Iolite软件处理LA-ICP-MS线扫描数据适用性研究

LA-ICP-MS分析技术是获取矿物/岩石内部的元素和同位素成分变化的重要手段。在利用该技术对地质样品进行线/面扫描时,仪器输出的初始数据量远远大于点分析,数据的处理和计算是一个关键问题。本文以磷质结核样品为例,阐述了利用Iolite软件进行元素线扫描数据计算的主要过程,包括背景信号的扣除、标准物质信号的拟合、线分析数据的导出等。借助软件自带的分段导出功能,对不同时间和空间分辨率下采集数据得到的结果进行了比较。研究表明Iolite能有效处理线分析数据,分析结果与前人用传统化学全岩法测定得到的元素含量范围相当。对比不同空间分辨率下(10μm、50μm、100μm)获取的数据发现:相对于选用的束斑直径(40μm),在分辨率过小(10μm)或过大(100μm)的条件下获得的数据存在数据波动大以及细节不足等缺陷;而当分辨率(50μm)与选用的束斑直径接近时,数据质量得到最大优化。本研究展示了Iolite软件在处理线扫描数据方面具有很好的应用前景,通过分辨率的选取可实现数据的优化。     

吉林省南部太古宙花岗质岩石及其成因探讨

吉林省南部早太古宙高级区和晚太古宙花岗岩—绿岩带中的英云闪长岩、奥长花岗岩、花岗闪长岩等广泛发育,各岩体分布明显受太古宙边缘穹隆及中央卵形隆起控制。在岩石化学特征上明显反映出英云闪长岩—奥长花岗岩和钙碱性两个演化趋势。经稀土模拟计算,英云闪长岩和奥长花岗岩可能由石英榴辉岩经10—40部分熔融形成。     

秘鲁Ucayali盆地石油地质特征与油气成藏

基于对Ucayali盆地油气成藏要素的系统解剖,预测盆地内除已发现的逆冲背斜/断背斜外,还可能发育伸展断块、潜山、生物礁、地层尖灭、河道砂及逆冲断层下盘构造等多种圈闭类型,自西向东前展式推覆的逆冲背斜/断背斜为最主要的圈闭类型。前陆运动前盆地构造圈闭发育程度低,现今原油聚集多属前陆运动后二次调整成藏,淡水侵入使浅部油藏普遍遭受轻度降解。由于Shira隆起的分隔作用,西部次盆现今生成的烃类很难运移至东部圈闭中。而东部次盆烃源岩埋深小,Ene组展布面积有限,Ambo群趋于生气,在生油窗内生成的液态烃类相对有限,加之圈闭不断生长,圈闭充满度较低。同时,活动性断层对烃类侧向运移不利,其东侧的背斜圈闭往往无法得到有效充注,形成大规模原油聚集的潜力较小。南部和西部次盆成藏条件配置好,逆冲褶皱发育,圈闭可得到烃类持续充注,主要以天然气为主;南部次盆逆冲断层下盘构造圈闭为重要潜在勘探目标;Ene次盆勘探程度低,烃源岩品质好,仍有发现大型构造圈闭的潜力。     

Metallogeny and environmental impact of Hg in Zn deposits in China

Zinc smelting is currently regarded as one of the most important atmospheric Hg emission sources in the world. In order to assess the potential environmental impacts of Hg from Zn smelting in China, the distribution of total Hg concentration (HgT) in Zn concentrates (ZCs) from 100 Zn deposits in China was investigated. It was found that HgT varies depending on the ore types and their geneses. Zinc concentrates from sedimentary-exhalative deposits (SEDEX, geometric mean = 48.2 μg/g) have the highest HgT. The possible explanation is that the sources of mineralizing solutions for SEDEX deposits are deep formational brines in contact with sedimentary rocks, and there are much higher background Hg contents in sedimentary rocks. Zinc concentrates from volcanic hosted massive sulfide deposits (VMS, geometric mean = 11.5 μg/g) and Mississippi Valley-Type (MVT, geometric mean = 10.1 μg/g) deposits have intermediate HgT. VMS may receive most of their Hg from fluid–rock interaction and/or by direct input of gaseous Hg from a mantle source. However, the source of metals within MVTs may be the low-temperature hydrothermal solution formed by diagenetic recrystallization of the carbonates. Intrusion related deposits (IRs) have the lowest HgT (Geomean = 2.4 μg/g), and the dispersion of Hg in the IRs seems to be influenced by the temperature of ore formation and/or the nature of wall–rock alteration. Finally, it was estimated that the annual Hg emission to the atmosphere from Zn smelting in China was about 107.7 tons in 2006.     

Sorption characteristics of ethyl <Emphasis Type="Italic">tert</Emphasis>-butyl ether to Chinese reference soils

As a gasoline additive, ethyl tert-butyl ether (ETBE) has great market potential and its utilization might cause groundwater contamination problem. However, little research has been done on its sorption in soil. In this study, the sorption characteristics of ETBE to Chinese reference soils were studied in batch experiments. The results showed that the ETBE sorption to six soils can be described by linear sorption isotherm. The temperature influences the sorption process of ETBE to soils. The negative sorption enthalpy (ΔH < 0) indicated that the sorption process was exothermic. Furthermore, ΔH is in a range from −8 to −32 kJ/mol. This showed that van der Waals forces and other specific interactions happened simultaneously in the sorption process. With the increasing ionic strength, content of ETBE sorption to all soils decreased, which is probably also an indication of other sorption mechanisms besides ETBE partitioning into soil organic carbon.     

贵州省黔西县大寨地区中三叠统关岭组绿豆岩锆石U-Pb年代学、地球化学特征及地质意义

针对贵州省黔西县大寨地区中三叠统关岭组底部绿豆岩,利用LA-ICPMS锆石U-Pb测年手段,明确贵州黔西县大寨地区早—中三叠世界线年龄。对贵州省黔西县大寨地区中三叠统关岭组底部绿豆岩1件U-Pb年龄样品、 8件地球化学样品的测试分析,结果表明,锆石U-Pb加权年龄为248.6 Ma±2.7 Ma,谐和年龄为248.7 Ma±1.1 Ma;绿豆岩属于高硅(w_SiO2均值为62.40%)、铝(w_Al2O_3均值为14.61%)、钾(w_K2O均值为7.22%),低铁(w_Fe2O_3均值为0.94%,w_FeO均值为0.51%)、钛(w_TiO2均值为0.24%)的中酸性火山物质,具有稀土元素总量相对较低、相对富集轻稀土元素和轻重稀土元素分馏程度低的特征,负Eu异常显著,δEu=0.17～0.22。综合分析,该绿豆岩是由火山活动喷发的火山灰经风化、搬运、沉积改造而形成,为下三叠统嘉陵江组与中三叠统关岭组松子坎段界线岩性标志,同时为测区早—中三叠世界线年龄提供了准确的年代学证据。     

Three Alkali—Rich Intrusive Rock Belts Bewly Discovered in the Mt.Kunlkun—Mt.Altun Region,Xinjiang,China

The newly discovered three alkali-rich intrusive rock belts in the Mt.Kunlun Mt.Altun region of southern Xinjiang are the Lapeiquan-Yitunbulak alkali-rich intrusive fock belt, the Gez-Taxkorgan alkali-rich intrusive rock belt and the Beeilisai-Abulash alkali-rich intrusive rock belt.The former two belts were formed during the Yanshanian period,and the third one was formed during the Himalayan period,which is the youngest alkali-rich intrusive rock belt in China.The discovery of the alkali-rich intrusive rock belts is of great significance in shedding light on the history of tectono-magmatic activities in this region.     

极端干旱区黄土土壤容重的测量及其古气候意义

黄土和古土壤的容重,不仅可以反映东亚冬、夏季风强度的变化,而且还是计算粉尘沉积通量的基础,因此,在古气候研究以及亚洲内陆干旱化重建过程中具有重要的意义。目前,黄土土壤容重的研究大都集中在黄土高原地区,而作为黄土高原主要源区的中国西北内陆极端干旱区,关于土壤容重的测量方法以及古气候意义涉及的较少。在前人研究的基础上,提出了适合亚洲内陆极端干旱区黄土容重测量的理想方法,并发现该区的黄土容重值同粒度以及磁化率的变化均呈明显的负相关关系,这与黄土高原有很大的不同。进一步的分析表明,在极端干旱区,黄土容重的变化主要反映了源区干旱程度的变化,季风强度对容重的影响微弱。     

Wavelength dependence four-wave mixing spectroscopy in a micrometric atomic vapour

This paper presents a theoretical study of wavelength dependence four-wave-mixing (FWM) spectroscopy in a micrometric thin atomic vapour. It compares three cases termed as mismatched case I, matched case and mismatched case II for the probe wavelength less, equal and greater than the pump wavelength respectively. It finds that Dicke-narrowing can overcome width broadening induced by Doppler effects and polarisation interference of thermal atoms, and high resolution FWM spectra can be achieved both in matched and mismatched wavelength for many cases. It also finds that the magnitude of the FWM signal can be dramatically modified to be suppressed or to be enhanced in comparison with that of matched wavelength in mismatched case I or II. The width narrowing and the magnitude suppression or enhancement can be demonstrated by considering enhanced contribution of slow atoms induced by atom-wall collision and transient effect of atom-light interaction in a micrometric thin vapour.