Million-year-scale alternation of warm–humid and semi-arid periods as a mid-latitude climate mode in the Early Jurassic (late Sinemurian, Laurasian Seaway)

Clay mineral and stable isotope (C, O) data are reported from the upper Sinemurian (Lower Jurassic) of the Cardigan Bay Basin (Llanbedr–Mochras Farm borehole, northwestern Wales) and the Paris Basin (Montcornet borehole, northern France) to highlight the prevailing environmental and climatic conditions. In both basins, located at similar palaeolatitudes of 30–35∘ N, the clay mineral assemblages comprise chlorite, illite, illite–smectite mixed layers (R1 I-S), smectite, and kaolinite in various proportions. Because the influence of burial diagenesis and authigenesis is negligible in both boreholes, the clay minerals are interpreted to be derived from the erosion of the Caledonian and Variscan massifs, including their basement and pedogenic cover. In the Cardigan Bay Basin, the variations in the proportions of smectite and kaolinite are inversely related to each other through the entire upper Sinemurian. As in the succeeding Pliensbachian, the upper Sinemurian stratigraphic distribution reveals an alternation of kaolinite-rich intervals reflecting strong hydrolysing conditions and smectite-rich intervals indicating a semi-arid climate. Kaolinite is particularly abundant in the upper part of the obtusum zone and in the oxynotum zone, suggesting more intense hydrolysing conditions likely coeval with warm conditions responsible for an acceleration of the hydrological cycle. In the north of the Paris Basin, the succession is less continuous compared to the Cardigan Bay Basin site, as the oxynotum zone and the upper raricostatum zone are either absent or highly condensed. The clay assemblages are dominantly composed of illite and kaolinite without significant stratigraphic trends, but a smectite-rich interval identified in the obtusum zone is interpreted as a consequence of the emersion of the London–Brabant Massif following a lowering of sea level. Following a slight negative carbon isotope excursion at the obtusum–oxynotum zone transition, a long-term decrease in δ13Corg from the late oxynotum–early raricostatum zones is recorded in the two sites and may precede or partly include the negative carbon isotope excursion of the Sinemurian–Pliensbachian Boundary Event, which is recognised in most basins worldwide and interpreted to signify a late pulse of the Central Atlantic Magmatic Province volcanism

Impact of anaesthesia mode on evaluation of LEEP specimen dimensions.

&lt;p&gt;&lt;b&gt;OBJECTIVES: &lt;/b&gt;To study the influence of anaesthesia (local by cervical block vs. general or spinal anaesthesia) on height and volume of resection specimens in case of conization treatment for cervical intraepithelial neoplasia (CIN).&lt;/p&gt;&lt;p&gt;&lt;b&gt;METHODS: &lt;/b&gt;Prospective observational study of all patients who underwent a first treatment by loop electrosurgical excision procedure (LEEP) for CIN. Height of fresh resection specimens was first measured by the operator and then by the pathologist after formaldehyde fixation. Volume of fresh specimens was measured in a measuring cylinder by fluid displacement.&lt;/p&gt;&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;One hundred patients were included and 35% of LEEP were performed under local anaesthesia. There was a significant difference in height of specimens depending on anaesthesia mode: after fixation, the average height was 11.2mm in the general or spinal anaesthesia group vs. 8.8mm in the local anaesthesia group (P=0.002). There was also a difference in terms of volume depending on anaesthesia mode: 1.6mL in local anaesthesia group vs. 2.3mm in general and spinal anaesthesia group (P=0.01).&lt;/p&gt;&lt;p&gt;&lt;b&gt;CONCLUSIONS: &lt;/b&gt;Anaesthesia mode has an impact on height and volume of LEEP specimens. In our experience, local anaesthesia could reduce LEEP specimen height.&lt;/p&gt;</p

Sedimentology and U-Pb dating of Carboniferous to Permian continental series of the northern Massif Central (France): Local palaeogeographic evolution and larger scale correlations

The Carboniferous to Permian volcanic-sedimentary succession shown by the LY-F core from the Lucenay-lès-Aix area, in the northern part of the Massif Central, has been studied in order to obtain both landscape reconstructions (sedimentological analyses) and geochronological constraints (U-Pb dating on zircon and apatite). The lowermost part of the core consists mainly of lacustrine deposits with Gilbert-type delta and volcaniclastic-rich fan delta deposits including several altered volcanic ash layers (tonstein). In contrast, in the uppermost part of the core, playa-lake deposits dominate. LA-ICP-MS U-Pb analyses were performed on both zircon and apatite grains from interbedded tonsteins. This coupled U-Pb dating approach allows to assess potential reworking of volcanic material or the occurrence of non-volcanic grains, such as xenocrysts, in order to provide better evaluations for the depositional ages of the tonsteins. These investigations reveal that sedimentation took place between the late Gzhelian and the late Sakmarian (i.e., between c. 301 and 290 Ma). This sedimentary succession can therefore be compared to those from adjacent basins for which geochronological constraints are available (i.e., Autun and Lodève basins, resp. located north and south of the Massif Central). This study provides a reference section for future comparisons with similar sections from other Carboniferous to Permian basins, in France as well as elsewhere in Europe