Thermal evolution of the lithosphere beneath fracture zones inferred from geoid anomalies
Thermal evolution of the lithosphere beneath fracture zones inferred from geoid anomalies
复制标题
根据大地水准面异常推断断裂带下方岩石圈的热演化
DOI：
10.1029/gl015i006p00593
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发表时间：
1988
影响因子：
5.2
通讯作者：
A. Cazenave
中科院分区：
文献类型：
--
作者：
J. Marty;A. Cazenave
对跨断裂带(FZ)的Seasat大地水准面异常进行了全球调查，以表征大地水准面坡度随板块年龄的变化对岩石圈冷却的响应。我们给出了沿大西洋六个FZ(Gibbs、Pico、Doldrums、Romanne、Aenssion和Agulhas-Falkland FZ)大地水准面坡度随年龄变化的新结果。结合先前对太平洋FZ(Mendocino，Murray，Clarion和Unditsev FZ)的研究结果，我们确认大地水准面坡度不随年龄变化，因为传导冷却模型预测并表明其复杂行为是一个世界性现象。这些数据清楚地显示了两个趋势：(1)大地水准面坡度在非常年轻的时候开始急剧下降，(2)随后的上升，通常在30-40 Ma左右开始，在∼60 Ma达到顶峰。在少数情况下，大地水准面坡度上升的时间较晚，超过80 Ma。根据Robinson，Parsons和Driscoll最近发展的模型，这些趋势可能是由于FZ下面的水平温度梯度引起的小尺度对流，在亚层低粘层中发展的不稳定，其性质随年龄变化。
A global survey of Seasat derived geoid anomalies across fracture zones (FZ) has been conducted to characterize the behaviour of the geoid slope with age of plate in response to lithospheric cooling. We present new results for the geoid slope versus age along six FZ of the Atlantic ocean (Gibbs, Pico, Doldrums, Romanche, Ascension and Agulhas-Falkland FZ). Including results of a previous study on Pacific FZ (Mendocino, Murray, Clarion and Unditsev FZ), we confirm that the geoid slope does not vary with age as conductive cooling models predict and show that its complex behaviour is a worldwide phenomenum. Two trends are clearly shown up by the data: (1) a sharp initial decrease of the geoid slope at very young ages, (2) a subsequent increase which typically starts at ages around 30-40 Ma and culminates at ∼60 Ma. In a few cases, the rise of the geoid slope occurs later, beyond 80 Ma. According to the recent models developed by Robinson, Parsons and Driscoll, these trends may result from small scale convection induced by the horizontal thermal gradients underneath the FZ, instabilities developing in a sublithospheric low viscosity layer whose properties vary with age.