Current-Controlled Abyssal Sedimentation: Samoan Passage, Equatorial West Pacific
Current-Controlled Abyssal Sedimentation: Samoan Passage, Equatorial West Pacific
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水流控制的深海沉积：赤道西太平洋萨摩亚海峡
DOI：
10.1086/627965
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
P. Lonsdale
中科院分区：
文献类型：
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作者：
C. Hollister;David A. Johnson;P. Lonsdale
1971年对西赤道太平洋萨摩亚通道（168-170°W; 7-10°S）进行了地质和地球物理研究，利用了正在进行的地震反射剖面（3.5 kHz和sparker）、海底照片、海底电流测量、海底水温剖面和沉积物岩心。这些资料和以前的考察资料被综合到这次动态沉积过程的研究中。发现特定的沉积过程与海底表面（12 kHz）和地下（3.5 kHz）的形态和组成有关。(1)回波回波呈抛物线形，地形起伏，局部有整合底突（< 10 m）；过程-沉积物的远洋垂覆，不常发生的滑坡（通道壁）。(2)高反射率，地形光滑，无底下穿透，半硬化沉积物上有锰结核；过程-持续快速（20-50厘米/秒）的底部水流导致侵蚀或不沉积（通道轴）。(3)适度反射的底部，在(2)上面有高达20米的海底穿透，致密的非化石沸石和富含灰分的粘土，含有一些锰结核；过程——来自底流的致密沉积物缓慢沉积（5-10厘米/秒），“风板效应”（通道的背风部分和通道北部的某些地区）。(4)反射非常弱的底部，水下穿透深度可达80 m，含水的深海棕色粘土与改造和交叉层状的生物成因软泥互层；过程-沉积物从逐渐减少的含沙底流（通道北部）迅速堆积。通道内及周围的沉积记录表明，在早始新世至早渐新世之间的某个时期，通道内的水流相对强烈，并持续到第三纪的大部分时间。岩性资料表明，第四纪期间底流的腐蚀作用有显著的周期性波动。
A geological and geophysical study of the Samoan Passage in the west equatorial Pacific (168-170°W; 7-10°S) was carried out in 1971, utilizing underway seismic reflection profiles (3.5 kHz and sparker), bottom photographs, bottom current measurements, bottom water temperature profiles, and sediment cores. These data and those of previous expeditions were synthesized in this study of dynamic sedimentation processes. Specific sedimentation processes were found to be associated with surface (12 kHz) and subsurface (3.5 kHz) morphology and composition of the sea floor. (1) Parabolic echo returns, rugged topography, some local conformable subbottom penetration (< 10 m); process- pelagic draping of sediment, infrequent slumping (Passage walls). (2) Highly reflective, smooth topography, no subbottom penetration, manganese nodules on semi-indurated sediment; process- continued fast (20-50 cm/sec) bottom current flow causing erosion or non-deposition (Passage axis). (3) Moderately reflective bottom with up to 20 m of subbottom penetration lying over (2) above, compact unfossiliferous zeolitic and ash-rich clay containing some manganese nodules; process-slow deposition of compact sediment from bottom currents (5-10 cm/sec), the "wind slab effect" (lee portion of Passage and in certain areas north of the Passage). (4) Very weakly reflective bottom with up to 80 m of subbottom penetration, watery abyssal brown clays interbedded with reworked and cross bedded biogenic ooze; process-rapid accumulation of sediment from waning sediment-laden bottom currents (north of Passage). The sedimentary record in and around the Passage indicates that relatively intense current flow through the Passage was initiated at some time between the early Eocene and early Oligocene, and continued through most of the Tertiary. Lithologic data suggest significant periodic fluctuations in corrosive effects of bottom currents during the Quaternary.