The evolution of layered, basic plutons - evidence from small-scale structures

Many basic and ultrabasic plutons are commonly lithologically, texturally and compositionally layered on several scales. Associated with and defined by, the layering are a variety of small-scale structures, considered analogous to structures found in sedimentary rocks, and capable of interpretation using similar techniques. Observations on these small-scale structures are vised to infer the "depositional" and "diagenetic" processes that operated during the solidification of a number of' plutons. Erosion structures and structures associated with lithic fragments indicate that physical redistribution of solids, crystals and rock fragments, was an important process in the evolution of these bodies and that plagioclase was deposited at the floor even where it was less dense than the contemporary magma. From their relationships with lithic fragments normally graded layers are demonstrated to be the solidified remnants of crystal-laden density currents flowing across the transient floor of the magma chamber and are inferred to be the best approximation to truly chronostratigraphic horizons in layered plutons identified to date. The proposition that crystal- and rock-laden density currents can transport material vertically through the magma body is investigated experimentally by examining the nature of such flows in a small tank, Experiments and calculations indicate that such density currents straddle the range of conditions from laminar to fully turbulent. Laminar flows do not mix with the contemporary magma and will transport crystals to the transient chamber floor. It is suggested that such a process may have given rise to lensoid mafic layers of limited areal extent in the Kiglapait intrusion. Structures inferred to have formed during the "diagenetic" stage of the formation of the layered rocks include deformation structures, layers and replacement bodies. Examples of the latter two sets of structures are shown to have textures identical to those in rocks interpreted as cumulates and it is concluded that those textures alone are not sufficient basis on which to infer crystal growth from the contemporary magma. Many of the structures testify to the former presence of mobile pore liquids and the contemporaneity of pore liquids of different compositions. Movement of pore liquid is considered to have been driven by density differences due to variations in pore magma composition and thus the structures can be considered as evidence for interstitial compositional convection. Under certain circumstances pore liquids may be expelled from the crystal mush and mix with the contemporary magma. The chemical consequences of such mixing events are discussed and it is proposed that chromitite layers in the Eastern Layered Series of the Rum intrusion record the operation of the process. Several features of the Rum intrusion suggest that the magma chamber was thermally and compositionally zoned at times during its active history and this leads to the formulation of a new scheme for the formation of cyclic stratigraphy in the Rum layered intrusion, based on the progradation and regression of a liquid/liquid interface and two environments of accumulation

Observation of defects in device silicon

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Laser ablation ICP-MS analysis of olivine-hosted melt inclusions from the Mull plateau group lavas, Mull, Scotland

The 840 km lava field of the Isle of Mull, Scotland, represents only a small part of the North Atlantic Tertiary Igneous Province. The cause of this igneous activity at approximately 60 Ma, was the arrival and decompression melting of a hot plume. Previous work on the Mull lavas has focused on the whole rock geochemistry. The aim of this study is the analysis of olivine-hosted melt inclusions by Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS). Melt inclusions are small aliquots of melt trapped by growing crystals (i.e. olivine, plagioclase) during magma evolution prior to and during eruptions. Therefore, melt inclusions analysis can provide valuable information on crystallisation temperatures, the sequence of phase changes in the host magma during cooling, cooling rates, the composition and volatile content of the host magma and liquid lines of decent. In the context of Continental Flood Basalts, melt inclusions also have the potential to provide information on the timing, extent and geochemical effects of crustal contamination. Whole rock data indicated that the parental magmas of Mull Plateau Group lavas represent 4 to 13% melting of a depleted mantle source, located in the spinel-garnet transition zone. Whereas, melt inclusion data show that these parental magmas are mixtures of partial melts of between 2 and 20%, and that the whole rock values only reflect the mean extent of melting. These parental magmas rose through the lithosphere, with little interaction, before ponding near the lithospheric-crust boundary. Fractionation of spinel, olivine and clinopyroxene occurred concurrently with contamination of up to 8% Lewisian granulite by both Assimilation during Turbulent Assent and Assimilation during Fractional Crystallisation processes, with the hottest, most voluminous mantle melts suffering the greatest contamination. Many of the MPG lavas contain olivine phenocrysts enclosing decrepitated melt inclusions, which decrepitate in response to a drop in pressure, but without a corresponding drop in temperature. Therefore, the parental magmas of the MPG lavas rose rapidly from the lower crust, before being emplaced on Mull

'Out to an other side':the poetry of Paul Celan and Seamus Heaney and the poetic challenge to post-modern discussions of absence and presence in the context of theological and philosophical conceptions of language and artistic production

Martin Heidegger in 'The Origin of the Work of Art' seeks to approach the self-subsistent nature of art. The Greek Temple opens up a space within which our Being may dwell. It is the site of human civilization and religion, and of our capacity to dwell within abstractions like peace, justice, truth and representation. Art breaks open a new place and presents things in a fresh light. Language is the primary model for this activity. Paul Celan in his poetry offers a challenge to Heideggerian abstraction. Both poet and philosopher were intimately familiar with each other's work, yet there is no essay on Celan, or even a reference, in the entire Heideggerian corpus. Celan's poem 'The Straitening' conveys the breakdown of meaning that has occurred after the holocaust. In form and content it challenges any Heideggerian notion of the higher univocity achieved by great poetry. We will explore recent examples of how poets have examined the idea of cultural belonging exclusion. We present a distillation of this idea in the writings of Paul Celan, particularly his presentation of the moment of 'Shibboleth'. We explore the biblical origin of the term 'Shibboleth' in a conflict between the army of Jephtah and the Ephraimites. We look at a contemporary poem with 'shibboleth' as it theme. Seamus Heaney's 'Broagh'. A consistent theme of Maurice Blanchot's critical reflection from The Work of Fire in 1949 up to and including The Space of Literature in 1955, is the manner in which our being creatures unto death allows us to create art, and to think and write in the abstraction that is language. Life endures death and maintains itself in it. For Blanchot Rainer Maria Rilke is one of the most significant modern poets in the way in which he has presented and explored this theme. We challenge Blanchot's inadequate reading of Rilke in The Space of Literature as an instance of his own pre-conceived philosophical nihilism

A petrogenetic study of harrisite in the Isle of Rhum Pluton, Scotland

There is textural evidence in the Rhum pluton for crystallization of layered ultrabasic rocks ('harrisite') under conditions of massive olivine supersaturation. Some of these rocks are comb layered. This field, petrographic and experimental investigation of harrisite is aimed at determining (1) the degree of supercooling at which different shapes of olivine crystallized in harrisite, (2) how magma in a plutonic environment became massively supersaturated in olivine and (3) whether the parent magma of harrisite was basaltic or ultrabasic. The results have particular relevance to the conditions under which magmas crystallize close to, or on, their margins and enclosures, sometimes to produce comb layers. Harrisite is here defined as "an ultrabasic, plutonic, igneous rock in layered intrusions which contains >25 vol. percent of olivine. The olivine crystals are characterized by skeletal or dendritic shapes and have larger size than olivines in contiguous layers. Hydrous minerals are essential phases in the rock," Harrisite is a varietal type of peridotite, allivalite or olivine eucirite. Harrisite layers are mainly confined to the Western Layered Series of the Rhum pluton. They range in thickness from 7 cm to 10 m and have a preferred thickness of about 1 m. Individual layers vary laterally in thickness and olivine crystal shape. A few harrisite layers are intrusive into the Layered Series, but the majority crystallized in conformable sequence with cumulate layers. Five percent of the ultrabasic rock of the island is harrisite; sixty percent of the Transition Series is harrisite. The shapes of olivines in igneous rocks are classified into thirteen categories (those found in harrisite are underlined): polyhedral, porphyritic, granular, chain-like, parallel-growth, plate, branching (non-crystallographic, crystallographic, linked parallel-unit), randomly oriented, radiate, dendritic, lattice-work, swallow-tail and irregular olivines. Elongate olivines in harrisite can grow preferentially upwards, downwards, horizontally or in random orientation. There is a gradual, systematic upward change in layers from granular or polyhedral cumulus olivines to skeletal porphyritic olivines, to branching olivines (present only in some layers). This change is accompanied by up to a 10 vol. percent decrease in olivine content and by increases in contents of both chrome magnetite and hydrous minerals; also, olivine crystals increase up to 1000 times in size and plagioclase crystals increase in size up to 10 times. Olivine crystals in harrisite grew as fast as 10-4 cm/s. Olivine in harrisite has a composition range of Fo84- 73. Some crystals are reverse zoned (2 - 2.5 mol. percent Fo). Olivines in cumulate layers are up to 2 mol. percent poorer in Fo than those in contiguous harrisite layers. Augite (e.g., Wo46En46FS9) and rare orthopyroxene crystals (e.g., Wo1.3En79.4 Fs 19.3) indicate crystallization from a transitional magma. Plagioclases range from An87 in the generally broad, unzoned cores of crystals, to approximately An60 at in the extremity of the normally-zoned mantles. Cr-rich kaersutite and phlogopite crystallized by reaction of magma with pyroxene, whereas Cr-deficient varieties of the same minerals crystallized directly from the magma. Chrome magnetite composition is dependent on the enclosing silicate mineral- crystals enclosed in olivine are generally richer in Fe and poorer in Al, Cr and Mg than those enclosed by plagioclase and pyroxene. Variations in olivine, plagioclase and chrome magnetite compositions in one comb layer of harrisite are consistent with upward crystallization of the layer along a thermal gradient in the magma of increasing temperature with height. (Abstract shortened by Proquest

Towards a circular economy: fabrication and characterization of biodegradable plates from sugarcane waste

Bagasse pulp is a promising material to produce biodegradable plates. Bagasse is the fibrous residue that remains after sugarcane stalks are crushed to extract their juice. It is a renewable resource and is widely available in many countries, making it an attractive alternative to traditional plastic plates. Recent research has shown that biodegradable plates made from Bagasse pulp have several advantages over traditional plastic plates. For example, they are more environmentally friendly because they are made from renewable resources and can be composted after use. Additionally, they are safer for human health because they do not contain harmful chemicals that can leach into food. The production process for Bagasse pulp plates is also relatively simple and cost-effective. Bagasse is first collected and then processed to remove impurities and extract the pulp. The pulp is then molded into the desired shape and dried to form a sturdy plate. Overall, biodegradable plates made from Bagasse pulp are a promising alternative to traditional plastic plates. They are environmentally friendly, safe for human health, and cost-effective to produce. As such, they have the potential to play an important role in reducing plastic waste and promoting sustainable practices. Over the years, the world was not paying strict attention to the impact of rapid growth in plastic use. As a result, uncontrollable volumes of plastic garbage have been released into the environment. Half of all plastic garbage generated worldwide is made up of packaging materials. The purpose of this article is to offer an alternative by creating bioplastic goods that can be produced in various shapes and sizes across various sectors, including food packaging, single-use tableware, and crafts. Products made from bagasse help address the issue of plastic pollution. To find the optimum option for creating bagasse-based biodegradable dinnerware in Egypt and throughout the world, researchers tested various scenarios. The findings show that bagasse pulp may replace plastics in biodegradable packaging. As a result of this value-added utilization of natural fibers, less waste and less of it ends up in landfills. The practical significance of this study is to help advance low-carbon economic solutions and to produce secure bioplastic materials that can replace Styrofoam in tableware and food packaging production