ENVIRONMENTALISM AND EUROCENTRISM

ABSTRACT. Environmental determinism has served to validate a Eurocentric world history for several centuries, and it continues to do so today. This essay looks briefly at the historical marriage between environmental determinism and Eurocentric history, then develops a detailed critique of the environmental determinism put forward in two recent world-history books: Jared Diamond's Guns, Germs, and Steel (1997) and David Landes's The Wealth and Poverty of Nations (1998).     

The equation of state of CaSiO3 perovskite to 108 GPa at 300 K

Pressure–volume measurements have been performed for CaSiO₃ perovskite to 108 GPa at 300 K using NaCl and argon pressure-transmitting media, and energy dispersive X-ray diffraction (EDXD) in a diamond-anvil cell (DAC). By determining a parameter that is the product of the elastic anisotropy, S, and the uniaxial stress component, t, for each data point, we define the stress condition of the sample. For different points at the same pressure in a temperature-quenched sample, the St value can differ by as much as a factor of 5, indicating heterogeneity in the stress condition. This may be responsible for the large scatter of earlier P–V measurements in the DAC which in general used a large diameter X-ray beam. Also, the St value provides insight into the elastic anisotropy, S, of CaSiO₃ perovskite and platinum. The sign of S (positive) for CaSiO₃ perovskite agrees with first principles calculations but the magnitude may be inconsistent. A new compression curve at 300 K was obtained for CaSiO₃ perovskite by using those data points which represent the most nearly hydrostatic conditions. It is observed that the data points with high St values yield larger volumes than the points with small St values at a given pressure. By selecting the data points having low St values (St≤0.005), combining with lower pressure large volume press (LVP) measurements and fitting to third order Birch–Murnaghan equation of state (EOS), we find that CaSiO₃ perovskite is more compressible (V₀=45.58±0.05 ų, K_T0=236±4 GPa, and K_T0′=3.9±0.2 GPa) than suggested by previous studies. The density and bulk modulus of CaSiO₃ perovskite at lower mantle pressures and 300 K are 1–3% greater and 5–15% smaller, respectively, than found in previous studies. This study demonstrates that defining the stress state of the sample is crucial to obtain an accurate 300 K compression curve for unquenchable high-pressure phases.     

Mineral inclusions in microdiamonds and macrodiamonds from kimberlites of Yakutia: a comparative study

Chemical compositions were determined on mineral inclusions recovered from 290 microdiamonds (<1 mm) from 8 operating diamond mines in Yakutia. The sampled diamond mines include Mir, Udachnaya, Internatsionalnaya, Aykhal, Sytykanskaya, Yubileynaya, Komsomolskaya and Krasnopresnenskaya. The mineral inclusions include both ultramafic (peridotitic) suite (U-type) and eclogitic suite (E-type) examples. Olivines, chromites, Cr-pyropes, Cr-diopsides and enstatite were studied from U-type diamonds. Mg–Ca–Fe-garnets and omphacitic clinopyroxenes were studied from E-type microdiamonds. Abundances and compositions of these inclusions were compared with published and unpublished data on inclusions available from approximately 2000 macrodiamonds (>1 mm) from the same sources, and worldwide data for olivines and chromites. Although there are general similarities, notable exceptions were detected in about 10% of the inclusions from microdiamonds. For each of the pipes, anomalous compositions occur between the micro- and macrodiamond inclusions, but in different proportions, sometimes as high as 50% of the inclusions. Our study has demonstrated that mineral inclusions in microdiamonds are considerably more variable in their compositions and parageneses compared with inclusions in macrodiamonds.

Significant compositional anomalies in inclusions from microdiamonds include: (1) garnets containing pyroxene solid solution (majoritic component) both in U- and E-type microdiamonds from three pipes: Yubileynaya, Komsomolskaya and Krasnopresnenskaya. The moles of Si (pfu) in these garnets range from 3.07 to 3.13 and as high as 3.29, on the basis of 12 oxygens, along with a notable contents of Na₂O in two eclogitic garnets (0.43 and 0.93 wt.%) and uniquely high Cr₂O₃ and CaO contents in an ultramafic garnet of wehrlitic paragenesis; (2) coexisting wehrlitic garnets in a single microdiamond, one majoritic, the other normal, both with distinct +Eu anomalies, considered as signatures of crustal protoliths for the precursors to these garnets; (3) olivines with relatively low Fo (86–89) and high-NiO contents (0.46–0.64 wt.%), from Yubileynaya and Sytykanskaya microdiamonds; (4) chromites containing high-TiO₂ (up to 4.7 wt.%) and some extremely rich in MgO (Mg# 80). It is concluded that many of these compositional features observed may be related to a deeper origin for the microdiamond source region (>300 km), for at least a 10–30% portion of microdiamonds from each Yakutian pipe.     

New measurement of melting and thermal conductivity of iron close to outer core conditions

The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of which is flawed to a certain degree,which may explain the discrepancy.In this report,we present new data using a different method for determining the phase behavior and resistivity of iron in the laser-heated diamond cell by measuring the electrical resistance of both solid and liquid iron wires.The experiment avoids some of the major flaws of previous experiments,the most important of which is the detection of the onset of melting.These measurements confirm a shallow melting curve found earlier and the resistivity data imply a trend towards low thermal conductivity in the liquid outer core.     

Exploring for kimberlites in glaciated terrains using chromite in quaternary till—a regional case study from northern Finland

Prospecting for kimberlites and related rocks in till-covered terrains requires a methodology for recovering a few small grains within tens of kilograms samples, necessitating 1 ppb sensitivity or better. As part of reconnaissance survey for the kimberlite indicator minerals, i.e. pyrope garnet, picroilmenite, chromite and chromian diopside, the Geological Survey of Finland (GTK) developed such a system by significantly modifying and augmenting a 3″ Knelson Concentrator that accomplishes nearly complete recovery of moderately heavy minerals (>0.25 mm) from till samples.Diamondiferous kimberlites occur in the eastern Finland around the Kaavi–Kuopio and Kuhmo areas and much of the rest of the Karelian craton remains prospective based on the empirical evidence necessary for diamond preservation: thick (>200 km) lithospheric mantle, low heat flow and Archaean age rocks. A target area in Lapland, 20×50 km in size, was selected for a pilot study to test extraction of chromite for the (1) discrimination of regionally and locally derived populations, and (2) recognition of possible kimberlitic/lamproitic chromites. Area selection was based on the regional occurrence of a variety of mantle-derived rocks, the recovery of a chromian pyrope grain from till in 1996 and most importantly, the well-established Quaternary stratigraphy in the region. The sample material consisted of sixty-two 80-kg excavator and 40-kg shovel samples. Approximately 1000 chromite grains, almost exclusively 0.25–0.5 mm in diameter, were recovered and analysed by electron microprobe.Tills in the sampling area proved to contain at least two compositional populations of chromite. The first is present in almost every sample and is apparently derived from layered mafic intrusions distal to and up-ice from the study area. The second population consists of chromites with low Ti, high Cr and Mg similar to inclusions in diamond. It is present in approximately one third of the samples, concentrated in a couple of clusters within the target area and is therefore considered to be of more local derivation. Since no high-Ti, high-Cr chromites diagnostic for kimberlites and lamproites were present in the samples, the source for the low-Ti, high-Cr, high-Mg chromite grains remains uncertain, but is probably not kimberlitic. Although this apparently is a negative outcome for diamond exploration in the target area, the main goal of the study was realised by showing the applicability of the system to heavy mineral separation from Quaternary glacial deposits.     

The Fazenda Largo off-craton kimberlites of Piauí State, Brazil

In the late 1990s, the Fazenda Largo kimberlite cluster was discovered in the Piauí State of Brazil. As with earlier known kimberlites in this area – Redondão, Santa Filomena-Bom Jesus (Gilbues) and Picos – this cluster is located within the Palaeozoic Parnaiba Sedimentary Basin that separates the São Francisco and the Amazonian Precambrian cratons. Locations of kimberlites are controlled by the ‘Transbrasiliano Lineament’. The Fazenda Largo kimberlites are intensely weathered, almost completely altered rocks with a fine-grained clastic structure, and contain variable amounts of terrigene admixture (quartz sand). These rocks represent near-surface volcano-sedimentary deposits of the crater parts of kimberlite pipes. By petrographic, mineralogical and chemical features, the Fazenda Largo kimberlites are similar to average kimberlite. The composition of the deep-seated material in the Fazenda Largo kimberlites is quite diverse: among mantle microxenoliths are amphibolitised pyrope peridotites, garnetised spinel peridotites, ilmenite peridotites, chromian spinel + chromian diopside + pyrope intergrowths, and large xenoliths of pyrope dunite. High-pressure minerals are predominantly of the ultramafic suite, Cr-association minerals (purplish-red and violet pyrope, chromian spinel, chromian diopside, Cr-pargasite and orthopyroxene). The Ti-association minerals of the ultramafic suite (picroilmenite and orange pyrope), as well as rare grains of orange pyrope-almandine of the eclogite association, are subordinate. Kimberlites from all four pipes contain rare grains of G10 pyrope of the diamond association, but chromian spinel of the diamond association was not encountered. By their tectonic position, by geochemical characteristics, and by the composition of kimberlite indicator minerals, the Fazenda Largo kimberlites, like the others of such type, are unlikely to be economic.     

Progresses and Perspectives of Research of the Evolution of Kimberlite and Evaluation for Diamond Potential

Kimberlite is an effective vector for researches and discussions on mantle dynamics process, lithosphere evolution and other major scientific problems, which plays an important role in revealing the forming environment, origin, source and prospecting of diamond. Currently, the developing research process of Kimberlite is still hampered by several key scientific problems, such as the evolution and the significance of the Kimberlite, evaluation for diamond potential and so on. Based on high-pressure melt simulation experiments, researches about matrix mineral, fine syngenetic inclusion (cognate xenolith?) and cryptocrystalline in the margin area of Kimberlite pipe, it seems that the initial composition features of Kimberlitic magma can be effectively analyzed. However, these experiments and researches are not only difficult to identify source characteristics of Kimberlitic magma efficiently, but also difficult to distinguish those effects on magma from which is assimilation/contamination, fluid fractionation or devitrification. Lacking of systematic research reports about recrystallization and (or) regrowth mineral on micro-composition and micro-structure, it is hard to efficiently and accurately analyze the changes and degassing effects in Kimberlitic magma, so far as to reveal the process of Kimberlitic magma evolution. Although Kimberlite diamond potential can be evaluated based on mineral assemblage, water content of olivine, there still exist some kinds of problems, like the index system being too simple, and the data accumulation being too little. Carrying out the fine micro-fabric studies between diamond-bearing Kimberlite and non diamond-bearing one can establish the scientific foundation for rebuilding the Kimberlitic magma evolution mechanism effectively and reveal the response to deep geological process. Meanwhile, on the basis of known diamond mines, a model for initial grade prediction of diamond and analysis of preservation potential can be set up to realize final purpose to evaluate the diamond potential in unknown Kimberlite areas in effect validity.     

我国海洋产业数字化水平测度与时空演化分析

文章在厘清海洋产业数字化相关概念的前提下,基于钻石模型构建了海洋产业数字化水平测度指标体系并采用投影寻踪模型测度2014—2020年我国沿海11个省(自治区、直辖市)的海洋产业数字化水平;在此基础上运用多种空间计量模型对我国海洋产业数字化水平的时空演化规律进行深入分析。研究发现：我国海洋产业数字化水平总体上呈现快速增长趋势,但不同区域沿海省(自治区、直辖市)之间存在一定差异;区域内差异是研究期内我国海洋产业数字化水平地区差异的主导因素,其中北部沿海地区内部差异最大,东部沿海地区内部差异最小,南部沿海地区内部差异居中;三大海洋经济圈内海洋产业数字化集聚形式各具特征：北部海洋经济圈内沿海省(自治区、直辖市)形成“高-低”集聚型,南部海洋经济圈内沿海省(自治区、直辖市)形成“低-高”集聚型,东部海洋经济圈内沿海省(自治区、直辖市)则形成“高-高”集聚型。