气压计的误差传播:1.实验确定的端员反应位置的准确度与精度

提出解释反应过程动力学和实验及实际P—T参考坐标系间位移的计算端员反应的精度及准确度的新方法。对最近收集的实验数据的应用证明,采用单独一组实验数据,在变质温度(～900K)条件下的一端员反应位置的估算精度(1δ)可以在±100×10~5到±310×~5Pa以及准确度的最低估算值(1δ)可以在±270×10~5到±410×10~5Pa的等级,这取决于如何精确划定反应界限并假定压力和温度的1δ可能系统误差分别为±250×10~5Pa和±5℃。采用5种不同研究的钙铝榴石—钙长石—蓝晶石—石英(GASP)反应位置的准确度估算在900K条件下为±350×10~到±380×10~5Pa之间,这取决于是否采用独立的标准样校准了各个研究结果。     

石英—锡石—水体系氧同位素分馏作用实验研究

本文在400～500℃及250～370℃温度范围内,盐度为0～15wt%,压力约0.3～0.6kbar条件下,分别在水溶液中完成了由硅胶及非晶质SnO_2合成石英-锡石矿物对以及由非晶质SnO_2等合成的锡石与水之间氧同位素分馏的实验研究,获得了石英-锡石-水体系氧同位素分馏作用系数与温度的关系方程:1000lna_(石英-锡石)=3.11×10~6T~(-2)+1.63(400～500℃),1000lna_(石锡-水)=2.60×10~6T~(-2)-9.91(250～370℃±),1000lna_(锡石-水)=0.20×10~6T~(-2)-4.34(370±～500℃).     

锡石的原位高压X射线衍射研究

利用同步辐射能量色散X射线衍射(EDXD)方法和金刚石对顶砧(DAC)高压技术对采于四川平武的锡石进行原位高压(达24.0 GPa)结构研究发现:压力加载过程中,锡石在13.8 GPa时发生了从金红石型结构(P 42/m nm)到C aC l2型结构(P nnm)的位移式相变;在19.9 GPa时又由C aC l2型结构相变为黄铁矿型结构(P a3),此相变为重构式相变。对于第Ⅳ主族元素氧化物(S iO2,G eO2,SnO2和PbO2)及过渡金属氧化物(M nO2和R uO2)的高压行为进行了讨论,它们具有相似的高压相变序列,这些成果对与斯石英同构氧化物的高压行为研究提供了有价值的参考。     

一种确定火山岩淬火温压的新方法

火山岩中玻璃基质或细粒基质在淬火条件下形成,其熔体结构受淬火温压和熔体成分所控制。在已知熔体成分的条件下,淬火温压可根据熔体结构来确定。对于玄武质熔浆有NBO/T=0.098 57+2.77×10~(-4)T+9.13×10~(-10)p;对于粗面安山质熔浆有:NBO/T=-0.465 5+9.10×10~(-4)T+1.14×10~(-9);对于英安质熔浆有:NBO/T=-0.512 3+8.10×10~(-4)T+1.2×10~(-9)p。     

陕西凤县八卦庙超大型金矿床成矿地质特征及成矿作用

本文通过Ar-Ar同位素计时、稳定同位素示踪、石英位错观察、差异应力计算和热水沉积岩研究等,探讨了八卦庙超大型金矿床的成矿作用和成矿机制。NW向无根揉皱石英脉含Au 0.5×10~(-6)～4×10~(-6),矿化元素组合为Au+Cu+Pb+Zn,Ar-Ar坪年龄232.58±1.59Ma;NE向石英脉含An大于4×10~(-6),可达37.2×10~(-6),Au为主,Ar-Ar年龄为131.91±0.98Ma。研究表明:①泥盆纪热水沉积岩为金矿床的形成提供了矿源,成矿热液水以岩浆水为主,从矿质富集到成矿至少经历了印支期挤压推覆、韧性剪切→印支晚期—燕山期岩浆热液作用;②印支晚期和燕山早期(即韧性构造变形向脆性变形的转换期)是本区金矿成矿的高峰期;③多期成矿作用叠加、多次脉动式构造活动的“应力泵”作用是该超大型金矿床成矿的主因。     

^40Ar／^39Ar定年中干扰同位素的质谱校正与低温分离技术

将光谱纯的CaF_2和优级纯的K_2SO_4同样品一起在反应堆中照射,用MM-1200质谱计分别对其熔融释放的气体进行测定,得到干扰同位素校正因子: C_2=(~(36)Ar/~(37)Ar)_(Ca)=(2.40±0.24)×10~(-4) C_4=(~(39)Ar/~(37)Ar)_(Ca)=(8.06±0.10)×10~(-4) C_3=(~(40)Ar/~(39)Ar)_K=(3.18～6.86)×10~(-3) 将被照射过的含Cl样品释放的Ar和Cl混合气体,通入被冷却到-90℃的弯管,Cl被冷冻在弯管内,Ar气体通过弯管再经净化送入质谱计分析。实验证明,该法可有效的将~(36)Cl从样品气体中分离出去,消除了~(36)Cl的干扰。     

内蒙古头道桥地区蓝闪石片岩和相关变质岩石岩石学特征及其构造意义

内蒙古头道桥地区出露了一套经高压变质形成的岩石组合。本次研究通过岩相学和矿物化学分析,根据矿物组合的不同,识别出蓝片岩、绿片岩两种不同类型的岩石类型。其中,蓝片岩的矿物组合为角闪石（蓝闪石、蓝透闪石）+绿帘石+钠长石+绿泥石+石英+赤铁矿±多硅白云母±方解石±榍石;绿片岩的矿物组合为绿泥石+钠长石+石英±绿帘石±角闪石（阳起石、镁角闪石、蓝透闪石、冻蓝闪石等）±多硅白云母±赤铁矿。确定了蓝片岩的峰期变质级别为绿帘-蓝闪片岩相,峰期变质温度为400~600℃,压力为1.2~1.4 GPa。绿片岩的峰期变质级别为绿帘-角闪岩相。结合前人研究成果,认为蓝片岩和绿片岩的形成与额尔古纳地块和兴安地块的碰撞拼合有关。     

硅磷镍矿的高压状态方程与相变研究

硅磷镍矿(Ni,Fe)8(Si,P)3是一种4元陨石矿物,对探寻地核中轻元素的存在形式具有一定指示意义。采用同步辐射X射线衍射并结合金刚石压腔技术,笔者开展了硅磷镍矿的等温状态方程及其相变研究。实验结果表明常温下在0.0001~41.9 GPa内硅磷镍矿没有发生结构相变,但在34 GPa时其晶胞参数呈现不连续变化。这一异常变化可能与硅磷镍矿的磁性转变有关。对34 GPa前后的p-V实验数据分别进行拟合,得到了硅磷镍矿的状态方程参数V0=1.446(3)nm3、K0=231(8)GPa(p33 GPa)和V0=1.414(6)nm3、K0=343(18)GPa(p35 GPa)。而在高温高压条件下,硅磷镍矿会发生结构相变或者分解。     

地幔转换带520km地震不连续面及其成因

前人研究表明410km和660km地震不连续面分别由橄榄石向瓦兹利石相变和后尖晶石相变引起。但对520km地震不连续面(简称D520)的研究相对较少,对其成因的解释还存在很大争议。橄榄石中瓦兹利石-林伍德石相变以及CaSiO3钙钛矿的出溶反应被广泛认为是D520的相变成因。辉石相变为尖晶石+斯石英组合也曾被认为是D520的可能成因。1 400℃条件下对MgSiO3辉石相变的实验研究,结合前人对橄榄石相变的研究成果,计算了方辉橄榄岩在1 400℃、18GPa条件下因辉石-瓦兹利石+斯石英和瓦兹利石-林伍德石相变引起的密度增量和波速增量,发现俯冲方辉橄榄岩中辉石的相变对520km深度的密度增量和波速增量有很大的贡献,有助于形成D520。此外,在探讨D520的成因时应综合考虑地幔转换带中温度,水以及矿物间Fe、Mg、Ca等主量元素分配等因素的影响。     

特提斯喜马拉雅带东段哲古错含金（砷）细粒石英闪长岩的发现及其意义

在特提斯喜马拉雅带东段哲古错中低温热液型锑-金矿床内首次发现了含金(砷)细粒高镁石英闪长岩,它们呈岩脉或岩枝状侵入于上三叠统—下侏罗统黑色页岩中。矿区内及外围有许多辉长岩脉及少量橄榄二辉岩小岩体产出。含金(砷)细粒高镁石英闪长岩主要为细粒结构,其次为斑状结构,具有与高镁埃达克岩相似的地球化学特征,表现为:SiO_2≥56%,高Al_2O_3(＞15%)、高MgO(Mg~#值为48～59),高Cr(75×10~(-6)～130×10~(-6))、高Ni(54×10~(-6)～74×10~(-6)),富集LILE,亏损HREE及HFSE,(La/Yb)_N＞12,Eu弱负异常(δEu=0．81～0．91),Sr含量较高且变化大(209．28×10~(-6)～685．14×10~(-6),平均381×10~(-6))、低Y和Yb,Y＜16×10~(-6),Yb＜1．7×10~(-6),具有平坦的HREE配分型式,(Ho/Yb)_N≈1,Sr/Y值较高且变化大(14．58～47．28,平均24)。Nd-Sr-Pb同位素组成特征为:高I_(Sr)(0．709726～0．711203),ε_(Nd)(t)弱负(-3．08～-1．15),Pb同位素组成变化幅度不大,~(206)Pb/~(204)Pb=18．638～18．672,~(207)Pb/~(204)Pb=15．694～15．702,~(208)Pb/~(204)Pb=38．983～39．016。含金(砷)细粒高镁石英闪长岩的K-Ar年龄为42．54±0．94Ma和43．21±1．14Ma,其岩浆可能是由地球化学性质类似于哲古错辉长岩的底侵玄武质下地壳部分熔融形成的,此底侵玄武质岩浆源自轻度富集EMⅡ物质的大陆下岩石圈地幔,于晚侏罗世底侵到下地壳。距今65Ma前,印度板块与欧亚大陆碰撞,地壳逐渐加厚。约43Ma前,地壳加厚到40km以上,同时发生了构造事件,诱发玄武质下地壳熔融形成含金(砷)细粒高镁石英闪长岩岩浆,此岩浆与构造活动耦合上升到地壳浅部成岩成矿。细粒高镁石英闪长岩是对金成矿有利的岩石,并且赋存有斑岩型金(砷)矿(化)体,指示特提斯喜马拉雅东段可能存在斑岩型金矿带;同时,含金(砷)细粒高镁石英闪长岩的发现对特提斯喜马拉雅带构造-岩浆作用及地球动力学研究也有意义。     

钇铝石榴石晶体高压相变研究

采用金刚石压砧高压设备,对立方结构掺钕钇铝榴石多晶进行高温高压相变研究。实验分同时加温加压、独立加压、独立加温三类。对压力温度作用后相变产物进行了 X 射线衍射研究,对相变前后样品的配位数、晶体结构、晶胞参数、体积、密度进行了对比。     

HgO at high pressures: the transition to the NaCl structure (HgO-III) and the equation of state of tetragonal HgO-II

The high-pressure behavior of HgO-montroydite was investigated up to 36.5 GPa using angle-dispersive X-ray diffraction. The tetragonal phase of this material (HgO-II), a distortion of the NaCl structure, transforms into the cubic NaCl structure (HgO-III) above ~31.5 GPa. The transformation of mercury oxide from the orthorhombic Pnma (HgO-I) structure to a tetragonal I4/mmm structure (HgO-II) is confirmed to occur at 13.5 ± 1.5 GPa. Neither of the high-pressure phases, HgO-II nor HgO-III, is quenchable in pressure. The derived isothermal bulk modulus of HgO-II and its pressure derivative strongly depend on the assumed zero-pressure volume of this phase, but our elasticity results on HgO-II nevertheless lie significantly closer to theoretical calculations than prior experimental results, and the measured pressure of the phase transformation to the NaCl structure is also in agreement with recent theoretical results. The general accord with theory supports the existence of significant relativistic effects on the high-pressure phase transitions of HgO.     

The strength of ruby from X-ray diffraction under non-hydrostatic compression to 68 GPa

Polycrystalline ruby (α-Al₂O₃:Cr³⁺), a widely used pressure calibrant in high-pressure experiments, was compressed to 68.1 GPa at room temperature under non-hydrostatic conditions in a diamond anvil cell. Angle-dispersive X-ray diffraction experiments in a radial geometry were conducted at beamline X17C of the National Synchrotron Light Source. The stress state of ruby at high pressure and room temperature was analyzed based on the measured lattice strain. The differential stress of ruby increases with pressure from ~3.4 % of the shear modulus at 18.5 GPa to ~6.5 % at 68.1 GPa. The polycrystalline ruby sample can support a maximum differential stress of ~16 GPa at 68.1 GPa under non-hydrostatic compression. The results of this study provide a better understanding of the mechanical properties of this important material for high-pressure science. From a synthesis of existing data for strong ceramic materials, we find that the high-pressure yield strength correlates well with the ambient pressure Vickers hardness.     

Ortho/clinoenstatite transition

Pressure-induced phase transformation of orthoenstatite to clinoenstatite has been studied at 7–10 GPa using a multi-anvil high pressure device with low stress (< 10MPa) conditions. At 1000 °C clinoenstatite was stabilized at pressures above 7.5 GPa. The obtained phase boundary is consistent with natural observations and previous experimental studies performed under quasi-hydrostatic condition, suggesting that clinoenstatite is a stable high pressure phase. Large differences in dP/dT slope between this result and those of earlier studies performed with piston cylinder and belt apparatus may be attributed to large differential stress in the high pressure cells of latter studies. The present study suggests that clinoenstatite can be stabilized by either hydrostatic pressure or differential stress and that the latter tends to shift the transformation boundary defined under hydrostatic condition to lower pressure.     

Thermal equation of state of CaIrO<Subscript>3</Subscript> post-perovskite

The pressure–volume–temperature (P–V–T) relation of CaIrO₃ post-perovskite (ppv) was measured at pressures and temperatures up to 8.6 GPa and 1,273 K, respectively, with energy-dispersive synchrotron X-ray diffraction using a DIA-type, cubic-anvil apparatus (SAM85). Unit-cell dimensions were derived from the Le Bail full profile refinement technique, and the results were fitted using the third-order Birth-Murnaghan equation of state. The derived bulk modulus \( K_{T0} \) at ambient pressure and temperature is 168.3 ± 7.1 GPa with a pressure derivative \( K_{T0}^{\prime } \) = 5.4 ± 0.7. All of the high temperature data, combined with previous experimental data, are fitted using the high-temperature Birch-Murnaghan equation of state, the thermal pressure approach, and the Mie-Grüneisen-Debye formalism. The refined thermoelastic parameters for CaIrO₃ ppv are: temperature derivative of bulk modulus \( (\partial K_{T} /\partial T)_{P} \) = ?0.038 ± 0.011 GPa K^?1, \( \alpha K_{T} \) = 0.0039 ± 0.0001 GPa K^?1, \( \left( {\partial K_{T} /\partial T} \right)_{V} \) = ?0.012 ± 0.002 GPa K^?1, and \( \left( {\partial^{2} P/\partial T^{2} } \right)_{V} \) = 1.9 ± 0.3 × 10^?6 GPa² K^?2. Using the Mie-Grüneisen-Debye formalism, we obtain Grüneisen parameter \( \gamma_{0} \) = 0.92 ± 0.01 and its volume dependence q = 3.4 ± 0.6. The systematic variation of bulk moduli for several oxide post-perovskites can be described approximately by the relationship K _T0  = 5406.0/V(molar) + 5.9 GPa.     

The system Fe-FeO revisited

The results of a reconnaissance investigation of melting relationships in the system Fe-FeO at 16 GPa were recently described by Kato and Ringwood (1989). The principal sources of uncertainties in those experiments were caused by loss of FeO to sample capsules during runs and the estimation of sample temperatures by an indirect method, based upon a prior calibration of the relationship between power input and temperature. A further set of 24 runs at 16 GPa has been carried out using improved experimental techniques. The melting temperatures of iron and wüstite at 16 GPa are found to be 1945±20° C and 1875±25° C respectively. (Quoted errors do not include possible effects of pressure on thermocouple emf). The Fe-FeO eutectic is now located at 10±2 wt% FeO and 1670±20° C (previously 15.5±3 wt% FeO and 1700±25° C). The new determination of the depression of the melting point of iron by solution of FeO is 27.5° C/wt% FeO as compared to the previous value of 23° C/wt% FeO. The present results show that the contraction of the liquid immiscibility field in the system at high pressure is somewhat larger than was estimated previously. This study confirms the general topology of high pressure phase relationships in the Fe-FeO system obtained by Kato and Ringwood (1989) and has similar implications for the process of core formation within the Earth.     

Pressure-induced structural modifications in Mg2GeO4-olivine: A Raman spectroscopic study

Raman spectra of Mg₂GeO₄-olivine were obtained from ambient pressure up to 34 GPa at ambient temperature. Under quasi-hydrostatic pressure conditions, the following modifications in the Raman spectra occur as pressure increases: 1) near 11 GPa, two sharp extra bands appear in the 600–700 cm^?1 frequency range, and increase in intensity with respect to the olivine bands; 2) above 22 GPa, these two bands become very intense, and the number, position and relative intensity of the other vibrational bands drastically change; 3) the intensity of sharp bands progressively decreases above 25 GPa. The transformation occurs at lower pressures under non-hydrostatic conditions. During decompression to atmospheric pressure, the high-pressure phase partially reverts to olivine. These observations can be interpreted as the progressive metastable transformation from the olivine structure to a crystalline phase with four-fold coordinated Ge, in which the GeO₄ tetrahedra are polymerized. We propose that the metastable high-pressure phase is a structurally disordered spinelloid close to the hypothethical ω- or ?^*-phase, and forms by a shear mechanism assisted by the development of a dynamical instability in the olivine structure. Implications for the transformations undergone by olivines under far-from-equilibrium conditions (e.g. in subducting lithospheric slabs and in shocks) are discussed.     

Determination of the phase boundary between ilmenite and perovskite in MgSiO3 by in situ X-ray diffraction and quench experiments

Determination of the phase boundary between ilmenite and perovskite structures in MgSiO₃ has been made at pressures between 18 and 24 GPa and temperatures up to 2000 °C by in situ X-ray diffraction measurements using synchrotron radiation and quench experiments. It was difficult to precisely define the phase boundary by the present in situ X-ray observations, because the grain growth of ilmenite hindered the estimation of relative abundances of these phases. Moreover, the slow reaction kinetics between these two phases made it difficult to determine the phase boundary by changing pressure and temperature conditions during in situ X-ray diffraction measurements. Nevertheless, the phase boundary was well constrained by quench method with a pressure calibration based on the spinel-postspinel boundary of Mg₂SiO₄ determined by in situ X-ray experiments. This yielded the ilmenite-perovskite phase boundary of P (GPa) = 25.0 (±0.2) – 0.003 T (°C) for a temperature range of 1200–1800 °C, which is generally consistent with the results of the present in situ X-ray diffraction measurements within the uncertainty of ∼±0.5 GPa. The phase boundary thus determined between ilmenite and perovskite phases in MgSiO₃ is slightly (∼0.5 GPa) lower than that of the spinel-postspinel transformation in Mg₂SiO₄. Received: 19 May 1999 / Accepted: 21 March 2000     

1.0 GPa、高温下岩石熔融玻璃的弹性波速测量及其地球物理意义

利用超声波反射法,在1.0GPa、最高温度分别达900℃和730℃条件下,测量了岩石成分从酸性到基性的7种熔融玻璃的纵波波速(vp)和横波波速(vs)随温度的变化。实验过程证明,高压下升温过程中样品被压缩导致了样品中弹性波走时减少,而降温过程中样品长度基本保持不变。结果显示,1.0GPa下,随实验温度升高,不同成分玻璃的vp首先以-0.2×10-3km.s-1.℃-1到-0.7×10-3km.s-1.℃-1不等的速率缓慢降低,而其vs多以-0.1×10-3km.s-1.℃-1速率随温度升高而降低。当温度高于玻璃转变温度(Tg)后,玻璃的vp开始以-0.8×10-3km.s-1.℃-1到-3.6×10-3km.s-1.℃-1不等的速率快速下降。根据玻璃vp随温度变化速率的改变,拟合出这几种玻璃的转变温度从584℃到654℃。由实验获得的玻璃波速,利用Voigt-Reuss-Hill(VRH)平均计算出下地壳岩石中玻璃的存在将降低岩石的波速,并由此为下地壳低速层提出一种新的解释,即非晶质体的存在可能在下地壳形成地震波低速层。