楼主:
STAV72 (刁民党党务主委)
2025-06-18 18:16:50https://ibb.co/RL0bLBX
论文出处:
https://doi.org/10.1016/j.epsl.2025.119467
超级地幔柱是炽热、活跃的上升流,从地球约2890公里深度的地核-地函边界(CMB)上升
到地表。当它们上升至岩石圈—地球最坚硬的外壳—时,减压熔融会导致地表火山活动。
在大陆内部,较厚的岩石圈会限制地函柱的上升及其相关的减压熔融。然而,有限的大陆
火山活动是否意味着大陆次大陆地函柱的稀少仍不确定。本文,我们提供了跨学科证据,
揭示了阿曼东部第一个清晰的无岩浆“幽灵”地函柱-达尼地函柱。
尽管缺乏现今的地表火山活动,但此地函柱可以透过密集区域地震台网记录的远震P波和
S波到时残差进行清晰成像。
410公里不连续面约14公里的下沉和660公里不连续面约20公里的向上偏转进一步证实了
热异常。成像的低速结构被正的当今残余地形所覆蓋,该区域自晚始新世(约40Ma)
以来神秘地抬升。
Mantle plumes are hot, buoyant upwellings that rise from Earth’s
core-mantle-boundary (CMB) at ~2890 km depth to the surface. As they ascend
towards the lithosphere – our planet’s rigid outermost shell –
decompression melting results in surface volcanism. In continental interiors,
a thicker lithosphere restricts plume ascent and associated decompression
melting. However, it remains uncertain whether limited continental volcanism
implies few sub-continental mantle plumes.
Here, we present inter-disciplinary evidence revealing the first clear
example of an amagmatic “ghost” plume in eastern Oman – the Dani plume.
Despite lacking present-day surface volcanism, this plume is robustly imaged
using P- and S-wave arrival-time residuals from distant earthquakes,
recorded by a dense regional seismic network. A positive thermal anomaly is
further corroborated by a ~14 depression of the 410-km discontinuity and
a ~20 km upward deflection of the 660-km discontinuity.
The imaged low-velocity structure is overlain by positive present-day
residual topography in a region enigmatically uplifted since the
late Eocene (~40 Ma).
超级地幔柱有三种规模,小如冰岛大至德干暗色岩事件。
https://ibb.co/DfkgNhL6
德干暗色岩一连串的火山爆发可能持续了近三万年之久。火山爆发所喷出的气体可能是
白垩纪-第三纪灭绝事件的原因之一,该次灭绝事件灭绝了包含恐龙在内的大部分生物。
据估计,德干暗色岩火山爆发后所形成的原始熔岩区域约为150万平方公里,面积相当于
现在印度的一半,而后经由侵蚀作用与板块运动,形成现在的大小。目前所能直接观测的
熔岩面积约为51.2万平方公里。
目前还不确定阿曼的超级地幔柱会不会爆开就是。