Pembelajaran Menulis Karangan Narasi Menggunakan Pemetaan Alur Pikir Siswa SMAN 9 Kota Kupang

This study refers to the low interest of students in writing narrative essays, students prefer to work on the questions in the Student Worksheet (LKS) compared to writing assignments, learning to write essays, especially teacher narrative essays only explain the material and assign students to write essays freely without guidance from the teacher, in writing narrative essays students struggle to arrange essays chronologically. In fact, writing learning itself has been applied in schools, especially in Class X2 students of SMA Negeri 9 Kupang City, but there are still many students who do not understand how to write essays, especially writing narrative essays. Based on that the solution applied is the researchers chose to use the Mind Mapping model which aims to explore information from both inside and outside the brain in order to obtain new ideas, new concepts according to students' understanding and prove the effectiveness of learning to write narrative essays. This research uses Pre Experimental in the form of Pretest-Posttest Design. The research data were obtained from observations, questionnaires, test results and field notes. The results showed that in the pretest, the average value of students was 51.73 or less categorized. The scores on the pretest have not yet reached the KKM that has been set. While the posttest increased by 29.63 or 57.27% to 81.36 and was in the good category. The expected benefit of this research is the development of educational theory theory, specifically the problem of the effectiveness of mind-mapping technique to develop students' writing potential, can improve and provide a more varied choice of learning techniques in the learning process and can create a fun learning activity, to improve skills student writing

CO2 bubble generation and migration during magma-carbonate interaction

We conducted quantitative textural analysis of vesicles in high temperature and pressure carbonate assimilation experiments (1200 °C, 0.5 GPa) to investigate CO2 generation and subsequent bubble migration from carbonate into magma. We employed Mt. Merapi (Indonesia) and Mt. Vesuvius (Italy) compositions as magmatic starting materials and present three experimental series using (1) a dry basaltic-andesite, (2) a hydrous basaltic-andesite (2 wt% H2O), and (3) a hydrous shoshonite (2 wt% H2O). The duration of the experiments was varied from 0 to 300 s, and carbonate assimilation produced a CO2-rich fluid and CaO-enriched melts in all cases. The rate of carbonate assimilation, however, changed as a function of melt viscosity, which affected the 2D vesicle number, vesicle volume, and vesicle size distribution within each experiment. Relatively low-viscosity melts (i.e. Vesuvius experiments) facilitated efficient removal of bubbles from the reaction site. This allowed carbonate assimilation to continue unhindered and large volumes of CO2 to beliberated, a scenario thought to fuel sustained CO2-driven eruptions at the surface. Conversely, at higher viscosity (i.e. Merapi experiments), bubble migration became progressively inhibited and bubble concentration at the reaction site caused localised volatile over-pressure that can eventually trigger short-lived explosive outbursts. Melt viscosity therefore exerts a fundamental control on carbonate assimilation rates and, by consequence, the style of CO2-fuelled eruptions

CO2 bubble generation and migration during magma–carbonate interaction

We conducted quantitative textural analysis of vesicles in high temperature and pressure carbonate assimilation experiments (1200 °C, 0.5 GPa) to investigate CO2 generation and subsequent bubble migration from carbonate into magma. We employed Mt. Merapi (Indonesia) and Mt. Vesuvius (Italy) compositions as magmatic starting materials and present three experimental series using (1) a dry basaltic-andesite, (2) a hydrous basaltic-andesite (2 wt% H2O), and (3) a hydrous shoshonite (2 wt% H2O). The duration of the experiments was varied from 0 to 300 s, and carbonate assimilation produced a CO2-rich fluid and CaO-enriched melts in all cases. The rate of carbonate assimilation, however, changed as a function of melt viscosity, which affected the 2D vesicle number, vesicle volume, and vesicle size distribution within each experiment. Relatively low-viscosity melts (i.e. Vesuvius experiments) facilitated efficient removal of bubbles from the reaction site. This allowed carbonate assimilation to continue unhindered and large volumes of CO2 to be liberated, a scenario thought to fuel sustained CO2-driven eruptions at the surface. Conversely, at higher viscosity (i.e. Merapi experiments), bubble migration became progressively inhibited and bubble concentration at the reaction site caused localised volatile over-pressure that can eventually trigger short-lived explosive outbursts. Melt viscosity therefore exerts a fundamental control on carbonate assimilation rates and, by consequence, the style of CO2-fuelled eruptions

Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption

The eruption that started off the south coast of El Hierro, Canary Islands, in October 2011 has emitted intriguing eruption products found floating in the sea. These specimens appeared as floating volcanic "bombs" that have in the meantime been termed "restingolites" (after the close-by village of La Restinga) and exhibit cores of white and porous pumice-like material. Currently the nature and origin of these "floating stones" is vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The "restingolites" have been proposed to be either (i) juvenile high-silica magma (e.g. rhyolite), (ii) remelted magmatic material (trachyte), (iii) altered volcanic rock, or (iv) reheated hyaloclastites or zeolite from the submarine slopes of El Hierro. Here, we provide evidence that supports yet a different conclusion. We have collected and analysed the structure and composition of samples and compared the results to previous work on similar rocks found in the archipelago. Based on their high silica content, the lack of igneous trace element signatures, and the presence of remnant quartz crystals, jasper fragments and carbonate relicts, we conclude that "restingolites" are in fact xenoliths from pre-island sedimentary rocks that were picked up and heated by the ascending magma causing them to partially melt and vesiculate. They hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies in the Canary Islands as well as in similar Atlantic islands that rest on sediment/covered ocean crust (e.g. Cape Verdes, Azores). The occurrence of these "restingolites" does therefore not indicate the presence of an explosive high-silica magma that is involved in the ongoing eruption

Convergence to SPDEs in Stratonovich form

We consider the perturbation of parabolic operators of the form $\partial_t+P(x,D)$ by large-amplitude highly oscillatory spatially dependent potentials modeled as Gaussian random fields. The amplitude of the potential is chosen so that the solution to the random equation is affected by the randomness at the leading order. We show that, when the dimension is smaller than the order of the elliptic pseudo-differential operator $P(x,D)$, the perturbed parabolic equation admits a solution given by a Duhamel expansion. Moreover, as the correlation length of the potential vanishes, we show that the latter solution converges in distribution to the solution of a stochastic parabolic equation with a multiplicative term that should be interpreted in the Stratonovich sense. The theory of mild solutions for such stochastic partial differential equations is developed. The behavior described above should be contrasted to the case of dimensions that are larger than or equal to the order of the elliptic pseudo-differential operator $P(x,D)$. In the latter case, the solution to the random equation converges strongly to the solution of a homogenized (deterministic) parabolic equation as is shown in the companion paper [2]. The stochastic model is therefore valid only for sufficiently small space dimensions in this class of parabolic problems.Comment: 21 page

Corrigendum to "Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption" published in Solid Earth, 3, 97–110, 2012

No abstract available

magma mixing history and dynamics of an eruption trigger

The most violent and catastrophic volcanic eruptions on Earth have been triggered by the refilling of a felsic volcanic magma chamber by a hotter more mafic magma. Examples include Vesuvius 79 AD, Krakatau 1883, Pinatubo 1991, and Eyjafjallajokull 2010. Since the first hypothesis, plenty of evidence of magma mixing processes, in all tectonic environments, has accumulated in the literature allowing this natural process to be defined as fundamental petrological processes playing a role in triggering volcanic eruptions, and in the generation of the compositional variability of igneous rocks. Combined with petrographic, mineral chemistry and geochemical investigations, isotopic analyses on volcanic rocks have revealed compositional variations at different length scales pointing to a complex interplay of fractional crystallization, mixing/mingling and crustal contamination during the evolution of several magmatic feeding systems. But to fully understand the dynamics of mixing and mingling processes, that are impossible to observe directly, at a realistically large scale, it is necessary to resort to numerical simulations of the complex interaction dynamics between chemically different magmas

Traversing nature’s danger zone: getting up close with Sumatra’s volcanoes.

The Indonesian island of Sumatra, located in one of the most active zones of the Pacific Ring of Fire, is characterized by a chain of subduction-zone volcanoes which extend the entire length of the island. As a group of volcanic geochemists, we embarked upon a five-week sampling expedition to these exotic, remote, and in part explosive volcanoes (SAGE 2010; Sumatran Arc Geochemical Expedition). We set out to collect rock and gas samples from 17 volcanic centres from the Sumatran segment of the Sunda arc system, with the aim of obtaining a regionally significant sample set that will allow quantification of the respective roles of mantle versus crustal sources to magma genesis along the strike of the arc. Here we document our geological journey through Sumatra’s unpredictable terrain, including the many challenges faced when working on active volcanoes in pristine tropical climes.Swedish Science Foundation (VR), Scripps Institution of Oceanography, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Upp-sala University Centre for Natural Disaster Science (CNDS) and Otterborgska donationsfondenPublished64-702.3. TTC - Laboratori di chimica e fisica delle rocceN/A or not JCRrestricte

Skarn xenolith record crustal CO2 liberation during Pompeii and Pollena eruptions, Vesuvius volcanic system, central Italy

Limestone assimilation and skarn formation are important processes in magmatic systems emplaced within carbonate-rich crust and can affect the composition of the magma and that of associated volcanic gas. In this studywe focus on marble and calc-silicate (skarn) xenoliths fromcontact reactions between magma and carbonate wall-rock of the Vesuvius volcanic system. We present new elemental and C-O isotope data for marble and skarn xenoliths as well as for igneous rocks collected from the AD 79 (Pompeii) and AD 472 (Pollena) eruptions. The igneous samples have consistently high δ18Ovalues (9.3to10.8‰), but lowH2O contents (≤1.5%), indicating that magma–crust interaction prior to eruption took place. The marble xenoliths, in turn, record initial decarbonation reactions and fluid-mass exchange in their textures and δ13C and δ18O ranges, while the skarn xenoliths reflect prolonged magma–carbonate interaction and intense contact metamorphism. Skarn-xenoliths record Ca and Mg release from the original carbonate and uptake of Al and Si and span the full δ18O data range from unmetamorphosed carbonate (N18‰) to values typical for Vesuvius magmatic rocks (~7.5‰), which implies that skarn xenoliths comprise carbonate and magmatic components. Textural and chemical evidence suggest that direct carbonate dissolution into the host magmas occurred aswell as post-metamorphic skarn recycling, resulting in progressive Ca andMgliberation fromthe skarn xenoliths into themagma.Magma–carbonate interaction is an additional source of CO2 during carbonate break-down and assimilation and we calculate the amount of extra volatile components likely liberated by contact metamorphic reactions before and during the investigated eruptions. We find that the extra CO2 added into the volcanic systemcould have outweighed the magmatic CO2 component by ≥ factor seven and thus likely increased the intensity of both the Pompeii and the Pollena eruptive events