Geography and history of the Louisville Hotspot Chain in the southwest Pacific
Geography and history of the Louisville Hotspot Chain in the southwest Pacific
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西南太平洋路易斯维尔热点链的地理和历史
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发表时间：
1988
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通讯作者：
P. Lonsdale
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作者：
P. Lonsdale
路易斯维尔“海岭”是一条4300公里长的晚白垩世和新生代热点链，相当于南太平洋的夏威夷-皇帝链。它的西北端正在被汤加-Kermadec俯冲带吞噬，但海底和磁性测绘显示，这条火山链仍然包括60多座正极性和反极性的主要火山，分布在沿着75公里宽的地带，可以拟合成围绕太平洋板块/热点旋转的三个连续极点的小圆圈。这条带斜穿过Eltanin系统的断裂带，但几乎没有相互作用，也没有证据表明两个结构之间存在任何成因联系。路易斯维尔火山中有40座生长在海平面以上，并被保存为高纬度地区（即，无珊瑚）盖奥特。它们在大部分岛链上的间隔沿着不到100公里，但在岛链东南端的一个涌浪之下，在推测的热点目前位置的750公里范围内没有。路易斯维尔热点的火山建设速度在大约2000万年前急剧下降。前，在3-4×103 km ~ 3/m.y.在过去的5千万年里，路易斯维尔的火山在过去的1000万到1200万年间都没有形成。(the最丰富的夏威夷火山活动的时间）已经达到海平面。然而，在50.5°S，139.2°W处，从热点隆起的波峰起，一座挖掘出更新世熔岩的海山上升到海面540 m以内。盖奥特的高度表明，在已知的锚链寿命期间，几百米高的热点涌浪一直持续存在，有时在其负载的顶部有均衡低压。盖奥特陆棚断裂的深度系统地向西北方向增加（从530米到2100米），与火山年龄的平方根成正比，并伴有板块边界构造作用和局部均衡沉降和抬升造成的一些分散和倾斜。
The Louisville “Ridge” is a 4300-km-long Late Cretaceous and Cenozoic hotspot chain, the South Pacific equivalent of the Hawaiian-Emperor chain. Its northwestern end is being consumed by the Tonga-Kermadec subduction zone, but Seabeam and magnetic mapping shows that the chain still includes more than 60 major volcanoes, of both normal and reversed polarity, distributed along a 75-km-wide band that can be fitted to small circles about three successive poles of Pacific plate/hotspot rotation. This band obliquely crosses fracture zones of the Eltanin system, but there is little interaction and no evidence of any genetic connection between the two structures. Forty of the Louisville volcanoes grew above sea level and are preserved as high-latitude (i.e., coral-free) guyots. They are spaced less than 100 km apart along most of the chain, but there are none within 750 km of the inferred present location of the hotspot, beneath a swell at the southeast end of the chain. The rate of volcano building by the Louisville hotspot declined sharply about 20 m.y. ago, after being remarkably constant at 3–4×103 km3/m.y. for the previous 50 m.y., and none of the Louisville volcanoes built during the past 10–12 m.y. (the time of most profuse Hawaiian volcanism) has reached sea level. However, a seamount from which Pleistocene lavas were dredged rises to within 540 m of the sea surface from the crest of the hotspot swell at 50.5°S, 139.2°W. Guyot heights demonstrate that a hotspot swell several hundred meters high has persisted throughout the known life of the chain, and sometimes had an isostatic depression on its loaded crest. The depths of guyot shelf breaks increase systematically to the northwest (from 530 to 2100 m) proportional to the square root of volcano age, with some scatter and tilting caused by plate boundary tectonism and local isostatic subsidence and uplift.