Detrital zircon sources in the Ordovician metasedimentary rocks of the Moroccan Meseta: Inferences for northern Gondwanan passive-margin paleogeography

ABSTRACT Detrital zircon U-Pb geochronology has been widely used to constrain the pre-Carboniferous geography of the European and, to a lesser extent, the Moroccan Variscides. The latter have been generally considered as part of a long-lasting passive margin that characterized northern Gondwana from Ordovician to Devonian time, and was subsequently involved in the late Paleozoic Variscan orogeny. We report detrital zircon ages for three Early to Late Ordovician samples from the Beni Mellala inlier in the northeastern part of the Western Moroccan Meseta in order to discuss the temporal evolution of the sources of sediments in this region. The detrital zircon spectra of these samples, characterized by two main populations with mean ages of 630–610 Ma and 2170–2060 Ma, are typical of Cambrian–Devonian rocks from the Moroccan Variscides and confirm their link to the West African craton. A minor Stenian–Tonian population (peak at ca. 970 Ma) suggests the influence of a distant and intermittent NE African source (Sahara metacraton), which was probably interrupted after Ordovician time. Our data support previous interpretations of the Moroccan Meseta (and the entire northern Moroccan Variscides) as part of the northern Gondwana passive margin. The main sources of these sediments would have been the West African craton in the western regions of the passive margin (Moroc- can Meseta and central European Paleozoic massifs), and the Arabian-Nubian Shield and/or Sahara metacraton in the eastern areas (Libya, Egypt, Jordan, central and NW Iberian zones during Paleozoic time), where the 1.0 Ga detrital zircon population is persistent throughout the Ordovician–Devonian time span.

Inter and intra population phenotypic variability of Lippia integrifolia(Verbenaceae) and its natural situation in the west-center of Argentina

The species Lippia integrifoliais an aromatic, sub-woody shrub, distributed from Northwest and Central Argentina to Bolivia. It is among the most important native aromatic species. It presents medicinal properties, some of which have been scientifically proven. As an alternative to harvesting, the process of domestication of the species was initiated. The objective of this work was to assess the phenotypic variability based on botanical-taxonomic and morpho-agronomic descriptors and the use of indicators to evaluate its natural situation in the west-center of Argentina. We worked in five wild populations, registering morphological variables, phenology, natural regeneration, herbivory and presence of diseases. L. integrifoliapresents a wide morphological variability, which can be explained with three morphological descriptors. Natural regeneration ́s rate is very low to zero, in four of the sites. The results obtained are of importance to make decisions related to the sustainable use in situ, and to begin a program of domestication of the species.

Criticism of “Colonial Modernity” through Kurdish Decolonial Approaches

Western modernity with its colonial application has created an identity trauma and patriarchal domination of the memory of colonized and oppressed peoples. Critiques from colonized territories encourage us to reread the colonial epistemes of modernity, whether or not centered on the West. The Kurdish political movement thus defines a new interpretation of modernity based on the critique of colonialism and global capitalism: “democratic modernity.” This chapter problematizes the relations between modernity, the nation state, the destruction of ecology, social confinement, the relationship of the forces of these relations, but above all the modalities by which it becomes possible to act on them to break the “stalemate” of the modernity of thought in the twenty-first century.

An overview of strains in the Sevier thin-skinned thrust belt, Idaho and Wyoming, USA (latitude 42° N)

ABSTRACT Calcite twinning analysis across the central, unbuttressed portion of the Sevier thin-skin thrust belt, using Cambrian–Cretaceous limestones (n = 121) and synorogenic calcite veins (n = 31), records a complex strain history for the Sevier belt, Idaho and Wyoming, USA. Plots of fabric types (layer-parallel shortening, layer-normal shortening, etc.), shortening and extension axes for the Paris thrust (west, oldest, n = 11), Meade thrust (n = 46), Crawford thrust (n = 15), Absaroka thrust (n = 55), Darby thrust (n = 13), Lander Peak klippe (n = 5), eastern Prospect thrust (n = 6), and distal Cretaceous foreland (n = 3) reveal a W-E layer-parallel shortening strain only in the Prospect thrust and distal foreland. Calcite twinning strains in all western, internal thrust sheets are complex mixes of layer-parallel (LPS), layer-normal (LNS), and non-plane strains in limestones and synorogenic calcite veins. This complex strain fabric is best interpreted as the result of oblique convergence to the west and repeated eastward overthrusting by the Paris thrust.

Studies in Canarium urceus (Linnaeus, 1758) Part 6: A new Canarium species from the Andaman Sea (Gastropoda: Strombidae) and discussion on related species

This part of the Canarium (Canarium) urceus-complex (Linnaeus, 1758) review after Abbott’s revision (Abbott, 1960) revision examines material from the Andaman Sea. At present, material from that region has been synonymised under the name Canarium (Canarium) urceus (Linnaeus, 1758). Canarium (Canarium) andamanense new species is known from the Andamanian Subprovince, a semi enclosed basin that is centered on the Andaman Sea and enclosed by the west coasts of Myanmar and Thailand and the Mergui Archipelago in the east, to the northern Malacca Strait in the south, and to the Andaman and Nicobar Islands in the west. This species is recognized and differentiated by solid, sturdy shells with a triangular body whorl, large knobs on the shoulder and bright orange aperture. This study further confirms that there is a high degree of bioregionalisation within the Canarium complex.

Structure, variability, and dynamics of the West Greenland Boundary Current System

The ventilation of intermediate waters in the Labrador Sea has important implications for the strength of the Atlantic Meridional Overturning Circulation. Boundary current-interior interactions regulate the exchange of properties between the slope and the basin, which in turn regulates the magnitude of interior convection and the export of ventilated waters from the subpolar gyre. This thesis characterizes theWest Greenland Boundary Current System near Cape Farewell across a range of spatio-temporal scales. The boundary current system is composed of three velocity cores: (1) the West Greenland Coastal Current (WGCC), transporting Greenland and Arctic meltwaters on the shelf; (2) the West Greenland Current (WGC), which advects warm, saline Atlantic-origin water at depth, meltwaters at the surface, and newly-ventilated Labrador Sea Water (LSW); and (3) the Deep Western Boundary Current, which carries dense overflow waters ventilated in the Nordic Seas. The seasonal presence of the LSW and Atlantic-origin water are dictated by air-sea buoyancy forcing, while the seasonality of the WGCC is governed by remote wind forcing and the propagation of coastally trapped waves from East Greenland. Using mooring data and hydrographic surveys, we demonstrate mid-depth intensified cyclones generated at Denmark Strait are found offshore of the WGC and enhance the overflow water transport at synoptic timescales. Using mooring, hydrographic, and satellite data, we demonstrate that the WGC undergoes extensive meandering due to baroclinic instability that is enhanced in winter due to LSW formation adjacent to the current. This leads to the production of small-scale, anticyclonic eddies that can account for the entirety of wintertime heat loss within the Labrador Sea. The meanders are shown to trigger the formation of Irminger Rings downstream. Using mooring, hydrographic, atmospheric, and Lagrangian data, and a mixing model, we find that strong atmospheric storms known as forward tip jets cause upwelling at the shelfbreak that triggers offshore export of freshwater. This freshwater flux can explain the observed lack of ventilation in the eastern Labrador Sea. Together, this thesis documents previously unobserved interannual, seasonal, and synoptic-scale variability and dynamics within the West Greenland boundary current system that must be accounted for in future modeling.