Quaternary stratigraphy and chronology of Mauna Kea, Hawaii: A 380,000-yr record of mid-Pacific volcanism and ice-cap glaciation: Summary
Quaternary stratigraphy and chronology of Mauna Kea, Hawaii: A 380,000-yr record of mid-Pacific volcanism and ice-cap glaciation: Summary
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夏威夷莫纳克亚山第四纪地层学和年代学：38 万年中太平洋火山活动和冰盖冰川作用的记录：摘要
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发表时间：
1979
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通讯作者：
S. C. Porter
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作者：
S. C. Porter
已知的热带中太平洋冰川作用的证据仅限于莫纳克亚山的上部斜坡，莫纳克亚山是构成夏威夷岛的五座巨大盾状火山中最高的一座（图1）。莫纳克亚山主要是在更新世时期建造的，但在全新世时期经历了轻微的喷发活动，最后一次发生在大约3，600到5，000年前。现在山上没有冰川，因为雪线位于山顶（4，206米）之上。然而，在最后几个冰期，火山支持了一系列小冰盖，这可以从广泛的冰川地貌和上斜坡的许多地层剖面中得到证明。晚更新世火山爆发时断时续，这是因为当时的熔岩流和火山灰层都夹有冰川漂移层。位于前冰盖范围内的大多数熔岩流和相关的火山碎屑锥在地层学上与冰川沉积物有关，从而为火山和冰川事件的相对定年提供了基础。此外，夏威夷某些独特的火山地貌和沉积物显然是莫纳克亚山上斜坡所特有的，它们提供了冰下喷发的明显证据。这样的火山单位提供了一个直接的基础，获得几个事件的冰帽冰川的放射性年龄。虽然在1823年最早的记录上升之后，有许多关于莫纳克亚火山地质的观察报告，但第一次对火山进行系统研究是由Stearns和Macdonald（1946年）作为对该岛地质更广泛调查的一部分。莫纳克亚山的岩石被细分为两个主要的单元，Hamakua和Laupahoehoe火山系列（图2），其分布比例为1：125，000。随后出现了关于火山地质学、岩石学、年代学和地球物理学各个方面的较短的论文（Doell和考克斯，1965年; Funkhouser和其他人，1968年; Kinoshita和其他人，1963年; Macdonald，1945年，1949 a，1949 b，1968年; Macdonald和Abbott，1970年; Mc-Dougall，1969年; McDougall和Swanson，1972年; Malahoff和Woollard，1966年，1968年）。此外，从目前的调查中还发现了全新世火山作用、火山灰年代学和一个被掩埋的山顶破火山口的证据（Porter，1971年，1972年a，1972年b，1973年）。
Known evidence of glaciation in the tropical mid-Pacific is restricted to the upper, slopes of Mauna Kea, the highest of five massive shield volcanoes comprising the island of Hawaii (Fig. 1). Mauna Kea was built largely during Pleistocene time but has experienced minor eruptive activity during Holocene time, the last occurring about 3,600 to 5,000 yr ago. Glaciers do not exist on the mountain today, for the snowline currently lies above the summit (4,206 m). However, during the last several glacial ages, the volcano supported a succession of small ice caps, as evidenced by widespread glacial landforms and numerous stratigraphic sections on the upper slopes. Eruptions occurred intermittently during late Pleistocene time, for both lava flows and tephra layers of this age are intercalated with sheets of glacial drift. Most lava flows and associated pyroclastic cones lying within the limits of former ice caps can be related stratigraphically to the glacial deposits, thereby affording a basis for relative dating of volcanic and glacial events. Furthermore, certain distinctive volcanic landforms and deposits, which in Hawaii apparently are unique to the upper slopes of Mauna Kea, provide striking evidence of subglacial eruptions. Such volcanic units offer a direct basis for obtaining radiometric ages of several episodes of ice-cap glaciation. Although a number of observations on the geology of Mauna Kea were reported following the earliest recorded ascent in 1823, the first systematic study of the volcano was made by Stearns and Macdonald (1946) as part of a broader investigation on the geology of the island. The rocks of Mauna Kea were subdivided into two major units, the Hamakua and Laupahoehoe volcanic series (Fig. 2), and their distribution was mapped at a scale of 1:125,000. Shorter contributions on various aspects of the geology, petrology, chronology, and geophysics of the volcano have appeared subsequently (Doell and Cox, 1965; Funkhouser and others, 1968; Kinoshita and others, 1963; Macdonald, 1945, 1949a, 1949b, 1968; Macdonald and Abbott, 1970; Mc-Dougall, 1969; McDougall and Swanson, 1972; Malahoff and Woollard, 1966, 1968). In addition, reports bearing on Holocene volcanism, tephrochronology, and evidence of a buried summit caldera have resulted from the present investigation (Porter, 1971, 1972a, 1972b, 1973).