Annotated record of the detailed examination of Mn deposits from COCOTOW Expedition stations in the intersection of the Siqueiros Transform Fault and the East Pacific Rise

A near-bottom geological and geophysical survey was conducted at the western intersection of the Siqueiros Transform Fault and the East Pacific Rise. Transform-fault shear appears to distort the east flank of the rise crest in an area north of the fracture zone. In ward-facing scarps trend 335° and do not parallel the regional axis of spreading. Small-scale scarps reveal a hummocky bathymetry. The center of spreading is not a central peak but rather a 20-40 m deep, 1 km wide valley superimposed upon an 8 km wide ridge-crest horst. Small-scale topography indicates widespread volcanic flows within the valley. Two 0.75 km wide blocks flank the central valley. Fault scarps are more dominant on the western flank. Their alignment shifts from directions intermediate to parallel to the regional axis of spreading (355°). A median ridge within the fracture zone has a fault-block topography similar to that of the East Pacific Rise to the north. Dominant eastward-facing scarps trending 335° are on the west flank. A central depression, 1 km wide and 30 m deep, separates the dominantly fault-block regime of the west from the smoother topography of the east flank. This ridge originated by uplift due to faulting as well as by volcanism. Detailed mapping was concentrated in a perched basin (Dante's Hole) at the intersection of the rise crest and the fracture zone. Structural features suggest that Dante's Hole is an area subject to extreme shear and tensional drag resulting from transition between non-rigid and rigid crustal behavior. Normal E-W crustal spreading is probably taking place well within the northern confines of the basin. Possible residual spreading of this isolated rise crest coupled with shear drag within the transform fault could explain the structural isolation of Dante's Hole from the remainder of the Siqueiros Transform Fault.

Annotated record of the detailed examination of Mn deposits from the CLIMAX II (SCAN) Expedition stations aboard R/V Argo in the central North Pacific

A 0.25 m US Naval Electronics Lab box corer was used to take replicate samples from an oligotrophic bottom under the North Pacific Central Water Mass (approx. 28 degrees N, 155 degrees W). The bottom is a red clay with manganese nodules at a depth of 5500-5800 m. Macrofaunal density ranges from 84 to 160 individuals per m super(2) and is therefore much the same as in Northwest Atlantic Gyre waters. Of the macrofaunal taxa, polychaetes dominate (55 per cent), followed by tanaids (18 per cent), bivalves (7 per cent), and isopods (6 per cent). Meiofaunal taxa were only partially retained by the 297 micrometer screen used in washing. Even then, they are 1.5-3.9 times as abundant as the microfaunal taxa, with nematodes being numerically dominant by far. Foraminifera seem to comprise an important portion of the community, but could not be assessed accurately because of the inability to discriminate living and dead tests. Remains of what are probably xenophyophoridans are also very important, but offer the same problem. Faunal diversity is extremely high, with deposit feeders comprising the overwhelming majority. Most spp are rare, being encountered only once. The distributions of only 3 spp show any significant deviation from randomness. The polychaete fauna from box cores collected from 90 m to the north was not significantly different from that of the principal study locality. Concordance appeared at several taxonomic levels, from spp through microfaunal/ meiofaunal relationships. As a result, the variation in total animal abundance shows aggregation among cores. The authors discuss Sokolova's concept of a deep-sea oligotrophic zone dominated by suspension feeders, and reconcile it with our present findings. The high diversity of the fauna combined with the low food level contradict theories that relate diversity directly with productivity.

Location and ages of terrestrial peatlands located on continental shelves and in coastal sediments

This synthesis dataset contains records of freshwater peat and lake sediments from continental shelves and coastal areas. Information included is site location (when available), thickness and description of terrestrial sediments as well as underlying and overlying sediments, dates (when available), and references.

Annotated record of the detailed examination of Mn deposits from ARA Islas Orcadas Cruise 12 core stations

The purpose of this volume, the ninth in a series of similar publications (Goodell, 1964, 1965, 1968; Frakes 1971, 1973 ; Cassidy et al., 1977), is to continue a presentation to the research community of sediment core descriptions and attendant data of cored and otherwise obtained sediments retrieved in waters of the Southern Ocean aboard the research vessel, ARA Islas Orcadas (formerly, USNS Eltanin), as a part of the circumpolar survey begun by Eltanin in 1962 (see issue of Antarctic Journal of the United States, Vol. 8, No. 3, 1973). The data presented herein are concerned with the results of coring activities aboard cruise 1277 of Islas Orcadas, the third marine geology coring cruise of this vessel under the terms of the present United States-Argentine agreement. The core descriptions are organised as follows: 1) a brief summary of the coring objectives of the cruise, together with a discussion of core recovery; 2) a table and map of station location data for materials retrieved; 3) a table of tentative age-dates for each piston core; 4) an explanation of the laboratory procedures and descriptive criteria used in the description of the sediments, and 5) lithologic descriptions of the piston and trigger cores, and the piston and trigger core bag samples.

Annotated record and chemical composition of Mn deposits from R/V Mahi Cruise Abyssal Hills 69 stations

A University of Hawaii oceanographic cruise, Abyssal Hills 69, with the R/V Mahi, was carried out to study the association of manganese nodules with an abyssal hill. Manganese nodules from three dredge hauls on an abyssal hill located at 36°W and 157°W exhibited differences in morphology and composition between stations only three miles apart. The morphology of the nodules suggests that nodules from a single site have similar morphologies because they began growth at the same time, probably because of a volcanic event. Differences in morphology between stations indicate a local supply of elements. Atomic absorption analysis for manganese, iron, cobalt, nickel, and copper revealed that nodules nearest to a probable fault line and source of volcanism have a, lower manganese to iron ratio than nodules farther removed. This finding supports the theory that volcanism contributes to the formation of some nodules. Additional evidence showing association with volcanism consists of volcanic nuclei in nodules, crusts formed on layers of volcanic ash, and basalt encrusted to various degrees. The variation in cobalt, nickel, and copper contents Gt the nodules from a single dredge is two-to threefold, but iron content is more uniiorm. Four of the six cores from the area increased in manganese concentration with depth, suggesting that diffusion is concentrating manganese in the upper zone of the sediments or in nodules. The author concludes that volcanism is contributing to the formation of nodules by supplying nuclei and transition elements, but is not necessary for the formation of manganese nodules.

Seawater carbonate chemistry and calcification during experiments with coral communities, 2002

The effect of increased CO2 partial pressure (pCO2) on the community metabolism (primary production, respiration, and calcification) of a coral community was investigated over periods ranging from 9 to 30 d. The community was set up in an open-top mesocosm within which pCO2 was manipulated (411, 647, and 918 µatm). The effect of increased pCO2 on the rate of calcification of the sand area of the mesocosm was also investigated. The net community primary production (NCP) did not change significantly with respect to pCO2 and was 5.1 ± 0.9 mmol O2 m-2 h-1, Dark respiration (R) increased slightly during the experiment at high pCO2, but this did not affect significantly the NCP:R ratio (1.0 ± 0.2). The rate of calcification exhibited the trend previously reported; it decreased as a function of increasing pCO2 and decreasing aragonite saturation state. This re-emphasizes the predictions that reef calcification is likely to decrease during the next century. The dissolution process of calcareous sand does not seem to be affected by open seawater carbonate chemistry; rather, it seems to be controlled by the biogeochemistry of sediment pore water.

Annotated record and chemical analyses of a polygenetic manganese nodule (slab) from the Scott Plateau, Indian Ocean (core VA-16-13KD)

A large manganese nodule (manganese slab) was dredged from 2100 m on the Scott Plateau by R.V. Valdivia in 1977. It is an irregular ellipsoid, with a maximum dimension of 28 cm, parallel to the sea floor. Chemical analyses show that Mn and Fe proportions are comparable, and total Ni + Cu + Co content averages 0.7%. The nodule has a complex growth history which started with radial upward growth leading to coalescing into a continuous crust. The crust was coated with horizontal layers. After fracturing and infilling of cracks with calcareous sediment, further layers encased the nodule.

Annotated record of the detailed examination of Mn deposits from the H.M.S. Penguin expedition to the Coral Sea

The analyses of the samples from the Balfour Shoal show that these deposits contain a very large quantity of carbonate of lime, ranging from 88.7 per cent, on the summit to 71.9 per cent, in the deeper water at the base of the cone. The decrease in the quantity of carbonate of lime with increase of depth is not quite regular; still, a general fall in the percentage of lime is clearly indicated from shallower to deeper water. As might be expected in such a circumscribed area, there is a great uniformity both in the chemical composition and relative abundance of the organic and inorganic constituents of the deposits. In all cases the carbonate of lime is almost wholly made up of the dead shells which have fallen from the surface waters - belonging to Plankton organisms such as Pteropods, Heteropods, pelagic Foraminifera and coccoliths. The calcareous shells were in very many cases discoloured brown or black by depositions of the peroxide of manganese. On the north-east steep side of the Balfour Shoal there were indications that depositions of manganese peroxide were more abundant than elsewhere. In 1645 fathoms, there was an angular fragment of a mottled yellowish jasper coated with manganese peroxide, and in 1570 fathoms there were three characteristic spherical black manganese nodules from one-half to three-fourths of an inch in diameter, quite similar to those procured by the Challenger in many areas of the Pacific and Atlantic. In one of these nodules the nucleus was a sub-angular fragment of a light-coloured augite-granophyre.

Annotated record of the detailed examination of Mn deposits from C.S.S. Hudson Cruise 19 (1967) stations

The Bedford Institute of Oceanography provided ship time on the C.S.S. Hudson during the B.I.0. 1967 Metrology and IODAL Cruise for surveying two separate bottom features in the North Atlantic; the Flemish Cap and the San Pablo Seamount one of the Kelvin Seamounts (also known as the New England Seamounts) about 400 miles SSE of Halifax, Nova Scotia. Underwater photography, dredging, and drilling showed San Pablo seamount to have a very considerable covering of manganese deposit, which may be recoverable by mining. San Pablo Seamount was surveyed and sampled; good hauls were made both on the top and on the slopes, at various depths from 500-1000 fathoms; in all cases samples of an unusual stratified manganese-iron ore were recovered. In the hope of gaining additional information in the immediate sample area, one of the dredges had been previously modified to accommodate underwater photographic equipment. X-ray chemical analyses indicate that the ore contains 20 to 25 per cent MnO2, with similar amounts of Fe2O3. Since bottom photographs indicate that these deposits form a continuous cover 1 foot to 3 feet thick over most of the seamount, it is estimated that there are ore reserves in the order of 10 to 30 M tons above 1,000 fathoms.

Annotated record of the detailed examination of Mn deposits from DSDP Hole 2-12C

Site 12 of this report formerly was designated 14 by the Atlantic Advisory Panel. It was drilled in the Cape Verde Basin (latitude 19° 42'N, longitude 26° 01'W), which is underlain by 2000 to 2100 feet (0.9 to 1.1 seconds reflection time) of sediment. The bottom topography of the basin is fairly smooth but not to the degree of an abyssal plain. Site 12 was selected to provide material for paleontological investigations.

Annotated record of the detailed examination of Mn deposits from DSDP Site 20, Leg 3 (Holes 3-20, 3-20A and 3-20C)

Prior to arrival on this site, the only survey data available was from the Vema-20 crossing of the area. The recommended site location was over a relatively smooth valley in the bottom topography at about 4750 meters (15,580 feet) depth (uncorrected), about 10 kilometers wide E-W between peaks (or ridges) on either side. Sediment thickness was unknown. The center of the valley is near the peak of a wide (40 to 50 kilometers) positive magnetic anomaly, identified as Magnetic Anomaly 30 in the hypothesized geomagnetic time scale with an age of 72 million years.

Annotated record of the detailed examination of Mn deposits from DSDP Hole 3-13 and Hole 3-15

The preliminary planning and approach to site 13 were taken from the JOIDES Atlantic Advisory Panel Report and from a previous detailed survey of the site by R/V Vema of the Lamont Geological Observatory. Several CSP profiles crossing the selected site in various directions show an uplifted portion of the sea floor roughly circular in shape of about 10 kilometers in diameter. In contrast to the smooth bottom of the surrounding abyssal plain, the topography of the small rise selected for the site has a small-scale roughness of amplitude of 40 to 80 meters. The work reported here is a biostratigraphic summary of available samples. Only the most important and biostratigraphically significant components of the faunas have been noted. No attempt has been made to give an exhaustive faunal analysis of the samples seen.

Annotated record of the detailed examination of Mn deposits from DSDP Site 42, Leg 5 (Cores 5-42-5, 5-42-6, 5-42-9)

Site 42 is one of the series of sites selected by the Pacific Advisory Panel along the 140th meridian to sample the longitudinal variation in sediment composition in the eastern Pacific. The site is located in an area of abyssal hills between the Clarion and Clipperton Fracture Zones, and is at the northern margin of the thick development of acoustically transparent sediment extending along the equator.

Annotated record of the detailed examination of Mn deposits on the coral banks of the continental shelf in the south-western coastal area of the Gulf of Mexico off Texas

During U.S. Department of Interior, Bureau of Land Management (BLM) public hearings held in 1973, 1974 and 1975 prior to Texas Outer Continental Shelf (OCS) oil and gas lease sales, concern was expressed by the National Marine Fisheries Service, scientists from Texas A&M and the University of Texas and private citizens over the possible environmental impact of oil and gas drilling and production operations on coral reefs and fishing banks in or adjacent to lease blocks to be sold. As a result, certain restrictive regulations concerning drilling operations in the vicinity of the well documented coral reefs and biostromal communities at the East and West Flower Gardens were established by BLM, and Signal Oil Company was required to provide a biological and geological baseline study of the less well known Stetson Bank before a drilling permit could be issued. Considering the almost total lack of knowledge of the geology and biotic communities associated with the South Texas OCS banks lying in or near lease blocks to be offered for sale in 1975, BLM contracted with Texas A&M University to provide the biological and geological baseline information required to facilitate judgments as to the extent and nature of restrictive regulations on drilling near these banks which might be required to insure their protection. In pursuit of this, scientists from Texas A&M University were to direct their attention toward assessments of ground fish populations, unique biological and geological features, substratum type and distribution, and the biotic and geologic relationships between these banks and those farther north.

Annotated record of the detailed examination of Mn deposits from DSDP Site 34, Leg 5 (Core 5-34-17)

Site 34 had been located by the JOIDES Pacific Advisory Panel to be over a negative magnetic anomaly (31 million years B.P.) immediately to the east of Anomaly 10 (Site 33). The primary objective was to obtain samples of basement and basal sediment to provide comparison between adjacent positive and negative magnetic anomalies. A second objective was to obtain samples which would permit an analysis of the variability in sediment over relatively short distances (about 10 miles). Although basement had not been reached at Site 33 because of the unexpected chert, the use of a massive diamond bit at Site 34 permitted coring through the chert to basement at 383 meters below the sea floor. Even though the near basement sections of the paired sites (33 and 34) could not be compared, comparison would be possible above the chert layer.