Evidence from Gravity Anomalies for Thinning of the Lithosphere beneath the Rift Valley in Kenya   总被引：1，自引：0，他引：1  

R. C. Searle 《Geophysical Journal International》1970,21(1):13-31

  相似文献   

A gravity survey of Ngorongoro Caldera,Tanzania     

R. C. Searle 《Bulletin of Volcanology》1971,35(2):350-357

  相似文献   

Patterns of stress at midocean ridges and their offsets due to seafloor subsidence     

M.C. Neves  M.H.P. Bott  R.C. Searle   《Tectonophysics》2004,386(3-4):223-242

The effect of the seafloor subsidence on the horizontal stress field is investigated by combining the finite element method with a formulation that allows us to compute the two-dimensional (2D) horizontal stresses arising from isostatically compensated vertical loads. The topographic load created by the elevation of midocean ridges relative to old ocean floor is shown to be a significant source of ridge-parallel tensile stresses. These may predominate over the ridge-perpendicular stresses and explain observations at midocean ridge offsets such as (1) oblique normal faulting at ridge-transform intersections trending up to 60° relative to the ridge axis, and (2) nontransform offsets consisting of structures oriented at 45° relative to the ridge trend. At midocean ridge overlaps, rotation of the ridge-parallel tensile stresses favours rift propagation at more than 45° relative to the ridge trend. It is suggested that propagating rift tips that bend abruptly lead to partially unlocked offsets, and as a result large overlaps may eventually start to rotate and evolve into a microplate.  相似文献   

Sequence of thrusting and origin of culminations in the northern and central Oman Mountains     

M.P Searle 《Journal of Structural Geology》1985,7(2):129-143

Detailed mapping and structural analysis of three large-scale culminations (Sumeini and Asjudi half-windows and Haybi-Hawasina window) in the Oman Mountains shows a considerably more complex history of deformation than a simple foreland (or downward) sequence of thrust development. Early thrusting processes tended to create a regular stacking order of imbricate slices and major thrust sheets, complying with the “rules’ of thrust propagation, assembled progressively downwards and forwards in the direction of translation. ‘Out-of-sequence’ thrusts can also be demonstrated in places by truncation of footwall structures (folds, imbricate slices, etc.), gross strain differences between thrust sheets, downward-facing structures in footwall units and elimination of thrust sheets beneath. Late stage thrusts frequently cut up-section through the previously assembled stack putting previously younger, lower thrust sheets over previously older, higher ones. Many of the culminations in the northern and central Oman Mountains were formed by ramping associated with this late-stage leap-frog rethrusting event.  相似文献   

Isostatic response of the Alula-Fartak and Owen transforms in the Eastern Gulf of Aden and the adjoining Arabian Sea     

M. Radhakrishna  R. C. Searle 《Geophysical Journal International》2006,165(1):62-72

  相似文献   

Reply to Comment by F. Boudier and A. Nicolas on “Dating the geologic history of Oman’s Semail Ophiolite: insights from U–Pb geochronology” by C.J. Warren,R.R. Parrish,M.P. Searle and D.J. Waters     

C. J. Warren  M. P. Searle  R. R. Parrish  D. J. Waters 《Contributions to Mineralogy and Petrology》2007,154(1):115-118

  相似文献   

The structure of King's Trough, Northeast Atlantic, from bathymetric, seismic and gravity studies     

R. C. Searle  R. B. Whitmarsh 《Geophysical Journal International》1978,53(2):259-287

Summary . We present new seismic and gravity data from the linear chain of deeps and flanking ridges known collectively as King's Trough, and combine them to produce crustal models of the western end of the complex. These models show that there is an abnormally low-velocity, low-density crust under the trough itself, and that the whole King's Trough feature is situated in a region of slightly thicker than normal oceanic crust. The flanks and basins of King's Trough are not in local isostatic equilibrium, although the feature now appears to be inactive. We believe these data indicate a history of extension and of hot-spot activity at King's Trough, and that the feature was formed either as a slow-spreading arm of an R-R-R triple junction associated with a Mid-Atlantic Ridge hot-spot, or by subsequent rifting of a preexisting hot-spot trace.  相似文献   

Lithospheric Structure of the Azores Plateau from Rayleigh-Wave Dispersion     

R. C. Searle 《Geophysical Journal International》1976,44(3):537-546

  相似文献   

A Catalogue of Gravity Data from Kenya     

R. C. Searle 《Geophysical Journal International》1970,19(5):543-545

  相似文献   

Extensional faulting and segmentation of the Mid-Atlantic Ridge north of the Kane Fracture Zone (24° 00′ N to 24° 40′ N)     

Simon Allerton  Bramley J. Murton  Roger C. Searle  Malcolm Jones 《Marine Geophysical Researches》1995,17(1):37-61

The combination of multi-beam echo-sounder swath bathymetry and high-resolution deep-towed sidescan sonar provides a powerful database from which to examine mid-ocean ridge processes. We have used such a database, gathered from the Mid-Atlantic Ridge north of the Kane Fracture Zone (the MARNOK area), to examine the relationship between tectonic, volcanic, and bathymetric segmentation. We have identified structural domains, with different fault distributions, and neovolcanic segments that are distinct from the 2nd or 3rd order bathymetric segmentation.From their mutual relationships, a model is proposed for the magmatic accretion of oceanic crust at slow spreading ridges that relates the local melt supply to the tectonic style. We suggest that these are mutually interactive, and determine whether volcanic extrusion along the ridge is continuous and slow, or episodic and rapid.  相似文献