海底地形对不同时间尺度岩浆供给变化的响应

利用有限差分数值模拟方法, 恢复洋中脊地形的形成过程, 模型中岩浆供给按一定的时间周期和幅度规律性地变化。结果表明: 只有当岩浆供给变化周期的时间尺度大于在洋中脊同一侧形成两条断层的时间间隔时, 才能影响海底地形的形成过程并被记录。结合数值模拟实验结果和不同类型洋中脊的地形特征, 认为快速扩张洋中脊是唯一可能在地形上记录到米兰科维奇气候周期(偏心率(100 ka)、倾斜度(41 ka)和岁差(23 ka)) 3个时间尺度岩浆变化周期的洋中脊类型, 中速扩张洋中脊和部分岩浆供给充足慢速扩张洋中脊的地形可能与100 ka尺度的岩浆供给变化周期有关, 大部分慢速扩张洋中脊海底地形不受100 ka及以下的岩浆供给变化周期影响。

Seafloor Bathymetry Response to Different Time Scaleof Magmatic Supply Fluctuation

The finite-difference numerical simulation is used to reproduce the seafloor bathymetry near mid-oceanridges. The magma supply in the model changes regularly with fluctuation period and amplitude. The resultsindicate that only when the magmatic supply fluctuation period is greater than the time interval between theformation of two faults on the same side of mid-ocean ridge, the formation process of the seafloor bathymetry canbe influenced and recorded. Combined with numerical simulation results and different types of ocean ridgetopography, this paper considers that the fast spreading mid-ocean ridge is the only ridges type that can recordthree magmatic supply fluctuation period of Milankovich cycles (eccentricity (100 ka), obliquity (41 ka) andprecession (23 ka)) on the bathymetry. Bathymetry in mid-speed mid-ocean ridges and part of slow spreading midoceanridges with sufficient magmatic supply may be related to the magmatic supply fluctuation period on the 100ka time scale. seafloor bathymetry in most of the slow-spreading mid-ocean ridges is not affected by magmaticsupply fluctuation period of 100 ka or less.