Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?

Here we investigate sedimentary records from four small inland lakes located in the southern Cascadia forearc region for evidence of earthquakes. Three of these lakes are in the Klamath Mountains near the Oregon–California border, and one is in the central Oregon Coast range. The sedimentary sequences recovered from these lakes are composed of normal lake sediment interbedded with disturbance event layers. The thickest of these layers are graded, and appear to be turbidites or linked debrites (turbidites with a basal debris-flow deposit), suggesting rapid deposition. Variations in particle size and organic content of these layers are reflected in the density and magnetic susceptibility data. The frequency and timing of these events, based on radiocarbon ages from detrital organics, is similar to the offshore seismogenic turbidite record from trench and slope basin cores along the Cascadia margin. Stratigraphic correlation of these anomalous deposits based on radiocarbon ages, down-core density, and magnetic susceptibility data between lake and offshore records suggest synchronous triggering. The areal extent and multiple depositional environments over which these events appear to correlate suggest that these deposits were most likely caused by shaking during great Cascadia earthquakes.

Neotethys closure history of Anatolia: insights from 40Ar–39Ar geochronology and P–T estimation in high pressure metasedimentary rocks

The multiple high-pressure (HP), low-temperature (LT) metamorphic units of Western and Central Anatolia offer a great opportunity to investigate the subduction- and continental accretion-related evolution of the eastern limb of the long-lived Aegean subduction system. Recent reports of the HP–LT index mineral Fe-Mg-carpholite in three metasedimentary units of the Gondwana-derived Anatolide–Tauride continental block (namely the Afyon Zone, the Ören Unit and the southern Menderes Massif) suggest a more complicated scenario than the single-continental accretion model generally put forward in previous studies. This study presents the first isotopic dates (white mica 40Ar–39Ar geochronology), and where possible are combined with P–T estimates (chlorite thermometry, phengite barometry, multi-equilibrium thermobarometry), on carpholite-bearing rocks from these three HP–LT metasedimentary units. It is shown that, in the Afyon Zone, carpholite-bearing assemblages were retrogressed through greenschist-facies conditions at c. 67–62 Ma. Early retrograde stages in the Ören Unit are dated to 63–59 Ma. In the Kurudere–Nebiler Unit (HP Mesozoic cover of the southern Menderes Massif), HP retrograde stages are dated to c. 45 Ma, and post-collisional cooling to c. 26 Ma. These new results support that the Ören Unit represents the westernmost continuation of the Afyon Zone, whereas the Kurudere–Nebiler Unit correlates with the Cycladic Blueschist Unit of the Aegean Domain. In Western Anatolia, three successive HP–LT metamorphic belts thus formed: the northernmost Tavşanlı Zone (c. 88–82 Ma), the Ören–Afyon Zone (between 70 and 65 Ma), and the Kurudere–Nebiler Unit (c. 52–45 Ma). The southward younging trend of the HP–LT metamorphism from the upper and internal to the deeper and more external structural units, as in the Aegean Domain, points to the persistence of subduction in Western Anatolia between 93–90 and c. 35 Ma. After the accretion of the Menderes–Tauride terrane, in Eocene times, subduction stopped, leading to continental collision and associated Barrovian-type metamorphism. Because, by contrast, the Aegean subduction did remain active due to slab roll-back and trench migration, the eastern limb (below Southwestern Anatolia) of the Hellenic slab was dramatically curved and consequently teared. It therefore is suggested that the possibility for subduction to continue after the accretion of buoyant (e.g. continental) terranes probably depends much on palaeogeography.

Report on 2010-2013 Excavations at Horvat Kur, Galilee

Four seasons of excavations at Horvat Kur in the Galilee (250570/754485) have exposed the remains of a broadhouse synagogue from the Byzantine period. The building was entered through a portico on the west or a doorway on the south. The fill beneath the portico included the discarded remains of a once colored mosaic as well as more than 1000 coins. A low bench of basalt stones (some of which were plastered) runs along the interior walls, interrupted only by a stone bemah in the center of the southern wall. The synagogue is thus oriented toward Jerusalem. Near the bemah, an ornamented limestone seat was found in situ atop the bench. The building underwent several changes and repairs in the course of its lifespan. On either side of the bemah, north-south rows of columns rested on stylobate. A basalt stone table was found in re-use in the eastern stylobate. Nicknamed “the Horvat Kur stone,” this monolith features geometric figures on three sides and figurative representations on one side. Its original function is as yet subject of research. A narrow test-trench into the sediment of a cistern located outside the northern wall of the synagogue has produced nearly thirty intact vessels of the early Byzantine period, mostly cooking pots and water jars. In addition a dense sequence of pollen samples has been taken. Preliminary interpretation of these finds indicates that the Horvat Kur synagogue illustrates Byzantine synagogue construction, decoration, and use in the setting of a Galilean village of modest economic circumstances.

John Garstang at Sirkeli Höyük, Cilician Plain, in 1936-1937: Old Photographs and New Evidence from the Renewed Excavations

During the winter of 1936-1937, British archaeologist John Garstang (1876-1956) excavated several trenches at the site of Sirkeli Höyük, located in the Plain of Cilicia (18 km west of modern-day Ceyhan). After a single campaign, however, he left the site and his interest shifted to site of Yumuktepe/Mersin, where he then excavated for a number of years. Apart from two very brief preliminary reports of his excavations at Sirkeli Höyük, which were published in the journal 'Annals of Archaeology and Anthropology of the University of Liverpool', not much is known about the trenches and their associated finds. Unpublished photographs kept in the Special Archives of University College London shed new light on the location and orientation of some of Garstang’s trenches at the site. Furthermore, in the 2012 campaign of the renewed Turkish-Swiss excavations at the site, a trench was found in the western part of the northern terrace that most probably was excavated by Garstang, but was not mentioned by him in his reports. This hitherto unknown trench may be related to his discovery of a lion-shaped column base made of basalt that is now kept in the collections of the Archaeological Museum of Adana.