the present) would have necessitated corresponding changes 

 along all plate boundaries in the Pacific, perhaps even world- 

 wide. 



Geochcmical studies of Nazca Plate sediments by Oregon 

 State University (OSU) provide increasing evidence that sea- 

 water hydrothermal systems extract and transport metals initially 

 disseminated in newly erupted submarine volcanic rocks, that 

 this fundamental geochemical process influences the composi- 

 tion of seawater, and that this process has led to formation of a 

 variety of economically important ore bodies now preserved on 

 the continents. Examples arc; massive sulfides in Precambrian 

 greenschist belts, such as the Noranda deposits of the Abitibi 

 belt in Canada; gold ores in possible Precambrian "metalliferous 

 sediment" of the Homestake mine of South Dakota; the Pre- 

 cambrian Jerome Arizona copper ores; the massive sulfides of 

 the Troodos ophiolite complex on Cyprus, deposited in Creta- 

 ceous seas; and the Miocene Kuroko ore bodies in Japan. 



Scientists of Stanford University and the U.S. Geological 

 Survey are investigating the origin of heavy metals and deposits 

 at divergent plate boundaries. Preliminary laboratory experi- 

 ments indicate that within 1,500 hours adequate amounts of 

 iron, manganese, copper, lead, and silver are transferred from 

 basalt into seawater in concentrations adequate for generation 

 of heavy metal deposits. 



Work at the University of Texas at Dallas is directed to 

 determining the age and genesis of rocks from northern Chile, 

 particularly the paleogeography of the area as it relates to the 

 geologic evolution and interaction of continental South Amer- 

 ica and the Nazca Plate. Samples of igneous rocks crop out 

 with copper quartz porphyries in northern Chile are being 

 compared with oceanic crust and sediments from the Nazca 

 Plate for Sr'VSr"' ratios. This research attempts to use Sr iso- 

 topes to explain the origin of copper-rich quartz porphyries and 

 the age of associated hydrothermal alterations. 



Approximately 22.000 nautical miles of trackline data 

 from the RV Kama Keoki (HIG), 12,000 from the RV Ya- 

 QUiNA (OSU), and 32,000 from the OSS Oceanographer 

 (NOAA Pacific Marine Environmental Laboratory) were re- 

 ceived last year by NOAA Environmental Data Service's 

 National Geophysical and Solar-Terrestrial Data Center, in- 

 cluding bathymetric, magnetic, seismic-reflection profile, 3.5- 

 kHz echo sounder, and sonobuoy data. 



Mid-Atlanfic Ridge 



During Project FAMOUS (French American Mid-Ocean 

 Undersea Study) dives scientists in submersibles followed a 

 detailed mission plan, recording observations and collecting 

 samples, while other members of the team at the surface mon- 

 itored progress and the minute-to-minute location of the sub- 

 mersible. The resulting information includes; more than 

 100,000 photographs of the seabed; a set of rock, sediment, 

 and water samples from precisely known locations; and the 

 first direct observations of faults and lava flows of newly 

 formed sea floor. 



Until Project FAMOUS, there had been little success in 

 bridging the gap between small-scale features of the ocean 

 floor and larger geologic features, because single dredge sam- 

 ples and bottom photographs could not be located more accu- 

 rately than about 100 meters. By using submersibles to explore 

 the rift valley, locations of samples were determined to within 

 10 meters or less, making it possible to construct traditional 





The FAMOUS (French-American Mid-Ocean Undersea 

 Study) shoulder patch. 



geologic maps. Studies of the photographs and samples are 

 providing new information on sea-floor spreading, formation of 

 new crust, and hydrothermal emplacement of minerals. 



Results of Glomar Challenger drilling, 20 miles from 

 the FAMOUS dive sites, have been summarized in Deep Sea 

 Drilling Project, Leg 37, 11 September 1974. Hole 332A. 

 where water depth was 1 .84 1 meters, was drilled to 1 .858 meters 

 beneath the sea floor and then continuously cored to a total 

 depth 2,228 meters. Examination of the cores shows the follow- 

 ing; The upper part of the volcanic oceanic layer is made up of 

 submarine basalt flows interlayered with deep sea sediments. 

 The relative abundance of sediment decreases with depth until 

 only volcanic rocks are encountered. The accumulation of this 

 volcanic-sedimentary sequence occurred over a period of 

 100,000 to 200,000 years on the floor of the median valley (in 

 the Mid-Atlantic Ridge). New crust formed during cycles of 

 massive eruptions, which periodically decreased in their activity 

 and permitted deep sea sediments to collect on top of the lava 

 flows between eruptions. A number of repetitive volcanic cycles 

 have been identified in this sequence. A few unique types of 

 lava interrupt the cycles at odd intervals. 



Deep drilling also has been completed in an active geo- 

 thermal area in the Azores. In 1972, scientists from Dalhousie 

 University and Lamont-Doherty Geological Observatory began 

 deep drilling on the island of Bermuda in the western Atlantic. 

 This 800-meter hole into the oceanic crust showed some 100 

 separate volcanic units. In 1973, a second hole was drilled on 

 the island of Sao Miguel in the Azores (Muecke, M. J. and 

 others. Deep drilling in an active geothermal area in the Azores, 

 Nature 252(5841 ) ;281-285, November 22, 1974). Tempera- 



33 



