Loading tectonic

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

Molnar P, Anderson RS, Kier G, Rose J (2006) Relationships among probability distributions of stream discharges in floods, climate, bed load transport, and river incision. J Geophys Res 111, doi 10.1029/2005JF000310 Montgomery DR, Balco G, Willett SD (2001) Climate, tectonics, and the morphology of the Andes. Geology... 

Engelder, T. 1985. Loading paths to joint propagation during a tectonic cycle an example from the appalachian Plateau, USA. J. Struct. Geol. 7 459-476. 

Equation (14.12) can be decomposed in a part for the tectonic loading and a residual part for other processes, especially coseismic slip. The tectonic... 

It is not surprising that a model which imposes only tectonic loading and coseismic stress redistribution, produces no aftershocks, because it is likely that aftershocks are due to additional mechanisms triggered by the mainshock. A discussion on candidates for such mechanisms is given in [58]. A common feature is the presence of postseismic stress which generates aftershock activity. In [22], for instance, postseismic stress has been attributed to a viscoelastic relaxation process following the main-... 

In our thermal analysis, the sedimentary blanket, the lithosphere, and the upper part of the asthenosphere are considered together. This approach allows us to calculate the amplitude of tectonic subsidence by considering changes in the density distribution vs. depth in the lithosphere. Local isostatic response of the lithosphere on load is assumed, and then the comparison of relative variations in the amplitude of tectonic subsidence is calculated by traditional methods (removal of the water and sediment load on the basement surface), with the variations obtained by nontraditional methods (consideration of changes in the density profile in the basement) providing an additional opportunity to control the program s sequence of the tectonic and thermal events in the lithosphere. 

The thermal and burial histories of the basin for a variant that is free from erosion in the Permian were simulated for comparison with the main model (Fig. 6.7). This variant was controlled by present-day temperatures and vitrinite reflectance (similar to Fig. 6.6) and, by coincidence of the tectonic curve, calculated by removing the sediment and water load, resulting from variation in the thermal state of the basement (as... 

Fig. 6.10. Principals of tectonic subsidence calulation. a Situation with load on the basement surface when the columns AA (time t = o - onset of basin evolution) and 66 (time t > o) include water, sediments, and basement surface columns AiAi (time t = o - onset of basin evolution) and BiBi (time f > o) include only basement rocks. Equality of the weight of AA column to the weight of AiAi and of the weight of 66 to the weight of BiBi leads to Eq. 6.13 for calculating the first part ZTs of tectonic subsidence. In addition, the equality of the weight of the AiAi column to the weight of the BiBi column leads to Eq. 6.15 for calculation the second part ZTb of tectonic subsidence...

In the frame of the local isostatic approach,Eqs. 6.13,6.15, and 6.16 describe the main processes that can contribute to changes in the tectonic subsidence amplitude. The tectonic curve (Eq. 6.13), computed by removing of the water and the sediment load (solid line in Fig. 6.2c), must coincide with the subsidence (Eq. 6.15) determined by variations of temperature and pressure in the lithosphere (dashed line in Fig. 6.2c). The comparison of these tectonic curves allows additional control of the sequence of tectonic and thermal events in the lithosphere, and these variations are assumed in our basin modeling. This control, however, has a relative, rather than absolute, character. 

Our computer program simulates the burial and thermal histories and petroleum potential in sedimentary basins and considers the thermal regime in the sedimentary blanket and the underlying lithosphere. Consequently, modeled calculations of basement tectonic subsidence can be used to control the sequence of tectonic and thermal events in the lithosphere. These computations assume that the lithosphere has local isostatic response to load therefore, applications to areas in dynamic active belts having anomalously high values of free-air gravity require corrections for tectonic subsidence. 

Compaction of deep sediments (except Holocene sediments) includes both tectonic downwarping of basement sediments and compaction of Tertiary, Pleistocene, and older sediments. Tectonic downwarping is probably the only factor in major depositional areas such as large deltas, where the loads from massive amounts of sediments cause the bottom of the sedimentary basin to warp. In most studies of modern sediments, very little is known about this factor, so it is often treated as an unknown or something outside of the system. 

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