高温高压下部分熔融岩石和岩石玻璃弹性波速研究

人类对地球深部结构的认识主要依赖于天然地震的观测资料，高温高压下矿物、岩石和岩浆玻璃的弹性波速测量，是对野外地震波探测资料进行物质反演的重要依据，也为建立地球内部结构模型和地球动力学研究提供重要的实验数据。大量研究证实，高温高压下岩石的部分熔融将形成地震波低速层。然而，前人的研究中，多以岩石的纵波波速（Vp）测量结果来讨论区域地壳结构和低速层的成因，而且很少对实验过程中的中间产物进行观察分析。另一方面，由于玻璃在高温高压下具有特殊的弹性性质，一些科学家推测地球内部岩石的非晶质化也将导致地震波低速层形成。但目前这一推测尚缺乏充分的实验数据支持。为此，作者依托YJ-3000吨大腔体高压实验技术平台，利用脉冲反射法和透射－反射法，完成了： （Ⅰ）三江地区花岗岩和角闪斜长片麻岩在最高压力2.0GPa、最高温度1200℃下的纵波波速（Vp）和最高温度600℃下的横波波速（Vs）研究，并通过岩石物态变化过程中的取样实验，综合探讨岩石中矿物脱水、固－固相变、部分熔融对其弹性波速的影响。获得以下主要结论： ① 花岗岩和角闪斜长片麻岩的Vp和Vs随压力及温度的变化趋势基本一致。室温下岩石的Vp和Vs随压力升高而升高，岩石波速具明显的各向异性，而且其各向异性随压力增大到约0.5GPa后逐渐趋于一恒定值； ② 恒定压力下，岩石的Vp和Vs首先随温度升高近线性缓慢降低，当750℃ 950℃后，石英相变完成，岩石的波速由于熔体含量增加又快速降低； ③ 高温高压下岩石的Vp和Vs研究显示了对三江地区地壳结构一致的约束结果，即该区花岗岩主要分布在上地壳，而角闪斜长片麻岩从上地壳底部到中地壳底部均有分布，这一结果与前人利用Vp研究建立的该区地壳模型基本一致； ④ 在三江地区中上地壳高石英含量的岩石中，石英的α－β相变是地壳地震波低速层形成的主要因素，而随岩石中石英含量的变化，高温高压下岩石的部分熔融及岩石的波速各向异性也可能形成低速层。 （Ⅱ）化学成分从基性到酸性的7种岩石的熔体玻璃在1.0GPa和2.0GPa，最高温度1000℃下的Vp研究和最高温度730℃下的Vs研究。获得以下主要结论： ① 与岩石波速随压力增大而增大不同，室温、0.4－2.0GPa压力下，除两种基性岩石（正长辉石岩和粗面玄武岩）的熔体玻璃外，其它5种中酸性岩石的熔体玻璃的Vp均随压力增大而减小，而这7种玻璃的Vs全部随压力增大而减小。而且，玻璃波速随压力增加而异常降低的幅度随样品中SiO2含量的增高逐渐增大； ② 恒定压力下，随实验温度升高，各种玻璃的弹性波速缓慢降低。当温度高于玻璃转变温度Tg后，玻璃弹性波速的温度系数（∂V/∂T）增大约3倍以上； ③ 研究证实了一种新的地震波低速层成因模式，即上地幔岩石中如果含有超过10vol％的玄武岩玻璃，将会形成地震波低速层；假如下地壳基性岩石中中酸性非晶质体含量超过20vol％，也可能导致地壳低速层的形成。

华北北缘斜长角闪岩的部分熔融实验及其地质意义

基性岩类的（脱水）部分熔融实验是研究地球内部中酸性岩浆（熔体）形成的重要实验方法，自二十世纪70年代以来越来越受到地质学家的高度重视。华北北缘广泛分布的中生代埃达克质岩石的成因，十几年来引起国内外学者的激烈争论，至今仍没有定论。近年来的研究表明张家口地区同时出露的古老太古宙中基性下地壳岩石、中生代中酸性埃达克质岩浆岩以及汉诺坝基性麻粒岩包体等可能反映了源岩和熔融产物的综合信息，这为我们运用实验岩石学手段研究华北北缘埃达克质岩石成因提供了非常理想的条件。 本文在1.5-2.0GPa，800-1000℃条件下，对采自华北北缘的斜长角闪岩同时进行了块状与粉末状两种样品的部分熔融实验研究，利用电子探针对各实验产物进行了主量元素分析以及利用LA-ICP-MS对部分熔体进行了微量元素测试，进而比较了相同条件下块状和粉末状样品的熔融特征，并对比了实验获得的熔体与华北北缘中生代埃达克质岩石的地球化学特征，同时也将实验获得的残留体与汉诺坝基性麻粒岩包体进行了比较。获得以下主要认识： （1）相同的温度、压力和恒温时间条件下块状样品的熔融温度比粉末样品的更低。在1.5-2.0GPa，800℃时块状斜长角闪岩样品已经发生部分融融，而相同条件下粉末样品中没有观察到熔体，粉末样品的部分熔融发生在850℃左右。在850-1000℃温度范围内，相同条件下块状样品的熔体含量比粉末样品的熔体含量高出5-17vol.％，即相同条件下块状样品比粉末样品的熔融程度更高，说明块状样品更容易达到可以分凝形成岩浆的临界熔体分数（CMF），这可能暗示着自然界中的岩浆形成可能比以往通过粉末实验结果推测的更容易发生。此外，在较高的温度条件下（950-1000℃），块状样品与粉末样品的熔体在主量和微量元素上都具有大致相同的地球化学特征，可以认为二者在在岩石学应用上是等效的。 （2）1.5GPa下实验获得的熔体为花岗质－花岗闪长质熔体，850-1000℃熔体的主-微量元素的地球化学特征与华北北缘中生代埃达克质岩石的整体特征具有很好的相似性，并与实验原岩产地张家口地区的三个典型中酸性埃达克质岩体的地球化学特征类似。可以认为实验的斜长角闪岩在1.5GPa下部分熔融能够形成华北北缘中生代埃达克质岩石。2.0GPa下的实验熔体为花岗质－奥长花岗质成分，其主量和微量元素特征均与华北北缘埃达克质岩石存在较大的差别，说明该压力下不能够形成华北北缘埃达克质岩石。 （3）实验残留相主要组成为Hb+Cpx+Gt±Pl，相当于麻粒岩相或榴辉岩相的矿物组合。与汉诺坝基性麻粒岩包体的典型矿物组合Cpx+Opx+Pl存在较大差别，在化学成分上，残留相比麻粒岩包体也整体上富Fe、Al，而贫Mg、Ca。综合来看汉诺坝基性麻粒岩包体可能是多种源岩在相对低压的条件下经过多期部分熔融综合作用的结果，本次实验的原岩及条件难以完全解释其复杂的成因。 另外，针对实验熔体和华北北缘埃达克质岩石之间的一些差异，不排除可能同时存在其他与之类似的源岩，成分上具有相对富Mg、Ca而贫Fe、Al，以及不同程度的Th、U、Zr、Hf富集等特征，与斜长角闪岩一起部分熔融，共同形成中生代华北北缘的中酸性埃达克质岩石。

Low temperature specific heat and thermal stability of Fe-B ultrafine amorphous alloy particles

Fe-B ultrafine amorphous alloy particles (UFAAP) were prepared by chemical reduction of Fe3+ with NaBHO4 and confirmed to be ultrafine amorphous particles by transmission electron microscopy and X-ray diffraction. The specific heat of the sample was measured by a high precision adiabatic calorimeter, and a differential scanning calorimeter was used for thermal stability analysis. A topological structure of Fe-B atoms is proposed to explain two crystallization peaks and a melting peak observed at T=600, 868 and 1645 K, respectively.

Calorimetric study of Wood alloy

The heat capacities of Wood alloy have been measured with an automatic adiabatic calorimeter over the temperature range of 80 similar to 360 K. The thermodynamic data of solid-liquid phase transition have been obtained from the heat capacity measurements. The melting temperature, enthalpy and entropy of fusion of the substance are 345.662 K, 18.47 J.g(-1) and 0.05343 J.g(-1).K-1, respectively. The necessary thermal data are provided for the low temperature thermodynamic study of the alloy.

Spatial temperature gradient capillary electrophoresis for DNA mutation detection

A continuous spatial temperature gradient was established in capillary electrophoresis by using a simple temperature control device. The temperature profile along the capillary was predicted by theoretical calculations. A nearly linear spatial temperature gradient was established and applied to DNA mutation detection. By spanning a wide temperature range, it was possible to perform simultaneous heteroduplex analysis for various mutation types that have different melting temperatures.

Heat capacity and thermodynamic properties of N-(2-cyanoethyl) aniline (C9H10N2)

The low temperature heat capacities of N-(2-cyanoethyl)aniline were measured with an automated adiabatic calorimeter over the temperature range from 83 to 353 K. The temperature corresponding to the maximum value of the apparent heat capacity in the fusion interval, molar enthalpy and entropy of fusion of this compound were determined to be 323.33 +/- 0.13 K, 19.4 +/- 0.1 kJ mol(-1) and 60.1 +/- 0.1 J K-1 mol(-1), respectively. Using the fractional melting technique, the purity of the sample was determined to be 99.0 mol% and the melting temperature for the tested sample and the absolutely pure compound were determined to be 323.50 and 323.99 K, respectively. A solid-to-solid phase transition occurred at 310.63 +/- 0.15 K. The molar enthalpy and molar entropy of the transition were determined to be 980 +/- 5 J mol(-1) and 3.16 +/- 0.02 J K-1 mol(-1), respectively. The thermodynamic functions of the compound [H-T - H-298.15] and [S-T - S-298.(15)] were calculated based on the heat capacity measurements in the temperature range of 83-353 K with an interval of 5 K. (c) 2004 Elsevier B.V. All rights reserved.

Determination of heat capacities and thermodynamic properties of 2-(chloromethylthio)benzothiazole by an adiabatic calorimeter

The molar heat capacities of 2-(chloromethylthio)benzothiazole (molecular formula C8H6ClNS2, CA registry no. 28908-00-1) were measured with an adiabatic calorimeter in the temperature range between (80 and 350) K. The construction and procedures of the calorimeter were described in detail. The performance of the calorimetric apparatus was evaluated by heat capacity measurements on alpha-Al2O3. The deviation of experiment heat capacities from the corresponding smoothed values lies within 0.3%, whereas the uncertainty is within +/-0.5%, compared with that of the recommended reference data over the whole experimental temperature range. A fusion transition was found from the C-p-T curve of 2-(chloromethylthio)benzothiazole. The melting temperature and the molar enthalpy and entropy of fusion of the compound were determined to be T-m = (315.11 +/- 0.04) K, Delta(fus)H(m) = (17.02 +/- 0.03) kJ(.)mol(-1), and Delta(fus)S(m) = (54.04 +/- 0.05) J(.)mol(-1.)K(-1), respectively. The thermodynamic functions (H-T - H-298.15) and (S-T - S-298.15) were also derived from the heat capacity data. The molar fraction purity of the 2-(chloromethylthio)benzothiazole sample used in the present calorimetric study was determined to be 99.21 by fraction melting.

Heat capacity and thermodynamic properties of myclobutanil

The low-temperature heat capacities of myclobutanil (C15H17CIN4) were precisely measured with an automated adiabatic calorimeter over the temperature range from 78 to 368 K. The sample was observed to melt at (348.800 +/- 0.06) K. The molar enthalpy and entropy of the melting as well as the chemical purity of the substance were determined to be Delta(fus)H(m) = (30931 +/- 11) J.mol(-1), Delta(fus)S(m) = (88.47 +/- 0.02) J.mol(-1).K-1 and 99.41%, respectively. Further research of the melting process for this compound was carried out by means of DSC technique. The result was in agreement with that obtained from the measurements of heat capacities.

Heat capacity and enthalpy of fusion of fenoxycarb

Fenoxycarb was synthesized and its heat capacities were precisely measured with an automated adiabatic calorimeter over the temperature range from 79 to 360 K. The sample was observed to melt at (326.31 +/- 0.14) K. The molar enthalpy and entropy of fusion as well as the chemical purity of the compound were determined to be (26.98 +/- 0.04) kJ-mol(-1), (82.69 +/- 0.09) J-K-1-mol(-1) and 99.53% +/- 0.01%, respectively. The thermodynamic functions relative to the reference temperature (298.15 K) were calculated based on the heat capacity measurements in the temperature range between 80 and 360 K. The extrapolated melting temperature for the absolutely pure compound obtained from fractional melting experiments was (326.62 +/- 0.06) K. Further research on the melting process of this compound was carried out by means of differential scanning calorimetry technique. The result was in agreement with that obtained from the measurements of heat capacities.