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F.T. Manheim

Publications and source records attributed to F.T. Manheim.

At least 37 records · Page 2Linked to original sources
USGS1986

Marine cobalt resources

Ferromanganese oxides in the open oceans are more enriched in cobalt than any other widely distributed sediments or rocks. Concentrations of cobalt exceed 1 percent in ferromanganese crusts on seamounts, ocean ridges, and other raised areas of the ocean. The cobalt-rich crusts may be the slowest growing of any earth material, accumulating one molecular layer every 1 to 3 months. Attention has been drawn to crusts as potential resources because they contain cobalt, manganese, and platinum, three of the four priority strategic metals for the United States. Moreover, unlike abyssal nodules, whose recovery is complicated by their dominant location in international waters, some of the most cobalt-rich crusts occur within the exclusive economic zone of the United States and other nations. Environmental impact statements for crust exploitation are under current development by the Department of the Interior.

Science↗
USGS1984

Ferromanganese crust resources in the Pacific and Atlantic Oceans

Ferromanganese crusts on raised areas of the ocean floor have joined abyssal manganese nodules and hydrothermal sulfides as potential marine resources. Significant volumes of cobalt-rich (about 1% Co) crusts have been identified to date within the US Exclusive Economic Zone (EEZ) in the Central Pacific: in the NW Hawaiian Ridge and Seamount region and in the seamounts in the Johnston Island and Palmyra Island regions. Large volumes of lower grade crusts, slabs, and nodules are also present in shallow ( greater than 1000 m) waters on the Blake plateau, off Florida-South Carolina in the Atlantic Ocean. Data on ferromanganese crusts have been increased by recent German and USGS cruises, but are still sparse, and other regions having crust potential are under current investigation. The authors discuss economic potentials for cobalt-rich crusts in the Central Pacific and Western North Atlantic oceans, with special reference to US EEZ areas. Additional research is needed before more quantitative resource estimates can be made.

Conference Paper↗
USGS1984

Ferromanganese micronodules from the surficial sediments of Georges Bank

Ferromanganese micronodules have been found on Georges Bank, off the U.S. northeast coast, distributed throughout the surficial sediments within an area about 125 km long and at least 12 km wide. These coarse, sand-sized concretions have precipitated from metal-rich interstitial waters and contain many of the textural and structural features common to other neritic nodules. Most of the nodules have accreted around detrital grains, and X-ray powder diffraction analyses indicate the presence of geothite and vernadite (  -MnO 2 ) in the ferromanganese layers. Chemical analyses of the micronodules, when compared with similar data on deep-sea manganese nodules, reveal lower Mn/Fe ratios, significantly higher concentrations of V and As, comparable values of Mo, and an order of magnitude less of Co, Ni, Ce and most other metals.

Georges Bank↗
USGS1984

Seismic reflection studies of sinkholes and limestone dissolution features on the northeastern Florida shelf

High-resolution seismic-reflection profiles show that the shelf off northern Florida is underlain by solution deformed limestone of Oligocene, Eocene, Paleocene and late Cretaceous age. Dissolution and collapse features are widely scattered. They are expressed in three general forms: as sinkholes that presently breach the sea floor, such as Red Snapper Sink and the Crescent Beach submarine spring; as sinkholes that have breached the seafloor in the past but are now filled with shelf sands; and as dissolution collapse structures that originate deep within the section and have caused buckling and folding of overlying Eocene, Oligocene, and to a lesser extent, Neogene strata. Although deformation caused by solution and collapse can be shown to be a continuous process, the major episode of karstification occurred in the late Oligocene and early Miocene when the shelf was exposed to subaerial conditions.

Conference Paper↗
USGS1982

Analysis of barium and strontium in sediments by dc plasma emission spectrometry

The dc plasma arc is suited to analysis of barium and strontium in a wide range of sedimentary rock matrices, from sands, shales, and carbonates, to ferromanganese nodules. Samples containing 10 ppm to more than 3000 ppm barium and strontium were studied. Both alkali (3500 ppm lithium borate, from a preliminary fusion) and lanthanum salts (1%) in the final solution are needed to achieve freedom from systematic effects due to extreme variation in matrix. In the absence of La, neither Li, Na, K, nor Cs totally eliminated effects of Al and other constituents on emission. Silica addition to the fusion helps achieve proper flux viscosity to aid removal of fused beads from graphite crucibles. The effect of refractory-substance formers such as aluminum with calcium can be reduced or removed by selection of a portion of the arc for emission measurement. However, it was decided not to pursue this approach because of loss in analytical sensitivity and need for greater precision in optical adjustment. Analysis of standard rock samples showed generally satisfactory agreement with precision methods of analysis, and some new standard rock data are reported.

Applied Spectroscopy↗
USGS1981

Patterns of groundwater salinity changes in a deep continental-oceanic transect off the southeastern Atlantic coast of the U.S.A.

Investigations of formation-fluid salinities in a transect from western Georgia to the edge of the Blake Plateau off the coast of Georgia show surprisingly similar hydrochemical features offshore and onshore. A fresh-brackish wedge of groundwater (<25 g/kg total dissolved solids) lies beneath the shelf to a depth of ∼ 900 m. On land, brackish waters extend to a maximum depth of ∼ 1.2 km below sea level in Lowndes County, Georgia. In deeper horizons, hypersaline brines (> 100 g/kg) occur in Lower Cretaceous (?) strata. These strata have a pronounced evaporitic (anhydritic) character in the offshore segment. Strong salinity gradients in interstitial waters signify buried evaporite deposits at drill sites beneath the Blake Plateau.

Florida, Georgia, South Carolina↗
USGS1980

Dissolution and analysis of amorphous silica in marine sediments

The analytical estimation of amorphous silica in selected Atlantic and Antarctic Ocean sediments, the U.S.G.S. standard marine mud (MAG-1), A.A.P.G. clays, and samples from cultures of a marine diatom, Hemidiscus, has been examined. Quantitative recovery of sedimentary amorphous silica was achieved by reacting 2 M Na 2 CO 3 with a sample for 4 hours at 90 degrees -100 degrees C; where necessary, aluminum analysis is used to correct for the extraction of non-amorphous silica. Oceanic sediments having an amorphous SiO 2 /clay ratio of 1.0 or more can be analyzed by a single extraction with 2 M Na 2 CO 3 , without correction for non-amorphous additions. Marine sediments having an amorphous SiO 2 /clay ratio of from 1.0 to 0.25 can be corrected for inputs of clay-derived silica using an aluminum determination and an empirical correction factor. Sediments with amorphous SiO 2 /clay ratios of less than 0.25, samples containing non-silica-bearing aluminous materials such as gibbsite, or materials having low absolute levels of amorphous silica require successive leaches to accurately correct for silica inputs from non-amorphous sources. Our values for amorphous silica-rich circum-Antarctic sediments are equal to or greater than literature values, whereas our values for a set of amorphous silica-poor sediments from a transect of the North Atlantic at 11 degrees N, after appropriate correction for silica released from clays, are significantly lower than previous estimates from the same region.

Journal of Sedimentary Petrology↗
USGS1979

U.S. Geological Survey core drilling on the Atlantic shelf

The first broad program of scientific shallow drilling on the U.S. Atlantic continental shelf has delineated rocks of Pleistocene to Late Cretaceous age, including phosphoritic Miocene strata, widespread Eocene carbonate deposits that serve as reflective seismic markers, and several regional unconformities. Two sites, off Maryland and New Jersey, showed light hydrocarbon gases having affinity to mature petroleum. Pore fluid studies showed that relatively fresh to brackish water occurs beneath much of the Atlantic continental shelf, whereas increases in salinity off Georgia and beneath the Florida-Hatteras slope suggest buried evaporitic strata. The sediment cores showed engineering properties that range from good foundation strength to a potential for severe loss of strength through interaction between sediments and man-made structures.

Science↗
USGS1976

Preliminary summary of the 1976 Atlantic Margin Coring Project of the U.S. Geological Survey

The U.S. Geological Survey Atlantic Margin Coring Project, 1976, a 60-day expedition to obtain core samples by drilling beneath the floor of the Continental Shelf and Slope of the eastern United States, was carried out in July, August, and September 1976 aboard D/V GLOMAR CONCEPTION. The coring penetrated as much as 310 meters below the sea floor at 19 sites along the continental margin from Georgia to Georges Bank off New England in water depths ranging from 20 to 300 meters; 1,020 meters of material were recovered in 380 cores, ranging in age from Late Cretaceous to Holocene. One of the major findings was the discovery of relatively fresh water (salinities less than 3 parts per thousand) extending beneath the Continental Shelf as much as 60 nautical miles seaward from the New Jersey coast. Water of about 1 part per thousand salinity was found beneath the shelf more than 7 nautical miles off Ocean City, Maryland and Barnegat Inlet, New Jersey. Analyses for light hydrocarbons in the cores show the highest concentrations (as much as 412,000 ppm) at sites in water depth greater than 200 meters (the shelf-slope break), principally in Pleistocene sediments, although methane concentrations greater than 400,000 ppm also were found in Miocene sediments at one site near the shelf edge. (Woodard-USGS)

Open-File Report↗
USGS1975

Interstitial solutions and diagenesis in deeply buried marine sediments: Results from the Deep Sea Drilling Project

Through the Deep Sea Drilling Project samples of interstitial solutions of deeply buried marine sediments throughout the World Ocean have been obtained and analyzed. The studies have shown that in all but the most slowly deposited sediments pore fluids exhibit changes in composition upon burial. These changes can be grouped into a few consistent patterns that facilitate identification of the diagenetic reactions occurring in the sediments. Pelagic clays and slowly deposited (<1 cm/10 3 yr) biogenic sediments are the only types that exhibit little evidence of reaction in the pore waters. In most biogenic sediments sea water undergoes considerable alteration. In sediments deposited at rates up to a few cm/10 3 yr the changes chiefly involve gains of Ca 2+ and Sr 2+ and losses of Mg 2+ which balance the Ca 2+ enrichment. The Ca-Mg substitution may often reach 30 mM/kg while Sr 2+ may be enriched 15-fold over sea water. These changes reflect recrystallization of biogenic calcite and the substitution of Mg 2+ for Ca 2+ during this reaction. The Ca-Mg-carbonate formed is most likely a dolomitic phase. A related but more complex pattern is found in carbonate sediments deposited at somewhat greater rates. Ca 2+ and Sr 2+ enrichment is again characteristic, but Mg 2+ losses exceed Ca 2+ gains with the excess being balanced by SO 4 post staggered2- losses. The data indicate that the reactions are similar to those noted above, except that the Ca 2+ released is not kept in solution but is precipitated by the HCO 3 post staggered- produced in SO 4 post staggered2- reduction. In both these types of pore waters Na + is usually conservative, but K + depletions are frequent. In several partly consolidated sediment sections approaching igneous basement contact, very marked interstitial calcium enrichment has been found (to 5.5 g/kg). These phenomena are marked by pronounced depletion in Na + , Si and CO 2 , and slight enhancement in Cl - . The changes are attributed to exchange of Na + for Ca 2+ in silicate minerals forming from submarine weathering of igneous rocks such as basalts. Water is also consumed in these reactions, accounting for minor increases in total interstitial salinity. Terrigenous, organic-rich sediments deposited rapidly along continental margins also exhibit significant evidences of alteration. Microbial reactions involving organic matter lead to complete removal of SO 4 post staggered2- , strong HCO 3 post staggered- enrichment, formation of NH 4 post staggered+ , and methane synthesis from H 2 and CO 2 once SO 4 post staggered2- is eliminated. K + and often Na + (slightly) are depleted in the interstitial waters. Ca 2+ depletion may occur owing to precipitation of CaCO 3 . In most cases interstitial Cl - remains relatively constant, but increases are noted over evaporitic strata, and decreases in interstitial Cl - are observed in some sediments adjacent to continents.

Geochimica et Cosmochimica Acta↗
USGS1973

Interstitial water studies on small core samples from the Mediterranean Sea

Of ten Leg 13 sites studied by us, eight give definite evidence of the existence of halite-containing sediments beneath the seabed. This conclusion is based on the existence on continuous sodium and chloride enrichments in interstitial waters with depth. This is the only direct evidence of the existence of salt at these sites, for only evaporitic dolomite, gypsum, and/or anydrite were recovered in cores. Among other ionic relationships, influence of evaporites is seen in calcium, magnesium and sulfate concentrations. Record high barium (216 ppm) and strontium (345 ppm) concentrations were observed in sulfate depleted pore fluids of Site 128 in the Hellenic Trench.

Initial reports of the Deep Sea Drilling Project↗
USGS1972

Interstitial water studies on small core samples, Leg 9

The chemistry of the pore fluids obtained on Leg 9 is remarkable primarily in its constancy. Excepting silicon and strontium, only at one site do the concentrations of the major and minor constituents deviate notably from sea water concentrations (see Tables 1 and 2). The trends, or lack of them, seen in these samples have been discussed previously and only references will be given here. The constancy of composition and similarity to sea water is particularly noteworthy, as the sediments at all of the 9 sites are thought to be intruded by the basal basalt. The pore fluid chemistry exhibits no evidence of intrusion except possibly at Site 84.

Initial reports of the Deep Sea Drilling Project↗