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Industrial and urban produced impacts
Published in David Drew, Heinz Hötzl, Karst Hydrogeology and Human Activities, 2017
The main results (Eiswirth 1995, Eiswirth & Hötzl 1997) are summarised by reference to one of the sections (Fig. 5.41). During the soil gas investigation on this profile soil gas CO2-maxima were detected at location 73 m and 85 m, corresponding clearly with detected minima in soil gas O2. Both anomalies refer to contaminant transport on the extensional fault zone. The elevated CO2 and depressed O2 concentrations are caused by biodegradation of leachate in a discrete flow paths within the karstified limestones. The results of the 222Rn investigations indicate also a main anomaly at location 73 m and three minor anomalies. The first refers to the main fault zone distinguished by high radon concentrations. The results of the electromagnetic soundings showed a broad zone below 35 m and two areas with low apparent electrical resistivities. The zone below 35 m depth refers to the groundwater of the karst aquifer. These very low resistivities (<50 Ω·m) possibly indicate saturated conditions (water, leachate) within the limestones. Similar results were received from the parallel sections so that one of the main water path for the contaminant flow could be determined and followed to the North. The results were used also for the location of the deep boreholes.
Geological, geochemical and geophysical characteristics of geothermal fields
Published in D. Chandrasekharam, Jochen Bundschuh, Low-Enthalpy Geothermal Resources for Power Generation, 2008
D. Chandrasekharam, Jochen Bundschuh
In contrast to most other geothermal areas in Central America, the geothermal provinces in Honduras derive heat not due to Quaternary volcanism, but from deep-circulation systems related to extensional fault structures. Platanares, San Ignacio, Azacualpa Sambo creek, Pavana, and El Olivar are the main geothermal provinces in Honduras where exploration started in the 1970s (for locations see Figure 5.12). The Platanares field, located in the western part of Honduras, represents the best high-enthalpy geothermal site with measured temperatures of about 160 °C at the shallow depth of 250 m (Sussman 1995), and reservoir temperature was estimated to be around 225 °C.
Textural and cathodoluminescence evidence for the origin of black dolomite matrix breccias in the Irish Zn-Pb orefield
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
M.J. Lee, J.J. Wilkinson, G. Earls
The Cooleen breccias form the hostrock for sulphide mineralization and are composed of a series of smaller breccia bodies stacked one on top of another to form a broadly stratiform, wedge shaped body ∼4 × 3 × 0.2km in size. The breccia body shows marked thickening in the immediate hangingwall of a WNW-ESE striking extensional fault (Fig. 2a). The breccias are concentrated within a basin controlled by movement along the main WNW-ESE fault and perpendicular steeply dipping normal faults running NNE-SSW (Fig. 2b). Episodic fault movement is believed to have encouraged footwall material to spall into this depression.
Characteristics and variations of sinters in the Coromandel Volcanic Zone: application to epithermal exploration
Published in New Zealand Journal of Geology and Geophysics, 2019
Ayrton R. Hamilton, Kathleen A. Campbell, Julie V. Rowland, Shaun Barker, Diego Guido
Within the CVZ, the Hauraki Goldfield encompasses more than 50 adularia-sericite vein-style Au-Ag epithermal deposits, and several porphyry copper-style deposits (Figure 1(C)) (Christie et al. 2007), ranging in age from 16 to 5 Ma (Mauk et al. 2011). Adularia-sericite epithermal systems develop from near-neutral alkali-chloride waters that have meteoric and magmatic components (Heald et al. 1987). They form in extensional regimes and produce veins, sinters and alteration zones that are heterogeneous due to physical and chemical changes within the systems over time (Hedenquist 1991). Numerous hydrothermal features associated with adularia-sericite epithermal systems are present within the Hauraki Goldfield, including epithermal veins, hydrothermal eruption breccias, regional propylitic alteration, regional and localised silicification, and silica sinter deposits (Christie et al. 2007). Au-Ag epithermal veins in the CVZ are controlled by steeply dipping extensional fault arrays (Brathwaite et al. 2001). At regional to local scales, these faults are inferred to be partially inherited from structures within the Mesozoic metasedimentary basement (Skinner 1986; Rowland et al. 2016).
The Listafjorden–Drangedal Fault Complex of the Agder–Telemark Lineament Zone, southern Norway. A structural analysis based on remote sensing and potential field data
Published in GFF, 2019
Roy H. Gabrielsen, Odleiv Olesen, Alvar Braathen, Jan Inge Faleide, Vikas Chand Baranwal, Conrad Lindholm
The Blåkedalen subsegment (Fig. 3) parallels the master fault (ENE-WSW; N60E). It is dominated by a low-angle extensional fault associated with a 5–10 m thick zone of fault rocks, dipping 44° SE (Fig. 8A). Metre-thick lenses of protocataclasite are developed in the lowermost part of the hanging wall fault block above a 2–3 m thick cataclasite. Discontinuous pods of fault gouge separate the two. The fault zone is overprinted by steeper extensional faults with throws in the order of decimetres and zones of even younger, steeply dipping to vertical joints. A completely exposed fault section is found in a road section at the southern shore of Hanekilen, ca. 9 km east of Blåkedalen (map sheet 1411 I Bjelland, UTM 087 834). This fault strikes parallel to the Blåkedalen segment but represents a separate branch of the fault complex. It has a similar configuration to the fault in Blåkedalen.
How do Local Earthquake Tomography and inverted dataset affect earthquake locations? The case study of High Agri Valley (Southern Italy)
Published in Geomatics, Natural Hazards and Risk, 2019
Vincenzo Serlenga, Tony Alfredo Stabile
In addition to this, a natural, very sparse, low-magnitude earthquake activity is detectable (). However, this area remains one of the most seismic in Italy since the historical catalogue (CPTI11, Rovida et al. 2011) indicates seven events with Mw ≥4.5 including the 1857 Mw 7.0 Basilicata earthquake. The issue about which of the two extensional fault systems is responsible for the seismogenic potential of the area is still debated. Many authors ascribe it to the EAFS [Figure 1(b)] (Benedetti et al. 1998; Cello and Mazzoli 1999; Borracini et al. 2002; Cello et al. 2003; Barchi et al. 2007). Other researchers attribute the seismogenic potential to MMFS [Figure 1(b)] (Valensise and Pantosti 2001; Maschio et al. 2005; Burrato and Valensise 2008).