Geological evolution of a tectonic and climatic transition zone: the Beysehir-Sugla basin, lake district of Turkey

Central-west Turkey is a transition zone both tectonically and climatically between the quite different central and western regions of Anatolia. Central Anatolia represents the seismically quiet part of the otherwise highly active Turkey. On the other hand, this region has some of the lowest precipitation and highest evaporation ratios of Turkey. Conversely, west Anatolia is one of the most rapidly extending regions of the world and seismically very active. The climate is very different from the central part of Turkey and more humid. The zone between these two regions is also known geologically as the Isparta Angle. This reverse-V-shaped fold and thrust belt has several lake basins today, which have archived the geological and geomorphological history of this tectonic and climatic transition zone. The Beysehir-Sugla basin is located on the eastern part of this zone. This NW-SE trending basin includes the largest natural freshwater lake of the Mediterranean region: Lake Beysehir. Lakes Beysehir and Sugla are located in this tectonic depression that discharge into an incised river gorge opening to the Konya closed basin. In order to shed light on the development of the Beysehir-Sugla basin, our study was mainly conducted within the Neogene and Quaternary units of the region. Our structural results indicate that the depression was probably formed by a transtensional regime in the middle Miocene, which is controlled by extensional tectonics since the early Quaternary. Also, the current depression has mainly embodied the structures that are the products of these tectonic phases. According to our sedimentary data and palaeoecological interpretation of available palaeontological data, the Beysehir-Sugla basin was developed initially under a humid and warm climate in the middle Miocene; then since the late Miocene-Pliocene it was controlled by a relatively more arid and, at times, humid climate more like the central Anatolian basins. Although the Beysehir-Sugla basin is hydrologically connected to the Konya closed basin in central Anatolia, it was protected from arid climatic conditions for over millions of years as evidenced by the lack of evaporites in the studied basin and surrounding basins located in the interior part of the Isparta Angle. While the regional climate seems to have changed consistently with the geomorphic response to large-scale tectonics (i.e. orographic barrier development), the Beysehir-Sugla basin seems to be protected from hydrological closure by the existence of karstic features in the surrounding carbonate basement rocks.Ankara University Scientific Research Projects Unit (AuBAP) [12B4343002]; Scientific and Technological Research Council of Turkey (TuBTAK) [BDEB2211-A]This study was funded by the Ankara University Scientific Research Projects Unit (AuBAP, Grant No: 12B4343002). E.G. acknowledges support from the Scientific and Technological Research Council of Turkey (TuBTAK, BDEB2211-A). The authors would like to thank F. Sarolu (JEMRKO) for fruitful discussions in the office, and Y. Suludere (JEMRKO), S. oncel (GTu), o. leri (MTA) and M. Kibar (Au) for discussions in the field, S. Karada, L. Ata and S. unal (BoE) for their hospitality during our field studies, and four anonymous reviewers for their constructive comments and suggestions that significantly improved the quality of the manuscript

What can Olympus Mons tell us about the Martian lithosphere?

Under gravitational loading, a volcanic edifice deforms, and the underlying lithosphere downflexes. This has been observed on Earth, but is equally true on other planets. We use finite element models to simulate this gravity-driven deformation at Olympus Mons on Mars. Eleven model parameters, including the geometry and material properties of the edifice, lithosphere and underlying asthenosphere, are varied to establish which parameters have the greatest effect on deformation. Values for parameters that affect deformation at Olympus Mons, Mars, are constrained by minimising misfit between modelled and observed measurements of edifice height, edifice radius, and flexural moat width. Our inferred value for the Young's modulus of the Martian lithosphere, 17.8 GPa, is significantly lower than values used previously, suggesting that the Martian lithosphere is more porous than generally assumed. The best-fitting values for other parameters: edifice density (2111 – 2389 kg.m –3) and lithosphere thickness (83.3 km) are within ranges proposed hitherto. The best-fitting values of model parameters are interdependent; a decrease in lithosphere Young's modulus must be accompanied by a decrease in edifice density and/or an increase in lithosphere thickness. Our results identify the parameters that should be considered within all models of gravity-driven volcano deformation; highlight the importance of the often-overlooked Young's modulus; and provide further constraints on the properties of the Martian lithosphere, namely its porosity, which have implications for the transport and storage of fluid throughout Mars' history

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

Background Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications. Methods We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC). Findings In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683–0·717]). Interpretation In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required. Funding British Journal of Surgery Society