San Francisco Coastal System grain size and geochemical data for sand provenance study

Over 150 million cubic meter of sand-sized sediment has disappeared from the central region of the San Francisco Bay Coastal System during the last half century. This enormous loss may reflect numerous anthropogenic influences, such as watershed damming, bay-fill development, aggregate mining, and dredging. The reduction in Bay sediment also appears to be linked to a reduction in sediment supply and recent widespread erosion of adjacent beaches, wetlands, and submarine environments. A unique, multi-faceted provenance study was performed to definitively establish the primary sources, sinks, and transport pathways of beach sized-sand in the region, thereby identifying the activities and processes that directly limit supply to the outer coast. This integrative program is based on comprehensive surficial sediment sampling of the San Francisco Bay Coastal System, including the seabed, Bay floor, area beaches, adjacent rock units, and major drainages. Analyses of sample morphometrics and biological composition (e.g., Foraminifera) were then integrated with a suite of tracers including 87Sr/86Sr and 143Nd/144Nd isotopes, rare earth elements, semi-quantitative X-ray diffraction mineralogy, and heavy minerals, and with process-based numerical modeling, in situ current measurements, and bedform asymmetry to robustly determine the provenance of beach-sized sand in the region.

Sedimentology of core M74/4_1143-1

Periplatform ooze is an admixture of pelagic carbonate and sediment derived from neritic carbonate platforms. Compositional variations of periplatform ooze allow the rectonstruction of past sea-level changes. Periplatform ooze formed during sea-level highstands is finer grained and richer in aragonit through the elevated input of material from the flooded platform compared to periplatform ooze formed during the episodes of lowered sea level. In many cases, however, the sea floor around carbonate platforms is subjected to bottom currents which are expected to affect sediment composition, i.e. through winnowing of the fine fraction. The interaction of sea-level driven highstand shedding and current impact on the formation of periplatform ooze is influenced or even distorted by changing current activity, an integrated study using seismic, hydroacoustic and sedimentological data has been performed on periplatform ooze deposited in the Inner Sea of the Maldives. The Miocene to Pleistocene succession of drift deposits is subdivided into nine units; limits of seismostratigraphic units correspond to changes or turnarounds in grain size trends in cores recovered at ODP Site 716 and NEOMA Site 1143. For the Pleistocene it can be shown how changes in grain size occur in concert with sea-level changes and changes of the monsoonal system, which is thought to be a major driver bottom currents in the Maldives. A clear hightstand shedding pattern only appears in the data at a time of of relaxation of monsoonal strength during the last 315 ky. Results imply (1) that drift sediments provide a potential target for analyzing past changes in oceanic currents and (2) that the ooze composition bears a mixed signal of input and physical winnowing at the sea floor.

Grain size and heavy mineral analysis of Sander in Schleswig-Holstein, Germany

Die Sandergebiete sind von 5 Zentren her geschüttet, den Gletschertoren bei Flensburg, Frörup/Översee, Idstedt/Lürschau, Schleswig, Owschlag. Die Körnung der Schmelzwassersande nimmt mit zunehmender Entfernung von den Gletschertoren zunächst schnell, von Medianwerten über 1 mm auf Medianwerte um 0,4 mm in 10 km, dann langsam bis auf Medianwerte unter 0,2 mm in 30 km Entfernung ab. Sortierung und Symmetrie der Sande steigen entsprechend. Aus den Kornverteilungen lassen sich die Fließgeschwindigkeiten bei der Ablagerung ablesen. Sie sind geringer gewesen, als es die mächtigen und verbreiteten Akkumulationen erscheinen lassen. Bereits in 6 km Entfernung vom Eisrand flossen die Schmelzwässer als träge Bäche (0,3 m/sec) ab. In den Gletschertoren traten stoßweise extreme Fließgeschwindigkeiten auf, waren aber nur in geringem Maße am Gesamtaufbau der Sander beteiligt. Die Verbreitung der Würmsande paßt sich den Formen einer älteren Landschaft an. Sie läßt sich im behandelten Gebiet mit Hilfe der Schwermineralanalyse deutlich gegenüber den rißzeitlichen Ablagerungen abgrenzen, da die Verteilungen in den verschiedenaltrigen Sedimenten unterschiedlich sind. Vor Allem das Hornblende/Epidotverhältnis (Hornblendezahl nach STEINERT) ist ein gutes Kriterium. Da rißzeitliche Ablagerungen von den Schmelzwässern aufgearbeitet wurden, und zudem die Hornblenden im Laufe des Transportes stark abrollen, verwischen sich die Unterschiede in weiter Entfernung vom Eisrand. Schmelzwassersande der Würmvereisung sind vor Allem im Norden des Arbeitsgebietes weit nach Westen, bis an die nordfriesischen Inseln, geschüttet worden. Die Schmelzwässer benutzten als Durchlässe zu den Senken des Eemmeeres an der Westküste Täler in rißzeitlichen Hochgebieten. Die Wassermengen wurden hier gebündelt, sodaß sich auf den Eemablagerungen im Anschluß an die Durchlässe "Sekundärsander" ausbreiteten. Die Mächtigkeit der anstehenden Würm-Sandergebiete beträgt bis zu 20 m, meistens zwischen 10 und 15 m. An der Westküste sind die Schmelzwasserablagerungen von marinem Alluvium überdeckt. Teile der morphographisch als junge Sanderebenen erscheinenden Gebiete bestehen in Wirklichkeit aus rißzeitlichen, von jungen Schmelzwässern allenfalls oberflächlich umgearbeiteten Ablagerungen der älteren Vereisung. So ist der westliche und südwestliche Teil des Schleisanders schon während der Rißvereisung aufgeschüttet.

Mediterranean cold-water coral measurements

This study presents aggradation rates supplemented for the first time by carbonate accumulation rates from Mediterranean cold-water coral sites considering three different regional and geomorphological settings: (i) a cold-water coral ridge (eastern Melilla coral province, Alboran Sea), (ii) a cold-water coral rubble talus deposit at the base of a submarine cliff (Urania Bank, Strait of Sicily) and (iii) a cold-water coral deposit rooted on a predefined topographic high overgrown by cold-water corals (Santa Maria di Leuca coral province, Ionian Sea). The mean aggradation rates of the respective cold-water coral deposits vary between 10 and 530 cm kyr?1 and the mean carbonate accumulation rates range between 8 and 396 g cm?2 kyr?1 with a maximum of 503 g cm?2 kyr?1 reached in the eastern Melilla coral province. Compared to other deep-water depositional environments the Mediterranean cold-water coral sites reveal significantly higher carbonate accumulation rates that were even in the range of the highest productive shallow-water Mediterranean carbonate factories (e.g. Cladocora caespitosa coral reefs). Focusing exclusively on cold-water coral occurrences, the carbonate accumulation rates of the Mediterranean cold-water coral sites are in the lower range of those obtained for the prolific Norwegian coral occurrences, but exhibit much higher rates than the cold-water coral mounds off Ireland. This study clearly indicates that cold-water corals have the potential to act as important carbonate factories and regional carbonate sinks within the Mediterranean Sea. Moreover, the data highlight the potential of cold-water corals to store carbonate with rates in the range of tropical shallow-water reefs. In order to evaluate the contribution of the cold-water coral carbonate factory to the regional or global carbonate/carbon cycle, an improved understanding of the temporal and spatial variability in aggradation and carbonate accumulation rates and areal estimates of the respective regions is needed.

Effects of introspection on meta and structural attitude bases

Introspection is the process by which individuals question their attitudes; either questioning why they hold their attitudes (Why introspection), or how they feel about a particular attitude object (How introspection). Previous research has suggested that Why-introspection induces attitude change, and that Why and How introspection influence attitude-behaviour consistency,persuasion, and other effects. Generally, psychologists have assumed that affective and cognitive attitude bases are the mechanism by which introspection leads to these effects. Leading perspectives originating from these findings suggest that either Why introspection changes the content of cognitive attitude bases (the skewness hypothesis), or increases the salience of cognitive attitude bases (the dominance hypothesis); whereas How introspection may increase the salience of affective attitude bases (another part of the dominance hypothesis). However, direct evidence for these mechanisms is lacking, and the distinction between structural and meta bases has not been considered. Two studies investigated this gap in the existing literature. Both studies measured undergraduate students’ attitudes and attitude bases (both structural and meta, affective and cognitive) before and after engaging in an introspection manipulation (Why introspection / How introspection / control), and after reading a (affective / cognitive) persuasive passage about the attitude object. No evidence was found supporting either the skewness or dominance hypotheses. Furthermore, previous introspection effects were not replicated in the present data. Possible reasons for these null findings are proposed, and several unexpected effects are examined.