underthrust


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underthrust

[¦ən·dər¦thrəst]
(geology)
A thrust fault in which the lower, active rock mass has been moved under the upper, passive rock mass.
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References in periodicals archive ?
the Porgera intrusive system lies 24 km south of the Lagaip Fault which marks where the leading, northern edge of the Australian continental plate starts to underthrust the central mountain belt of P.
The result shows that (1) beneath the southernmost portion of the profile there are two sets of strong north-dipping reflectors between 10 s-19 s TWT, which we interpreted to indicate that the LB may underthrust beneath the BNS; (2) there is a well-developed northward thrust beneath the shallow crust near the BNS; (3) there is a broad, gently folded reflection that presents close to the southern segment of the BNS at 10s and shallower to ca.
The figure on page 96 shows seismic reflection and drilling data for the Nankai accretionary prism, where coring penetrated the incoming sedimentary sequence completely, transecting the frontal thrust, the decollement zone (zone of detachment that separates accreted and underthrust sediments), and underthrust deposits to the ocean basement.