Solution of H2O in diopside melts: a thermodynamic model

Structural similarities between dry diopside melt and superhydrous albite melt (X _w >0.5) — both lack three-dimensional silicate units — suggest that thermodynamic relations may be similar. A model based on that assumption successfully predicts diopside melting relations and H₂O solubilities. For the model, the three partial differential equations describing solution of H₂O in albite melt for X _w >0.5 have been integrated for diopside melt from X _w =0 to X _w at least as large as 0.76, with two exceptions: an alternative partial differential equation for Henrian solution of H₂O in dilute melts was applied for X _w <0.20, and an alternative differential equation for the pressure dependence of a _w at pressures below 2 kbar was developed. The latter alternative equation yields relatively small ¯V_w's at low pressures rather than the large ¯V_w's calculated from the equation from the albite system. Available experimental solubility data are not precise enough to offer a choice between the small-¯V_w and large-¯V_w equations. Integration of all the partial differential equations was constrained solely by the P and T of a single experimentally-determined point on the H₂O-saturated solidus.Solubilities calculated by a Henrian-analogue solution model (a _di=X _di ² ) from the experimental H₂O saturated solidus lie outside experimental solubility constraints for dilute melts. On the other hand, a Henrian model (a _di=X_di) successfully predicts solubilities in dilute melts. The formulation of the Henrian model and magnitudes of model molar entropies of solution are consistent with the hypothesis that H₂O dissolves in diopside melt as an essentially undissociated species with little ordering on melt structural sites. That species could in turn be consistently, if not uniquely, interpreted to be molecular H₂O or a hydroxylation (OH^–) complex formed from nonbridging oxygens.     

贵州新民铝土矿矿床Li的地球化学特征与富集机制探究

新民铝土矿床位于黔北务川-正安-道真地区(简称务正道地区)大塘向斜东翼,铝土矿(岩)型Li资源丰富.含矿岩系大竹园组(P1d)不同岩性的w(Li)有差别:土状-半土状铝土矿平均w(Li)为16.34×10-6,致密块状铝土矿平均w(Li)是803.84×10-6,铝土岩平均w(Li)是1436.22×10-6,黏土岩的平均w(Li)是786.62×10-6,梁山组泥岩的平均w(Li)是51.82×10-,韩家店群泥岩(页岩)的平均w(Li)是48.52×10-6,黄龙组灰岩的平均w(Li)是 11.99×10-6.由此可知,研究区铝土矿(岩)型Li资源主要富集在含矿岩系中上部的致密块状铝土矿、铝土岩和黏土岩中,顶板、底板以及土状-半土状铝土矿w(Li)较低.Li主要赋存于高岭石中,伊利石(水云母)和残存的三水铝石、勃姆石也可富集少量Li,当样品中赋锂矿物(高岭石、伊利石(水云母)、三水铝石和勃姆石)都存在时,高w(Li),主量元素w(Al3O2)、w(SiO2)、w(MgO)、w(K2O)、w(TiO2)和w(TFe2O3)与w(Li)的相关性也证实了上述结果.研究区的地球化学比值 CIA、w(Sr)/w(Cu)、u(CaO)/w(MgO)、w(Sr)/w(Ba)、w(V)/w(V+Ni)和 w(La)/w(Y)综合显示,炎热潮湿的古气候下,有机质腐烂形成酸性环境,半封闭海湾环境下,黏土化阶段中等强烈的化学风化程度和适宜的风化暴露剥蚀时间利于铝硅酸盐矿物和硅酸盐矿物化学键断裂,富集Al3+形成高岭石;风化程度过于强烈和长时间的风化剥蚀,继续脱Si富Al形成以硬水铝石为主的铝土矿;弱酸性-弱碱性以及氧化-还原过渡条件下,使得高岭石能最大程度的吸附Li元素.     

P-V-T equation of state of lawsonite

A pressure-volume-temperature data set has been obtained for lawsonite [CaAl₂Si₂O₇(OH)₂.H₂O], using synchrotron X-ray diffraction and an externally heated diamond anvil cell. Unit-cell volumes were measured to 9.4 GPa and 767 K by angle dispersive X-ray diffraction using imaging plates. Phase changes were not observed within this pressure-temperature range, and lawsonite compressed almost isotropically at constant temperature. The P-V-T data have been analyzed using a Birch- Murnaghan equation of state and a linear equation of state expressed as β=–1/V₀ (∂V/∂P) _T . At room temperature, the derived equation of state parameters are: K ₀=124.1 (18) GPa K'₀ set to 4) and β^–1=142.0(24) GPa, respectively. Our results are intermediate between previously reported measurements. The high-temperature data show that the incompressibility of lawsonite decreases with increasing temperature to ∼500 K and then increases above. Hence, the second order temperature derivative of the bulk modulus is taken into account in the equation of state; a fit of the volume data yields K ₀=123.9(18) GPa, (∂K/∂T)_P=–0.111(3) GPa K^–1, (∂² K/∂T ²)_P=0.28(6) 10^–3 GPa K^–2, α₀=3.1(2) 10^–5 K^–1, assuming K'₀=4. Received: 2 June 1998 / Revised, accepted: 12 Ocotber 1998     

The high-pressure and temperature equation of state of a majorite solid solution in the system of Mg4Si4O12-Mg3Al2Si3O12

The high-pressure and temperature equation of state of majorite solid solution, Mj_0.8Py_0.2, was determined up to 23 GPa and 773 K with energy-dispersive synchrotron X-ray diffraction at high pressure and high temperature using the single- and double-stage configurations of the multianvil apparatuses, MAX80 and 90. The X-ray diffraction data of the majorite sample were analyzed using the WPPD (whole-powder-pattern decomposition) method to obtain the lattice parameters. A least-squares fitting using the third-order Birch-Murnaghan equation of state yields the isothermal bulk modulus, K _T0  = 156 GPa, its pressure derivative, K′ = 4.4(±0.3), and temperature derivative (∂K _T /∂T) _P = −1.9(±0.3)× 10⁻² GPa/K, assuming that the thermal expansion coefficient is similar to that of pyrope-almandine solid solution. Received: 5 October 1998 / Revised, accepted: 24 June 1999     

How well known are the thermodynamics of Fe–Mg–Ca garnet? Evidence from experimentally determined exchange equilibria

ABSTRACT Many thermodynamic calculations relating to metamorphic rocks hinge on the thermodynamic parameters of garnet. Though some models are widely used, it is not clear whether their underlying premise is correct: that a single set of equations can be written for the activities of the end-members of garnet covering the whole compositional range. A voluminous body of data can be used to constrain the thermodynamics of garnet, namely Fe–Mg exchange experimental data involving garnet and another mineral, particularly clinopyroxene, orthopyroxene and olivine. However, examination of these data reveals inconsistencies, apparently stemming from differences between the thermodynamics of low-Ca and high-Ca garnets, with a boundary of about X^g_Ca= 0.15. In the two regions, for the high P–T of the experimental data, the thermodynamics follow the regular model, with values for the interaction parameters in the low Ca region of about w^g_FeMg= 50R and w_aFe–w^g_MgCa=– 1300R, in which R is the gas constant, and in the high Ca region of about w^g_FeMg= 1100R and w^g_CaFe–w^g_MgCa=– 2200R. Using the subregular, rather than the regular, model does not remove the discrepancy. The cause of the discrepancy needs to be identified if reliable calculations on rocks are to be made.     

辽南42号金伯利岩管地质特征及找矿预测

辽南42号金伯利岩岩管主要由东部42-1号大岩管、西部42-2号小岩管和中部42-3号小小岩管组成。42-1号岩管从地表到40 m标高形态急剧收缩;42-2号岩管为烟筒状,40 m标高至-160 m标高面积比为1∶1.15;42-3岩管在-200 m标高处延深为脉状。42号岩管岩石类型为斑状金伯利岩、斑状富金云母金伯利岩、含或富含围岩角砾金伯利岩和含岩球斑状金伯利岩。岩石化学特征研究表明,岩石中w(SiO₂)、w(Al₂O₃)、w(TiO₂)值比山东胜利Ⅰ号金伯利岩和戴里值偏高,w(MgO)、w(Cr₂O₃)、w(K₂O)、w(Na₂O)、w(P₂O₅)值较戴里值偏低,但w(K₂O)、w(Na₂O)、w(P₂O₅)值比山东胜利Ⅰ号金伯利岩略高;w(ΣFe₂O₃+FeO)、w(CaO+H₂O)值与山东胜利Ⅰ号金伯利岩及戴里值相当。通过采样分析42-2号岩管金刚石含量高,42-1号岩管金刚石含量低;研究认为受造岩矿物橄榄石和金云母的影响,金刚石含量与橄榄石斑晶含量正相关,与金云母含量呈负相关;伴生矿物铬铁矿、镁铝榴石、碳硅石含量高,则金刚石含量也随之增高,为正相关;而锐钛矿于金刚石含量为负相关。基于研究区的三维建模、推覆构造研究,推测42号岩管不是根部相,其东部可能存在深部金伯利岩体。     

Experimental study and constitutive modelling of elasto‐plastic damage in heat‐treated mortar

This study investigates the effect of a heat‐treatment upon the thermo‐mechanical behaviour of a model cement‐based material, i.e. a normalized mortar, with a (w/c) ratio of 0.5. First, a whole set of varied experimental results is provided, in order to either identify or validate a thermo‐mechanical constitutive model, presented in the second paper part. Experimental responses of both hydraulic and mechanical behaviour are given after different heating/cooling cycling levels (105, 200, 300, 400^°C). The reference state, used for comparison purposes, is taken after mass stabilization at 60^°C. Typical uniaxial compression tests are provided, and original triaxial deviatoric compressive test responses are also given. Hydraulic behaviour is identified simultaneously to triaxial deviatoric compressive loading through gas permeability K_gas assessment. K_gas is well correlated with volumetric strain evolution: gas permeability increases hugely when ε_v testifies of a dilatant material behaviour, instead of contractile from the test start. Finally, the thermo‐mechanical model, based on a thermodynamics approach, is identified using the experimental results on uniaxial and triaxial deviatoric compression. It is also positively validated at residual state for triaxial deviatoric compression, but also by using a different stress path in lateral extension, which is at the origin of noticeable plasticity. Copyright © 2009 John Wiley & Sons, Ltd.     

The equation of state of Al,H-bearing SiO2 stishovite to 58 GPa

We have determined the P-V equation of state of Al-rich H-bearing SiO₂ stishovite by X-ray powder diffraction at pressures up to 58 GPa using synchrotron radiation. The sample contained 1.8 wt% Al₂O₃ and up to 500 ppm H₂O, and had a composition that would coexist with Mg-silicate perovskite in a subducted slab. By fitting a third-order Birch-Murnaghan equation of state to our compression data, we obtained a bulk modulus K _T0=298(7) GPa with K′=4.3(5). With K′ fixed to a value of 4, the bulk modulus K _T0=304(3) GPa. Our results indicate that Al³⁺ and H⁺ have a small effect on the elastic properties of stishovite. Compared with data obtained up to 43.8 GPa, peak intensities changed and we observed a decreased quality of fit to a tetragonal unit cell at pressures of 49 GPa and higher. These changes may be an indication that the rutile↔CaCl₂ transition occurs between these pressures. After laser annealing of the sample at 58.3(10) GPa and subsequent decompression to room conditions, the cell volume is the same as before compression, giving strong evidence that the composition of the recovered sample is also unchanged. This suggests that Al and H are retained in the sample under extreme P-T conditions and that stishovite can be an agent for transporting water to the deepest lower mantle.     

基性-超基性岩铜镍矿与铬铁矿含矿性判别研究

岩石与矿物地球化学数据常用于判别岩石成因、构造环境等,事实上它们也可以用于判别岩石成矿专属性,从而更好地指导找矿工作。通过对含铜镍矿的基性-超基性岩与含铬铁矿的基性-超基性岩全岩主量、铂族元素和铬铁矿尖晶石地球化学特征进行综合对比研究结果显示:1)铜镍矿的m/f值主要集中在1.5～8.5,铬铁矿主要集中在6.5～12.5,有一定重叠,因此通过m/f值确定是否成矿具有不确定因素;利用全岩主量元素的二元图解进行判别也存在重叠区域,不利于成矿专属性的判别。2)铜镍矿基性-超基性岩全岩具有高的w(PPGE)/w(IPGE)值(0.06～343.75,平均16),w(Pd)/w(Ir)1;铂族元素具有左倾的原始地幔配分模式;铬铁矿尖晶石高w(TiO_2)、Fe~#值,Cr~#、Mg~#值变化范围较大。3)铬铁矿基性-超基性岩全岩具有低的w(PPGE)/w(IPGE)值(0.000 4～20.34,平均0.55),w(Pd)/w(Ir)1,铂族元素具有右倾的原始地幔配分模式;铬铁矿尖晶石低w(TiO2),Fe~#、Mg~#值,高Cr~#值。因此,利用基性-超基性岩的铂族元素与铬铁矿地球化学特征值能有效指示成矿专属性,可成为基性-超基性岩铬铁矿与铜镍矿的勘查工具。     

Estimation of surface heat flux and inversion height with a Doppler acoustic sounder

In this paper, acoustic sounder (sodar) derived vertical velocity variance (σ _w ² ) and inversion height (Z _i) are used to compute the surface heat flux during the convective activity in the morning hours. The surface heat flux computed by these methods is found to be of the same order of magnitude as that obtained from tower measurements. Inversion heights derived from sodar reflectivity profiles averaged for an hour are compared with those obtained from the σ _w ² /Z profile. Variation of σ _w ² in the mixed layer is discussed. The data were collected during the Monsoon Trough Boundary Layer Experiment 1990 at Kharagpur. The analysis is made for four days which represent the pre-monsoon, onset, active and relatively weak phases of the summer monsoon 1990. The interaction of the ABL with the monsoon activity is studied in terms of the variation of inversion height, vertical velocity variance and surface heat flux as monsoon progresses from June to August.     

辽北西丰地区晚侏罗世营厂岩体LA-ICP-MS锆石U-Pb年龄及岩石地球化学特征

营厂岩体分布于辽北西丰县和隆镇境内，研究结果表明，该岩体主要为似斑状二长花岗岩，锆石²⁰⁶Pb/²³⁸U年龄加权平均值为156.1 Ma±1.5 Ma，形成时代为晚侏罗世。营厂岩体w（Na₂O）/w（K₂O）平均值为1.07，属高钾钙碱性系列；里特曼指数σ平均值为2.15，属钙碱系列；铝饱和指数A/CNK平均值为1.16，A/CN平均值为1.99，属过铝型；Rb、Sr、Ba、Th、Hf含量偏高，Cr、Ni、Co、V、Rb、Zr、Nb等元素含量低，为"S"型花岗岩特征。稀土元素总量平均值为w（ΣREE）＝82.80×10^-6，w（LREE）/w（HREE）=15.76，w（La）_N/w（Yb）_N=24.32，表明其轻稀土相对富集，重稀土相对亏损，稀土配分曲线右倾。δEu=0.80，铕弱负异常，说明成因与板块运动有关，w（Sm）/w（Nd）=0.20，w（Ba）/w（Sr）=1.60，w（K）/w（Rb）=249.15，表明具有壳源性质。营厂岩体具有埃达克岩的特点，其属于受太平洋板块向欧亚板块俯冲作用的影响，在挤压环境下加厚下地壳部分熔融，从而形成活动陆缘型花岗岩。     

Hydrostatic compression and crystal structure of pyrope to 33 GPa

The equation of state and crystal structure of pyrope were determined by single crystal X-ray diffraction under hydrostatic conditions to 33 GPa, a pressure that corresponds to a depth of about 900 km in the lower mantle. The bulk modulus K _T0 and its pressure derivative K ^' _T0 were determined simultaneously from an unweighted fit of the volume data at different pressures to a third order Birch-Murnaghan equation of state. They are 171(2) GPa and 4.4(2), respectively. Over the whole pressure range, MgO₈ polyhedra showed the largest compression of 18.10(8)%, followed by AlO₆ and SiO₄ polyhedra, with compression of 11.7(1)% and 4.6(1)%, respectively. The polyhedral bulk moduli for MgO₈, AlO₆ and SiO₄ are 107(1), 211(11) and 580(24) GPa, respectively, with K ^' _T0 fixed to 4. Significant compression of up to 1.8(1)% in the very rigid Si−O bonding in pyrope could be detected to 33 GPa. Changes in the degree of polyhedral distortion for all three types of polyhedra could also be observed. These changes could be found for the first time for AlO₆ and SiO₄ in pyrope. It seems that the compression of pyrope crystal structure is governed by the kinking of the Al−O−Si angle between the octahedra and tetrahedra. No phase transition could be detected to 33 GPa. Received: 24 March 1997 / Revised, accepted: 29 July 1997     

The weathering of stones due to dissolution

We hypothesize that the weathering of building stones can be attributed to surface dissolution processes. We assume that chemical interactions occur on grain boundaries and/or microcracks and that diffusion is the controlling process. A dissolution layer (rind) develops adjacent to the weathering surface. We quantify the extent of dissolution by introducing a damage variable f; f=0 for pristine rock, and when f=1 the rock disintegrates. We assume that the variations of the damage variable are given by the diffusion equation. We solve two problems. The first is for the structure of the transient dissolution boundary layer prior to surface disintegration. We find an incubation time t_i, before active weathering (disintegration) begins. The second is the solution for steady-state weathering with a constant weathering velocity v_w. Our results are entirely consistent with weathering studies on Carrara marble gravestones in the United Kingdom. Typical incubation times are t_i=20–30 years, and typical steady-state weathering velocities are v_w=5–50 m year^–1.     

The stability and equation of state for the cotunnite phase of TiO2 up to 70 GPa

The stability and equation of state for the cotunnite phase in TiO₂ were investigated up to a pressure of about 70 GPa by high-pressure in situ X-ray diffraction measurements using a laser-heated diamond anvil cell. The transition sequence under high pressure was rutile → α-PbO₂ phase → baddeleyite phase → OI phase → cotunnite phase with increasing pressure. The cotunnite phase was the most stable phase at pressures from 40 GPa to at least 70 GPa. The equation of state parameters for the cotunnite phase were established on the platinum scale using the volume data at pressures of 37–68 GPa after laser annealing, in which the St value, an indicator of the magnitude of the uniaxial stress component in the samples, indicates that these measurements were performed under quasi-hydrostatic conditions. The third-order Birch-Murnaghan equation of state at K ₀′ = 4.25 yields V ₀ = 15.14(5) cm³/mol and K ₀ = 294(9), and the second-order Birch-Murnaghan equation of state yields V ₀ = 15.11(5) cm³/mol and K ₀ = 306(9). Therefore, we conclude that the bulk modulus for the cotunnite phase is not comparable to that of diamond.     

Can shells of freshwater mussels (Unionidae) be used to estimate low summer discharge of rivers and associated droughts?

This paper examines if shell oxygen isotope ratios (δ¹⁸O_ar) of Unio sp. can be used as a proxy of past discharge of the river Meuse. The proxy was developed from a modern dataset for the reference time interval 1997–2007, which showed a logarithmic relationship between discharge and measured water oxygen isotope ratios (δ¹⁸O_w). To test this relationship for past time intervals, δ¹⁸O_ar values were measured in the aragonite of the growth increments of four Unio sp. shells; two from a relatively wet period and two from a very dry time interval (1910–1918 and 1969–1977, respectively). Shell δ¹⁸O_ar records were converted into δ¹⁸O_w values using existing water temperature records. Summer δ¹⁸O_w values, reconstructed from δ¹⁸O_ar of 1910–1918, showed a similar range as the summer δ¹⁸O_w values for the reference time interval 1997–2007, whilst summer reconstructed δ¹⁸O_w values for the time interval 1969–1977 were anomalously high. These high δ¹⁸O_w values suggest that the river Meuse experienced severe summer droughts during the latter time interval. δ¹⁸O_w values were then applied to calculate discharge values. It was attempted to estimate discharge from the reconstructed δ¹⁸O_w values using the logarithmic relationship between δ¹⁸O_w and discharge. A comparison of the calculated summer discharge results with observed discharge data showed that Meuse low-discharge events below a threshold value of 6 m³/s can be detected in the reconstructed δ¹⁸O_w records, but true quantification remains problematic.     

青海喀雅克登锌多金属矿床二长花岗岩锆石U-Pb定年及其地质意义

青海喀雅克登锌多金属矿床与成矿关系密切的二长花岗岩通过LA-MC-ICP-MS锆石U-Pb测年,年龄为(403.1±1.2)Ma,MSWD=0.46,属于早泥盆世;矿区的锌多金属矿体主要产于二长花岗岩与古元古代金水口岩群白沙河岩组大理岩岩段接触部位的夕卡岩中,表明喀雅克登锌多金属矿床形成于(或晚于)(403.1±1.2)Ma。二长花岗岩中w(MgO)=0.21%~0.87%,w(FeO_t)=0.93%~3.93%,Mg~#=25.5~34.66,K_2O/Na_2O=1.0~1.72,A/CNK=0.89~1.17,属高钾钙碱性、准铝质花岗岩系列,为壳源岩浆。喀雅克登锌多金属矿床形成于后碰撞阶段,受幔源岩浆底侵改造。     

Testing the predictive power of seagrass depth limit models

The power of equations predicting seagrass depth limit (Z_c) from light extinction (K _z) was tested on data on seagrass depth limits collected from the literature. The test data set comprised 424 reports of seagrass colonization depth and water transparency, including data for 10 seagrass species. This data set confirmed the strong negative relationship betweenZ _c andK _z. The regression equation in Duarte (1991) overestimated the realized seagrass colonization depths at colonization depths < 5 m, while there was no prediction bias above this threshold. These results indicated that seagrass colonizing turbid waters (K _z 0.27 m^-1) have higher apparent light requirements than those growing in clearer waters. The relationship between seagrass colonization depth and light attenuation shifts at a threshold of light attenuation of 0.27 m^-1, requiring separate equations to predictZ _c for seagrass growing in more turbid waters and clearer waters, and to set targets for seagrass restoration and conservation efforts.     

Impact of pore water conductivity and porosity on the electrical conductivity of kaolinite

The purpose of this study is to quantify the magnitudes of surface conduction and pore water conduction from the measured electrical conductivity of kaolinite, with the ultimate goal of estimating the electrical conductivity of kaolinite with a wide range of pore water conductivities (σ _w = 0.013–3.356 S/m) and porosities (n = 0.368–1.0). Therefore, the theoretical background of the electrical conductivity in soils was reviewed, and electrical conductivity measurements on kaolinite were performed using both slurry and consolidation tests in this study. The results of this study demonstrate that the variations of measured electrical conductivity (σ _mix) with n are debatable according to the values of σ _w, because a decrease in n results in both an increase in surface conduction (K _s) and a decrease in pore water conduction (K _w); this causes the relative magnitude of K _s compared to that of K _w to vary with σ _w and n. Consequently, this study develops the relation between the porosity-normalized K _s/K _w and 1/σ _w. Additionally, the surface conductivity of the tested kaolinite is back-calculated and compared with the previous relationship between K _s and zeta potential of kaolinite. The measured and estimated σ _mix values are compared with the varying pore water conductivity and porosity values.     

贵州省凯里市大田铝土矿矿床地质特征及成矿规律分析

凯里市大田铝土矿是贵州省重要铝土矿成矿带凯里─黄平矿集区(带)内的重要矿床。通过工作发现:①二叠系梁山组是其含矿层位,矿体呈似层状、透镜状/漏斗状产出,总体走向NE,平均厚2.59 m,w(Al₂O₃)平均值为64.25%,铝硅比平均为5.25,铝土矿(332+333)矿石资源量978.38×10⁴ t;②矿石矿物以一水硬铝石为主,矿石结构一般为自形、半自形或它形粒状结构,构造主要为块状构造、孔隙状构造、层纹状构造,矿石类型以低硫低铁铝土矿为主;③矿床受断裂构造影响较大,在该区西北部的泥质岩相带中铝土矿成矿较好,矿体厚度与含矿岩系厚度成正比,矿石的w(Al₂O₃)值与w(SiO₂)值成反比;④高坡场组古岩溶洼地、槽沟是该区铝土矿找矿的有利部位。     

内蒙古嘎仙镍钴矿区岩浆作用与成矿

内蒙古嘎仙矿床为大兴安岭北段与岩浆作用有关的大型低品位镍钴硫化物矿床,成矿作用主要与花岗质岩浆作用有关。文章主要对矿区内矿体下盘的花岗岩类(花岗斑岩、长石斑岩、伟晶状花岗岩、黑云母花岗岩)进行了锆石LA-ICP-MS U-Pb定年,获得花岗斑岩的谐和线年龄(125.3±1.1)Ma～(127.5±4.5)Ma,长石斑岩的谐和线年龄为(128.1±2.2)Ma,伟晶状花岗岩的谐和线年龄为(127.9±2.3)Ma,黑云母花岗岩的谐和线年龄为(127.9±1.4)Ma,说明这些花岗岩类主要形成于中生代早白垩世。通过对矿化超镁铁岩、科马提岩、镁铁岩(辉绿岩、玄武岩)、长英质岩(闪长岩、长石斑岩、斜长花岗岩、花岗斑岩、伟晶状花岗岩、黑云母花岗岩)及围岩(大理岩)的主量、微量元素地球化学测试分析,结果表明,与吉峰科马提岩成分相比较,矿化超镁铁岩具有较高的w(SiO_2)(40.53%～54.96%)、w(TiO_2)(0.24%～0.86%)、w(Al_2O_3)(3.58%～10.47%)、w(FeO)(5.30%～8.80%)、w(CaO)(7.35%～13.66%)、w(Na_2O)(0.01%～0.76%)、w(K_2O)(0.02%～0.66%)和w(P_2O_5)(0.06%～0.61%);镁铁岩(包括辉绿辉长岩、玄武岩)铝含量较高,w(Al_2O_3)=16.34%～17.74%;长英质岩类也富铝质(Al_2O_3/(CaO+Na_2O+K_2O)=1.34～1.63),多数岩石属于钙碱性系列。闪长岩与镁铁岩相比,具有较高的硅、铝、钾、钠,较低的铁、镁和钙,微量元素具有大离子亲石元素富集,高场强元素相对亏损的右倾模式;稀土元素具有轻稀土元素富集,重稀土元素相对亏损特征,超镁铁岩类成分点位于N-MORB与OIB范围之间,而镁铁岩和长英质岩类成分点位于E-MORB和OIB之间。镁铁岩落入火山弧玄武岩范围,长英质岩落入火山弧花岗岩+同碰撞花岗岩范围,同属于造山后花岗岩的范围,因此镁铁质岩的形成应属于俯冲-碰撞环境,而长英质岩的形成应属于造山后伸展环境。根据各岩类所含成矿元素和亲流体元素分析,认为含矿热液来自矿区西部的深部,并且构建了嘎仙矿床的成矿模型,即超镁铁岩先期侵位,后期经历了区域的变质变形,最后发生燕山期大规模花岗质岩浆活动及成矿流体的蚀变矿化。