157.55.39.152 on Sat, 26 Nov 2016 04:11:28 UTC All use subject to http://about.jstor.org/terms M. E. Katz and K. G. Miller: Latest Oligocene to Earliest Pliocene benthicforaminiferal biofacies of the northeastern Gulf of Mexico TABLE 1 Age model parameters Datum Age (Ma) Depth (feet below sea level) E68-136 E66-73 E68-151 FO C. acutus & 5.

We have evaluated the planktonic foraminiferal biostratigraphy of several Gulf of Mexico Eureka boreholes, emphasizing the Miocene depositional history of the northeastern region (De Soto Canyon). The E68-136 borehole (De Soto Canyon; 1826', 557m present depth) provides the most continuous Miocene record, although deposition was punctuated by several short (

In view of recent controversy over the number and timing of late Eocene impact events, we evaluated biostratigraphic correlations at Deep Sea Drilling Project (DSDP) Site 612, New Jersey continental slope. Radiolarian and foraminiferal biostratigraphy indicate that the tektite layer at Site 612 is biostratigraphically older than a microtektite layer in Barbados which has been correlated with the North American strewn field. Strontium and oxygen isotope stratigraphies are consistent with magnetobiostratigraphic correlations. The late Eocene impact events do not correlate with climate changes inferred from the marine isotope record

Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) calculated from three samples of benthic forminifers and one mallusc indicate an age range from 23.8 to 27.0 Ma for the Nuwok Member of the Sagavanirktok Formation, eastern North Slope, Alaska. Previous correlations derived paleontologically (foraminifers, ostracodes, and molluscs) for the Nuwok beds have differed greatly (Oligocene to Pliocene), but strontium isotope ratios substantiate the late Oligocene age determined from benthic foraminifers. The results constitute an important test case, illustrating the effectiveness of the strontium isotope method in correlating high-latitude carbonate samples to the standard Oligocene chronostratigraphy. In addition, a sample from the Kugmallit sequence in the Beaufort Sea Edlok N-56 well provided a strontium isotope age estimate of 30.7 Ma. The Edlok sample was paleontologically correlated to just below the early/late Oligocene boundary (30.0 Ma).

Since the inception of their use in commercial micropaleontology, benthic foraminifera have proven to be eminently useful in the solution of geological problems. The utilitarian credentials of benthic foraminifera in estimating paleodepths from marsh through neritic environments with a reasonable degree of accuracy and to indicate approximate ages (viz. subdivision of series/epochs) have been established in both commercial and academic applications. Benthic foraminifera are generally more resistant to dissolution than planktonic foraminifera, and have wide distributions; many taxa have restricted stratlgraphic ranges, making them suitable for correlation and paleo-environmental studies. Yet, three problems have tended to limit the utility of benthic foraminifera: 1) there is a lack of uniformity in taxonomy (Boltovskoy, 1980; Douglas & Woodruff, 1982); 2) attempts to erect zonal schemes using benthic foraminifera have resulted in boundaries which are later proven to be diachronous relative to planktonic zonatlons (e.g. the California provincial stages, Poore, 1976); and 3) attempts to interpret paleodepths from deep-sea benthic foraminifera have produced widely-varying results. One could perhaps conclude, as Boltovskoy (1965a) did over a decade ago, that these problems indicate “…the near future of this science is rather bleak.”

Previous studies of benthic foraminiferal isotopic composition have demonstrated that a latest Eocene–earliest Oligocene benthic foraminiferal δ18O increase occurred in the Pacific, Southern and Atlantic Oceans1–9. A Middle Miocene δ18O increase has been noted in the Pacific, Southern and South Atlantic Oceans1–3,7,10,11 and tentatively identified in the North Atlantic12,13. Due to the incomplete nature of the North Atlantic stratigraphical record14,15, however, the Oligocene to Middle Miocene isotopic record of this ocean is poorly understood. In the modern ocean, the North Atlantic and its marginal seas has a critical role in abyssal circulation, influencing deep- and bottom-water hydrography as far away as the North Pacific16–18. We now report oxygen isotope measurements on Oligocene to Middle Miocene (12–36 Myr BP) benthic foraminifera in the western North Atlantic which show two periods of enriched 18O values: early Oligocene and early Middle Miocene. These enriched intervals are interpreted as resulting, in part, from the build-up of continental ice sheets. The Oligocene to Middle Miocene δ13C record shows three cycles of enrichment and depletion of large enough magnitude to be useful for time–Stratigraphical correlations. Within the biostratigraphical age resolution, δ18O and δ13C records correlate with records from other oceans, helping to establish a useful Tertiary isotopic stratigraphy. An Atlantic–Pacific δ13C contrast of 0.3–0.9‰ during the latest Oligocene to Middle Miocene (12–26 Myr BP) indicates North Atlantic deep and bottom-water production analogous to modern North Atlantic deep water (NADW).

Expression screening was used to isolate cDNA clones encoding a synaptic vesicle membrane protein, VAT-1, which is specifically expressed in the electric lobe of marine rays. The predicted protein has a molecular weight of 41,572 daltons and contains several hydrophobic regions. An antibody raised against a fusion protein synthesized in E. coli recognizes an abundant 42 kd protein that copurifies largely with synaptic vesicles. Trypsin digestion of intact and lysed vesicles as well as membrane extractions suggests that VAT-1 is an integral membrane protein. The VAT-1 RNA is localized to the electromotor nucleus, and the fusion protein antibody stains the electric organ, demonstrating that the protein is transported to nerve terminals. These studies define a novel synaptic vesicle protein that is likely to play a central role in the functions mediated by specific classes of synaptic vesicles.

A major change in Cenozoic deep-sea benthic foraminifera occurred in the Atlantic, Indian, and Pacific oceans near the Paleocene/Eocene boundary. Benthic foraminiferal abundance changes began at about 61.5 Ma at Pacific Deep Sea Drilling Project (DSDP) Site 577. A major extinction event followed at 58–57 Ma (between Zones P6a and P6b), and a series of first appearances continued until circa 55.5 Ma (Zone P6c). These faunal changes occurred during a 6°C warming of Pacific bottom water and may indicate that the primary cause was changing temperature. Other potential causes of the faunal turnover include global changes in surface ocean productivity and changing bottom water source regions. Comparison of benthic and planktonic δ13C records requires no change in the ratio of oceanic phosphorous to carbon during the late Paleocene to early Eocene, which weakens the case for (but does not disprove) a change in surface ocean productivity at this time. Interbasinal comparisons of benthic foraminiferal δ13C records document that water with high δ13C values filled the Cape Basin during the late Paleocene and possibly the early Eocene (circa 61–57 Ma), but apparently did not extend into the western basins of the Atlantic. This pattern suggests a supply of Antarctic source water for the Cape Basin and possible tectonic isolation of the western Atlantic basins during at least part of the late Paleocene. Carbon isotope comparisons show that bottom water supply to the Cape Basin was reduced in the early Eocene. Eolian grain size data suggest that a decrease in zonal wind intensity occurred at the end of the Paleocene. These late Paleocene climatic changes (bottom water warming and decreased wind intensity) correspond with evidence for an important global tectonic reorganization and extensive subaerial volcanism, which may have contributed to climatic warming through increased supply of CO2.

A necessary and sufficient condition for a homogeneous left invariant partial differential operator P on a nilpotent Lie group G to be hypoelliptic is that π(P) be injective in π for every nontrivial irreducible unitary representation π of G. This was conjectured by Rockland in [18], where it was also proved in the case of the Heisenberg group. The necessity of the condition in the general case was proved by Beals [2] and the sufficiency by Helffer and Nourrigat [4]. In this paper we present a microlocal version of this theorem when G is step two nilpotent. The operator may be homogeneous with respect to any family of dilations on G, not just the natural dilations. We may also consider pseudodifferential operators as well as partial differential operators.

We present here oxygen and carbon isotopic records of Eocene to Oligocene benthic f oraminif era from two Bay of Biscay Deep Sea Drilling Project (DSDP) sites (119 and 401). δ18O of benthic foraminifera increases 1.9‰ from a middle Eocene minimum (Zones P10–P11) to an earliest Oligocene maximum (Zone NP21). Approximately 1.4‰ of the increase in benthic foraminiferal δ18O occurs during the late Eocene to earliest Oligocene (Zones P15/16–NP21). Previous results from other North Atlantic DSDP sites (400A and 398) have significantly lower δ18O values of benthic foraminifera, some by as much as 2‰ (refs 1–3). We believe that these differences result from diagenetic alteration of the sediments in the deeper-buried Sites 400A and 398.

A major change in benthic foraminiferal assemblages occurred in the deep Bay of Biscay (> 3 km water; DSDP Sites 119, and Site 400A) between early middle Eocene and earliest Oligocene. Predominant Eocene deep-sea taxa (Nuttallides truempyi, Clinapertina spp., Abyssamina spp.) and associated rarer species became extinct in this interval. These extinctions were followed by an increase in abundance of bathymetrically wide-ranging and stratigraphically long-ranging taxa: Globocassidulina subglobosa, Oridorsalis spp., Gyroidinoides spp., and the Cibicidoides ungerianus plexus. The extinctions cannot be dated precisely from the stratigraphic record recovered to date in the Bay of Biscay; however, the replacement of the N. truempyi-dominated assemblage has been noted previously in the deep South Atlantic/Caribbean as occurring near the middle/late Eocene boundary. Other than the decrease in abundance and extinction of N. truempyi, no major abundance changes are noted within the Eocene at the shallower Site 401 (∼ 2 km water) in the Bay of Biscay. During the Oligocene, Nuttallides umbonifera replaced the Eocene species N. truempyi as the predominant deep-sea benthic foraminifera, reaching peak abundance in the middle Oligocene at Sites 119 and Site 400A. In the modern oceans, the abundance ot N. umbonifera is positively correlated with increased corrosiveness of bottom water, while at Site 119 the abundance of Nuttallides spp. is negatively correlated with δ 13C values in benthic foraminifera. As lower δ 13C values are often associated with older water masses, large numbers of Nuttallides spp. are thought to reflect older, and more corrosive bottom water. The faunal data and oxygen and carbon isotopic data are compared with a circulation model derived from North Atlantic seismic stratigraphic studies to show that old, warm, corrosive, and sluggish Eocene bottom water was replaced by younger, colder, less corrosive, more vigorously circulating bottom water of northern origin by the early Oligocene. Faunal and isotopic data suggest that bottom water became older and more corrosive again in the middle Oligocene, reflecting a reduction in circulation that can also be inferred from the seismic record in the nearby Rockall Plateau region.

We improved upper Eocene to Oligocene deep-sea chronostratigraphic control by integrating isotope (87Sr/86Sr, δ18O, δ13C) stratigraphy and magnetostratigraphy. Most previous attempts to establish the timing of isotope fluctuations have relied upon biostratigraphic age estimates which have uncertainties of 0.5 to over 4.0 m.y. Deep Sea Drilling Project (DSDP) Site 522 contains the best available upper Eocene to Oligocene magnetostratigraphic record which allows first-order correlations of isotope records (87Sr/86Sr, δ18O, δ13C) to the Geomagnetic Polarity Time Scale (GPTS). Empirical calibrations between the 87Sr/86Sr of foraminifera and magnetochronology at Site 522 allow more precise correlation of “unknown” samples with the GPTS. For example, shallow water and high-latitude sections may be tied into the deep-sea record. Sr-isotope stratigraphic resolution for the latest Eocene to Oligocene is approximately 2 m.y.

Tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale, making use of improved chronostratigraphic control and additional Oligocene isotope data. Synchronous changes in both benthic and planktonic δ18O values which occurred in the Oligocene to Miocene (36–5.2 Ma) are interpreted, in part, to represent ice growth and decay. The inferred ice growth events correlate with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records. This association is consistent with a link between Oligocene to Miocene erosional events and rapid (>15 m/m.y.) glacioeustatic lowerings of about 50 m. High benthic foraminiferal δ18O values suggest the presence of continental ice sheets during much of the Oligocene to Recent (36–0 Ma). Substantially ice-free conditions probably existed throughout the Paleocene and Eocene (66–36 Ma). The mechanisms and rates of sea level change apparently were different between the early and late Tertiary, with glacioeustatic changes restricted to the past 36 m.y. Pre-Oligocene erosion on passive continental margins was caused by eustatic lowerings resulting from global spreading rate changes. We apply a model which suggests that large areas of the continental shelves were subaerially exposed during such tectonoeustatic lowstands, stimulating slope failure and submarine erosion. The different mechanisms and rates of eustatic change may have caused contrasting erosional patterns between the early and late Tertiary on passive continental margins. This speculation needs to be confirmed by examination of data from several passive margins.

Vortex boundaries are compared for vortex blobs in equilibrium with an irrotational flow past on obstacle. The ambient flow has circulation around the obstacle. The curves are varied among those which are star-shaped with respect to the equilibrium position of a stable point vortex and which bound an area fixed by giving the circulation of the vortex. The computations are based on a variational principle for energy as a functional of vorticity.

Let P P be a right-invariant pseudodifferential operator with principal part P 0 {P_0} on a simply connected two-step nilpotent Lie group G G of type H H . It will be shown that if π ( P 0 ) \pi (P_0) is injective in S π {\mathcal {S}_\pi } for every nontrivial irreducible unitary representation π \pi of G G , then P P has a pseudodifferential left parametrix. For such groups this generalizes the Rockland-Helffer-Nourrigat criterion for the hypoellipticity of a homogeneous right-invariant partial differential operator on G G . If, in addition, π ( P ) \pi (P) is injective in S π {\mathcal {S}_\pi } for every irreducible unitary representation of G G , it will be shown that P P has a pseudodifferential left inverse. The constructions of the inverse and parametrix make use of the Kirillov theory, their symbols being obtained on the orbits individually and then pieced together.

Let P be a left-invariant differential operator on the Heisenberg group H n , P homogeneous with respect to the dilations on H n . We show that a necessary and sufficient condition for the hypoellipticity of P is that π ( P ) be an injective operator for every irreducible unitary representation π of H n (except the trivial representation). Furthermore, hypoellipticity is preserved if the homogeneous operator P is perturbed by terms of lower order of homogeneity. (Homogeneity means homogeneity with respect to dilations of H n .) It is also shown that if P is homogeneous, left-invariant and hypoelliptic on H n , then its formal adjoint is hypoelliptic.

Seismic, lithostratigraphic, faunal, and isotopic evidence from the western and northern North Atlantic indicates that formation of northern sources for strongly circulating bottom water began in the late Eocene to early Oligocene. The widely distributed reflector R4 correlates with an unconformity eroded along basin margins at the Eocene/Oligocene boundary. This change in abyssal regime also correlates with a major benthic foraminiferal turnover in the deep southern Labrador Sea (DSDP Site 112) and with a faunal reorganization in the Bay of Biscay. The principal bottom-water source probably was of Arctic origin; it entered the Norwegian Sea following separation of Greenland and Spitsbergen and flowed south across the Greenland-Scotland Ridge through the Faeroe-Shetland Channel and possibly across a sill east of Greenland. This flow may have been supplemented by dense Arctic water entering the basin via Nares Strait and Baffin Bay, and by cooling and sinking of saline surface water south of the Greenland-Scotland Ridge and in the Labrador Sea. Current-controlled sedimentation and erosion, often of a chaotic nature, continued through the Oligocene above reflector R4, but the general intensity of abyssal circulation is thought to have decreased. Above reflector R2 (upper lower Miocene) current-controlled sedimentation became more coherently developed, and a major phase of sedimentary drift development was initiated. We interpret this to be a result of a further general reduction and especially a stabilization of the abyssal circulation, possibly linked with degeneration of numerous fracture-zone conduits that previously funnelled bottom water across the Reykjanes Ridge. The gross nature of the circulation has not changed substantially since the middle Miocene, although it has been punctuated by further climatic and tectonic events.

On developpe une methode d'etude et d'estimation des operateurs pseudodifferentiels invariants sur les groupes de Lie nilpotents a deux pas

Seismic stratigraphic evidence indicates that a major change in abyssal circulation occurred in the latest Eocene-earliest Oligocene of the North Atlantic. Reflector R4 reflects a change from weakly (Eocene) to vigorously circulating bottom water (early Oligocene). Sediment distribution studies indicate a northern source for this bottom water, probably from the Arctic via the Norwegian-Greenland Sea/Faeroe-Shetland Channel. Current-controlled sedimentation and erosion continued through the Oligocene; however, above reflector R3 (upper Oligocene), the general intensity of abyssal currents decreased. Above reflector R2 (lower Miocene) a further reduction in abyssal currents resulted in more coherent current-controlled sedimentation and a major phase of sediment drift development. Major deep-sea benthic foraminiferal changes occurred between the middle Eocene and earliest Oligocene: an agglutinated assemblage was replaced by a calcareous assemblage (abyssal Labrador Sea), and an indigenous Eocene calcareious fauna became extinct (abyssal Bay of Biscay). In shallower Atlantic sites ( 3km paleodepth), a Nuttallides truempyi assemblage was replaced by an assemblage of long- and wide-ranging taxa in the early late Eocene.

Integrated magnetostratigraphic and biostratigraphic studies of DSDP Sites 563 and 558 (western North Atlantic) show that, except for a short (~2 Ma) early Miocene hiatus, deposition was continuous from time of seafloor formation (Site 563, between Anomalies 12 and 13; Site 558, between Anomalies 13 and 15) through the Miocene at both sites. Several biostratigraphic datum levels, which have been correlated firmly with magnetic polarity chrons elsewhere, allow correlation of the magnetostratigraphy with the geomagnetic polarity time scale. Based upon that calibration, sediment accumulation rates were low to moderate (< 10 m/Ma) in the Oligocene-early Miocene and higher (> 10 m/ Ma) in the middle-late Miocene after a short hiatus (Chron C5E is missing at both sites). The established magnetochronology is used to make direct magnetobiostratigraphic correlations. For the Oligocenelower Miocene samples, these correlations agree well with previously published first-order correlations. However, our correlations differ from the earlier indirect middle to upper Miocene correlations. In particular, indirect methods were previously used to correlate magnetostratigraphic Chron 11 ( = Zone NN9) with marine Anomaly 5A (Chron C5AN). However, Zone NN9 ( = Chron 11) and associated Zone N16 occur in a long normal interval at Sites 563 and 558 that best correlates with marine magnetic Anomaly 5. This reassignment (Chron 11 = Anomaly 5 = Chron C5N) requires an approximately 1.5 2 Ma upward shift in nannofossil zonal boundaries NN7/NN8 through NN10/NN11. The stratotype lower upper Miocene (Tortonian) is biostratigraphically linked with Zones NN9-NN11. Because Zone NN9 occurs in magnetic Anomaly 5 correlative (Chron C5N), the middle-upper Miocene boundary (basal Tortonian) is probably near the base of Chron C5N, with an estimated magnetochronologic age of 10.4 Ma.

Virtually identical agglutinated (arenaceous) benthonic foraminiferal assemblages (ca 30 genera, 45-50 taxa), characteristic of the Alpine-Carpathian flysch basins, occur in the Upper Cretaceous-Paleogene fine-grained clastic (?turbidite) sequences of the East Newfoundland basin, Labrador and North Seas. The assemblages terminate in both areas in the late Eocene or Oligocene although, in the central (deepest) part of the North Sea, elements of this flysch-type fauna have been observed extending into lower or middle Miocene levels. Independent geologic evidence indicates that these assemblages have an extensive (paleo)bathymetric distribution ( 4 km). Depth alone is not considered a significant factor in their occurrence. In marginal basins, we favor a model which involves relatively rapid deposition of organic rich, fine-grained clastics under somewhat restricted bottom-water circulation conditions, leading to lower pH and low positive or negative eH at the sea floor. The disappearance of the agglutinated assemblage in all but the deepest part of the North Sea may have been due to the shallowing of the basin by sediment infilling resulting in shallower, more oxygenated conditions. On the Canadian margin, decreases in clay and organic carbon content are associated with the exit of the agglutinated assemblages. In contrast, in the deep Labrador Sea (Site 112), lithology and percent organic carbon are relatively constant across this faunal change. This suggests that, at least in the deep sea, these properties may not be critical to the development of predominantly agglutinated assemblages. We suggest that the exit of agglutinated assemblages in the deep Labrador Sea was due to a change in hydrographic properties associated with the evolution of the psychrosphere. Sedimentologic evidence indicates initiation of northern sources of vigorous bottom water in the late Eocene-early Oligocene which may explain the exit of agglutinated foraminifera. This circulation chang resulted in the influx of higher oxygen bottom waters and a lowering of the CCD which may have favored the replacement of predominantly agglutinated assemblages by calcareous assemblages. End_of_Article - Last_Page 892

Geochemical analyses of the carbonate tests calcified by foraminifera have provided much of the foundation for reconstructions of past ocean and climate conditions, and for chemostratigraphy. In particular, reconstructions of climate history (including temperature, salinity, and ice volume), ocean paleocirculation patterns, the carbon cycle, paleoproductivity, marine carbonate chemistry, and chemostratigraphy have relied on measurements of isotopic and trace element composition of foraminiferal calcium carbonate, and variations in these geochemical records through time and space. Substantial work has been done on details of traditional proxies (e.g., d 18 O, d 13 C) and on emerging proxies (e.g., d 11 B, eNd) in recent years; hence, a new overview of these proxies provides a timely reference and educational tool. We review the geochemical proxies that utilize foraminiferal carbonate tests, including potential uses of the proxies for reconstructions through time: d 18 O, d 13 C, trace elements (Mg, Cd, Ba, Zn, B, U), 87 Sr/ 86 Sr, d 26 Mg, d 11 B, and eNd. Both planktic and benthic foraminifera are included; planktic foraminifera provide information on the upper few hundred meters of the surface ocean, whereas benthic foraminifera provide information on conditions at the seafloor and in shallow porewaters, from shallow seas to deep ocean basins.

Using exome sequencing, we have identified de novo variants in MAPK8IP3 in 13 unrelated individuals presenting with an overlapping phenotype of mild to severe intellectual disability. The de novo variants comprise six missense variants, three of which are recurrent, and three truncating variants. Brain anomalies such as perisylvian polymicrogyria, cerebral or cerebellar atrophy, and hypoplasia of the corpus callosum were consistent among individuals harboring recurrent de novo missense variants. MAPK8IP3 has been shown to be involved in the retrograde axonal-transport machinery, but many of its specific functions are yet to be elucidated. Using the CRISPR-Cas9 system to target six conserved amino acid positions in Caenorhabditis elegans, we found that two of the six investigated human alterations led to a significantly elevated density of axonal lysosomes, and five variants were associated with adverse locomotion. Reverse-engineering normalized the observed adverse effects back to wild-type levels. Combining genetic, phenotypic, and functional findings, as well as the significant enrichment of de novo variants in MAPK8IP3 within our total cohort of 27,232 individuals who underwent exome sequencing, we implicate de novo variants in MAPK8IP3 as a cause of a neurodevelopmental disorder with intellectual disability and variable brain anomalies.

Steady vortex flows past a circular cylinder are obtained numerically as solutions of the partial differential equation Δψ = f(ψ), f(ψ) = ω(1 − H(ω − α)), where H is the Heaviside function. Only symmetric solutions are considered so the flow may be thought of as that past a semicircular bump in a half-plane. The flow is transplanted by the complex logarithm to a semi-infinite strip. This strip is truncated at a finite height, a numerical boundary condition is used on the top, and the difference equations resulting from the five-point discretization for the Laplacian on a uniform grid are solved using Fourier methods and an iteration for the nonlinear equation. If the area of the vortex region is prescribed the magnitude of the vorticity ω is adjusted in an inner iteration to satisfy this area constraint.Three types of solutions are discussed: vortices attached to the cylinder, vortex patches standing off from the cylinder and strips of vorticity extending to infinity. Three families of each type of solution have been found. Equilibrium positions for point vortices, including the Föppl pair, are related to these families by continuation.

Magnetostratigraphic records from western North Atlantic Deep Sea Drilling Project (DSDP) Sites 563 and 558 are correlated with the geomagnetic polarity time scale (GPTS; Berggren et aI., 1984a, 1984b) using marine magnetic anomalies and selected biostratigraphic datum levels. The magnetochronology established is used to make direct magnetobiostratigraphic correlations that agree with previous Oligocene-early Miocene studies. However, we show that Zones NN8 partim and NN9 and associated Epoch 11 correlate with Magnetic Anomaly 5 (= Chron C5n). This contrasts with previous indirect correlations of Epoch 11 with Anomaly 5A and requires an upward adjustment of 1.5-2.0 m.y. for middle-late Miocene calcareous nannofossil zones. We correlate the middle/late Miocene boundary with Zone NN8 and earliest Chron C5n (10.4 Ma).

Drilling at Site 549, located on the Goban Spur in the northern Bay of Biscay (Irish continental margin), penetrated an apparently continuous section of upper Eocene–lower Oligocene nannofossil chalks. The Eocene-Oligocene boundary as identified by nannofossils does not coincide with that recognized using planktonic foraminifers. Regardless of which biostratigraphic criteria are used, no dramatic nannofloral or planktonic foraminiferal change occurred at the boundary. There was a gradual transition from warm-water to cool-water assemblages through the late Eocene, with more intense cooling indicated by low-diversity assemblages in lower Oligocene sediments. A bottom-water temperature drop occurred in the late Eocene through early Oligocene as indicated by an 18 O enrichment in benthic foraminifers, although some of this enrichment may have been caused by increased ice volume. A major benthic foraminiferal faunal change, from a Nuttallides truempyi –dominated assemblage to one dominated by wide- and long-ranging taxa, occurred in the early late Eocene. No major benthic assemblage changes occurred at the Eocene-Oligocene boundary.

Oligocene foraminiferal δ 18 O records suggest the development of ice caps (= inferred glacio–eustatic falls) at ca. 36, 31, and 25 Ma. Biostratigraphic analyses of wells from the United States east coast and Irish continental margins consistently show that upper Oligocene sediments overlie a diachronous erosional surface, underlain by lower Oligocene to Eocene strata. At the minimum, the hiatus extends between ca. 34 and 30 Ma. We speculate that erosion during a glacio–eustatic fall near the early/late Oligocene boundary (ca. 32–31 Ma) developed (1) an unconformity on the margins, (2) numerous canyons noted in seismic profiles from the margins of the North Atlantic, and (3) a coastal offlap event. Using δ 18 O data, we apply a model for eustatic changes and margin response that explains the relationships of sea level, unconformities, and coastal onlap/offlap events.

We have identified and dated a major Miocene erosional surface (M1) on the New Jersey continental slope. This surface was penetrated at Deep Sea Drilling Project (DSDP) Site 612, which was drilled near the thalweg of a buried V-shaped canyon. Biostratigraphic data at Site 612 firmly constrain the age of strata above the buried canyon surface as Zones CN7 (=NN9) and N16 (lowermost upper Miocene); the upper Miocene surface at Site 612 lies above lowermost Oligocene strata because of coalesced unconformities. We traced the M1 erosional surface to the COST B-3 well where upper middle Miocene strata underlie it. Biostratigraphic studies of other New Jersey continental slope boreholes (ASP 14, ASP 15) suggest that elsewhere the sediments immediately below the M1 surface encompass the Globorotalia fohsi robusta Zone (= Zone N12-earliest N13; middle middle Miocene). The best age estimate is that M1 was eroded between 11.5 and 10.0 Ma. This erosional event apparently correlates with a similar event on the Irish and Florida continental margins and with oxygen-isotope evidence for a glacio-eustatic lowering.