Sedimentology and fluvial styles of the uppermost Cretaceous continental deposits of the Austral-Magallanes Basin, Patagonia, Argentina

The sedimentary infill of the Austral-Magallanes Basin since the onset of its foreland stage in the Lago Argentino region is dominated by deep-marine and coastal deposits. However, during the Late Cretaceous the basin accumulated a thick and poorly known continental sedimentary succession, which has received different lithostratigraphic names. The aim of this work is to characterize the here defined Uppermost Cretaceous Continental Deposits (UCCD) from a detailed facies and architectural analysis, as well as the resulting stacking pattern. Seven Facies Associations (FAs) were discriminated in order to define the sedimentary paleoenvironments: FA1, gravelly sheet bodies; FA2, tabular bodies of conglomerates with mud rip-up clasts; FA3, complex tabular sandy bodies; FA4, simple tabular sandy bodies; FA5, tabular bodies of structureless sandstones; FA6, heterolithic deposits; and FA7, fine-grained deposits. Three different fluvial styles were recognized: meandering systems dominated by avulsion and meander abandonment processes (fluvial style a), braided systems (fluvial style b), and meandering systems dominated by overbank flood processes (fluvial style c). The stacking pattern of the FAs allowed to divide the UCCD into two major depositional stages related to the accommodation space vs sediment supply (A/S) ratio. Stage I is characterized by the alternation of fluvial styles a and b, while the Stage II is represented by the alternation of fluvial styles c and b, and the Stage III is characterized entirely by fluvial style c deposits. Although the UCCD are considered as a whole within a framework of low A/S ratio, several high frequency variations were recognized. The Stage I records seven high frequency intervals of which four are characterized by high A/S ratio interrupted by three events of low A/S. While the stage II is represented by six high frequency periods of low A/S ratio and other five high frequency events of high A/S ratio. The Stage II is considered as deposited in a relative higher A/S context in comparison with the Stage I, based on the behavior of the moderate to high sinuosity meander fluvial systems. Finally, the Stage III is represented entirely by a high frequency low A/S ratio event.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

Sedimentology and fluvial styles of the uppermost Cretaceous continental deposits of the Austral-Magallanes Basin, Patagonia, Argentina

The sedimentary infill of the Austral-Magallanes Basin since the onset of its foreland stage in the Lago Argentino region is dominated by deep-marine and coastal deposits. However, during the Late Cretaceous the basin accumulated a thick and poorly known continental sedimentary succession, which has received different lithostratigraphic names. The aim of this work is to characterize the here defined Uppermost Cretaceous Continental Deposits (UCCD) from a detailed facies and architectural analysis, as well as the resulting stacking pattern. Seven Facies Associations (FAs) were discriminated in order to define the sedimentary paleoenvironments: FA1, gravelly sheet bodies; FA2, tabular bodies of conglomerates with mud rip-up clasts; FA3, complex tabular sandy bodies; FA4, simple tabular sandy bodies; FA5, tabular bodies of structureless sandstones; FA6, heterolithic deposits; and FA7, fine-grained deposits. Three different fluvial styles were recognized: meandering systems dominated by avulsion and meander abandonment processes (fluvial style a), braided systems (fluvial style b), and meandering systems dominated by overbank flood processes (fluvial style c). The stacking pattern of the FAs allowed to divide the UCCD into two major depositional stages related to the accommodation space vs sediment supply (A/S) ratio. Stage I is characterized by the alternation of fluvial styles a and b, while the Stage II is represented by the alternation of fluvial styles c and b, and the Stage III is characterized entirely by fluvial style c deposits. Although the UCCD are considered as a whole within a framework of low A/S ratio, several high frequency variations were recognized. The Stage I records seven high frequency intervals of which four are characterized by high A/S ratio interrupted by three events of low A/S. While the stage II is represented by six high frequency periods of low A/S ratio and other five high frequency events of high A/S ratio. The Stage II is considered as deposited in a relative higher A/S context in comparison with the Stage I, based on the behavior of the moderate to high sinuosity meander fluvial systems. Finally, the Stage III is represented entirely by a high frequency low A/S ratio event.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

Paleosols and related soil-biota of the early Miocene Santa Cruz Formation (Austral-Magallanes Basin, Argentina) : A multidisciplinary approach to reconstructing ancient terrestrial landscapes

The middle and upper parts of the lower Miocene Santa Cruz Formation (~17–15.9 Ma) in the southeastern Austral-Magallanes Basin (southern Patagonia, Argentina) crop out as a fluvial succession that in parts is pedogenically modified. The study of the paleosols of this unit combined with the study of ichnofossils, microremains, and fossil vertebrates present in these allows us to reconstruct past environmental, ecological, and climatic conditions, as well as paleolandscape evolution of the Santa Cruz Formation during ~1 my. These reconstructions demonstrate three different stages during which very weak to moderate pedogenesis took place. The first one (middle part of the unit) is an epiclastic distal floodplain bearing Calcisols or paleo-calcic Inceptisols, which record a relatively dense vegetation integrating trees, shrubs, palms, and short grasses. Soil fauna is scarce and it is in association with a vertebrate fauna typical of coastal “Santacrucian assemblages”. The second landscape stage (the bottom of the lowermost upper part of the unit) is composed of epiclastic distal floodplain areas and minor pyroclastic proximal floodplain settings that contain mainly Vertisols. Vertisols record an ecosystem dominated by grasses and palms adapted to variable conditions in hydric availability (C4 plants) and by solitary bee larvae, and adult and nymph soil beetles. Finally, up-section, the third stage attests to the existence of an epiclastic and pyroclastic distal and proximal floodplain over which Protosols developed. Past ecosystems supported grass vegetation (C3 plants), oligochaete annelids and a moderately diverse insect soil fauna (interpreted by their trace fossils) composed of solitary bee larvae, soil beetles and their pupae, cicada nymphs, and myriapods. This combined abiotic (paleosols) and biotic (ichnofossils, microremains, and vertebrates) study indicates that several factors controlled the landscape evolution during the early Miocene of southeastern Patagonia. Highly aggrading fluvial conditions, variations in the position in the floodplain and in sedimentation/pedogenesis ratio, the input of pyroclastic materials, the length of landscape stability, changing hydrologic conditions, and fluctuations of wetter and drier phases in a context of relatively warm and humid climate, seem to be the main factors controlling the landscapeCentro de Investigaciones GeológicasFacultad de Ciencias Naturales y Muse

A singular Hegetotheriinae (Notoungulata, Typotheria) from the late Oligocene-Early Miocene of the Subandean Region of Bolivia

Geological studies in the northern sector of the Chaco foreland Basin, Bolivia, yielded new fossils coming from late Oligocene-late Miocene of the Petaca Formation. Few fossil mammals were known from the Subandean Region of Bolivia. We report a partially complete mandible of a hegetotheriid Hegetotheriinae (Notoungulata, Typotheria) from Abapo (Rio Grande River). The specimen (YPFB-LIT-PAL-005) is very close in size and dental morphology to the late Oligocene (Deseadan South American Land Mammal Age, SALMA) — Santacrucian (early Miocene) Prohegetotherium schiaffinoi (Kraglievich 1932) from Fray Bentos (Uruguay and Argentina), Salla (Bolivia), Divisadero Largo-Potrerillos and Quebrada Fiera (Argentina). However, mandibular characteristics, as the shape with a marked change in height along its length, increasing towards the back, a prominent masseteric crest, a deep mandibular groove, and a remarkable thickening of the ventral rim of the mandible, indicate differences between this specimen and Prohegetotherium schiaffinoi and the other Hegetotheriinae. The affinity of YPFB-LIT-PAL-005 with P. schiaffinoi suggests a late Oligocene to early Miocene for the upper bearing horizon of the Petaca Formation (in Abapo), an older age than previously assigned to the top of this unit (late Miocene), and confirms the taxon distribution between ∼ 36 ° to ∼ 17 ° south latitude.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

NHC metal complexes containing naphtyl substituent

Bu çalışmanın amacı naftil veya kinolin sübstiüenti içeren imidazolin-2-iliden metal komplekslerinin sentezi ve bu komplekslerinin organik tepkimelerde katalitik aktivitesinin incelenmesidir. Bu tez üç bölümden oluşmaktadır. Birinci bölümde naftalin, kinolin ve N-heterosiklik karbenlere ait temel bilgiler, önemi ve kullanım alanları özetlendi. İkinci bölümde deneysel çalışmalara yer verildi. Üçüncü bölümde ise sentezlenen imidazolinyum tuzları ve bunların rutenyum komplekslerin sentezi, karakterizasyonu ve katalitik özellikleri gösterilmiştir. Bu çalışmada N-(1-naftil)-etilendiamin ve 8-amino kinolinden yola çıkarak simetrik ve simetrik olmayan imidazolinyum tuzları (2a″- 2d″, 2a ve 2bq) ve bunların rutenyum(II) kompleksleri (3a ve 3a″-3d″) sentezlendi. Sentez basamakları şema 1 de özetlenmiştir. Sentezlenen bu yeni kompleksler (3a, 3a″- 3d″) hidrojen kaynağı olarak 2-propanolün kullanıldığı, KOH varlığında asetofenonun transfer hidrojenasyonunda katalizör olarak kullanıldı ve sonuçlar tartışıldı. Asetofenonun transfer hidrojenasyonunda 3b″ ile en iyi sonuç elde edild

Incidence and risk factors for gangrene in patients with systemic sclerosis from the EUSTAR cohort

Objective: In patients with SSc, peripheral vasculopathy can promote critical ischaemia and gangrene. The aim of this study was to investigate the prevalence, incidence and risk factors for gangrene in the EUSTAR cohort. Methods: We included patients from the EUSTAR database fulfilling the ACR 1980 or the ACR/EULAR 2013 classification criteria for SSc, with at least one visit recording data on gangrene. Centres were asked for supplementary data on traditional cardiovascular risk factors. We analysed the cross-sectional relationship between gangrene and its potential risk factors by univariable and multivariable logistic regression. Longitudinal data were analysed by Cox proportional hazards regression. Results: 1757 patients were analysed (age 55.9 [14.5] years, disease duration 7.9 [10.3] years, male sex 16.7%, 24.6% diffuse cutaneous subset [dcSSc]). At inclusion, 8.9% of patients had current or previous digital gangrene, 16.1% had current digital ulcers (DUs) and 42.7% had ever had DUs (current or previous). Older age, DUs ever and dcSSc were statistically significant risk factors for gangrene in the cross-sectional multivariable model. During a median follow-up of 13.1 months, 16/771 (0.9%) patients developed gangrene. All 16 patients who developed gangrene had previously had DUs and gangrene. Further risk factors for incident gangrene were the dcSSc subset and longer disease duration. Conclusion: In unselected SSc patients, gangrene occurs in about 9% of SSc patients. DUs ever and, to a lesser extent, the dcSSc subset are strongly and independently associated with gangrene, while traditional cardiovascular risk factors could not be identified as risk factors