Chromite and PGE in the Logar Ophiolite Complex, Afghanistan

The Logar Ophiolite Complex (LOC) is located 30 km south of Kabul, Afghanistan, and extends over approximately 2000 km2. It comprises a lower lherzolitic-dunitic-harzburgitic-gabbro ultramafic-mafic unit that passes upwards into a dolerite dyke complex, basaltic pillow lavas and an uppermost sequence of volcaniclastic- and terrigenous-dominated sedimentary units. The ophiolite represents an obducted remnant of intra-Tethyan basin oceanic crust, thrust onto a platform-style cover component of the Kabul Terrane during the Himalayan orogeny. Platinum group minerals have been detected for the first time in chromitites and ultramafic units from the LOC. Two distinct types of chromitites and ultramafic lithologies with different origins have also been identified in this study. The first type is a low Cr, PGE-poor chromitite interpreted to have been produced in a mid ocean ridge (MOR) environment. The second type is a high Cr, relatively PGE-rich dunite and peridotite from a boninitic magma produced in a supra-subduction zone (SSZ) setting. Platinum group element (PGE) abundances in these chromitites average 12 ppb and 26 ppb for PtzPdzRh for the dunite and peridotite. Chondrite-normalised PGE patterns have two distinct trends: (a) the MOR rocks have a positive Ru anomaly with a negative Pt anomaly and a generally negative slope; and (b) the SSZ rocks show weak positive Ru and Pt anomalies and a positive slope. It is concluded that the negative sloping pattern is typical of PGE in most ophiolites elsewhere. In contrast, the positively sloping pattern is more unusual and may indicate PGE remobilisation and enrichment

The Impact of Macroeconomic Announcementson Emerging Market Bonds

This paper examines how emerging bond markets react to macroeconomic announcements. Global bond spreads respond to rating actions and changes in global interest rates rather than domestic data and policy announcements. All announcements affect market volatility. Data and policy announcements reduce uncertainty and stabilize the trading environment, while rating actions cause greater volatility. Results are broadly robust to country-specific and panel analyses, assuming conditional variance and controlling for the surprise content of news. In subsamples, announcements are found to matter less for countries with more transparent policies and higher credit ratings. In a crisis, rating actions become less important, and investors focus more on simple and timely indicators, like CPI.Announcements;bond, equation, bonds, financial markets, anova, statistic, independent variables, dummy variables, standard errors, bond markets, bond market, equations, independent variable, market bond, bond spreads, emerging market bonds, emerging market bond, statistics, bond prices, treasury bond, stock market, outliers, dummy variable, emerging bond markets, global bond, surveys, international bond, standard deviations, international financial markets, sovereign bonds, autocorrelation, time series, reserve requirements, econometrics, global bond market, treasury bonds, stock prices, constant variance, survey, bond index, financial economics, standard deviation, bond returns, deposit interest rates, correlation, stock returns, lagrange multiplier test, measurement errors, brady bonds, bond funds, statistical data, statistical information, stock markets, bond futures, high-yield bond, index bond, stock market index, eurobonds, global bond markets, international bonds, brady bond, deposit interest, statistical significance, bond investors, dollar bond, fitted value, financial stability, futures market, covariance, computation, sovereign bond, random error, constant mean, predictions, dollar bonds, maximum likelihood method