Deep Sea Drilling Project Leg 60: Cruise Objectives, Principal Results, and Explanatory Notes
Deep Sea Drilling Project Leg 60: Cruise Objectives, Principal Results, and Explanatory Notes
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深海钻探项目第 60 段：巡航目标、主要结果和解释说明
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
J. Natland
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文献类型：
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作者：
D. Hussong;S. Uyeda;R. Knapp;H. Ellis;S. Kling;J. Natland
DSDP在构造活动洋缘取样的一个主要目标是获得洋际俯冲带-岛弧-弧后盆地系统的完整断面。这种系统的一个典型例子是在西太平洋，在马里亚纳海沟后面（以西）形成了一系列明显的弧后盆地和火山弧。分配了两个连续的钻探腿（第59和60腿），沿沿着北纬18°钻探一个东西向的样带，从太平洋的马里亚纳盆地到菲律宾海最古老的不活跃岛弧和弧后扩张盆地。在第59航次期间，对该样带（菲律宾海、帕劳-九州海脊、帕雷斯贝拉盆地和西马里亚纳海脊-站点447451）的西部（较老的、不活跃的）一半进行了钻探。第60航次的目的是在一系列紧密间隔的钻孔中对样带的构造活动东部进行取样（图1和表1）跨越目前开放的弧后盆地（马里亚纳海槽，现场勘测目标SP-4，站点453456），马里亚纳弧本身（现场勘测目标SP-3b;现场457）、马里亚纳弧前区域（现场勘测目标SP-3;现场458和459）和马里亚纳海沟深处（现场勘测目标SP-2;现场460和461）。此外，在太平洋板块向海的海沟上钻取了一个地点（地点勘测目标SP-1，地点452），以获得沉积物和正在被运送到海沟的洋壳的参考剖面。尽管如此密集的钻探地点在复杂的弧-沟系统中提供的数据仍然很少，但人们希望通过钻探该地区的每一个主要结构要素，我们可以阐明马里亚纳海槽的扩张、沉降和沉积历史，马里亚纳弧的火山和构造历史，以及海沟和弧前区域的构造历史。由于在第60航次期间重点调查了样带最年轻和最活跃的部分，Glomar Challenger配备了测井、电阻率和井下热流仪器，以获得关于最近形成和活跃变形的海沟、弧和弧间盆地地壳的物理和热状态的现场数据。
A major goal of DSDP sampling of tectonically active ocean margins has been to obtain a complete transect of an interoceanic subduction zoneisland arcback-arc basin system. A classic example of such a system is in the western Pacific, where an apparent series of back-arc basins and volcanic arcs have formed behind (west of) the Mariana Trench. Two consecutive drilling legs (Legs 59 and 60) were assigned to drill an east-west transect of sites along latitude 18°N, from the Mariana Basin of the Pacific Ocean to the oldest inactive island arcs and back-arc spreading basins of the Philippine Sea. The western (older, inactive) half of this transect (Philippine Sea, Palau-Kyushu Ridge, Parece Vela Basin, and the West Mariana Ridge—Sites 447451) was drilled during Leg 59. The objective of Leg 60 was to sample the tectonically active eastern portion of the transect in a closely spaced series of holes (Fig. 1 and Table 1) across the presently opening back-arc basin (Mariana Trough, Site Survey Target SP-4, Sites 453456), the Mariana arc itself (Site Survey Target SP-3b; Site 457), the Mariana fore-arc region (Site Survey Target SP-3; Sites 458 and 459), and deep within the Mariana Trench (Site Survey Target SP-2; Sites 460 and 461). In addition, one site (Site Survey Target SP-1, Site 452) was drilled on the Pacific plate seaward of the trench to obtain a reference section of sediments and oceanic crust being delivered to the trench. Although even this geographical concentration of drill sites provided sparse data in the complex arc-trench system, it was hoped that by drilling each of the primary structural elements of the area we could elucidate the spreading, subsidence, and sedimentation history of the Mariana Trough, the volcanic and tectonic history of the Mariana arc, and the tectonic history of the trench and fore-arc region. Because of the emphasis on investigating the youngest and most active portions of the transect during Leg 60, the Glomar Challenger was equipped with logging, electrical resistivity, and downhole heat flow instruments to obtain in situ data on the physical and thermal state of recently formed and actively deforming trench, arc, and interarc basin crust.