Mineralogical and geochemical study of bentonite deposits of Garhi Chandan area,District Nowshera,Khyber Pakhtunkhwa,Pakistan

The Pliocene-Pleistocene Ghari Chandan Formation consists of lacustrine-fluvio-deltaic deposits exposed in the Attock-Cherat Range. Three beds of bentonite deposits occur in the upper part of the formation. An average thickness of each layer ranges from 0.4 to 1 m with a total strike length of ~5 Km. Montmorillonite and saponite clay minerals with admixtures of quartz, feldspar, muscovite, biotite, and hornblende were identified in these samples. Compositionally these beds are similar and comprised of dioctahedral smectite. The differential thermal analyses of bentonite reveals high thermal stability of the deposits. Detailed mineralogical and geochemical investigations suggest that the Garhi Chandan deposit is a mixture of calcic and sodic bentonite derived from andesitic and trachyandesitic source rock. Heavy metal concentration reduces the overall adsorbing capacity of the deposit.     

Side-by-Side Correlation of Texas Cone Penetration and Standard Penetration Test Blowcount Values

This paper presents side-by-side comparisons of blowcount values for the Texas cone penetration (TCP) test and the standard penetration test (SPT). The comparisons yielded statistically-significant regression models for both coarse-grained soils and fine-grained soils. Consistent with expected trends and published data, the TCP–SPT relationship is nonlinear, with weak to fair correlation strength (R² = 23–44%). For TCP blowcounts (N_{60, TCP}) varying from 25 to 200 blows/30 cm (1 ft), corresponding SPT blowcounts (N_{60, SPT}) are typically 30–60% lower than N_{60, TCP} in fine-grained soils. Likewise, corresponding N_{60, SPT} blowcounts are 10–70% lower than N_{60, TCP} in coarse-grained soils, all other things being equal. Comparative data were obtained from published sources and from project-specific field research sites used for full-scale deep foundation load tests. The final dataset consisted of 225 test pairs obtained in similar soils and geomaterials, at equivalent depths, with all blowcounts normalized to 30 cm (12 in.) penetration (i.e., blows/30 cm or blows/ft) within the bounds of typical test precision, and corrected to 60% hammer efficiency. The generally weak correlations do not support conversion of N_{60, TCP} to N_{60, SPT} (or vice versa) to compute foundation capacity for final design. But, engineers can certainly get an intuitive feel about site conditions and preliminary foundation capacity by using the correlation equations to translate their knowledge of one test to the other. This study extends previous work by formally comparing and contrasting the similar yet different SPT and TCP test methods in such a way as to make the results useful to users of both tests and to the broader geotechnical engineering community.     

Application of plurigaussian simulation to delineate the layout of alteration domains in Sungun copper deposit

An accurate estimation of mineral grades in ore deposits with heterogeneous spatial variations requires defining geological domains that differentiate the types of mineralogy, alteration and lithology. Deterministic models define the layout of the domains based on the interpretation of the drill holes and do not take into account the uncertainty in areas with fewer data. Plurigaussian simulation (PGS) can be an alternative to generate multiple numerical models of the ore body, with the aim of assessing the uncertainty in the domain boundaries and improving the geological controls in the characterization of quantitative attributes. This study addresses the application of PGS to Sungun porphyry copper deposit (Iran), in order to simulate the layout of four hypogene alteration zones: potassic, phyllic, propylitic and argillic. The aim of this study is to construct numerical models in which the alteration structures reflect the evolution observed in the geology.     

Mapping recharge from space: roadmap to meeting the grand challenge

Fields of diffuse recharge flux play pivotal roles in: (1) linking surface and subsurface hydrologic systems, (2) controlling the biogeochemistry of terrestrial systems, and (3) determining the sustainability of well withdrawals from aquifers. This hydrologic flux is intimately related to the distribution and functioning of vegetation cover and type. In turn, it also plays a significant role in the distribution of vegetation. Until now, recharge has been mostly estimated as residual of either surface or subsurface water balance. In situ instruments for measurement of this quantity are difficult to implement and maintain. Long-term and spatially explicit (mapped) monitoring of recharge flux have been elusive goals. A review is presented of the possible spaceborne and airborne remote sensing and data interpretation techniques that may address the grand challenge of recharge mapping on large scales. The approaches rely on microwave remote sensing in order to measure land surface states in the presence of atmosphere and vegetation cover that attenuate and disturb the signal as it travels from the surface to the sensor. The emphasis is on radar systems that also have beneficial ground spatial resolution characteristics. Finally, examples of two candidate space-borne systems are presented as feasible approaches to the required measurements.