Gicik düşük-sülfitli epitermal altın yatağının yüzey özellikleri, mineralojisi ve jeokimyası (ankara, orta anadolu)

Tethyan-Eurasian Metallogenic Belt was formed as a result of the Mesozoic-Cenozoic Alpine-Himalayan orogeny related to the opening and closure of the Tethyan ocean basins. Turkey forms a sector of this extensive belt, and hosts numerous precious and base metal deposits. Gicik Au mineralization is located at Sakarya zone and approximately 15 km north of Ankara. Gold mineralization is hosted within Middle Eocene (ca. 44 Ma) intermediate composition dacitic lavas and agglomerates that are widely exposed near Ankara, and unconformably overlying the Paleozoic metamorphic basement. Whole-rock geochemical analyses of volcanic rocks indicate that the volcanism is metaluminous, medium-K calc-alkaline in composition and related to subduction and post-collisional tectonic setting. Lithogeochemical and geochronological data strongly implies that the studied volcanic rocks belong to the earlier (Eocene) eruptive volcanic event at the north of Ankara which was followed by volcanic rocks of Galatean Volcanic Province (Miocene). These volcanic lithologies are cut by NNE–trending 2 to 10 meters thick siliceous veins that display stockwork, colloform banding and superimposed breccia textures or less commonly bladed textures. Main ore minerals in the Gicik area includes argentiferous tetrahedrite, pyrite and arsenopyrite. Alteration assemblages include widespread epidote-chlorite with less common calcite (propylitic), argillic (kaolinitesericite/illite-smectite-quartz-adularia) and silicification. 40Ar/39Ar age data obtained from sericite in Gicik deposit yielded age of 45 – 47 Ma suggesting synchronous formation of volcanism and mineralized system. Central Anatolia is remained relatively underexplored when compared to the eastern and western parts of the Eocene magmatic belt across the north of İzmir-Ankara-Erzincan suture. Presence of Eocene volcanism related Gicik mineralization in central Anatolia puts entire magmatic belt in a position potential to especially precious metal mineralization.Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Geological Engineering

Gicik Altın Yatağı (Ankara, Orta Anadolu): Dalma-Batma Sonrası Ortamda Gelişmiş Bir Düşük-Sülfidasyonlu Epitermal Sistem

Ankara şehir merkezinin yaklaşık 15 km kuzeyinde yer alan Gicik Au yatağı, Sakarya Zonu’nun güney kenarı üzerinde gelişmiş orta Eosen yaşlı andezitik–dasitik bileşimdeki volkanik istifin içerisinde yer alan bir dizi silisli damardan oluşmaktadır. Cevherin yan kayacı olan aglomeralar ve masif/akma bantlı lavlar orta-K’lu ve kalk-alkalen karakterdedir. Magmatik kayaçlarda gözlemlenen yüksek alan gerilmeli element fakirleşmesi ve büyük iyon çaplı litofil ve hafif nadir toprak element zenginleşmesi tipik yay magmalarına benzemektedir. KKD yönünde, doğrultu boyunca yaklaşık 2 km uzanmakta olan damarlar düşey veya dik açıyla BKB yönüne eğimlidir. Damarların tamamı verev-atımlı faylar boyunca yerleşmiştir ve bu durum damar oluşumu sırasında yapısal kontrolün önemli bir rol oynadığına işaret etmektedir. Altın cevherli sistemle ilişkili alterasyon kuzeyde Gicik’in kuzey kesimlerinden başlayıp güneyde Hüseyingazi Tepe’nin yamacına kadar olan bölgede oldukça geniş bir alanı kapsamaktadır. Hidrotermal alterasyon damar yakınlarında silisleşme ve killeşme ile temsil edilmekte, bunların çevresinde ise daha geniş yayılım gösteren propilitik zon bulunmaktadır. Silisli zonlar kalsedonik/ince taneli, masif veya kolloform bantlı kuvarsla birlikte daha iri taneli gri kuvars ve geç evrede ametistik kuvars içermektedir. Bunu çevreleyen kil alterasyonu kuvars-illit-kaolinit ile temsil edilmekte ve dışa doğru yerini bölgesel propilitik alterasyona ait klorit-epidot-karbonat-pirit mineral topluluğuna bırakmaktadır. Kuvvetli yüzey oksidasyonu nedeniyle damarlarda hematit ve götit gibi Fe-(hidr)oksit mineralleri gelişmiştir. Ancak görece daha taze damar örneklerinde kolloform bantlı veya gri kuvars fazlarıyla birlikte pirit, arsenopirit ve Ag-tetrahedritten oluşan basit bir mineral topluluğuna rastlanılmıştır. Elektron mikroprob analizleri ile bu sülfit ve sülfür tuzu fazlarında birkaç yüz ppm seviyesinde Au ve Ag içeriği saptanmıştır. Ayrıca Ag-tetrahedrit içerisinde kütlece %7’ye varan miktarlarda gümüş tespit edilmiştir. Magmatik ve hidrotermal kökenli mineraller üzerinde yapılan K-Ar and 40Ar/39Ar yaş analizleri volkanizma ve epitermal-tipi alterasyonun ~44 Ma civarında eşzamanlı geliştiğini göstermektedir. Orta Anadolu’nun kuzey kesimlerindeki yaygın Paleojen volkanizmasının son evrelerine denk gelen bu volkanik evre slab kırılması veya çarpışma süreçleriyle ilişkilendirilmektedir. Volkanizmayı tetikleyen nedenlerden bağımsız olarak Sakarya Zonu boyunca orta Eosen dönemde ortaya çıkan tektonomagmatik koşulların düşük-sülfidasyonlu (ve olasılıkla ortaç- sülfidasyonlu) epitermal cevherleşme gelişimi için uygun olduğu görülmektedir. Bu durum sadece Orta Anadolu’da değil aynı zamanda Biga Yarımadası ve Doğu Pontidler’deki benzer sistemler üzerinde de gözlemlenebilir.The Gicik Au deposit, located about 15 km north of Ankara, consists of a series of siliceous veins hosted within a sequence of middle Eocene andesitic–dacitic agglomerates and massive to flow-banded lavas that overlie the southern margin of the Sakarya Zone. Host volcanic rocks are medium-K calc-alkaline and metaluminous, and were derived from a high-field strength element-depleted and large-ion lithophile element- and light rare earth element-enriched magma source, typical of arc settings. The vein swarm extends in the NNE direction for about 2 km along strike and are either vertical or dip steeply towards WNW. A strong structural control exerted during vein development is evident since all vein segments have been localized along oblique-slip faults. Gold-mineralized system has a large alteration footprint extending from the north of Gicik in the north reaching towards the foothills of the Hüseyingazi Hill to the south. Hydrothermal alteration is characterized by vein-proximal silicification and argillic alteration, enveloped by a more extensive zone of propylitic alteration. Silicified zones consist of chalcedony/finegrained massive to colloform-banded quartz to coarser-grained gray quartz as well as late amethystic quartz. Surrounding argillic alteration is represented by quartz-illite-kaolinite assemblages that grade outward into the chlorite-epidote-carbonate-pyrite assemblages of the district-scale propylitic alteration. At the surface, veins have been extensively oxidized into Fe-(hydr)oxide minerals such as hematite and goethite. Relatively fresh exposures, however, contain sulfide phases that represent a simple mineral association consisting of pyrite, arsenopyrite, and Ag-tetrahedrite hosted mainly in colloform banded or gray quartz veins. Electron microprobe analysis indicated that several hundred ppm-levels of gold and silver are contained within these sulfide/sulfosalt minerals. Additionally, Ag concentrations in Ag-tetrahedrite were determined to reach up to ~7 wt.%. K-Ar and 40Ar/39Ar dating of igneous and hydrothermal minerals indicate overlapping ages and that volcanic activity and epithermal-style alteration occurred contemporaneously at ~44 Ma. This period corresponds to the terminal stages of widespread Paleogene volcanism in north central Anatolia, which has been attributed either to break-off of the northern Neotethyan slab following collision or to collisional processes. Regardless of the triggering mechanism, middle Eocene tectonomagmatic conditions along the Sakarya Zone appear to be favorable for generation of low- sulfidation (and possibly intermediate-sulfidation) epithermal mineralization as evidenced from such systems, not only in central Anatolia but also in Biga Peninsula and Eastern Pontides

Sıçan testisinde mezenkimal kök hücrelerin lokalizasyonu

Mezenkimal kök hücreler (mkh) stromal kökenli erişkin kök hücreleridir. Şimdiye kadar mkh’ler, kemik iliği, adipoz doku, kıkırdak, plasenta, ovaryum gibi birçok dokudan izole edilmişlerdir. Dokularda az miktarda bulunan mezenkimal kök hücrelerin ileri araştırma için kültüre edilip çoğaltılmaları gerekmektedir. Bizim bu çalışmadaki amacımız testisteki spermatojenik germ hücrelerinin nişini oluşturan mezenkimal kök hücrelerinin lokalizasyonunu immünohistokimya yöntemiyle tespit etmektir. Kemoterapi verilen hastalarda hem mezenkimal kök hücreler hem de spermatojenik germ hücreleri tahrip olmaktadır. Oluşturulacak stratejilerle bu hastalarda sperm dondurma yanında testisindeki mezenkimal kök hücrelerinin de izole edilip in vitro ortamda üretilerek sonrasında testise transplantasyon yöntemleri araştırılabilir

Effect of adjuvant chemotherapy in stage III cervical cancer patients treated with concurrent chemoradiation: A multicenter study

INTRODUCTION: A significant proportion of cervical cancer (CC) patients are diagnosed at a locally advanced stage. Concurrent chemoradiotherapy (CCRT) is the cornerstone of treatment for patients with locally advanced CC. However, the role of adjuvant chemotherapy (AC) after CCRT is controversial. In this study, we analyzed the efficacy of AC after CCRT in stage III CC patients. METHODS: We performed a multicenter, retrospective analysis of 139 International Federation of Gynecology and Obstetrics stage III CC patients treated with CCRT of whom 45.3% received AC. Our goal was to determine the impact of AC on survival in these patients. RESULTS: Five-year progression-free survival (PFS) was 37.5% and 16% in patients receiving CCRT with and without AC, respectively (p = 0.008). Median PFS was 30.9 months (CI 95% 14.8-46.9) and 16.6 months (CI 95% 9.3-23.9) in patients receiving CCRT with and without AC, respectively. Five-year overall survival (OS) was 78.2% and 28.4% in patients receiving CCRT with and without AC, respectively (p < 0.001). Median OS was 132.2 months (CI 95, %66.5-197.8) and 34.9 months (CI 95% 23.1-46.7) in patients receiving CCRT with and without AC, respectively. CONCLUSION: Our study suggests that AC provides OS and PFS benefit in stage III CC patients. Larger studies are needed to identify subgroups of patients who would benefit from AC

A snapshot of pediatric inpatients and outpatients with COVID-19: a point prevalence study from Turkey

This multi-center point prevalence study evaluated children who were diagnosed as having coronavirus disease 2019 (COVID-19). On February 2nd, 2022, inpatients and outpatients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were included in the study from 12 cities and 24 centers in Turkey. Of 8605 patients on February 2nd, 2022, in participating centers, 706 (8.2%) had COVID-19. The median age of the 706 patients was 92.50 months, 53.4% were female, and 76.7% were inpatients. The three most common symptoms of the patients with COVID-19 were fever (56.6%), cough (41.3%), and fatigue (27.5%). The three most common underlying chronic diseases (UCDs) were asthma (3.4%), neurologic disorders (3.3%), and obesity (2.6%). The SARS-CoV-2-related pneumoniae rate was 10.7%. The COVID-19 vaccination rate was 12.5% in all patients. Among patients aged over 12 years with access to the vaccine given by the Republic of Turkey Ministry of Health, the vaccination rate was 38.7%. Patients with UCDs presented with dyspnea and pneumoniae more frequently than those without UCDs (p < 0.001 for both). The rates of fever, diarrhea, and pneumoniae were higher in patients without COVID-19 vaccinations (p = 0.001, p = 0.012, and p = 0.027). Conclusion: To lessen the effects of the disease, all eligible children should receive the COVID-19 vaccine. The illness may specifically endanger children with UCDs. What is Known: • Children with COVID-19 mainly present with fever and cough, as in adults. • COVID-19 may specifically threaten children with underlying chronic diseases. What is New: • Children with obesity have a higher vaccination rate against COVID-19 than children without obesity. • Among unvaccinated children, fever and pneumoniae might be seen at a higher ratio than among vaccinated children