Extensional faulting on Tinos island, Aegean sea, Greece: How many detachments?

Zircon and apatite fission track (ZFT and AFT) and (U-Th)/He, 40Ar/39Ar hornblende, and U-Pb zircon ages from the granites of Tinos Island in the Aegean Sea, Greece, suggest, together with published ZFT data, that there are three extensional detachments on Tinos. The Tinos granites crosscut the Tinos detachment. Cooling of the granites was controlled by the Livadi detachment, which occurs structurally above the Tinos detachment. Our U-Pb zircon age is 14.6 ± 0.2 Ma and two 40Ar/39Ar hornblende ages are 14.4 ± 0.4 and 13.7 ± 0.4 Ma. ZFT and AFT ages go from 14.4 ± 1.2 to 12.2 ± 1.0 Ma and 12.8 ± 2.4 to 11.9 ± 2.0 Ma. (U-Th)/He ages are from 10.4 ± 0.2 to 9.9 ± 0.2 Ma (zircon) and 11.9 ± 0.5 to 10.0 ± 0.3 Ma (apatite). All ages decrease northeastward in the direction of hanging wall transport on the Livadi detachment and age-distance relationships yield a slip rate of 2.6 (+3.3 / −1.0) km Ma−1. This rate is smaller than a published slip rate of 6.5 km Ma−1 for the Vari detachment, which is another detachment structurally above the Tinos detachment. Because of the different rates and because published ZFT ages from the footwall of the Vari detachment are ∼10 Ma, we propose that the Vari detachment has to be distinguished from the older Livadi detachment. We discuss various models of how the extensional detachments may have evolved and prefer a scenario in which the Vari detachment cut down into the footwall of the Livadi detachment successively exhuming deeper structural units. The thermochronologic ages demonstrate the importance of quantitative data for constraining localization processes during extensional deformation

Sur la piézométrie de la nappe des «Craies» de la Vallée de la Haine (Mons-Belgique)

Godfriaux Ivan, Rorive Alain. Sur la piézométrie de la nappe des «Craies» de la Vallée de la Haine (Mons-Belgique). In: Bulletin de la Classe des sciences, tome 64, 1978. pp. 473-477

Note sur la découverte de dents de mammifères dans le Montien continental du Hainaut (Belgique)

Découverte dans le Montien continental d'Hainin (Hainaut-Belgique) de dents de mammifères qui se rapprochent des espèces nord-américaines du Paléocène moyen et supérieur. Dans le Tertiaire européen, cette faune est la plus ancienne datée.Godfriaux Ivan, Thaler L. Note sur la découverte de dents de mammifères dans le Montien continental du Hainaut (Belgique). In: Bulletin de la Classe des sciences, tome 58, 1972. pp. 536-541

Neogene upper-crustal cooling of the Olympus range (northern Aegean): major role of Hellenic back-arc extension over propagation of the North Anatolia Fault Zone

International audienceAbstract The North Anatolian Fault Zone ( NAFZ ) is one of the most hazardous active faults on Earth, yet its Pliocene space‐time propagation across the north Aegean domain remains poorly constrained. We use low‐temperature multi‐thermochronology and inverse thermal modelling to quantify the cooling history of the upper crust across the Olympus range. This range is located in the footwall of a system of normal faults traditionally interpreted as resulting from superposed Middle–Late Miocene N–S stretching, related to the back‐arc extension of the Hellenic subduction zone, and a Pliocene‐Quaternary transtensional field, attributed to the south‐westward propagation of the NAFZ . We find that accelerated exhumational cooling occurred between 12 and 6 Ma at rates of 15–35 °C Ma −1 and decreased to <3 °C Ma −1 by 8–6 Ma. The absence of significant Plio‐Pleistocene cooling across Olympus suggests that crustal exhumation there is driven by late Miocene back‐arc extension, while the impact of the NAFZ remains limited