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Possible precursory accelerated Benioff strain in the region of Sistan Suture Zone of Eastern Iran

Sarkar I.

Acta Geophysica

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2011

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Vol. 59, no. 2

239-261

EN

We investigated whether accelerated seismic strain release precedes large earthquakes occurring in and around the Sistan Suture Zone, Eastern Iran. Online catalogs of teleseismic events occurring post-1960 within the region 27.0°-37.0°N, 55.0°-65.0°E, report five Mw > 7.0 earthquakes, namely, 1968 Dasht-e-Bayaz, 1978 Tabas, 1979 Khuli- Buniabad, 1981 Sirch and 1997 Zirkuh-e-Q'aenat events. We defined four earthquake test episodes, 1968-1978, 1978-1981, 1979-1981, and 1981-1997, with all catalogued intermediate events having magnitudes within 2.0 units that of the final large event. Using the 1968 event as the starting point, we investigated possible increased moderate earthquake activity patterns prior to the large events of 1978, 1981 and 1997 by examining if the cumulative Benioff strain released from such preceding events followed a power law time-to-failure. Our investigation seem to suggest that the 1978, 1981 and 1997 events (i) followed a period of accelerated moderate earthquake activity and (ii) the radius of their optimal critical region, R, scaled with their magnitude, M, according to the scaling law log R . 0.36 M. Our suggestions conform to those proposed by similar investigations in varied seismotectonic regimes.

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Pelagic chondrichthyan microremains from the Upper Devonian of the Kale Sardar section, eastern Iran

Hairapetian V., Ginter M.

Acta Geologica Polonica

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2010

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Vol. 60, no. 3

357-371

EN

An assemblage of fifteen taxa of chondrichthyan microremains from late Frasnian through late Famennian pelagic deposits of the Kale Sardar section, eastern Iran, is described. Several taxa (Phoebodus bifurcatus, Phoebodus sophiae and Protacrodus vetustus) are reported for the first time from Iran. The presence of Deihim mansureae and Ph. sophiae in the Late rhenana to linguiformis Zones and Phoebodus rayi in the early triangularis Zone of the Kale Sardar section, provides new biostratigraphic information. The late Frasnian part of the assemblage corresponds to the faunas from the intrashelf basins of central europe, and the middle.late Famennian part is comparable to that from the tafilalt Platform of Morocco.

3

Lithostratigraphy of Jurassic sedimentary rocks in Qayen area, eastern Iran

Babazadeh S.

Volumina Jurassica

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2006

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Vol. 4, no. 1

78-78

EN

The Jurassic sedimentary rocks dominate the surface exposure of western Qayen. They are extensively located at Doust-abad region. The focus of this study is on the lithofacies analysis of the sediments. The Jurassic rocks consist of the shale-limestone unit with intercalation of sandstone followed by massive limestone and is topped by limestone-argillaceous limestone with thin parallel lamination of shale. Three patterns of facies dominate the formation. Gray to black shale-mudstone facies in the lower part, biointrasparite/biopelsparite in the middle part and gray micritic limestone/argillaceous limestone. The main marine fauna include Lenticulina aff. quenstedti, Nodosaria cf. striatojuensis, Lingulina nodosaria, Haurania aff. amiji, miliolids, corals, crinoids, ammonites and echinoids.