Toxic dinoflagellates and tidal power generation in the Bay of Fundy,Canada

The incidence of Paralytic Shellfish Poisoning along the eastern seaboard of America has increased and spread during the last decade. One of the core areas for Paralytic Shellfish Poison (PSP), a poison that is derived from toxic dinoflagellates, is centred on the Bay of Fundy. It is in the upper reaches of the Bay of Fundy that a proposal has been made to construct a tidal power generation plant; this project would have a considerable effect on the water circulation, tidal regime and sedimentation characteristics of the Bay of Fundy and Gulf of Maine. Alterations such as these to the hydrography of this area may lead to changes in the occurrence of toxic dinoflagellates and the associated patterns and intensity of PSP.     

Estimating the Surface Wind Speed Over Drifting Pack Ice from Surface Weather Charts

Routine surface wind speed data, vital for the study of drifting pack ice, are not available for the polar oceans. Over sea, it has been demonstrated by Hasse that estimates of surface wind speed may be obtained from the geostrophic wind speed using linear formulae. Comparing estimated with observed data for six sites in Canada, it is found that the formulae may also be applied to obtain estimates of surface wind speed over pack ice.     

Fatty acids and hydrocarbons in surficial sediments of Lake Huron

Fatty acid and hydrocarbon distributions in surficial sediments from ten locations in southern Lake Huron indicate both aquatic and terrigenous recent biological sources of these geolipid materials. Normal alkanoic acids appear to be derived primarily from aquatic sources whereas normal alkanes are from multiple origins. Geolipid distributions are determined by the nature of the biogenic source and are modified during transport and deposition. Sediments receiving urban runoff in Saginaw Bay contain large amounts of non-biogenic hydrocarbons of a petroleum or industrial nature.     

Distribution of copper,cobalt and nickel in ores and host-rocks,Ingladhal, Karnataka,India

Stratiform quartz-sulphide lodes in Ingladhal occur in a typical Precambrian green-stone-belt environment comprising metabasalts, tuff, chert and cherty iron-sulphide formation. Unusually high cobalt contents of metavolcanics and of sulphide minerals in orebodies suggest a consanguinity between ores and rocks. 90% of total nickel, 70% of total cobalt but only 30% of total copper in rocks occur in silicate phases and thus indicate an early separation of copper from cobalt and nickel. Unusually high non-sulphide copper in barren bedded cherts implies availability of Cu-rich solution prior to their lithification. Pyrite in sediments, in volcanics, and in orebodies is characterized by a distinctive pattern of Co-Ni distribution in each case. Partitioning of Co and Ni between coexisting sulphide pairs is complex, but gross equilibrium is indicated. Very high trace metal content of orebody pyrite sharply contrasts with very low such values in pyrite from adjacent sediments and points to a higher temperature of formation of orebodies.     

The mineralogy and petrology of manganese-rich rocks from St. Marcel,Piedmont, Italy

Manganese-rich metamorphic rocks containing violan from St. Marcel, Piedmont, Italy formed under blueschist facies conditions, yielding an unusual suite of minerals including omphacite-albite-quartz, braunite, microcline, hollandite, piedmontite, and strontian calcite. Violan, a violet-colored pyroxene, is shown to be a manganoan omphacite having a primitive unit cell, and is found in the same sample as diopside, possibly indicating a solvus relation. A manganoan phlogopite and a celadonitic muscovite coexist in one sample with microcline. The occurrence of celadonite and phlogopite is the first from the blueschist facies and the celadonite component in the dioctahedral mica is buffered at a maximum by coexistence with phlogopite, microcline, and quartz. Various phase relations are used to establish the P and T of equilibration at 8±1 kbar and 300±50 °C, respectively, while the oxygen fugacity is shown to have been very high, for these temperatures, as consistent with braunite+quartz and the presence of piedmontite. Contribution No. 343, from the Mineralogical Laboratory, Department of Geology and Mineralogy, The University of Michigan, Ann Arbor, MI 48109, USA     

The effect of erosion on palaeoclimatic and topographic corrections to heat flow

The increase of surface temperature following a recent period of glaciation lowers the heat flow at shallow depths. At greater depths, increase of heat flow above the steady-state value might be expected, reflecting lowered surface temperature during the glacial period itself. Thus a plot of the climatic perturbation to heat flow against depth should have a sigmate form. The fact that measurable negative and positive deviation in heat flow (measurable amplitude of the sigmate variation) has not been observed in some deep boreholes may be explained by taking into account the erosion which accompanies ice ages. Quite small amounts of erosion during the period of lowered surface temperature result in perturbations to heat flow which are nearly constant, or decrease smoothly with depth, damping the sigmate variation and rendering it undetectable. Measured heat flow in this situation is not strongly dependent on depth but is nevertheless significantly different from the steady-state value.Ignoring the effect of erosion on topographic corrections in regions which have been subjected to valley glaciation may result in large errors in heat flow estimates, particularly for shallow measurements, such as in lakes.     

Hyperbolic echo zones in the eastern Atlantic and the structure of the southern Madeira Rise

The Madeira Rise is a 450 km northeast-trending structural-sedimentary feature which lies west of the Madeira Islands. Its northern half is controlled by a basement ridge, but its southern section consists of an apparent current-controlled sediment deposit. Its maximum sediment thickness is about 1 km over a relatively level basement. There are two reflectors which can be traced within the sediment pile. A shallow reflector (R1) may mark the termination of a rapid constructional phase of the drift. Sediment cores taken on the southern Madeira Rise have recovered brown marls and chalks with sedimentation rates of only about 1.5 cm/1000 years over the last 225,000 years.A striking zone of hyperbolic reflectors mapped around the flank of the southern Madeira Rise in the 4000–4800 m depth range may be the expression of bedforms created by contour-following currents. Another zone of hyperbolic echoes is found on the continental rise at about 24–26°N in a similar depth range. Trend determinations in this area suggest that the bedforms which give rise to the hyperbolae are oriented north-northeast and may be similar to the abyssal furrows discovered by DEEP-TOW observations on the Blake-Bahama Outer Ridge.The bottom photographs available from both hyperbolic echo zones show a tranquil bottom. This suggests that the hyperbolic bedforms are relict.     

Characterization of sedimentary humic matter by alkaline hydrolysis

Humic matter fractions from modern sediments of Lake Huron and Lake Michigan have been compared. Large yields of saccharinic acids from alkaline hydrolysis suggest that these fractions contain large portions of carbohydrate materials. Evidence for contributions of aquatic lipid (C-16 fatty acids) and of liginin (phenolic acids) to these sediments is also present in the hydrolysis products. Qualitative differences among fulvic acid, humic acid and humin from the same lake are minor, suggesting common (or similar) organic sources for these fractions. The lability of sedimentary humic matter to alkaline hydrolysis is inversely related to its degree of exposure to oxidative weathering. Lability may also be related to diagenetic state as fulvic acids generally yield greater quantities of hydrolysis components than humic acids which in turn yield more than humin.     

Origin of biotite-hornblende-garnet coronas between oxides and plagioclase in olivine metagabbros,Adirondack region,New York

Complex multivariant reactions involving Fe-Ti oxide minerals, plagioclase and olivine have produced coronas of biotite, hornblende and garnet between ilmenite and plagioclase in Adirondack olivine metagabbros. Both the biotite (6–10% TiO₂) and the hornblende (3–6% TiO₂) are exceptionally Titanium-rich. The garnet is nearly identical in composition to the garnet in coronas around olivine in the same rocks. The coronas form in two stages:

1. Plagioclase+Fe-Ti Oxides+Olivine+water =Hornblende+Spinel+Orthopyroxene±Biotite +more-sodic Plagioclase
2. Hornblende+Orthopyroxene±Spinel+Plagioclase =Garnet+Clinopyroxene+more-sodic Plagioclase

The Orthopyroxene and part of the clinopyroxene form adjacent to olivine. Both reactions are linked by exchange of Mg²⁺ and Fe²⁺ with the reactions forming pyroxene and garnet coronas around olivine in the same rocks. The reactions occur under granulite fades metamorphic conditions, either during isobaric cooling or with increasing pressure at high temperature.