Solubility of carbon dioxide in aqueous fluids and mineral suspensions at 294 K and subcritical pressures

An experimental investigation has been carried on the solubility of CO₂ in water and 1 M NaCl between 0.3 and 4 MPa, in order to test the validity of the results given by various modelling codes. In addition to experiments with pure fluids, the effect of a range of likely reservoir minerals on CO₂–water interactions, including K-feldspar, kaolinite, calcite, Ca-montmorillonite and Na-montmorillonite were also investigated. In addition to measurements of CO₂ solubility, the pH of the CO₂-saturated suspensions was also measured directly at pressures of up to 1 MPa. The results demonstrate that predictions of CO₂ solubility made with PHREEQC and Geochemist’s Workbench agree to within 20% with the experimental value, provided corrections are first made off-line for the fugacity coefficient of CO₂, while predictions from standalone models are slightly more accurate. In the presence of mineral suspensions, PHREEQC and Geochemist’s Workbench give good results for calcite and kaolinite but underestimate the pH of montmorillonite-bearing assemblages while slightly overestimating the pH of K-feldspar suspensions. These results are significant because they indicate that CO₂-charged fluids reacted with clays may be less acidic than indicated by the models, which will impact predictions of the potential for dissolution of reservoir and cap rock minerals, as well as the potential for leaching of toxic metals.     

Geo-Characterization at selected accelerometric stations in Crete (Greece) and comparison of earthquake data recordings with EC8 elastic spectra

To estimate the seismic response according to Eurocode (EC8) and almost all other national codes, site conditions have to be properly characterized so that soil amplification and the corresponding peak ground motion can be calculated. In this work, different geophysical and geotechnical methods are combined in order to define the detailed ground conditions in selected sites of the Hellenic Accelerometric Network (HAN) in Crete. For this purpose, the geological information of the sites and shear wave velocity, calculated from surface wave measurements, is used. Additionally, ground acceleration data recorded through HAN have been utilized from intermediate depth earthquakes in the broader area of South Aegean Sea. Using the recorded ground motion data and the procedure defined in EC8, the corresponding elastic response spectrum is calculated for the selected sites. The resulting information is compared to the values defined in the corresponding EC8 spectrum for the seismic zone that includes the island of Crete. The comparison shows that accurate definition of ground type through geological, geotechnical and geophysical investigations is important. However, our current comparison focuses on the distribution of values rather than the absolute values of EC8-prescribed spectra, and the results should be considered in this context.     

马鞍桥金矿床中香沟岩体锆石U-Pb定年、地球化学及其与成矿关系研究

对出露马鞍桥金矿床中香沟二长花岗斑岩进行了单颗粒锆石U-Pb定年和岩石地球化学研究.结果表明,锆石的LA-ICPMS U-Pb年龄值为(242.0±0.8)Ma,与前人确定的秦岭造山带的主造山时间((242±21)Ma)一致,显示香沟岩体可能和印支期华北与扬子板块的碰撞事件有关.香沟岩体以高硅富碱为特征,属于高钾钙碱性系列花岗岩类.香沟岩体高Al(Al2O3=14.49~15.61)和Sr(457.10~630.82μg/g)、亏损Y(<16μg/g)和HREE(Yb<0.45μg/g),并具有较高的Sr/Y(76.24~97.34)和(La/Yb)N(29.65~46.10)比值及强分异的稀土元素组成模式,其地球化学特征显示香沟岩体花岗岩类属于C型埃达克质(adakitic)岩石.岩石初始Sr同位素比值ISr=0.70642~0.70668,εNd(t)=-4.5~-4.0,TDM=1152~1220Ma.香沟岩体具有较低的εNd(t),ISr值和较高的TDM值,同时其Na2O/K2O接近1(Na2O/K2O=0.95~1.10),显示香沟花岗岩不是俯冲洋壳部分熔融形成的Ⅰ型埃达岩或底侵玄武质下地壳熔融所产...     

Neuere Veröffentlichungen

Ohne Zusammenfassung     

Profondità ipocentrali e coefficienti di assorbimento per zone Etnee

Riassunto Si discutono le diverse formule che permettono il calcolo, con i dati macrosismici, delle profondità ipocentrali dei terremoti e dei coefficienti di assorbimento delle zone interessate. Si indicano delle modifiche, nella conduzione dei calcoli richiesti dalla formula delKövesligethy, apportanti notevoli semplificazioni ai calcoli stessi. In base ai metodi indicati vengono studiati i terremoti della regione etnea e particolarmente di quella orientale. Per le profondità ipocentrali i valori ottenuti, compresi fra 0.1 e 2.5 Km, confermano le idee che si hanno sulla genesi dei terremoti della zona. Per i coefficienti di assorbimento invece i risultati, compresi fra 0.03 e 0.35, hanno permesso, di trovare una legge di variazione del coefficiente stesso con la profondità, legge che per la bassa regione orientale ha l'espressione seguente: (x)=0.27e ^–3.5x.

---

Summary They discuss the various formulae which enable to calculate, by means of the macrosismical data, the ipocentral earthquake depths and the absorption coefficients. They propose some modifications in the calculus required by theKövesligethy formula, which simplify considerably these calculations. On the basis of the indicated methods, the earthquakes of the Aetna area, especially those of the eastern side, are examined. The values obtained for the ipocentral depths, comprised between 0.1 and 2.5 Km, confirm the opinion they have on the origin of the earthquakes of this area. On the contrary the results for the absorption coefficients comprised between 0.03 and 0.35 enabled to find a variation law of this coefficient with the depth. For the low eastern region this law has the following form: (x)=0.27e ^–3.5x.

     

Paläomagnetische Untersuchungen im Schilfsandstein (Trias,Km2) Westeuropas

Zusammenfassung Von insgesamt 46 beprobten Profilen aus dem Schilfsandstein (Trias, Km2) Westeuropas wurden bislang 41 Profile mit 343 Einheiten und 870 Handstücken mit 1897 Einzelkernen auf ihren paläomagnetischen Inhalt untersucht.Thermische Entmagnetisierungsversuche an 277 Proben zeigen, daß die natürliche remanente Magnetisierung (NRM) von mehreren, an verschiedene Magnetisierungsträger gebundenen Komponenten getragen wird.Als charakteristische remanente Magnetisierung (CARM), von der angenommen wird, daß sie das zur Ablagerungszeit herrschende Paläofeld abbildet, kristallisiert sich für die Sedimentationsräume Weserbergland und Franken eine Deklination (DR=Deklination rotiert) von 60° und eine Inklination (IR=Inklination rotiert) von 30° (DR/IR 60/30) und für Schwaben und die Nordschweiz DR/IR 240/–30 heraus.Neben der stabilen Paläofeldrichtung werden auch sedimentäre und tektonische Gefüge als weitere stabile Magnetisierungsrichtungen abgebildet. Diese Richtungen liegen der Achse maximaler Suszeptibilität (K1 max) parallel.Unter Annahme einer normalen Polarität des Erdmagnetfeldes zur Zeit der Schilfsandsteinablagerung im Weserbergland und Franken und einer reversen Polarität zur Zeit der Ablagerung in Schwaben und der Nordschweiz errechnet sich ein Paläonordpol bei 111 E 28 N; er fällt damit in die Nähe des Triaspoles der Europäischen Polwanderungskurve (McElhinny, 1973).Für den Ablagerungszeitraum des Raibler Sandsteins in den Südalpen wird ein Paläonordpol bei 128 W 48 N errechnet.Die magnetostratigraphische Zeitskala der Trias (Burek, 1970) kann um die Einstufung des Schilfsandsteins in das höhere obere Karn mit beginnender normaler Polarität und dann reverser Polarität ergänzt werden.

---

In the Schilfsandstein (Triassic, Km2) of Western Europe 41 sections with 343 units and 1897 cores were sampled for palaeomagnetic investigations. By thermal demagnetization experiments different magnetic minerals were determined as carriers of the natural rémanent magnetization (NRM).The characteristic remanent magnetization (CARM) reflecting the palaeofield direction is described in the Weserbergland and Franken by DR/IR 60/30 (DR = declination after tectonic correction/IR=inclination after tectonic correction) and in Schwaben and Northern Switzerland by DR/IR 240/–30.In addition stable directions are reported which are related to sedimentary and tectonic fabric. These directions are parallel to the axis of maximum susceptibility (Klmax).Assuming normal polarity for the magnetic field during deposition of the Schilfsandstein in the Weserbergland and Franken and assuming reversed polarity in Schwaben and Northern Switzerland a palaeonorthpole is estimated at 111 E 28 N. This poleposition fits near the Triassic poleposition of the European polar wandering curve (McElhinny, 1973).The poleposition of the Bergamasker Alps (Raibler Sandstein, Southern Alps) is figured out at 128 W 48 N.The triassic magnetostratigraphic time scale ofBurek (1970) can be completed as far as the Schilfsandstein is to arrange into the highest Upper Carnian starting with normal polarity going on with reversed polarity.

---

Résumé Dans le Grès à roseaux (Trias, Km 2) de l'Europe occidentale, 343 prélèvements provenant de 41 profils et 1897 carrottes extraites de 870 échantillons ont fait l'objet de recherches paléomagnétiques. — Des essais de démagnétisation thermique sur 277 échantillons ont révélé différents minéraux magnétiques comme étant les porteurs de l'aimantation rémanente naturelle (NRM). — L'aimentation rémanente caractéristique (CARM) reflétant la direction du paléochamp magnétique au moment de la sédimentation donne des valeurs de 60/30 pour DR/IR (DR=déclinaison après correction tectonique, — IR=inclinaison après correction tectonique) dans le Weserbergland et en Franconie et 240/– 30 pour DR/IR en Souabe et dans la Suisse septentrionale. — En plus de la direction stable du paléo champ, on a trouvé d'autres directions d'aimentation stables reliées aux structures sédimentaires et tectoniques. Ces directions sont parallèles à l'axe de la susceptibilité magnétique maximale (K1 max). — En supposant une polarité normale du champ magnétique terrestre au moment de la sédimentation du Grès à roseaux dans le Weserbergland et la Franconie, et une polarité inversée pendant sa formation en Souabe et en Suisse septentrionale, il en résulte une position géographique de 111 E et 28° N pour le paléopôle Nord, ce qui coïncide à peu près avec la position du pôle triasique sur la courbe polaire de l'Europe (McElhinny, 1973). Pendant la sédimentation du Grès de Raibler dans les Alpes bergamasques, le paléopôle Nord se trouvait à 128° O 48° N. — L'echelle magnétostratigraphique pour le Trias (Burek, 1970) peut maintenant être complétée en datant le Grès à roseaux dans la partie supérieure du Carnien supérieur, débutant par une aimantation normale et continuant par une aimantation inversée.

---

343 41 ( ) 1897 870 . 277 , — NRM — . — CARM —, , , , , (DR = Deklination rotiert) 60°, (IR = Inklination rotiert) 30° (DR/IR 60/30), DR/IR 240/-30. , . /_1makc. , 111 E 28 N, . ., . 128 W 48 N. (Burek, 1970) . . , .

     

Environmental Geochemistry of Iron and Manganese in Six Himalayan Lakes

The distribution and abundance of iron and manganese, the two important mobile metals, in an aquatic environment have been presented. These metals play an important role in the binding of nutrients and toxic elements by virtue of their high specific area in the oxide form. The concentration of Fe ranged from 1.08 to 5.2 mg/g and that of Mn from 0.27 to 2.17 mg/g. The Dal lake sediments were rich in Fe and those of the Wular lake had the lowest mean concentration of Fe. It was observed that the smaller particle size fractions had a higher metal content in comparison to large size fractions. Data on the selective extraction of Fe and Mn and their accumulation in humus material have also been given.     

模拟CO_2埋藏的煤储层元素迁移实验研究

采用高压超临界CO2地球化学反应器对CO2在煤储层中的地质埋藏进行模拟,利用电感耦合等离子体发射光谱仪(ICP-OES)以及电感耦合等离子体质谱(ICP-MS)分别对淋滤液和煤样中的10种微量元素进行测试,对煤中微量元素在CO2的地质埋藏过程中的迁移进行了实验研究。结果表明:在CO2的地质埋藏过程中对煤的有机组成和无机矿物等均具有改造作用,从而影响到煤中微量元素的赋存和迁移特征,Cr、Zn、Cu等元素迁移能力相对较强,而Co、Ba、V等元素相对较弱;元素迁移能力大小顺序为:CrZnCuNiCdMnCoBaV。     

Seismotectonic deformations related to the 2010 Maule earthquake at different stages of the seismic cycle from satellite geodetic observations

Doklady Earth Sciences - The interpretation of multiannual satellite geodetic observations after the 2010 Maule earthquake is given on the basis of the keyboard concept of the subduction region...