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Abstract: We revised an equation for estimating palaeostress magnitude using the microboudin technique by incorporating the influence of time on the fracture strength of minerals. The equation was used to estimate triaxial palaeostresses from a rare sample of metachert from Turkey that contains microboudinaged, columnar tourmaline grains in a wide range of orientations within the foliation plane. The estimated principal palaeostresses are σ 1 =605 MPa, σ 2 =598 MPa, and σ 3 =597 MPa. As the microboudinage is considered to have occurred immediately before the rock encountered the brittle-plastic transition during exhumation, these stress values correspond to conditions at approximately 18 km depth and 300 °C within a Cretaceous orogenic belt. [Copyright &y& Elsevier]

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Geomorphologic mapping and cosmogenic radionuclide (36Cl) dating of an offset fluvial terrace yield a preferred late Holocene slip rate of 20.5 ± 5.5 mm/yr for the central part of the North Anatolian fault, Turkey; an independent slip rate constrained by 14C ages is 20.5 ± 8.5 mm/yr. These rates are generally similar to, but possibly slightly slower than, the shortterm rate of elastic strain storage of 25 ± 1 measured geodetically across this major strike-slip fault (Reilinger et al., 2006), suggesting that loading and strain release on this part of the North Anatolian fault have been relatively constant when averaged over the past ∼2-2.5 k.y. We attribute this consistency to the relatively simple structure of the Anatolia-Eurasia plate boundary in north-central Turkey, where almost all plate boundary strain is accommodated along the North Anatolian fault. The absence of other moderate to high slip rate faults (and the earthquakes they produce) leads to a relatively simple stress evolution for the fault dominated by steady tectonic loading. [ABSTRACT FROM AUTHOR]