Sedimentary and Volcanic History: East Mariana Basin and Nauru Basin
Sedimentary and Volcanic History: East Mariana Basin and Nauru Basin
复制标题
沉积和火山历史：东马里亚纳盆地和瑙鲁盆地
DOI：
10.2973/dsdp.proc.89.129.1986
复制
发表时间：
1986
期刊：
影响因子：
--
通讯作者：
R. Moberly
中科院分区：
文献类型：
--
作者：
S. Schlanger;R. Moberly
第89航次期间在深海钻探项目525号现场发现的沉积剖面记录了东马里亚纳盆地白垩纪和新生代历史上的火山活动、板块运动和其他事件。太平洋岩石圈的这一部分形成于侏罗纪;到阿普第时代晚期，它位于南纬22°左右，并沉降到约5000米的深度。在阿普第亚和阿尔必安，火山爆发在附近建造了主要的火山建筑物，这些建筑物是在525号遗址发现的大量火山碎屑流和浊积岩的来源。现在深蚀的沉积物最初是石英规范拉斑玄武岩的组成，与一些后来的碱性玄武岩的贡献。珊瑚礁碎片，卵状体，并在透明层和其他火山成分的底栖有孔虫移位表明，一些火山达到浅水。它们现在是东马里亚纳盆地东端北部和南部的海山和盖奥特。在浊积岩中重新沉积的富含有机碳的碎屑中，提取的岩芯显示出赛诺曼-土伦期海洋缺氧事件的证据，岩芯古地磁显示在坎帕尼亚-马斯特里赫特期的赤道下通过的证据，以及渐新世（P21-P22）海平面下降暴露海山从而导致浊积岩活动恢复的证据。第61航次期间发现的瑙鲁盆地火成杂岩由于第89航次期间加深了462 A孔而获得了另外12个火山单元的岩心。这些（和上覆的）席流中的矿物学和地球化学同质性，以及它们的小变化性质和少量的层间沉积物，表明大量的中板岩浆生成并迅速喷发。第89航次期间钻探的最低流量可能为130 Ma（Valanginian）。他们躺在M26岁的脊顶地壳（约145马，牛津），火山成因的沉积物和岩床代表至少两个其他情节的中板火成岩活动，即在Aptian和Albian（约100马）和Campanian（约75马）。
The sedimentary section recovered during Leg 89 at Deep Sea Drilling Project Site 525 provided a record of volcanism, plate motion, and other events of the Cretaceous and Cenozoic history of the East Mariana Basin. This part of the Pacific lithosphere had formed in the Jurassic; by late Aptian time it was at about 22°S and had subsided to a depth of about 5000 m. In the Aptian and Albian, eruptions built major volcanic edifices nearby that were the sources of massive volcaniclastic debris flows and turbidites found at Site 525. The now deeply altered sediment originally was of quartz-normative tholeiitic basalt composition, with some later alkalic basalt contributions. Reefal debris, ooids, and displaced benthic foraminifers within the hyaloclastic and other volcanogenic components show that some of the volcanoes reached shallow water. They are now the seamounts and guyots north and south of the eastern end of the East Mariana Basin. Recovered cores show evidence of the Cenomanian-Turonian oceanic anoxic event in debris rich in organic carbon redeposited in turbidites, of passage under the equator in Campanian-Maestrichtian time from core Paleomagnetism, and of the Oligocene (P21-P22) fall of sea level that exposed seamounts and thereby caused renewed turbidite activity. The Nauru Basin igneous complex discovered during Leg 61 yielded cores of 12 additional volcanic units as a result of the deepening of Hole 462A during Leg 89. The mineralogical and geochemical homogeneity within these (and overlying) sheet flows, as well as their little-altered nature and small amount of interlayered sediment, indicate that the great volume of midplate magma was generated and erupted rapidly. The lowest flows drilled during Leg 89 probably are 130 Ma (Valanginian). They lie on M26-aged ridge-crest crust (about 145 Ma, Oxfordian), and underlie volcanogenic sediment and sills representing at least two other episodes of midplate igneous activity, namely in the Aptian and Albian (about 100 Ma) and in the Campanian (about 75 Ma).