An ultraslow-spreading class of ocean ridge
An ultraslow-spreading class of ocean ridge
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DOI：
10.1038/nature02128
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发表时间：
2003-11-27
期刊：
影响因子：
64.8
通讯作者：
Schouten, H
中科院分区：
文献类型：
--
作者：
Dick, HJB;Lin, J;Schouten, H
对西南印度洋和北极海脊的新调查揭示了一种超低速扩张的洋脊，其特征是间歇性的火山活动和缺乏转换断层。我们发现，地幔在这样的脊不断侵位到海底的大区域。超慢速扩张脊和慢速扩张脊之间的差异与慢速扩张脊和快速扩张脊之间的差异一样大。超低速扩张洋脊的形成速度通常小于12毫米/年（-1），尽管它们的特征通常是在高达20毫米/年（-1）的速度下形成的。超低速扩张脊由相连的岩浆和无岩浆增生脊段组成。的amagmatic段是一个以前未被认识到的类增生板块边界结构，并可以采取任何方向，与角度相对于扩展方向的范围从正交到尖锐。这些无岩浆段有时与岩浆脊段共存数百万年，形成稳定的板块边界，或者随着扩张速率、地幔热结构和脊几何形状的变化，可能会被转变和岩浆脊段取代或被取代。
New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced continuously to the seafloor over large regions. The differences between ultraslow- and slow-spreading ridges are as great as those between slow- and fast-spreading ridges. The ultraslow- spreading ridges usually form at full spreading rates less than about 12 mm yr(-1), though their characteristics are commonly found at rates up to approximately 20 mm yr(-1). The ultraslow-spreading ridges consist of linked magmatic and amagmatic accretionary ridge segments. The amagmatic segments are a previously unrecognized class of accretionary plate boundary structure and can assume any orientation, with angles relative to the spreading direction ranging from orthogonal to acute. These amagmatic segments sometimes coexist with magmatic ridge segments for millions of years to form stable plate boundaries, or may displace or be displaced by transforms and magmatic ridge segments as spreading rate, mantle thermal structure and ridge geometry change.