Gotowa bibliografia na temat „Biological heterogeneities”

The Llucmajor platform on southern Mallorca Island (Spain) is one of the best-exposed Miocene shallow-water carbonate platforms known in the world. Up to 90 m vertical sea cliffs provide a clean, continuous and detailed 3D view of the facies architecture and continuous cores from fifty-two water wells, affording information to interpret the 3D architecture of this 20 km-wide and only slightly deformed carbonate platform. Forty years of research on the Llucmajor platform provided insights into how the mutual interaction of biological and physical processes control the type of carbonate production and sediment dynamics which, along with changes in sea-level, determine the facies stacking patterns and the distribution of internal heterogeneities. Moreover, the ‘modern character’ of the carbonate-producing biota permits to capture the response of the carbonate system to changing ecological and oceanographic conditions. Although learnings from the Llucmajor platform do not apply to older platforms, it is this process-product type of analysis that can be applied to carbonate systems of all ages. Thus through this field guide, two carbonate factories working out of phase and with a non-linear response to sea-level changes are identified. A shallow-water euphotic (well lit) production (corals, red and green calcareous algae and associated heterozoan biota) predominated during rising sea-level when linear reefal rims grading to broad lagoons expanded and increased production and the sediment shed-off from these reef-lagoon systems built-out thick slopes. A deeper oligophotic (low light) factory expanded during the lowstands of sea-level when the light reached the basin floor; red algae, larger benthic foraminifers and molluscs were the prime producers. The Llucmajor platform grew up during the late Miocene, through the transition from greenhouse to icehouse climate that characterised the late Cenozoic. Its building blocks occur hierarchically stacked in response to the sea-level cyclicity. At the bed scale, the sigmoids consist of a lagoonal bed passing successively into sigmoidal reef core and then into slope clinobed and basinal deposits and bounded by an erosion surface onto the lagoon and reef and its correlative conformity basinward. Sigmoids stack in sets of sigmoids, these in cosets of sigmoids and these last in megasets, all of them fitting the characteristics of a depositional sequence when the genetic processes are analysed. Departures from the sequence model rely on the inter-dependence between depth gradient, the type of carbonate-producing biota and the ranges of sea-level cyclicity. Through the visit to a series of selected outcrops, this field guide offers a comprehensive assessment of the Llucmajor reef-rimmed shelf from the basin to the coral-dominated reefal margin and across the open-lagoon to restricted lagoon that defined the shelf top. The itinerary focusses on numerous topics and at different scales, from the study of discrete rock bodies to km-wide outcrop windows resembling high-resolution seismic profiles. The field guide integrates facies analysis, stratal architecture and distinct diagenetic features such as extensive secondary porosity after the dissolution of aragonitic components and pervasive dolomitization. Impressive sub-vertical collapse structures were produced by karstic dissolution during lowstands of sea-level and gravitational collapse of the roof complete the suite of diagenetic overprint. Altogether, the depositional and diagenetic attributes of the Llucmajor platform reveal a complex and highly heterogeneous carbonate system that is used as outcrop analogue for numerous Miocene carbonate reservoirs across the world.

The interaction of solidification fronts with embedded heterogeneities, such as particles and living cells, is an important physical ingredient underlying the successful solidification processing of some materials. An example in the first category is the processing of metal-matrix composites (MMCs) where solidifying metal dendrites interact with ceramic reinforcements [1–3]. Processing of biological material, such as cells and tissue for cryopreservation [4], falls into the second category. In each case, the evolving solidification microstructure interacts in complex ways with the embedded par

Flow and transport phenomena in porous media are the governing processes in many natural and industrial systems. For the numerical description of these systems their multiscale behavior plays an important role. In one part of the system highly complex flow and transport processes may necessitate an examination of the processes on a fine spatial and temporal scale, while in other parts of the system, physically simpler processes may be examined on coarser scales. The heterogeneous structure of the porous medium itself also shows a high dependence on the spatial scale. Whereas different kinds of

Micro-heterogeneity of biological tissue arises from the multiplicity of components that make up the extracellular matrix (ECM) and the constituent cells. Components that have distinct mechanical properties will fundamentally impact the distribution of mechanical stress in the local cellular environment, ultimately determining how physical forces are transferred between macro and micro scales [1]. Atomic force microscope (AFM) indentation is well suited for probing heterogeneities in cell and tissue micromechanics [2], though subsequent data analysis assumes a mechanically homogeneous substrat

Abstract The interpretation of depositional environments following sedimentological description is one of the most fundamental steps for the understanding of the vertical and lateral lithofacies groups’ distribution. This is directly linked to sequence stratigraphy and reservoir quality heterogeneity. Despite its importance, many interpretative lithofacies association schemes fail to capture, in a clear, systematic and flexible way, the key environmental features affecting the depositional fabrics’ distribution and their associated reservoir quality. This is especially true in carbonate system