Rb–Sr,Sm–Nd,and Ar–Ar isotopic systematics of lherzolitic shergottite Yamato 000097

Isotopic analysis of the Martian lherzolitic shergottite Yamato 000097 yields a Rb–Sr age of 147 ± 28 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.710490 ± 0.000072, a Sm–Nd age of 152 ± 13 Ma with an initial ɛ¹⁴³Nd-value of +11.7 ± 0.2, and a ³⁹Ar–⁴⁰Ar age of ∼260 Ma. The near concordance of these ages, in combination with the Rb–Sr and Sm–Nd initial isotopic signatures, suggests that Yamato 000097 crystallized from low Rb/Sr, light rare earth element depleted source materials ∼150 Ma ago. Although the obtained ³⁹Ar–⁴⁰Ar age is significantly higher than the Rb–Sr and Sm–Nd ages, Yamato 000097 shows little or no evidence of trapped Martian atmospheric ⁴⁰Ar. The trapped ⁴⁰Ar concentration of Yamato 000097 is similar to that of Zagami, suggesting that both basaltic and lherzolitic shergottites may have similarly inherited excess ⁴⁰Ar from their magmas.The Rb–Sr and Sm–Nd ages, and initial ⁸⁷Sr/⁸⁶Sr and ɛ¹⁴³Nd-values of Yamato 000097 and Yamato 793605 lie on the same isotopic ingrowth curves, suggesting that they came from very similar mantle sources. Allan Hills 77005 was also probably derived from the same source, but Lewis Cliff 88516 appears to be from a distinct but similar source. Yamato 000097 represents the most recent known magmatism from its source, and is the youngest Martian meteorite for which concordant Rb–Sr and Sm–Nd ages have been determined.     

Mineralogy and petrology of paired lherzolitic shergottites Yamato 000027, Yamato 000047, and Yamato 000097: Another fragment from a Martian “lherzolite” block

Y000027, Y000047, and Y000097 are new lherzolitic shergottites that show a poikilitic texture with interstitial non-poikilitic basaltic areas. They have identical mineral compositions and petrography, confirming their pairing. The Y00 shergottites first crystallized olivine and chromite, which were then partially enclosed by low-Ca pyroxenes. Interstitial areas of melt then formed as a result of oikocryst accumulation. Plagioclase and Fe-rich pyroxene crystallized from the interstitial melt, forming the non-poikilitic basaltic areas. The cooling rate during crystallization of the basaltic area was fast enough to preserve chemical zoning within olivine and pyroxene in poikilitic areas. The Y00s have similar petrology and mineralogy to other lherzolitic shergottites: all are likely to have originated from the same igneous block on Mars. The subtle mineralogical differences that exist are probably due to spatially variable cooling rates during crystallization of the basaltic area. In terms of mineral composition, the Y00s are most similar to (although distinct from) LEW88516, Y-793605, and NWA1950. Olivine and pyroxene compositions within interstitial areas may be related to the abundance of intercumulus melt, which, as with the nakhlite case, varied spatially in the igneous block. Although the Y00s and other lherzolitic shergottites (ALH77005, LEW88516, Y-793605, GRV99027, GRV020900, and NWA1950) were located within deeper levels of the block, RBT04262, a new shergottite similar in petrology and mineralogy to lherzolitic shergottites, may have been located at a slightly shallower level characterized by abundant, evolved interstitial melts.     

同位素地质年代测定原理——以Rb—Sr法为例

本文阐述了同位素测年的原理、前提、方法,重点介绍了Rb—Sr法的原理、使用要求、适用范围、原理、结果解释及优缺点。     

A Sm－Nd mineral isochron of mafic granulite from the Sφstrene Island， East Antarctica

任留东，刘小汉ＡＳｍ－ＮｄｍｉｎｅｒａｌｉｓｏｃｈｒｏｎｏｆｍａｆｉｃｇｒａｎｕｌｉｔｅｆｒｏｍｔｈｅＳφｓｔｒｅｎｅＩｓｌａｎｄ，ＥａｓｔＡｎｔａｒｃｔｉｃａ￥ＲｅｎＬｉｕｄｏｎｇ（ＩｎｓｔｄｕｔｅｏｆＧｅｏｌｏｇｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏ...     

内蒙古黄旗海不同粒级湖泊沉积物Rb、Sr组成与环境变化

内蒙古黄旗海湖泊沉积物剖面层次结构清晰完整,通过对该剖面全样、77 μm~20 μm和小于20 μm三个不同粒级Rb、Sr含量和磁化率的系统测定,结果表明,湖泊沉积物中小于20 μm粒级成分的Rb、Sr含量和Rb/Sr值变化阶段明显,Rb/Sr值与磁化率分布曲线十分吻合,因此,小于20 μm粒级成分的Rb/Sr值与磁化率包含更加真实的古气候环境信息。Rb/Sr值反映了风化的强度,因而可以作为指示夏季风环流强度的代用指标。黄旗海湖泊沉积物的地球化学Rb、Sr元素含量和Rb/Sr值以及磁化率值波动特征具有深刻的环境演变背景,由此揭示的环境特征在一定程度上反映了全新世气候千百年尺度的波动变化,与全球气候波动有关。     

内蒙古黄旗海不同粒级湖泊沉积物Rb、Sr组成与环境变化

Based on the geochemical elements Rb and Sr in sediments with three different grain size fractions from profile H3 on the northern lacustrine bottomland 13 m above the Huangqihai Lake surface in 1986,the paper investigates the record of palaeolake stand state, sedimentary environmental evolution,and winter monsoon change.First,these samples are separated into three different grain size fractions,i.e.,total sediments,77-20μm and〈20μm. Second,the chemical elements-Rb and Sr-of the grain size separation were tested and analyzed systematically in this paper.Then the elements compositions of these samples are measured using VP-320 mode fluorescence spectrum instrument,respectively.The magnetic susceptibility of these samples is measured using Kappabridge KLY-3 mode instrument made in Czech AGICO Company.The results showed the elements and the ratios varied regularly with the grain size.But the ratio of Rb/Sr in the sediments〈20μm correlates positively with the magnetic susceptibility of these samples.Therefore,the ratio of Rb/Sr in the fraction〈20 μm from the lake sediments reflected the strengthening of the weathering in the deposition sites.It is a good indicator of the summer monsoon-induced weathering and pedogenesis fluctuations and can be used to reconstruct the conditions of the paleoclimate and paleoenvironment.     

Fourier transform–infrared studies on the effects of salt and drought stress on the chemical composition and protein conformation changes in Arabidopsis leaves

We examined the changes of chemical composition and protein conformation in Arabidopsis leaves by Fourier transform–infrared (FT-IR) spectrometry Arabidopsis under 50 mmol/L NaCl salt and ?0.5 mPa polyethylene glycols 8000 (PEG 8000) drought stress during the early stages of growth. We primarily analyzed the absorption band areas in the 1,745 cm^-1 (ester), 1,600–1,700 cm^-1 (amide I), and 1,100 cm^-1 (carbohydrate) changes under salt stress and drought stress within 24 hours. The results showed that ester content declined at the beginning and then increased steadily during 24 hours of drought stress. But under salt stress, it declined steadily, and it was about 40 percent of the control after 24 hours. The protein synthesis increased by 25 percent after one hour of salt stress and then reached about 85 percent of the control after 24 hours. Under drought stress, the protein synthesis decreased and reached a minimal level at the 4-hr time point; it then recovered to the control level at the 24-hr point. The patterns of the accumulation of carbohydrates in the 1,100 cm^-1 band areas resembled that of amide I band changes under drought stress and salt stress. Analyzing the ratio A_1,627cm-1/A_1,658cm-1 under drought stress revealed that the leaves’ entire protein structure maintained a higher-level ordered form than did those under salt stress. Thus our results indicate the existence of different strategies of the Arabidopsis adaptation to salt stress and drought stress.     

Recent progress of glaciological studies in China

1IntroductionIn the early 1960s, glaciers in western China were classified into maritime- and continental-types by different glacial environment and physical characteristics (Shi and Xie, 1964). With extensive glaciological investigations in the western regions (Lanzhou Institute of Glaciology and Geocryology of CAS, 1988), Lai and Huang (1990) suggested a new classification of temperate, subpolar and quasipolar glaciers, corresponding to the maritime-, subcontinental- and extremely contin…     

南极乔治王岛晚白垩世地幔源火山岩Nd、Sr同位素和微量元素证据

对乔治王岛上白垩统半三角组火山岩样品进行了 Rb- Sr同位素等时线年龄测定 ,所获结果为 71 .3 3± 0 .3 Ma。通过 εND(T) - 14 7Sm/14 4Nd,14 3 Nd/14 4Nd- 87Sr/86 Sr,87Sr/86 Sr- Sr和 87Sr/86 Sr- K2 O/(K2 O+Na2 O)的相关性研究表明 ,该火山岩物质主要来自亏损地幔 (DMM)源区 ,基本上未受到地壳物质混染。其中 6个样品的平均 Sm- Nd模式年龄 (TNd DM)为 443 .3± 2 0 .6 Ma,可能反映了在研究地区的岩浆源区化学分异事件的时代。微量元素的特点表明 ,半三角组样品属典型的钙碱性火山岩系列 ,与长城站地区第三系火山岩相类似 ,同属于岛弧火山活动的产物。     

Relationships between variations of the land–ocean–atmosphere system of northeastern Asia and northwestern North America

This study is a broad-scale synthesis of information on climate changes in two Arctic terrestrial regions, eastern Siberia and the Alaska–Yukon area of North America. Over the past 60 years (1951–2010), the trends of temperature and precipitation in the two regions are broadly similar in their seasonality. However, atmospheric advection influences the two regions differently during winter. The differential advective effects are much weaker in the other seasons. The Pacific Decadal Oscillation is the strongest correlator with interannual variability in the two regions, followed by the Arctic Oscillation and the El Niño/Southern Oscillation.Projected changes by the late 21st Century are qualitatively similar to the changes that have been ongoing over the past 60 years, although the rate of change increases modestly under mid-range forcing scenarios (e.g., the A1B scenario). The greatest warming is projected to occur farther north over the Arctic Ocean in response to sea ice loss. Precipitation is projected to increase by all models, although increases in evapotranspiration preclude conclusions about trends toward wetter or drier land surface conditions. A notable feature of the future climate simulations is a strong maximum of pressure decreases in the Bering Sea region, implying further advective changes.     

Pareto–Lognormal Modeling of Known and Unknown Metal Resources

Recently, large worldwide databases with statistics on amounts of metal in mineral deposits have become available. Frequently, most metal is contained in the largest deposits for a metal. A major problem in meaningful modeling of the size–frequency distributions of the largest deposits is that they are very rare. Until now it was rather difficult to establish the exact form of their size–frequency distribution. However, because of the new very large databases it can now be concluded that two commonly used approaches (lognormal and Pareto) thought to be mutually incompatible in the past, are both correct with a high probability. One approach does not necessarily exclude validity of the other. Patiño-Douce (Nat Resour Res 25(1):97–124, 2016b) has shown that metal tonnage frequency distributions for worldwide metal deposits are approximately lognormal with similar standard deviations (σ) of log-transformed data. In this paper, it is assumed that worldwide metals satisfy both lognormal and Pareto models simultaneously. Copper and Au are taken for example for comparison with results previously obtained for these two metals in the Abitibi area of the Canadian Shield. Worldwide there are 2541 Cu deposits approximately satisfying a lognormal distribution. Total amount of Cu in these deposits is 2.319 × 10⁹ tons of Cu. However, the 45 largest deposits, which together contain 1.281 × 10⁹ tons of Cu, satisfy a Pareto distribution. If their lognormal model would apply in the upper tail as well, these 45 largest deposits should have contained only about 0.076 × 10⁹ tons of Cu. It is shown in detail for Cu that the best statistical model for Cu deposits is a worldwide Pareto–lognormal model in which the basic lognormal size–frequency distribution is flanked by two juxtaposed Pareto distributions for the largest and smallest Cu deposits, respectively. Both Pareto distributions smoothly change into the central lognormal by means of bridge functions that can be determined separately. The worldwide Pareto–lognormal model also was found to be applicable to several other metals, especially Ag, Ni, Pb, and U. For Au, the model does not work as well for the upper tail Pareto distribution as it does for the other metals taken for example.     

An Analysis of the Commuting and Jobs–Housing Patterns of Older Adult Workers

Many researchers have explored the relationships between land use and transportation via the jobs–housing balance concept. This type of research involves the disaggregation of commuter groups to understand variances in the relationship between land use and transportation outcomes. Disaggregation by commuter age has not been considered, however. To address this gap, we analyze spatially and temporally disaggregate census data for five areas in Florida. Using several jobs–housing balance metrics we compare and contrast the outcomes of different commuter age groups, across different geographies, and over time (2002–2011). Generally, commutes vary more by region than they do by any age category of commuter. Most of the differences in the commute metrics among the older age group tend to depend on where those commuters live. The results also suggest that there are more efficient and less sprawling commuting landscapes for older workers located near other older workers.     

Temporal and spatial changes of temperature and precipitation in Hexi Corridor during 1955–2011

This study is focused on the northwestern part of Gansu Province, namely the Hexi Corridor. The aim is to address the question of whether any trend in the annual and monthly series of temperature and precipitation during the period 1955-2011 appears at the scale of this region. The temperature and precipitation variation and abrupt change were examined by means of linear regression, five-year moving average, non-parameter Mann-Kendall test, accumulated variance analysis and Pettitt test method. Conclusions provide evidence of warming and wetting across the Hexi Corridor. The mean annual temperature in Hexi Corridor increased significantly in recent 57 years, and the increasing rate was 0.27℃/10a. The abrupt change phenomenon of the annual temperature was detected mainly in 1986. The seasonal average temperature in this region exhibited an evident upward trend and the uptrend rate for the standard value of winter temperature indicated the largerst of four seasons. The annual precipitation in the Hexi Corridor area displayed an obviously increasing trend and the uptrend rate was 3.95 mm/10a. However, the annual precipitation in each basin of the Hexi Corridor area did not passed the significance test. The rainy season precipitation fluctuating as same as the annual one presented insignificant uptrend. No consistent abrupt change was detected in precipitation in this study area, but the rainy season precipitation abrupt change was mainly observed in 1968.     

Experimental Analysis of the Dynamic Effects of Coal–Gas Outburst and a Protean Contraction and Expansion Flow Model

Natural Resources Research - As one of the most serious dynamic disasters in underground coal mining, coal–gas outburst (CGO) leads to very high casualties and economic losses. To research...     

Spatial Patterns of Larceny and Aggravated Assault in Miami–Dade County, 2007–2015

The combination of crime mapping and geospatial analysis methods has enabled law enforcement agencies to develop more proactive methods of targeting crime-prone neighborhoods based on spatial patterns, such as hot spots and spatial proximity to specific points of interest. In this article, we investigate the spatial and temporal patterns of the neighborhood crimes of aggravated assault and larceny in 297 census tracts in Miami–Dade County from 2007 to 2015. We use emerging hot spot analysis (EHSA) to identify the spatial patterns of emerging, persistent, continuous, and sporadic hot spots. In addition, we use geographically weighted regression to analyze the spatial clustering effects of sociodemographic variables, poverty rate, median age, and ethnic diversity. The hot spots for larceny are much more diffused than those for aggravated assaults, which exhibit clustering in the north over Liberty City and Miami Gardens and in the south near Homestead, and the ethnic heterogeneity index has a moderate and positive effect on the incidence of both larceny and aggravated assaults. The findings suggest that law enforcement can better target prevention programs for violent versus property crime using geospatial analyses. Additionally, the ethnic concentration of neighborhoods influences crime differently in neighborhoods of different socioeconomic status, and future studies should account for spatial patterns when estimating conventional regression models.     

Spatio-temporal distribution and transformation of cropland in geomorphologic regions of China during 1990–2015

Journal of Geographical Sciences - Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance...     

Experimental Investigation of Rheological Behavior and Wax Deposition of Waxy Oil–Disulfide Oil Systems

Natural Resources Research - In this work, we studied the feasibility of using disulfide oil (DSO) as a solvent for wax prevention in pipelines. Several tests were carried out to determine the...     

Change of parameters of BCC/RCG-WG for daily non-precipitation variables in China: 1951–1978 and 1979–2007

Parameters of weather generator BCC/RCG-WG for daily non-precipitation variables including maximum temperature, minimum temperature and sunshine hours at 669 stations in China are estimated using history daily records from 1951 to 1978 and from 1979 to 2007 respectively. The changes in the parameters for the two periods are revealed to explore the impact of climate change on these parameters. The results show that the parameters of the non-precipitation variables have experienced different changes. While the annual means and the amplitudes of the seasonal cycle show a clear change, the interannual variability, the timings of the seasonal cycles, and the temporal correlations for each variable remain practically unchanged. This indicates that climate changes in China over the last 57 years are mainly reflected in variations in the means and in the strength of the seasonal cycles. The changed parameters have implications for the stationary assumption implied in the parameter estimation and use of the weather generator for climate change studies.     

How many is enough? Determining optimal count totals for ecological and palaeoecological studies of testate amoebae

Testate amoebae are increasingly used in ecological and palaeoecological studies of wetlands. To characterise the amoeba community a certain number of individuals need to be counted under the microscope. To date, most studies have aimed for 150 individuals, but that sample size is not based on adequate evidence. When testate amoeba concentrations are low, it can be difficult or impossible to reach this total. The impacts of lower count totals have never been seriously scrutinised. We investigated the impact of count size on number of taxa identified, quantitative inferences of environmental variables and the strength of the links between amoebae and environmental data in the context of predicting depth to water table. Low counts were simulated by random selection of individuals from four existing datasets. Results show progressively diminishing returns by all criteria as count size increases from low numbers to counts of 150. A higher count is required to identify all taxa than to adequately characterise the community for transfer function inference. We suggest that in most cases, it will be a more efficient use of time to count a greater number of samples to a lower count. While a count of 50 individuals may be sufficient for some samples from some sites we recommend that counts of 100 individuals should be sufficient for most samples. Counts need only be increased to 150 or more where the aim is to identify relatively minor, but still potentially ecologically relevant community changes. This approach will help reduce lack of replication and low resolution, which are common limitations in testate amoeba-based palaeoecological and ecological studies.