Fracture zones

Collapse Breccia Pipe Deposits. The primary occurrence of coUapse breccia pipe deposits is in circular, vertical pipes fiUed with down-dropped fragments. Uranium is concentrated in the permeable breccia matrix and in the accurate fracture zones enclosing the pipe. An example of... 

Deposits which are forming are frequentiy characterized by venting streams of hot (300°C) mineralized fluid known as smokers. These result in the local formation of metalliferous mud, rock chimneys, or mounds rich in sulfides. In the upper fractured zone or deep in the rock mass beneath the vents, vein or massive sulfide deposits may be formed by the ckculating fluids and preserved as the cmstal plates move across the oceans. These off-axis deposits are potentially the most significant resources of hydrothermal deposits, even though none has yet been located. 

Equation (8.46) applies to the motion until fracture is complete. After this the form of (8.45) applies. Kipp and Grady (1985) have shown that the time to fracture (time from inception to completion of failure at the fracture zone) depends on the material and kinematic properties of the problem according to... 

Fluid loss additives are used widely as additives for drilling fluids. When fracturing zones have high permeability, concern exists about damage to the matrix from deeply penetrating fluid leak-off along the fracture or caused by the materials in the fluid that minimize the amount of leak-off. 

A similar approach led Sturm et al. (2000) to propose some °Th-" U and Pali ages for the Mark area. South of the Kane Fracture Zone of the Mid-Atlantic Ridge. 

Walker, D., Shibata, T. DeLong, S. E. (1979). Abyssal tholeiites from the Oceanographer Fracture Zone. Contrib. Mineral. Petrol., 70, 111-25. 

In oceanic fracture zones as well as in actively-upwelling forearc mud volcanoes, seawater or other marine fluids interact directly with mantle rock (Bonatti 1976 Fryer 1985). Serpentinization of mantle rocks at temperatures broadly <350°C involves influx of water, as well as general increase in Li concentration in the newly-formed hydrous assemblage. Considering the low temperatures involved, Li isotope exchange during seawater-mantle... 

In terms of Li content and isotopic signature, the Yellowknife mine waters are similar to waters from Sudbury (Ontario) area mines (0.05 to 2.9 ppm Li and 5T i = +27.9 to +42.6 Bottomley et al. 2003). Composihons of the Sudbury brines are consistent with predominance of preserved marine Li. These waters contrast with samples from mines in central Manitoba, which are dilute (Li concentration < seawater) and show a wide range of 5 Li (+15.0 to +46.9 Bottomley et al. 2003). These waters are plausibly mixtures of isotopically heavy brine (developed through fluid-rock interachon in fracture zones) and waters that had interacted with isotopically hght cormtry rocks. 

Improves verification of contaminant capture since recovery wells can be directly connected to fractures along the entire cross section of the fracture zone. 

Results from a subsequent in situ combustion experiment on this site (18), to produce shale oil from oil shale, indicated that combustion could be sustained in an explosively fractured zone. 

The eroded surface resulting from 90° impact exhibited a higher area fraction of brittle-fracture zones compared to that produced by 30° impacts. Pullout and transgranular chipping of the whiskers as well as microfracture of the fine matrix grains were observed. 

In the Atlantic, deep water anomalies in 3He were found to be considerably less than in the Pacific, in accord with the conclusions based on total saturation anomalies (Section 4.3), but nevertheless quite definitely present in a characteristic level <5 He = 5% (Jenkins et al., 1972). Albeit at a lower level than in the Pacific, the deep Atlantic 3He excesses also show considerable structure in a detailed study of the western Atlantic, Jenkins, and Clarke (1976) observed a maximum <53He of 13% and identified a localized source in the Gibbs Fracture Zone southwest of Iceland. To the south (at about 30°N), a section across the Mid-Atlantic Ridge shows no perceptible influence of the ridge itself on <53He (Lupton, 1976), a result in marked contrast to the comparable data for the East Pacific Rise (Figure 4.4). 

Virtually over its entire extension, the continental slope of the Black Sea is dissected by numerous faults and underwater canyons. These canyons, confined to tectonic dislocations (fracture zones or grabens), are later transformed by turbidity flows, which use them as channels for the transport of mineral particulate matter from the near-shore zone to the foot of the continental slope. At the places of discharge of turbidity flows, alluvial fans are formed, which may be cut by runoff channels [10]. 

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