Coordinates of multichannel seismic line GeoB05-004

Major plastered drift sequences were imaged using high-resolution multichannel seismics during R/V Meteor cruises M63/1 and M75/3 south of the Mozambique Channel along the continental margin of Mozambique off the Limpopo River. Detailed seismic-stratigraphic analyses enabled the reconstruction of the onset and development of the modern, discontinuous, eddy-dominated Mozambique Current. Major drift sequences can first be identified during the Early Miocene. Consistent with earlier findings, a progressive northward shift of the depocenter indicates that, on a geological timescale, a steady but variable Mozambique Current existed from this time onward. It can furthermore be shown that, during the Early/Middle Miocene, a coast-parallel current was established off the Limpopo River as part of a lee eddy system driven by the Mozambique Current. Modern sedimentation is controlled by the interplay between slope morphology and the lee eddy system, resulting in upwelling of Antarctic Intermediate Water. Drift accumulations at larger depths are related to the reworking of sediment by deep-reaching eddies that migrate southward, forming the Mozambique Current and eventually merging with the Agulhas Current.

Common depth points and associated geographic coordinates

Fluids in subduction zones can influence seismogenic behaviour and prism morphology. The Eastern Makran subduction zone, offshore Pakistan, has a very thick incoming sediment section of up to 7.5 km, providing a large potential fluid source to the accretionary prism. A hydrate-related bottom simulating reflector (BSR), zones of high amplitude reflectivity, seafloor seep sites and reflective thrust faults are present across the accretionary prism, indicating the presence of fluids and suggesting active fluid migration. High amplitude free gas zones and seep sites are primarily associated with anticlinal hinge traps, and fluids here appear to be sourced from shallow biogenic sources and migrate to the seafloor along minor normal faults. There are no observed seep sites associated with the surface expression of the wedge thrust faults, potentially due to burial of the surface trace by failure of the steep thrust ridge slopes. Thrust fault reflectivity is restricted to the upper 3 km of sediment and the deeper décollement is non-reflective. We interpret that fluids and overpressure are not common in the deeper stratigraphic section. Thermal modelling of sediments at the deformation front suggests that the deeper sediment section is relatively dewatered and not currently contributing to fluid expulsion in the Makran accretionary prism.

Table 1: Station data for the entire survey, including coordinates and description of BPBASE

During GANOVEX VI new gravity data were collected along an east-west profile in North Victoria Land south of the Drygalski Ice Tongue, extending 150 km across the Transantarctic Mountains, and comprising 21 data points. Thirty five additional data points were collected over a small area near Brimstone Peak, near the western end of the regional profile. The survey south of the Drygalski has been connected to northern gravity data (GANOVEX V) by a survey line of 12 points. All data have been terrain corrected, and are further constrained by satellite elevation (GPS) and radar ice-thickness measurements. A pronounced regional Bouguer gravity gradient decreasing to the west by approximately 3 mgal/km is superimposed over a coast-parallel belt of granitoid basement rock. West of this belt the local gravity fields become mote variable. Over Beta Peak (Ferrar dolerite) a 50 mgal spike is obser- ved. Within this area, the Ferrar sills are exposed at the surface. West of Brimstone Peak (Ferrar/Kirk patrick sequences), a smooth regional gradient appears to reassert itself. We interpret the initial gradient east (oceanward) of the break-in-slope to be representative of the crust/mantle boundary within the study area. We interpret the initial break-in-slope and the apparent flattening of the regional gradient to be an effect of the N-S trending zone of dense Ferrar sills and associated deep crusttil fractionate replacing less dense basement. We attribute the variability of the local field to be the product of sub-glacial density contrasts that cannot be removed. The regional gravity gradient of the profile is steeper than that observed to the north (Mt. Melbourne quadrangle) and shallower than that reported to the south (McMurdo Sound). The absolute values of the coastal points of origin south of the Drygalski and within the Mt. Melbourne quadrangle differ by 60 to 100 mgal. In addition, topographic relief within the regional transect area is subdued relative to the Transantarctic Mountains to the north and south. We speculate that the root structure of the Transantarctic Mountains undergoes a change somewhere between the Mt. Melbourne quadrangle and the region south of the Drygalski Ice Tongue.

Trace element content and coordinates for factors at DSDP Hole 72-516F

This study involves samples of Santonian to Eocene age (Cores 516F-125 to 516F-38) taken from the Rio Grande Rise in the South Atlantic Ocean. These samples are from DSDP Site 516 occupied during Leg 72 of the Glomar Challenger (details given in site chapter, Site 516, this volume). Only Santonian to Paleocene cores have been well sampled, and analyses of the Eocene samples are preliminary results. Results of the trace element analyses (Mg, Sr, Mn, Ni, Fe, Na, K) of the carbonate fraction and CaCO3 percentage for each sample can be found in Renard and others (1983). Whole geochemical data are treated by the statistical method of correspondence analysis. Oxygen and carbon isotopic ratios measured on samples close to the Cretaceous/Tertiary boundary are not used in this study.

The influence of temperature and seawater carbonate saturation state on 13C-18O bond ordering in bivalve mollusks

The shells of marine mollusks are widely used archives of past climate and ocean chemistry. Whilst the measurement of mollusk delta 18O to develop records of past climate change is a commonly used approach, it has proven challenging to develop reliable independent paleothermometers that can be used to deconvolve the contributions of temperature and fluid composition on molluscan oxygen isotope compositions. Here we investigate the temperature dependence of 13C-18O bond abundance, denoted by the measured parameter Delta 47, in shell carbonates of bivalve mollusks and assess its potential to be a useful paleothermometer. We report measurements on cultured specimens spanning a range in water temperatures of 5 to 25 °C, and field collected specimens spanning a range of -1 to 29 °C. In addition we investigate the potential influence of carbonate saturation state on bivalve stable isotope compositions by making measurements on both calcitic and aragonitic specimens that have been cultured in seawater that is either supersaturated or undersaturated with respect to aragonite. We find a robust relationship between Delta 47 and growth temperature. We also find that the slope of a linear regression through all the Delta 47 data for bivalves plotted against seawater temperature is significantly shallower than previously published inorganic and biogenic carbonate calibration studies produced in our laboratory and go on to discuss the possible sources of this difference. We find that changing seawater saturation state does not have significant effect on the Delta 47 of bivalve shell carbonate in two taxa that we examined, and we do not observe significant differences between Delta 47-temperature relationships between calcitic and aragonitic taxa.

Present day and paleo-geographic coordinates, thicknesses and isopach area of the Early Eocene +19 ash layer (Table 1)

23 layers of altered volcanic ash (bentonites) originating from the North Atlantic Igneous Province have been recorded in early Eocene deposits of the Austrian Alps, about 1,900 km away from the source area. The Austrian bentonites are distal equivalents of the ''main ash-phase'' in Denmark and the North Sea basin. We have calculated the total eruption volume of this series as 21,000 km**3, which occurred in 600,000 years. The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km**3 of ash material, which makes it one of the largest basaltic pyroclastic eruptions in geological history. The clustering of eruptions must have significantly affected the incoming solar radiation in the early Eocene by the continuous production of stratospheric dust and aerosol clouds. This hypothesis is corroborated by oxygen isotope values, which indicate a global decrease of sea surface temperatures between 1 and 2 C during this major phase of explosive volcanism.

LatLong Converter - converts positions from geodetic system to Gauss-Krüger or UTM coordinates

LatLongConverter converts positions from geodetic system to Gauss-Krüger or UTM coordinates. This program is distributed as freeware for the operating systems Microsoft Windows, Apple OS X and Linux.