Lithostratigraphy and Sedimentological Characteristics of the Calciturbidites of the Babadağ Formation-Tavas Nappe (SW Turkey)

The Lycian Nappes contain slices of ophiolites and sedimentary rocks of various ages that crop out in SW Turkey. They evolved and were emplaced under the effect of the Late Cretaceous-Miocene compressional regime. The Tavas Nappe is part of the Lycian Nappes and contains Jurassic-Eocene sediments. The Babadağ Formation, forming the middle part of the Tavas Nappe, is composed of limestone at the base and various sized calciturbidites with chert intercalations in the upper part. The Standard Microfacies Classification (SMF of FLÜGEL, 2004) indicates that the entire unit was deposited mainly in a deep-shelf environment (Facies Zone – FZ-2), deep-sea (FZ-1), toe of slope (FZ-3) and on the continental slope (FZ-4). Calcite and quartz dominate the bulk mineralogy of the calciturbidites with higher SiO2 and CaO weight percentages than other major oxides. Additionally, the presence of Na2O, K2O, Al2O3, MgO, TiO2 and Fe2O3 is associated with the local sediment input. Tectonism and sea level fluctuations were the main triggering factors of the changes in the original depositional environment of the Babadağ Formation. Additionally, grain size and the amount of sediment input control the calciturbidite type and extension. Si enriched water circulation and Si and Ca substitution were responsible for the abundant chert formation during diagenesis of the units. Post depositional tectonic activities during transportation and emplacement of the nappes resulted in calcite filled cracks that cut both the calciturbidites and cherts. Study of the different nappe slices provides valuable information about syn- and post- depositional changes of the lithostratigraphic units.

Mg or Zn for Ca substitution improves the sintering of bioglass 45S5

Bioglass 45S5 is well-known for its bioactivity, but it possesses poor sintering behaviour owing to viscous flow being inhibited by the crystallisation of sodium calcium silicate phases. Mg or Zn were partially (0, 25, 50, 75%) or fully (100%) substituted for Ca on a molar base, and thermal properties (differential scanning calorimetry, dilatometry) and sintering (heating microscopy, SEM and X-ray diffraction) were investigated. Here we show that sintering can be improved significantly by partial or complete substitution of Mg or Zn for Ca, owing to a pronounced decrease in crystallisation tendency. Glass transition temperature and dilatometric softening point went through minima for mixed compositions, with random mixing of Mg/Ca or Zn/Ca ions in the glass structure and the resulting effect on configurational entropy being a likely explanation. As the onset of crystallisation did not vary much with substitution, substituted glasses possessed a wider temperature range for sintering, resulting in up to 57% and 27% sample height reduction for Mg and Zn substituted glasses, respectively, compared to only 3% height reduction for Bioglass 45S5. Taken together, these results suggest that using a combination of modifiers, particularly alkaline earths or zinc, may be a promising approach for improving the sintering of Bioglass 45S5.