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.

Growth rates and possible age of a North Pacific manganese nodule

The rate of accumulation of a ferromanganese coating on a fragment of pillow basalt was estimated using a variety of techniques. Unsupported 230 Th activity decrease in the oxide layer, K/A dating of the basalt, fission tracks dating of the glassy layer around the basalt, thickness of the palagonitization rind, and integrated 230 Th activity give ages from approximately 3 x 10-6 years to 5 x 10-3 years. Data suggest that the ferromanganese material formed rapidly (33 mm/10-6 years) and by hydrothermal or volcanic processes.

Annotated record of the detailed examination of Mn deposits from DSDP Site 40, Leg 5 (Cores 5-40-1, 5-40-11)

Site 40 was located by the JOIDES Pacific Advisory Panel in the region between the Molokai and Clarion Fracture Zones with the objective of recovering a continuous sediment core for the paleontologic and biostratigraphic study of the variation in sediment components at the transition between the North Pacific gyral and the Equatorial Current System.

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.

(Table 2, Page 270) Average chemical composition of manganese nodules and crust collected at different localities the Pacific Ocean

Considerable regional variations in the chemical composition of manganese nodules from a wide range of the Pacific Ocean have been observed. These variations can be more exactly expressed in terms of inter-element relationships. In particular, Cu-Mn and Cu-Ni associations reveal that Cu content in pelagic nodules increases rapidly in proportion to those of Mn or Ni. In nodules from continental borderland and hemipelagic areas, even if Mn or Ni contents increase, that of Cu increases only slightly. It is suggested that the considerable chemical differences within individual nodules and between nodules from the same site, at a limited pelagic area where there is no marked change in depositional conditions of nodules, are due to the role of hydrolyzable trace elements in the formation of nodules.

Description of manganese nodules and crust collected from the Hakuho Maru Cruise KH-68-3, July-August, 1968, in Northwestern Pacific Ocean

The cores and dredges described in this report were taken on the KH-68-3 Expedition in July-August, 1968 by the Ocean Research Institute, University of Tokyo from the Hakuho Maru. A total of 16 cores and dredges sites have been were.

Annotated record of the detailed examination of Mn deposits from DSDP Site 39, Leg 5 (Cores 5-39-1, 5-39-2)

Site 39 was located in the region between the Pioneer and Murray Fracture Zones, with the objective of recovering a continuous sediment core for paleontologic and stratigraphic study of the longitudinal variations in sediment components in the eastern Pacific. This site was selected, together with the adjacent ones in the north-south line along 140°W, to provide information on the geologic history of the North Pacific gyral, insofar as this might be recorded in the sediments.

Annotated record of the detailed examination of Mn deposits from DSDP Site 33, Leg 5 (Core 5-33-2)

The proposed location of Site 33 was over north-south Magnetic Anomaly 10 (Pittman-Heirtzler, 32 million years) in order (a) to provide a basis for comparison of the age of the basal sediments with the age based on the magnetic anomaly, (b) to provide a basis for evaluation of relative movement along the Pioneer and Mendocino Fracture Zones, and (c) by being paired with Site 34, to provide comparison of basement materials for adjacent positive and negative magnetic anomalies.

Description of manganese nodules and crust collected from the Hakuho Maru Cruise KH-69-2, April-June, 1969, in the Japan Trench and Sea of Japan areas

The cores and dredges described in this report were taken on the KH-69-2 Expedition in April-June, 1969 by the Ocean Research Institute, University of Tokyo from the Hakuho Maru. A total of 12 cores and dredges sites have been recovered.

Annotated record of the detailed examination of Mn deposits from R/V Hakuho Maru Cruise KH-74-4 stations

Using scanning electron microscopy (SEM) the authors have examined the microtexture of Mn nodules. Previous researches using SEM observation on marine Mn nodules have revealed many characteristic features which may relate to their formation. They report the discovery of in situ calcareous nannoplankton fossils in a Mn nodule collected during the RV Hakuho-Maru Cruise KH-74-4, and present a preliminary calculation of the growth rate, using a biostratigraphic method. They also discuss the potential value of Mn nodule biostratigraphy in terms of deep sea palaeoenvironments.

Annotated record of the detailed examination of Mn deposits from DSDP Site 41, Leg 5 (Cores 5-41-1, 5-41-5)

Site 41 marks the transition from the North Pacific gyral to the Equatorial Current System. The JOIDES Pacific Advisory Panel selected a site at this latitude along the longitudinal profile of 140°W in order to obtain information on the history of migrations of these current systems.