Report of Visual Observation on Topographic and Geologic Features of the Sagami Knoll, Central Sagami Bay and the Iro Submarine Canyon, South of Izu Peninsula, Based on the Deep Ocean Floor Survey System <i>DEEP TOW</i> during the YK14-22 Cruise

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  • 相模湾中央部相模海丘および伊豆半島南方沖石廊海底谷における海底地形・地質の目視観察 —ディープ・トウによるYK14-22 次航海調査報告—
  • 相模湾中央部相模海丘および伊豆半島南方沖石廊海底谷における海底地形・地質の目視観察 : ディープ・トウによるYK14-22次航海調査報告
  • サガミワン チュウオウブ サガミカイ オカ オヨビ イズ ハントウ ナンポウオキセキロウカイテイダニ ニ オケル カイテイ チケイ ・ チシツ ノ モクシ カンサツ : ディープ ・ トウ ニ ヨル YK14-22ジ コウカイ チョウサ ホウコク

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<p> From December 27 to 28, 2014, using the deep sea survey system DEEP TOW on the Research Vessel “Yokosuka” YK 14-22 cruise (KO-OHO-O cruise IV), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), we conducted submarine surveys at the Sagami Knoll in the Sagami Bay in twice (YKDT # 160, # 161), and at the branch of the Iro Submarine Canyon in the southern Izu Peninsula offshore (YKDT # 162). In the Sagami Knoll, the survey was made along the steep slope of the south side of the Knoll and the dive started from the middle terrace and then progressed in the direction of rising along the slope. The slope consists mainly of mudstone, but three to four layers of conglomerate were found therein. Ten rock samples were collected by the dredgers during the dive (YKDT # 161). In the branch of the Iro Submarine Canyon, diving started from the downstream side, focusing on the stricture part of the canyon midstream, passing through the narrowing toward upstream, and finally rose up the ridge-like topography of the narrowing. Outcrops were widely observed near the stricture, where were found the conglomeratic body in the lower and the layered and massive complex in the upper. The valley floor of the stricture part was sandy and/or pebbly and ripple marks were widely observed on the sea floor. Those ripple marks show the flow direction mostly from the downstream side to the upstream side. It is not a normal flow along the canyon, and infers some flow due to bottom current. On the basis of the rock samples collected in this submarine survey, we examined the compositions of volcanic rocks and confirm that they are andesite to dacite.</p>

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