Donald H. Lindsley

Bio: Donald H. Lindsley is an academic researcher from Stony Brook University. The author has contributed to research in topics: Phase (matter) & Oxide minerals. The author has an hindex of 7, co-authored 7 publications receiving 913 citations.

A geochemical classification for granitic rocks

Abstract: This geochemical classification of granitic rocks is based upon three INTRODUCTION variables. These are FeO/(FeO + MgO) = Fe-number [or Although granitoids are the most abundant rock types FeO/(FeO + MgO) = Fe∗], the modified alkali–lime index in the continental crust, no single classification scheme (MALI) (Na2O + K2O – CaO) and the aluminum saturation has achieved widespread use. Part of the problem in index (ASI) [Al/(Ca – 1·67P + Na + K)]. The Fe-number granite classification is that the same mineral assemblage, (or Fe∗) distinguishes ferroan granitoids, which manifest strong iron quartz and feldspars with a variety of ferromagnesian enrichment, from magnesian granitoids, which do not. The ferroan minerals, can be achieved by a number of processes. and magnesian granitoids can further be classified into alkalic, Granitoids can form from differentiation of any hyalkali–calcic, calc-alkalic, and calcic on the basis of the MALI persthene-normative melt and from partial melting of and subdivided on the basis of the ASI into peraluminous, metamany rock types. Furthermore, granitic melts may be luminous or peralkaline. Because alkalic rocks are not likely to be derived solely from crustal components, may form from peraluminous and calcic and calc-alkalic rocks are not likely to be evolved mantle-derived melts, or may be a mixture peralkaline, this classification leads to 16 possible groups of granitic of crustal and mantle-derived melts. Because of this rocks. In this classification most Cordilleran granitoids are magnesian complexity, petrologists have relied upon geochemical and calc-alkalic or calcic; both metaluminous and peraluminous classifications to distinguish between various types of types are present. A-type granitoids are ferroan alkali–calcic, although granitoids. Approximately 20 different schemes have evolved over the past 30 years [see Barbarin (1990, 1999) some are ferroan alkalic. Most are metaluminous although some are for a summary thereof]. Most of these schemes are either peraluminous. Caledonian post-orogenic granites are predominantly genetic or tectonic in nature. This paper is an attempt magnesian alkali–calcic. Those with <70 wt % SiO2 are domto present a non-genetic, non-tectonic geochemical clasinantly metaluminous, whereas more silica-rich varieties are comsification scheme that incorporates the best qualities of monly peraluminous. Peraluminous leucogranites may be either the previous schemes, and to explain the petrologic magnesian or ferroan and have a MALI that ranges from calcic to processes that makes this scheme work. alkalic.

Melting of a dry peridotite KLB‐1 up to 14 GPa: Implications on the Origin of peridotitic upper mantle

Abstract: Melting phase relations of a fertile lherzolite KLB-1 have been studied in the pressure range from 1 atm to 14 GPa (140 kbar). Olivine is the liquidus phase at all pressures studied. The second mineral to crystallize changes with increasing pressure; chromian spinel (1 atm), Ca-poor orthopyroxene (up to 3 GPa), pigeonitic clinopyroxene (up to 7 GPa), pyrope-rich garnet (above 7 GPa). The melting temperature interval of the peridotite is more than 600°C wide at 1 atm but narrows to about 150°C at 14 GPa. The partial melts along the peridotite solidus become increasingly more MgO-rich as pressure increases throughout the pressure range studied. At 5–7 GPa, the partial melts formed within 50°C of the solidus contain more than 30 wt % MgO and are very similar to Al-undepleted-type peridotitic komatiite which is common in Archean volcanic terrains. Due to the increase of enstatite component in clinopyroxene solid solution at high pressure and temperature, the orthopyroxene liquidus field narrows as pressure increases and disappears at 3.5 GPa. Harzburgites which are common in the basal peridotite in ophiolite suites may have been produced as residues by partial melting at relatively shallower depths ( 100 km). A diapiric model is consistent with the genesis of komatiite magma by partial melting of mantle peridotite at 150–200 km depth. Based on the following observations, (1) convergence of the liquidus and solidus of the peridotite at pressures > 14 GPa, (2) the near solidus partial melt composition very close to the bulk rock at 14 GPa, and (3) change in liquidus mineral from olivine to majorite garnet at pressures between 16 and 20 GPa in preliminary experiments, it is proposed that the upper mantle peridotite was generated originally as a magma (or magmas) by partial melting of the primitive earth at 400–500 km depth.

An introduction to metamorphic petrology

Abstract: This second edition is fully updated to include new developments in the study of metamorphism as well as enhanced features to facilitate course teaching. It integrates a systematic account of the mineralogical changes accompanying metamorphism of the major rock types with discussion of the conditions and settings in which they formed. The use of textures to understand metamorphic history and links to rock deformation are also explored. Specific chapters are devoted to rates and timescales of metamorphism and to the tectonic settings in which metamorphic belts develop. These provide a strong connection to other parts of the geology curriculum. Key thermodynamic and chemical concepts are introduced through examples which demonstrate their application and relevance. Richly illustrated in colour and featuring end-of-chapter and online exercises, this textbook is a comprehensive introduction to metamorphic rocks and processes for undergraduate students of petrology, and provides a solid basis for advanced study and research.

Optimized standard state and solution properties of minerals

Abstract: An internally consistent set of standard state and mixing properties has been derived for olivine, or- thopyroxene, garnet, cordierite, and ilmenite in the sys- tem FeO-MgO-CaO-Al2O3-TiO2-SiO2-H2O from analy- sis of relevant phase equilibrium and thermophysical data. Solubility of Al 2 O 3 in orthopyroxene is accounted for in addition to Fe-Mg mixing. Added confidence in the retrieved properties stems from the representation within reasonable uncertainties of data for seven linearly dependent Fe-Mg exchange equilibria, as well as net transfer equilibria, among the above phases. Critical to successful analysis was the extension of the mathemati- cal programming technique to include bulk composition constraints which force an observed assemblage of fixed composition to be stable at experimentally studied condi- tions. The final optimization reproduces the extremely tight constraints on endmember properties while invok- ing very simple macroscopic solution models that afford an excellent opportunity for extrapolation beyond the data considered in this study. Compatibility among the experimental data is improved markedly by incorpora- tion of recently published Cp data on pyrope and forster- ite. Electrochemical data defining the oxygen fugacity of Fe-Fa-Qz, Fa-Mt-Qz, and Mt-Hm allow excellent compatibility of almandine thermochemical properties derived from phase equilibrium data obtained at both reducing (Fe-Wst) and oxidizing (Hm-Mt) conditions. Analysis of the combined data involving endmembers and solid solutions removes many of the ambiguities in mixing property magnitudes that arise in analyses of more restricted sets of data. In addition, the consider- ation of the solid solution data allows further refinement of some endmember properties. Nonideal mixing parameters, although correlated, are well defined by the combination of experimental data, with G Ol .G Ilm .G Gt .G Opx .G Cd , and 0.7,W Ol ,4.1 kJyatom of iso- morphous Fe-Mg at 1000 K. Experiments defining the Al2O3 solubility of Opx in equilibrium with Gt and Cd1Qz define negative Fe-Al interactions that have an important effect on Fe-Mg partitioning in Opx. Applica- tions of this data set to high-grade metamorphic rocks are described in a companion paper, published as part II of the present work.

A two-pyroxene thermometer

Abstract: Experimentally determined pyroxene phase relations at 800-1200 C are combined with calculated phase equilibria for the Di-En and Hd-Fs joins to yield a graphical two-pyroxene thermometer that should be suitable for a wide variety of rocks from the earth, the moon, and meteorites. The thermometer can be used directly with natural pyroxenes having low contents of Al and other minor components. Samples having higher contents of 'other' components require special projection onto the Ca-Mg-Fe pyroxene quadrilateral; Wo, En, and Fs as normally calculated will not yield correct temperatures. The special projection is required to approximate the activities of those components in natural pyroxenes. Whereas the effects of pressure are nonnegligible, they can be corrected for. It is pointed out that use of the thermometer for slowly cooled rocks may pose special problems if the pyroxenes have undergone granule exsolution (coalescence of exsolved material to form separate grains).