Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes

Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7-6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7-6.4, 4.0-3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge. The second change recorded by benthic foraminiferal faunas occurs at 3.4 Ma in the Caribbean and 4.0-3.2 Ma in the Pacific. At this time the Caribbean is flooded with cold AABW, which is either gradually warmed or is replaced by Glacial Bottom Water (GBW) at 2.0 Ma and by NADW at 1.1 Ma. These changes are related to global climatic events and to the depth of the sill between the Caribbean and Atlantic rather than the rising Isthmus of Panama. Benthic foraminiferal faunas at East Pacific Site 503 indicate a gradual change from cold PDW to warmer PDW between 4.0 and 3.2 Ma. The PDW is replaced by the warmer, poorly oxygenated PIW at 2.1 Ma. Although the PDW affects the faunas during colder intervals between 1.4 and 0.7 Ma, the PIW remains the principal bottom-water mass in the Guatemala Basin of the East Pacific.

Chemical composition of sepiolites and palygorskites from bottom sediments of the Eastern Indian

In fault zones of the East Indian Ridge and adjacent areas of ocean floor almost monomineral sepiolite- and palygorskite clays have been found. They have been studied by a complex of optical and physical methods. Formation of authigenic sepiolites and palygorskite had occurred under influence of Mg- and Si-rich hydrothermal solutions by metasomatic replacement of montmorillonite clays, or by precipitation from saturated solutions in cracks of various rocks.

Geochemistry of surface sediment samples from the equatorial Atlantic south of the Azores

In order to recognize the distribution of hydrothermal tracers south of the Azores, a series of cores has been sampled during the GEOFAR cruise. The distribution of the Mn concentrations shows that the hydrothermal influence is maximum within and to the north-west of the Lucky Strike segment. North of the East-Azores Fracture Zone the sediments are enriched in Ba which could be derived from different sources. The chemical composition of the interstitial water shows that water advection is limited. Mn, Cu, Ni fluxes evaluated in one site have increased during isotopic stages 4 and 2 and the deglaciation.

Ages and sedimentation rates of bottom sediments from the south arid zone of the Pacific Ocean

Radiocarbon datings are used to calculate mean sedimentation rates of metalliferous sediments in the southern arid zone of the Pacific Ocean adjoining the axis of the East Pacific rise (20°S). Owing to low sedimentation rates and intense mixing, only averaged figures could be obtained for ages less than 16 ky. Sedimentation rate varies from 0.3 to about 1 cm/1000 years in the surface layer and is several times higher in the time interval from 20 ky to 45 ky ago. Formulas for calculating mean sedimentation rates with allowance for benthic mixing are presented.

Effectiveness and Challenges of Three Economic Corridors of the Greater Mekong Sub-region

Since the Greater Mekong Sub-region (GMS) program began in 1992, activities have expanded and flourished. The three economic corridors are composed of the East-West, North-South, and Southern; these are the most important parts of the flagship program. This article presents an evaluation of these economic corridors and their challenges in accordance with the regional distribution of population and income, population pyramids of member countries, and trade relations of member economies.

Valedictory poem delivered in the Chapel of Harvard University on the 21 June 1796: in the presence of the President Proffers & Tutors & the four classes of understudents at the request of the class who completed their college studies on that day

Handwritten draft of the Charles P. Sumner’s valedictory poem to the Harvard class of 1796, in a 19th century hardcover binding beginning “The youth by adverse fortune forced to roam…”. The poem mentions John Russell, a member of the Class of 1796 who died in November 1795. The copy includes edits and struck-out words.

" Lines upon the late proceedings of the College Government" collection, 1787-1917

This collection contains various manifestations of a humorous poem, most often called "Lines upon the late proceedings of the College Government," written by classmates John Quincy Adams and John Murray Forbes in 1787. Both Adams and Forbes were members of the class of 1787, and the poem recounts events surrounding the pranks and ensuing punishment of two members of the class behind them, Robert Wier and James Prescott. Wier and Prescott had been caught drinking wine and making "riotous noise," and they were publicly reprimanded by Harvard President Joseph Willard and several professors and tutors, including Eliphalet Pearson, Eleazar James, Jonathan Burr, Nathan Read, and Timothy Lindall Jennison. The poem mocks these authority figures, but it spares Samuel Williams, whom it suggests was the only professor to find their antics humorous.

Middle Miocene isotope stratigraphy and paleoceanographic evolution of the northwest and southwest Australian margins (Wombat Plateau and Great Australian Bight)

The benthic stable isotope record from ODP Site 761 (Wombat Plateau, NW Australia, 2179.3 m water depth) documents complete recovery of the middle Miocene delta13C excursion corresponding to the climatic optimum and subsequent expansion of the East Antarctic Ice Sheet. The six main delta13C maxima of the "Monterey Excursion" between 16.4 and 13.6 Ma and the characteristic stepped increase in delta18O between 14.5 and 13.9 Ma are clearly identified. The sedimentary record of the shallower ODP Sites 1126 and 1134 [Great Australian Bight (GAB), SWAustralia, 783.8 and 701 m water depth, respectively] is truncated by several unconformities. However, a composite benthic stable isotope curve for these sites provides a first middle Miocene bathyal record for southwest Australia. The delta18O and delta13C curves for Sites 1126 and 1134 indicate a cooler, better-ventilated water mass at ~700 m water depth in the Great Australian Bight since approximately 16 Ma. This cooler and younger water mass probably originated from a close southern source. Cooling of the bottom water at ~16 Ma started much earlier than at other sites of equivalent paleodepths in the central and western parts of the Indian Ocean. At Site 761, the delta18O curve shows an excellent match with the global sea level curve between ~11.5 and 15.1 Ma, and thus closely reflects changes in global ice volume. Prior to 15.1 Ma, the mismatch between the delta18O curve and the sea level curve indicates that delta18O fluctuations are mainly due to changes in bottom water temperature.

Phosphorus dynamics in waters of the Pacific Ocean

Tagged phosphorus was used to measure principal indices of mineral phosphorus variations in the euphotic zone of the East Pacific, i.e. total rate of uptake of phosphate phosphorus by microplankton (A_t), fraction consumed by phytoplankton (A_p/A_t), and turnover time (T). A_t reached its greatest values (150-280 ng/l/hour) in the upwelling zone of the Peru traverse, where development of phytoplankton was induced by upwelling. In other areas of this traverse values were 40-80 ng/l/hour in surface layers. In less productive waters on two other profiles (off Central America and California), values were lower, between 20 and 40 ng/l. On the vertical profile maxima of A_t were found at the upper boundary of the thermocline. Turnover time of PO4 phosphorus (T) in zones of phytoplankton abundance was very short, between 1.5 and 4 days. At most other stations it was 10-40 days, increasing to 100-200 days or longer at the lower boundary of the euphotic zone. In areas of phytoplankton abundance it accounted for 60-80% of total uptake of PO4 phosphorus. But in zones of elevated bacterial abundance, A_p/A_t fell to 20-40%. Data indicating lack of correlation between PO4 phosphorus and productivity are presented. It is emphasized that the above measures of PO4 phosphorus dynamics can be used for obtaining measures of functional condition and successional phase of marine plankton communities.

Kaye's and Malleson's History of the Indian mutiny of 1857-8 /

Vols. 3-6, by Malleson, first appeared under title: History of the Indian mutiny, 1857-1858, commencing from the close of the second volume of Sir John Kaye's History of the Sepoy War.

Shaker music : inspirational hymns and melodies illustrative of the resurrection life and testimony of the Shakers.

"Errata": p. [1] at end.

A catalog of the Napoleon library of De Paul university,

Mode of access: Internet.