GEOLOGICAL MANIFESTATIONS OF RIDGE COLLISION - EVIDENCE FROM THE GOLFO-DE-PENAS-TAITAO BASIN, SOUTHERN CHILE
GEOLOGICAL MANIFESTATIONS OF RIDGE COLLISION - EVIDENCE FROM THE GOLFO-DE-PENAS-TAITAO BASIN, SOUTHERN CHILE
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DOI：
10.1029/tc004i005p00477
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发表时间：
1985-01-01
期刊：
影响因子：
4.2
通讯作者：
NELSON, E
中科院分区：
文献类型：
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作者：
FORSYTHE, R;NELSON, E
最近在智利海隆与秘鲁-智利海沟（ANT-NAZ-SAM三联点）交汇处附近的南部安第斯山脉进行的地质和地球物理研究揭示了南美洲太平洋边缘沿着独特的许多特征和新近纪地质历史。这一历史包括：（1）第三纪-第四纪海洋盆地的发展，沉积物填充长达3 km（Golfo de Penas‐Taitao盆地，GTB）;（2）一系列断层的破坏，包括正常和走滑运动;（3）局部化的火山活动、近海沟火山活动和浅成深成岩活动以及相关的热液活动。GTB的北方部分在晚中新世（可能更早）开始沉降，随后变形、抬升和暴露。重力和地震反射数据表明，该盆地继续离岸，今天仍在积极沉降（Golfo de Penas）。因此，该地区的沉降和抬升是历时性的，尽管尚不清楚佩纳斯湾的沉降何时开始。该地区的构造破坏可能与Liquiñe-Ofqui断层（LOF）有关，这是一个主要的NS向地壳剪切带，向西弯曲并终止于Golfo de Penas。LOF有向西和向右的横向偏移，并将东部的主要安第斯山脉与西部的大型地壳块体（奇洛埃块体）分开。我们假设GTB已经发展为拉分盆地，以响应Chiloe区块沿着LOF向北的运动。我们提出了一个动态模型，其中的应力梯度，纵向下降远离智利隆起/秘鲁-智利海沟的交汇处成立，因为最年轻的，最浮力，海洋岩石圈被俯冲在三联点。智利海隆被视为一种压头，其作用是在向北迁移的三联点前方驱动奇洛埃地块向北移动。该模型解释了该地区独特的地质特征，并表明脊-沟相互作用可能是活动大陆边缘造山作用的一个重要因素。
Recent geological and geophysical studies in the southern Andes adjacent to the intersection of the Chile Rise with the Peru‐Chile Trench (ANT‐NAZ‐SAM triple junction) have revealed a number of features and a Neogene geologic history that are unique along the Pacific margin of South America. This history includes (1) development of a Tertiary‐Quaternary marine basin with up to 3 km of sediment infill (Golfo de Penas‐Taitao basin, GTB), (2) disruption of the region by a series of faults with both normal and strike slip movements, and (3) localization of silicic, near‐trench volcanism and epizonal plutonism and related hydrothermal activity. The northern portion of the GTB began to subside in the Late Miocene (possibly earlier), and has subsequently been deformed, uplifted, and exposed. Gravity and seismic reflection data suggest that the basin continues offshore where it is still actively subsiding today (Golfo de Penas). Subsidence and uplift have thus occurred diachronously in the region, although it is unclear when subsidence began in the Golfo de Penas. Tectonic disruption of the region is likely related to the Liquiñe‐Ofqui fault (LOF), a major, NS‐trending, crustal shear zone that curves westward and terminates in the Golfo de Penas. The LOF has both down‐to‐the‐west and right lateral offset and separates the main Andean Cordillera on the east from a large crustal block (the Chiloe block) on the west. We hypothesize that the GTB has developed as a pull‐apart basin in response to northward movement of the Chiloe block along the LOF. We propose a dynamic model whereby a stress gradient that decreases longitudinally away from the Chile Rise/Peru‐Chile Trench intersection is set up because the youngest, most buoyant, oceanic lithosphere is being subducted at the triple junction. The Chile Rise is viewed as a type of indenter which is acting to drive the Chiloe block northward in front of the northward‐migrating triple junction. This model explains the unique set of geologic features found in the region, and suggests that ridge‐trench interactions may be an important factor in orogenesis at active continental margins.