The Philippine wrench fault system in the Ilocos Foothills, northwestern Luzon, Philippines
The Philippine wrench fault system in the Ilocos Foothills, northwestern Luzon, Philippines
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菲律宾吕宋岛西北部伊罗戈山麓的菲律宾扳手断层系统
DOI：
10.1016/0040-1951(90)90417-7
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
J. Stephan
中科院分区：
文献类型：
--
作者：
N. Pinet;J. Stephan
吕宋岛是台湾-吕宋岛-民都洛岛移动的带的一部分，该带标志着欧亚板块和菲律宾海板块之间的板块边界。在吕宋岛，菲律宾断层平行于菲律宾群岛延伸超过1300 km，是一条活动的左旋走滑断层，形成了一个辫状系统。在中科迪勒拉新生代岩浆弧西侧的伊罗科斯山麓进行了详细的野外测绘以及构造和生物地层分析。这一地区位于吕宋岛西北端，似乎由三个大型构造单元组成，它们连续超过200 km，并以与菲律宾断层有关的主要左旋走滑断层为界。从西到东，这些单位如下：1。(1)Vigan-Laoag海岸带（VLCS）由一个超镁铁质基底组成，该基底被强烈的构造作用和不整合地覆盖在相对未变形的中中新世至上新世沉积盖层上。(2)Vintar Median Strip（VMS）西部以Vigan-Aggao扳手断层为界，该断层向西上冲，东部以Abra River走滑断层为界。该单元由一个厚的（6-10 km）晚始新世至上新世火山碎屑岩序列组成，该序列沉积在一个盆地中，该盆地主要由中央科迪勒拉山脉提供补给，但直到中新世早期，也由一个由VLCS基底组成的超镁铁质高地提供补给;该序列强烈褶皱。(3)东带是由渐新世和中新世岩石侵入的晚始新世-中新世火山岩序列，其构造格局是两个主要构造幕的结果：1。(1)中中新世晚期至晚中新世的事件包括阿布拉河走滑断层。其特征是一个20公里宽的带的折叠和与阿布拉河断层限制弯曲有关的山脊（横向于构造带）的形成。该脊似乎吸收了压缩变形，而走滑分量则被沿阿布拉河断层沿着的几乎纯走滑断层所容纳。(2)上新世（？）第四纪时期，阿布拉河断裂（在此阶段相对不活跃）向西扩展至Vigan-Aggao扳手断裂，Vigan-Aggao断裂位于超镁铁质古隆起（高度变形的中生代蛇绿岩）与古基底之间的边界，古基底中充填着厚层的晚始新世至中新世沉积序列。这个特殊的位置似乎证明了最近使用的一个古老的主要构造特征。
Luzon is part of the Taiwan-Luzon-Mindoro mobile belt which marks the plate boundary between the Eurasian and Philippine Sea plates. On Luzon, the Philippine Fault runs parallel to the Philippine archipelago for more than 1300 km, and is an active, left-lateral, strike-slip fault which forms a braided system.Detailed field mapping together with structural and biostratigraphic analysis have been conducted in the Ilocos Foothills, on the western flank of the Central Cordillera Cenozoic magmatic arc. This area, on the northwestern tip of Luzon, appears to consist of three large tectonic units which are continuous for more than 200 km and bounded by major left-lateral strike-slip faults related to the Philippine Fault. From west to east these units are as follows:1.(1) the Vigan-Laoag Coastal Strip (VLCS) consists of an ultramafic basement which is strongly tectonized and unconformably overlain by a relatively undeformed Middle Miocene to Pliocene sedimentary cover.2.(2) The Vintar Median Strip (VMS) is bounded to the west by the Vigan-Aggao wrench fault which upthrusts westwards, and to the east by the Abra River strike-slip fault. This unit is composed of a thick (6–10 km) Late Eocene to Pliocene volcaniclastic sequence deposited in a basin which was fed mainly by the Central Cordillera but also, until the early Miocene, by an ultramafic high composed of the VLCS basement; this sequence is strongly folded.3.(3) The Eastern Strip (ES) is a Late Eocene to Miocene volcaniclastic sequence intruded by Oligocene and Miocene rocks.This structural pattern results from two major tectonic episodes:1.(1) The late Middle to Late Miocene episode comprises the Abra River strike-slip faulting. This is characterized by the folding of a 20 km wide band and by the creation of a ridge (transverse to the tectonic strips) related to the Abra River Fault restraining bend. This ridge seems to have absorbed the compressive deformation, whereas the strike-slip component was accommodated by the nearly pure strike-slip faulting along the Abra River Fault.2.(2) The Pliocene(?) to Quaternary episode involved strike-slip activity propagating westward from the Abra River Fault (relatively inactive during this phase) to the Vigan-Aggao wrench fault.The Vigan-Aggao Fault is located at the boundary between an ultramafic palaeo high (highly deformed Mesozoic ophiolite) and a palaeobasin filled with a thick Late Eocene to Miocene sedimentary sequence. This particular location seems to attest to the recent use of an older major tectonic feature.