| 释义 |
overthrust, n. Geol.|ˈəʊvəθrʌst|
[over- 1, 9.]
The thrust of the strata or series of rocks on one side of a fault over those on the other side, esp. of lower over higher strata, as in an overfault or faulted overfold; a reverse fault; (used more particularly in reference to the distance through which the mass of dislocated strata has been thrust or moved forward over the thrust-plane). In mod. use (also overthrust fault), a reverse fault in which the fault plane makes a relatively small angle with the horizontal. Also attrib.
1883[see overfault]. 1885C. Callaway in Daily News 8 Jan. 3/5 The extraordinary overthrust of old rocks on to newer strata in Sutherlandshire. 1888Q. Jrnl. Geol. Soc. 385 Confirming Nicol's conclusions..that the line of junction of the unaltered Palaeozoic rocks is a line of fault and overthrust. 1890Boyd Dawkins in Nature 31 July 320 The coal-measures are folded, broken and traversed by great ‘overthrust’ faults. 1892Lapworth Pres. Address Brit. Ass. Edin., The overthrust plane or overfault, where the septal region of contrary motion in the fold becomes reduced to, or is represented by, a plane of contrary motion. 1894Jrnl. R. Agric. Soc. June 390 Eastbourne, where on the foreshore the Cretaceous strata are repeated by faults and overthrusts. 1903A. Geikie Text-bk. Geol. (ed. 4) I. 690, 1. Normal Faults... 2. Reversed Faults or Overthrusts. 1944A. Holmes Princ. Physical Geol. vi. 80 Reverse or Thrust Faults... When the resulting fracture is inclined at an angle between 45° and the horizontal..the corresponding fault is described as an overthrust. 1957Bull. Geol. Soc. Amer. LXVIII. 168/1 The Medicine Lodge overthrust, a low-angle fault with a displacement of many miles. 1969Ibid. LXXX. 953 Overthrust fault surfaces are actually undulatory rather than plane.
So overˈthrust v.; hence ˈoverthrust ppl. a., overˈthrusting vbl. n.
1883Lapworth in Geol. Mag. Aug. 339 In many cases this overthrusting effect is due to the relief of downward pressure caused by the erosion of the brow of the arch. 1900[see crust n. 13 b]. 1901Nature 3 Jan. 234/1 Huge masses of country have been overfolded, fractured, and overthrust, the older being pushed over the newer. 1942M. P. Billings Structural Geol. x. 184 The thrusts dip north, and the overthrust sheets have traveled northward relative to the underlying formations. 1956W. J. Arkell Jurassic Geol. World ix. 225 The Jurassic and Cretaceous systems were strongly folded and overthrust in the post-Oligocene, pre-Miocene orogeny. 1968[see foreland 5]. |