Geoscientific investigations from the Scott Plateau off northwest Australia to the Java Trench

In 1977 the R.V. Valdivia carried out a survey between Scott Plateau and the Java Trench, during which 1700 km of 24-channel seismic data, and 2550 km of bathymetric, gravity and magnetic data, were recorded; and 31 bottom samples were obtained, in water depths ranging from 2000 m to 5800 m. The Scott Plateau trends NNE and is bounded to the west by the Argo Abyssal Plain and to the north by the Roti Basin. The plateau is a foundered continental block, and lies at an average depth of 2000-3000 m. On the plateau the dominant fault direction is NW to WNW, an ancient strike direction on the Australian continent. The western margin probably formed as a series of NE-trending rifts and NW-trending transforms during Late Jurassic breakup. Canyons cut the western margin, and some of these appear to be fault-bounded. One such fault forms the northern margin of a major NW-trending feature, the Wilson Spur. This appears to be a transform fault and perhaps extends across the abyssal plain as far as the eastern end of the Java Trench. Valdivia seismic profiles suggest that, at the trench, it separates thrust-faulted continental crust to the east from oceanic crust to the west. This could explain the eastern termination of the deep part of the trench. The bathymetric depression of the Roti Basin, which lies southeast of the Java Trench, links the trench to the Timor Trough. The Argo Abyssal Plain slopes gently southward, with water depths ranging from 5000 m near the Java Trench to 5730 m in the south. Oceanic basement varies from smooth to hummocky and irregular, and is overlain by about 400 m of acoustically semi-transparent Late Jurassic and Cretaceous sediments, that is in turn unconformably overlain by 200 m of layered Tertiary sediment. Bottom samples taken by R.V. Valdivia from the outer Scott Plateau have provided new information about seismic sequences. They show that Callovian breakup was preceded by a period of basic volcanism and shallow marine sedimentation, that restricted shallow marine conditions followed in the Late Jurassic, and that bathyal carbonate sedimentation prevailed by the Late Cretaceous (Campanian). Quaternary marls cored on the northern Scott Plateau straddled the Pleistocene-Holocene boundary, and siliceous oozes cored on the southern slope of the Java Trench contain nannofossils which, below a few decimetres, are older than late Pleistocene. The Java Trench cores indicate that the calcite compensation depth was apparently between 5420 and 5700 m in the early or middle Pleistocene, and is above 4950 m now. The Scott Plateau cores indicate that the present calcite compensation depth in the region lies below 3290 m. On the Scott Plateau Holocene sedimentation rates are about 5 cm/I000 years, but in the Java Trench they are much lower. Manganese oxide crusts and nodules were recovered from the Scott Plateau, but their content of valuable metals was low.

1977年，研究船瓦尔迪维亚号（R.V. Valdivia）在斯科特海台（Scott Plateau）与爪哇海沟（Java Trench）之间开展了海洋勘测，期间共采集到1700千米的24道地震数据、2550千米的水深测量、重力及磁力数据，并获取了31个海底底质样品，采样水深范围为2000米至5800米。
斯科特海台呈北北东向延伸，西侧以阿戈深海平原（Argo Abyssal Plain）为界，北侧与罗蒂海盆（Roti Basin）毗邻。该海台属于沉没陆块，平均水深为2000~3000米。海台上的优势断裂走向为北西至北西西向，与澳大利亚大陆上的古构造走向一致。其西缘大概率形成于侏罗纪晚期的板块裂解过程，当时发育了一系列北东向裂谷与北西向转换断层。
海底峡谷切割了该海台的西缘，其中部分峡谷表现为受断裂控制的构造。其中一条断裂构成了威尔逊海脊（Wilson Spur）这一大型北西向构造的北缘，该构造被认为是一条转换断层，或许可横穿阿戈深海平原延伸至爪哇海沟的东端。瓦尔迪维亚号获取的地震剖面显示，在爪哇海沟处，该断层将东侧的逆冲断裂大陆地壳与西侧的洋壳分隔开来，这一特征可解释爪哇海沟深部区段的东端终止现象。
位于爪哇海沟东南侧的罗蒂海盆的水深洼地，将海沟与帝汶海槽（Timor Trough）连通起来。阿戈深海平原整体向南缓缓倾斜，水深范围从爪哇海沟附近的5000米变化至南部的5730米。洋壳基底地形形态多样，从平坦、丘状到崎岖不均均有分布，其上覆盖有约400米厚的声学半透明侏罗纪晚期及白垩纪沉积物，该套沉积物之上又不整合覆盖了200米厚的层状第三纪沉积层。
研究船瓦尔迪维亚号从斯科特海台外缘采集的底质样品，为区域沉积层序研究提供了新的资料。分析结果显示，卡洛夫期（Callovian）的板块裂解事件之前，存在一段基性火山作用与浅海沉积阶段，随后在侏罗纪晚期出现局限浅海环境，并在白垩纪晚期（坎潘期，Campanian）以半深海碳酸盐沉积为主。
在斯科特海台北部钻取的第四纪泥灰岩样品跨越了更新世-全新世界线；爪哇海沟南侧斜坡钻取的硅质软泥中含有超微化石，在数分米以下的层位中，这些化石的年代早于晚更新世。爪哇海沟的岩芯数据显示，早更新世或中更新世时期，方解石补偿深度（calcite compensation depth, CCD）大致介于5420米至5700米之间，而当前该深度已升至4950米以上。斯科特海台的岩芯数据则表明，该区域当前的方解石补偿深度低于3290米。
斯科特海台的全新世沉积速率约为5厘米/千年，但爪哇海沟内的沉积速率要低得多。研究人员还从斯科特海台回收了氧化锰结壳与锰结核，但其中有价金属的含量较低。