SEDIMENTARY ROCKS FROM THE CONTINENTAL SHELF AND SLOPE OFF THE CENTRAL COAST OF OREGON. By Neil J. Maloney and John V. Byrne

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1 SEDMENTARY ROCKS FROM THE CONTNENTAL SHELF AND SLOPE OFF THE CENTRAL COAST OF OREGON By Neil J. Maloney and John V. Byrne Reprinted from: The ORE BN, vol. 26, no. 5, May 1964 Oregon Department of Geology and Mineral ndustries 1069 State Office Building, Portland, Oregon 97215

2 The ORE BN Volume 26, No. 5 May, 1964 SEDMENTARY ROCKS FROM THE CONTNENTAL SHELF AND SLOPE OFF THE CENTRAL COAST OF OREGON By Neil J. Maloney and John V. Byrne* During the period from July 1961 to September 1963, rocks were collected from 138 different locations on the continental shelf and slope off the central coast of Oregon by the Department of Oceanography, Oregon State University. The sample locations, types of samplers, and general lithologies for all of the samples are listed in Table 1. The sample positions are plotted in Figure 1. n Table 1 the samples are numbered consecutively according to their geographic position. The OSU Sample Number, by which the sample is filed at the Department of Oceanography, is given also. Two locations are listed for those samples collected by dragging a dredge along the bottom for some distance. The two positions indicate the start and finish of the dredge haul. Other types of samples have only one location listed. Positions are based on navigation by loran or by radar. The approximate depths from which the samples were taken can be estimated from the contours in Figure 1. Gravity corers, grab samplers, and a variety of dredges were used to collect the rocks. The gravity corer was allowed to fall free into the bottom. The weight of the instrument (about 59 pounds) was sufficient to drive the core barrel 3 to 4 inches into soft rock. The grab sampler used was a Dietz-Lafond "snapper" type and was successful in collecting rocks lying loose on the bottom. Four types of dredges were employed: The anchor dredge and the otter trawl are primarily biological dredges; the frame or Agassiz dredge is used both by geologists and biologists; and the pipe dredge, designed for collecting rocks, is employed almost solely by geologists. n essence, ail of the dredges aresimply open frames to which is attached some type of collecting bag or container. As the dredge is dragged across the sea floor, it scoops up whatever it enc,- inters. General lithologies are listed in Table 1. The rocks are predominantly si tstones, with a few samples of sandstone and limestone. Limestone sampl es * Department of Oceanography, Oregon State University, Corvallis, (77)

3 TABLE 1. Rock Samples - Oregon Continental Terrace No. OSU Sample No. Latitude Longitude Type of 1/ Sampler Rock Type P Silty limestone OC OT Calcareous siltstone with vugular aragonite P Silty limestone P Shaley mud F Siltstone P Green pellet, calcareous siltstone P Limestone P Silty limestone P Silty limestone F Limestone P Limestone G Siltstone C Stiff, gray, silty clay C Clayey siltstone C Limestone pebbles F Siltstone P Silty limestone G Calcareous siltstone pebble C Friable clayey siltstone F Silty limestone C Friable clayey siltstone C Diatomaceous clayey siltstone F Diatomaceous siltstone F Siltstone P Diatomaceous siltstone C Friable clayey siltstone C Friable clayey siltstone C Friable clayey siltstone F Diatomaceous siltstone, calcareous pebble F Calcareous fine sandstone and siltstone P Stiff clay and shale chips P Pebbles C Friable clayey siltstone C Limestone pebbles C Friable clayey siltstone F Silty limestone cobble, diatomaceous siltstone Type of Sampler C-Corer,F-Frame Dredge, G-Grab Sampler, OT-Otter Trawl, P-Pipe Dredge, AD-Anchor Dredge. Compiled November 1%3, Department of Oceanography, Oregon State University. (78)

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6 TABLE 1. Rock Samples - Oregon Continental Terrace, Continued No. OSU Sample No. Latitude Longitude Type of Sampler Rock Type C Limestone pebbles ) C Friable clayey siltstone C Friable clayey siltstone C Friable clayey siltstone F Siltstone C OT Calcareous fine sandstone P Clayey siltstone F Clayey siltstone, calcareoussiltstone F Green pellet sandstone, calcareous siltstone, diatomaceoussiltstone F Siltstone, calcareous siltstone, green pellet sandstone, breccia F Siltstone, calcareous siltstone, green pellet sandstone, breccia G Clayey siltstone, limestone pebble G Clayey siltstone C Clayey siltstone G Calcareous siltstone pebble G Siltstone F Green pellet sandstone, siltstone P Stiff, gray clay F Siltstone, calcareous siltstone G Limestone pebble, friable siltstone C Calcareous siltstone, friable sandstone G Siltstone C Friable clayey siltstone C Friable silty clay G Limestone pebble F Sandstone F Silty limestone G Limestone pebbles G Si itstone G Siltstone G Siltstone, gravel F Siltstone, calcareous siltstone F Green pellet sandstone, diatomaceous siltstone F Diatomaceol- siltstone, silty limestone boulckr 71 OC OT Mudstone, diatomite P Pebbles, shale chips ( 79

7 No. TABLE 1. OSU Sompie No. Rock Samples - Oregon Continental Terrace, Continued Type of Latitude Longitude Sampler Rock Type G Gravel G Limestone pebbles C Friable Fine sandstone F Siltstone C Clayey siltstone F Clayey siltstone 79 OC OT Clayey siltstone OC OT Silty limestone C OT Silty mudstone 82 0C G Diatomaceous siltstone 83 0C G Siltstone, limestone, pebbles 84 OC G Silty limestone, diatomaceous siltstone 85 OC OT Diatomaceous siltstone 86 0C G Siltstone 87 0C G Si tstone 88 0C G Siltstone F Siltstone F Calcareous siltstone OC OT Mudstone, clinker OC OT Wood, clinker, clayey siltstone 93 0C OT Clinker 94 OC G Calcareous siltstone 95 0C Siltstone F Calcareous siltstone F Siltstone F Silty limestone, siltstone F Diatomaceous siltstone F Siltstone, calcareous siltstone with green pellets F Silty limestone, calcareous siltstone 102 0C OT Siltstone, calcareous siltstone F Silty limestone, calcareoussiltstone C Clayey siltstone with diatoms F Calcareous sit tstone F Calcareous siltstone, siltstone F Siltstone, calcareous siltstone 108 0C AD Friable fine sandstone F Siltstone 110 0C G Diatomaceous siltstone F Siltstone F Calcareous siltstone 113 0C F Diatomaceous siltstone 114 OC G Calcareous siltstone, siltstone pebbles 115 OC AD Coal, clinker (80)

8 TABLE 1. Rock Samples - Oregon Continental Terrace, Continued No Sample No. Latitude Longitude Type of Sampler Rock Type 116 0C G Siltstone 117 OC OT Siltstone 118 0C AD Clayey siltstone 119 OC AD Silty mudstone C AD Calcareous siltstone 121 0C AD Friable sandstone 122 OC Diatomaceous siltstone, calcareous siltstone 123 0C Diatomaceous siltstone 124 OC F Clayey siltstone with diatoms 125 0C F Silty limestone C AD Sandstone, siltstone 127 OC AD Calcareous siltstone, clayey siltstone 128 OC AD Clayey siltstone 129 OC limestone 130 OC AD Sandstone, clayey silt 131 0C Calcareous siltstone 132 OC F Sil tstone 133 0C F Calcareous siltstone, silty limestone 134 0C F Clinker 135 OC G Diatomaceous siltstone 136 0C F Coal P Friable mudstone 138 0C F Silty limestone may represent calcareous concretions which have "weathered" from the less resistant siltstone or shale. The stiff gray clay (sample 54) may be shale in a stage of formation, or possibly is a submarine "weathering" product of a shale or mudstone. Several samples are believed to have been dropped from ships, and are thought not to have been in place at the time of collection, for example, the clinkers and coal of samples 93, 115, 134, 136. n view of the current interest in the petroleum possibilities of the area off the coast of Oregon, these rock samples have been made available for examination at the Department of Oceanography on the campus of Oregon State University in Corvallis. Arrangements for such an examination may be made by contacting Dr. John V. Byrne at the Department of Oceanography. Acknowledgements: The rocks were collected during the course of research carried out under contract with the Office of Naval Research, Contract Nonr 1286; (10) Project NR

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