Mineral Resources

Summary Trace-element data for mid-ocean ridge basalts (MORBs) and ocean island basalts (OIB) are used to formulate chemical systematics for oceanic basalts. The data suggest that the order of trace-element incompatibility in oceanic basalts is Cs ≈ Rb ≈ (≈ Tl) ≈ Ba(≈ W) > Th > U ≈ Nb = Ta ≈ K > La > Ce ≈ Pb > Pr (≈ Mo) ≈ Sr > P ≈ Nd (> F) > Zr = Hf ≈ Sm > Eu ≈ Sn (≈ Sb) ≈ Ti > Dy ≈ (Li) > Ho = Y > Yb. This rule works in general and suggests that the overall fractionation processes operating during magma generation and evolution are relatively simple, involving no significant change in the environment of formation for MORBs and OIBs. In detail, minor differences in element ratios correlate with the isotopic characteristics of different types of OIB components (HIMU, EM, MORB). These systematics are interpreted in terms of partial-melting conditions, variations in residual mineralogy, involvement of subducted sediment, recycling of oceanic lithosphere and processes within the low velocity zone. Niobium data indicate that the mantle sources of MORB and OIB are not exact complementary reservoirs to the continental crust. Subduction of oceanic crust or separation of refractory eclogite material from the former oceanic crust into the lower mantle appears to be required. The negative europium anomalies observed in some EM-type OIBs and the systematics of their key element ratios suggest the addition of a small amount (⩽1% or less) of subducted sediment to their mantle sources. However, a general lack of a crustal signature in OIBs indicates that sediment recycling has not been an important process in the convecting mantle, at least not in more recent times (⩽2 Ga). Upward migration of silica-undersaturated melts from the low velocity zone can generate an enriched reservoir in the continental and oceanic lithospheric mantle. We propose that the HIMU type ( eg St Helena) OIB component can be generated in this way. This enriched mantle can be re-introduced into the convective mantle by thermal erosion of the continental lithosphere and by the recycling of the enriched oceanic lithosphere back into the mantle.

An empirical strength criterion for rocks and rock masses is proposed. The nonlinear criterion includes the uniaxial compressive strength of the intact rock material and introduces two dimensionless parameters, m and s. The parameter m varies with rock type, the angle of interblock or interparticle friction and the degree of block or particle interlock. The parameter s varies from 1.0 for intact rock material to zero for granular aggregates and depends on the interparticle tensile strength and the degree of interlock within the rock mass. For anisotropic rock, both m and s vary with the orientations of the planes of weakness to the principal stress directions. Approximate relationships between rock type, rock mass quality indices, and the rock mass strength parameters m and s, are presented. These relationships have been found useful in preliminary design calculations for slopes and underground excavations in jointed rock.

It is standard practice that a positive reversal test is claimed on the basis of inability to reject the hypothesis that two distributions share a common mean direction, and thus the claim of a positive reversal test is in fact often based on a lack of information. This is unsatisfactory. Therefore it is suggested that positive reversal tests should be classified according to the amount of information that was available for the test. This amount of information is readily indicated by the critical angle (e.g., at the 95 per cent confidence level) between the two sample mean directions at which the hypothesis of common mean direction for the distributions would be rejected. It is recommended that 5", 10" and 20" be used as the breakpoints in the classification.

Abstract Machine contouring must not introduce information which is not present in the data. The one-dimensional spline fit has well defined smoothness properties. These are duplicated for two-dimensional interpolation in this paper, by solving the corresponding differential equation. Finite difference equations are deduced from a principle of minimum total curvature, and an iterative method of solution is outlined. Observations do not have to lie on a regular grid. Gravity and aeromagnetic surveys provide examples which compare favorably with the work of draftsmen.

Abstract Lead isotopic compositions of young volcanic rocks from different tectonic environments have distinctive characteristics. Their differences are evaluated within the framework of global tectonics and mantle differentiation. Ocean island leads are in general more radiogenic than mid-ocean ridge basalt (m.o.r.b.) leads. They form linear trends on lead isotopic ratio plots. Many of the trends extend toward the field of m.o.r.b. On plots of 207P b /204Pb against 206Pb /204Pb, their slopes are generally close to 0.1. Island arc leads in general are confined between sediment and m.o.r.b. type leads with slopes of ca. 0.30 on a plot of 207P b /204Pb against 206Pb /204Pb. Pb, Sr and Nd isotopic data of Hawaiian volcanics are closely examined. Data from each island support a two-component mixing model. However, there is a lack of full range correlation between islands, indicating heterogeneity in the end members. This mixing model could also be extended to explain data from the Iceland-Reykjanes ridge, and from 45° N on the Atlantic Ridge. The observed chemical and isotopic heterogeneity in young volcanic rocks is considered to be a result of long-term as well as short-term mantle differentiation and mixing. Lead isotopic data from ocean islands are interpreted in terms of mantle evolution models that involve long-term (more than 2 Ga) mantle chemical and isotopic heterogeneity. Incompatible element enriched ‘plume’-type m.o.r.b. have Th/U ratios ca. 3.0 too low and Rb/Sr ratios ca. 0.04 too high to generate the observed 208Pb and 87Sr respectively for long periods of time. Elemental fractionation in the mantle must have occurred very recently. This conclusion also applies to mantle sources for ocean island alkali basalts and nephelinites. Depletion of incompatible elements in m.o.r.b. sources is most probably due to continuous extraction of silicate melt and/or fluid phase from the low-velocity zone throughout geological time. Data on Pb isotopes, Sr isotopes and trace elements on volcanic rocks from island arcs are evaluated in terms of mixing models involving three components derived from (1) sub-arc mantle wedge, (2) dehydration or partial melting of subducted ocean crust, and (3) continental crust contamination. In contrast to the relation between 87Sr/86Sr and 143Nd /144Nd ratios of ocean volcanics, there is a general lack of correlation between Pb and Sr isotopic ratios except that samples with very radiogenic Pb (206Pb /204Pb > 19.5) have low 87Sr/87Sr ratios (0.7028- 0.7035). These samples also have inferred source Th/U ratios (3.0-3.5) not high enough to support long-term growth of 208Pb. Data suggest that their mantle sources have long-term integrated depletion in Rb, Th, U and light r.e.e. High 238U /204Pb (y a)values required by the Pb isotopic data are most probably due to depletion of Pb by separation of a sulphide phase. Relations between Pb, Sr and Nd isotopic ratios of young volcanic rocks could be explained by simultaneous upward migration of silicate and/or fluid phase and downward migration of a sulphide phase in a differentiating mantle.ration of a sulphide phase in a differentiating mantle.

Research Article| March 01, 1986 Detachment faulting and the evolution of passive continental margins G. S. Lister; G. S. Lister 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia Search for other works by this author on: GSW Google Scholar M. A. Etheridge; M. A. Etheridge 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia Search for other works by this author on: GSW Google Scholar P. A. Symonds P. A. Symonds 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information G. S. Lister 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia M. A. Etheridge 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia P. A. Symonds 1Bureau of Mineral Resources, Geology and Geophysics, Canberra City, A.C.T. 2601, Australia Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1986) 14 (3): 246–250. https://doi.org/10.1130/0091-7613(1986)14<246:DFATEO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation G. S. Lister, M. A. Etheridge, P. A. Symonds; Detachment faulting and the evolution of passive continental margins. Geology 1986;; 14 (3): 246–250. doi: https://doi.org/10.1130/0091-7613(1986)14<246:DFATEO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Major detachment faults play a key role in the lithospheric extension process in the Basin and Range province and may also be important in other continental extension terranes. Such detachment faulting leads to an inherent asymmetry of extensional structure and of uplift/subsidence patterns. Detachment models developed for the formation of metamorphic core complexes can also be applied to the formation of passive continental margins. We therefore suggest the existence of upper-plate and lower-plate passive margins. These give rise to a complementary asymmetry of opposing margins after continental breakup. Transfer faults offset marginal features and allow margins to switch from upper-plate to lower-plate characteristics along strike. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Journal Article The Importance of Residual Source Material (Restite) in Granite Petrogenesis Get access B. W. CHAPPELL, B. W. CHAPPELL 1Department of Geology, The Australian National UniversityCanberra, ACT 2601 Australia Search for other works by this author on: Oxford Academic Google Scholar A. J. R. WHITE, A. J. R. WHITE 2Department of Geology, La Trobe UniversityBundoora, Victoria 3083 Australia Search for other works by this author on: Oxford Academic Google Scholar D. WYBORN D. WYBORN 3Bureau of Mineral ResourcesCanberra, ACT 2601 Australia Search for other works by this author on: Oxford Academic Google Scholar Journal of Petrology, Volume 28, Issue 6, December 1987, Pages 1111–1138, https://doi.org/10.1093/petrology/28.6.1111 Published: 01 December 1987 Article history Received: 13 November 1985 Accepted: 01 June 1987 Published: 01 December 1987

The limited resources and uneven distribution of lithium stimulate strong motivation to develop new rechargeable potassium-ion batteries that use alternative charge carriers.

Transition-metal activated phosphors are an important family of luminescent materials that can produce white light with an outstanding color rendering index and correlated color temperature for use in light-emitting diodes.

Abstract An enthalpy formulation for convection/diffusion phase change is developed. The essential feature of this formulation is that latent heat effects are isolated in a source term. This formulation is applicable to a general convection/diffusion phase change, i.e. it is valid in the cases of evolution of latent heat either at an isothermal temperature or over a temperature range. Before implementation of the enthalpy formulation, a technique is required to ensure that velocities predicted to be in a solid region actually take the value zero. Three alternative schemes for achieving this are presented. The enthalpy formulation and velocity correction schemes are independent of the numerical technique. As an example of how the method can be implemented a control volume numerical discretization is chosen. This implementation is applied to two test problems: a solidification phase change in a cavity under conduction and the same phase change under conduction and natural convection. The natural convection problem is used to compare the performances of the various velocity correction schemes. The results of the problems are in good agreement with available analytical solutions and previous numerical solutions.

Previous techniques for judging the significance of a palaeomagnetic fold test are either invalid or insufficiently flexible. It is shown that under appropriate circumstances an isolated-observation test may be added to the range of statistical tests used to judge a fold test. A powerful new test is developed based on a test statistic that is sensitive to correlation between the distribution of site-mean directions about the overall mean direction and the tectonic corrections. This test is sufficiently flexible that it should cover most circumstances.

The question of whether basaltic rocks in continental flood basalt provinces are primary magmas or whether they are descended in general from picritic parent magmas is reviewed. It is suggested that the latter is more likely to be correct on the evidence of phase relations and the relative rareness of mantle materials with appropriate Fe/Mg ratios. Major element variations in the residual liquids of fractional and equilibrium crystallization of basaltic magmas are modelled for a variety of crystallizing assemblages. It is concluded that crystallization of olivine, clinopyroxene, and plagioclase has a marked effect on buffering chemical change in many important elements. It is this effect which accounts for the apparent uniformity of large volumes of flood basalts, not, as has sometimes been supposed, a series of implausible coincidences in the amount of material fractionated from each magma batch. It is further argued that much of the variation seen in basalts may be imposed by polybaric fractionation operating throughout crustal depths, that is at pressures up to at least 12 kb. Parental picritic magmas rising from the mantle reach the surface in exceptional areas of crustal thinning. More usually, however, it is suggested that they intrude the base of the crust as a series of sills which differentiate into upper gabbroic and lower ultramafic portions. Much of the ‘low pressure’ fractionation of basaltic magmas may take place in this deep crustal sill complex and evolved liquids are transmitted to the surface as their density becomes sufficiently low. This implies that in areas of flood vulcanism a potentially large new contribution to the crust is made by under-plating, the volumes of concealed cumulates being at least as large as the amount of erupted surface lava.

Rare earths are used in the renewable energy technologies such as wind turbines, batteries, catalysts and electric cars. Current mining, processing and sustainability aspects have been described in this paper. Rare earth availability is undergoing a temporary decline due mainly to quotas being imposed by the Chinese government on export and action taken against illegal mining operations. The reduction in availability coupled with increasing demand has led to increased prices for rare earths. Although the prices have come down recently, this situation is likely to be volatile until material becomes available from new sources or formerly closed mines are reopened. Although the number of identified deposits in the world is close to a thousand, there are only a handful of actual operating mines. Prominent currently operating mines are Bayan Obo in China, Mountain Pass in the US and recently opened Mount Weld in Australia. The major contributor to the total greenhouse gas (GHG) footprint of rare earth processing is hydrochloric acid (ca. 38%), followed by steam use (32%) and electricity (12%). Life cycle based water and energy consumption is significantly higher compared with other metals.

The age distribution of the crust is a fundamental parameter in modeling continental evolution and the rate of crustal accretion through Earth’s history, but this is usually estimated from surface exposures. The exposed Yangtze craton in eastern China consists mainly of Proterozoic rocks with rare Archean outcrops. However, the U-Pb ages and Hf isotope systematics of xenocrystic zircons brought to the surface in lamproite diatremes from three Proterozoic outcrop areas of the craton suggest the widespread presence of unexposed Archean basement, with zircon age populations of 2900–2800 Ma and 2600– 2500 Ma and Hf model ages of 2.6 to ca. 3.5 Ga or older. The zircons also record thermal events reworked on the craton ca. 2020 Ma (remelting of older crust) and 1000–850 Ma (addition of juvenile mantle material). The observation of deep crust significantly older than the upper crust will require revision of models for the rates of crustal generation through time. The National Natural Science Foundation of China (40425002), the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT-IRT0441), and the Australian Research Council (ARC) Discovery Project and Linkage International grants (O’Reilly and Griffin).

Calculations of support pressure—tunnel convergence relationships, or ground response curves are used to improve understanding or rocksupport interaction and to aid in the dimensioning of tunnel support elements. Methods of response curve calculation are presented for a tunnel of circular cross‐section excavated in a rock mass initially subjected to a hydrostatic in situ stress field. Plane strain conditions are assumed. The two solutions presented use nonlinear peak and residual rock mass strength criteria. Particular consideration is given to the influence of plastic volumetric strains in the rock mass surrounding the tunnel. A closed‐form solution is presented for an elastic‐brittle‐plastic material behavior model in which post‐peak dilatancy occurs at a constant rate with major principal strain. A second solution is presented as a stepwise sequence of calculations for an elastic‐strain, softening‐plastic model in which post‐peak dilatancy occurs at a lower rate with major principal strain in the constant strength plastic zone than in the strain softening zone. These two solutions are applied in illustrative examples.

Abstract The aim of this paper is to categorize the major fixed grid formulations and solution methods for conduction controlled phase change problems. Using a two phase model of a solid/liquid phase change, the basic enthalpy equation is derived. Starting from this equation, a number of alternative formulations are obtained. All the formulations are reduced to a standard form. From this standard form, finite element and finite volume discretizations are developed. These discretizations are used as the basis for a number of fixed grid numerical solution techniques for solidification phase change systems. In particular, various apparent capacity and source based enthalpy methods are explored.

Research Article| May 01, 1992 An early India-Asia contact: Paleomagnetic constraints from Ninetyeast Ridge, ODP Leg 121 Chris T. Klootwijk; Chris T. Klootwijk 1Bureau of Mineral Resources, Canberra, ACT 2601, Australia Search for other works by this author on: GSW Google Scholar Jeff S. Gee; Jeff S. Gee 2Scripps Institution of Oceanography, La Jolla, California 92093 Search for other works by this author on: GSW Google Scholar John W. Peirce; John W. Peirce 3Geophysical Exploration & Development Corporation, Calgary, Alberta T2P 0Z3, Canada Search for other works by this author on: GSW Google Scholar Guy M. Smith; Guy M. Smith 4Department of Earth and Planetary Sciences, St. Louis University, Laclede Station, St. Louis, Missouri 63156 Search for other works by this author on: GSW Google Scholar Phil L. McFadden Phil L. McFadden 1Bureau of Mineral Resources, Canberra, ACT 2601, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Chris T. Klootwijk 1Bureau of Mineral Resources, Canberra, ACT 2601, Australia Jeff S. Gee 2Scripps Institution of Oceanography, La Jolla, California 92093 John W. Peirce 3Geophysical Exploration & Development Corporation, Calgary, Alberta T2P 0Z3, Canada Guy M. Smith 4Department of Earth and Planetary Sciences, St. Louis University, Laclede Station, St. Louis, Missouri 63156 Phil L. McFadden 1Bureau of Mineral Resources, Canberra, ACT 2601, Australia Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (5): 395–398. https://doi.org/10.1130/0091-7613(1992)020<0395:AEIACP>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Chris T. Klootwijk, Jeff S. Gee, John W. Peirce, Guy M. Smith, Phil L. McFadden; An early India-Asia contact: Paleomagnetic constraints from Ninetyeast Ridge, ODP Leg 121. Geology 1992;; 20 (5): 395–398. doi: https://doi.org/10.1130/0091-7613(1992)020<0395:AEIACP>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract New paleomagnetic results from sedimentary rock and basement of the Ninetyeast Ridge (Ocean Drilling Program Leg 121, Sites 756-758) detail the northward movement of the Indian plate for the past 80 m.y. Analysis of the combined paleolatitude-age profile indicates a distinct reduction in India's northward movement rate at 55+ Ma, interpreted as completion of suturing of Greater India and Asia. India's northward motion slowed from 18-19.5 cm/yr to 4.5 cm/yr for the location of Site 758. Comparison of this profile with paleomagnetic data from the wider Himalayan region indicates that initial contact between northwestern Greater India and southern Asia was already established by Cretaceous-Tertiary time. This supports a possible causal link between the India-Asia convergence and the Deccan Traps extrusion. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Metal additive manufacturing (AM) refers to any process of making 3D metal parts layer-upon-layer via the interaction between a heating source and feeding material from a digital design model. The rapid heating and cooling attributes inherent to such an AM process result in heterogeneous microstructures and the accumulation of internal stresses. Post-processing heat treatment is often needed to modify the microstructure and/or alleviate residual stresses to achieve properties comparable or superior to those of the conventionally manufactured (CM) counterparts. However, the optimal heat treatment conditions remain to be defined for the majority of AM alloys and are becoming another topical issue of AM research due to its industrial importance. Existing heat treatment standards for CM metals and alloys are not specifically designed for AM parts and may differ in many cases depending on the initial microstructures and desired properties for specific applications. The purpose of this paper is to critically review current knowledge and discuss the influence of post-AM heat treatment on microstructure, mechanical properties, and corrosion behavior of the major categories of AM metals including steel, Ni-based superalloys, Al alloys, Ti alloys, and high entropy alloys. This review clarifies significant differences between heat treating AM metals and their CM counterparts. The major sources of differences include microstructural heterogeneity, internal defects, and residual stresses. Understanding the influence of such differences will benefit industry by achieving AM metals with consistent and superior balanced performance compared to as-built AM and CM metals.

We have determined the abundances of 16O, 17O, and 18O in 31 lunar samples from Apollo missions 11, 12, 15, 16, and 17 using a high-precision laser fluorination technique. All oxygen isotope compositions plot within +/-0.016 per mil (2 standard deviations) on a single mass-dependent fractionation line that is identical to the terrestrial fractionation line within uncertainties. This observation is consistent with the Giant Impact model, provided that the proto-Earth and the smaller impactor planet (named Theia) formed from an identical mix of components. The similarity between the proto-Earth and Theia is consistent with formation at about the same heliocentric distance. The three oxygen isotopes (delta17O) provide no evidence that isotopic heterogeneity on the Moon was created by lunar impacts.

Rare earth elements (REE) are indispensable to infrastructure, technology, and modern lifestyles, which has led to an increasing demand for these elements. The current global rare earth oxides (REO) market is dominated by Chinese production, which peaked in 2006 at 133,000 tonnes REO per year, accounting for some 97.1% of global production, causing concern about the long-term supply of REE resources. Although the REE consist of 17 individual elements (15 lanthanides plus scandium and yttrium) that are hosted by numerous types of mineralization, the relatively modest scale of the global REE mining sector has limited our knowledge of REE mineral resources and mineralizing systems compared to metals such as copper and iron, which are produced in much larger quantities. In order to quantitatively analyze the mineralogy, concentrations, and geologic types of REE deposits, we compiled a global dataset of REE mineral resources based on the most recently available data (2013-2014). This compilation yields minimum global contained total rare earth oxides plus yttrium oxide (TREO + Y) resources of 619.5 Mt split between 267 deposits. Deposits with available grade and tonnage data (260 of the 267 deposits in our database) contain some 88,483 Mt of mineral resources at an average concentration of 0.63% TREO + Y, hosting 553.7 Mt TREO + Y. Of the 267 total deposits in our database, some 160 have mineral resources reported using statutory mining codes (e.g., JORC, NI43-101, SAMREC), with the remaining 107 projects having CRIRSCO-noncompliant mineral resources that are based on information available in the industry literature and peer-reviewed scientific articles. Approximately 51.4% of global REO resources are hosted by carbonatite deposits, and bastnäsite, monazite, and xenotime are the three most significant REE minerals, accounting for ≥90% of the total resources within our database.