Search

Cognitive models provide a substantively meaningful quantitative description of latent cognitive processes. The quantitative formulation of these models supports cumulative theory building and enables strong empirical tests. However, the nonlinearity of these models and pervasive correlations among model parameters pose special challenges when applying cognitive models to data. Firstly, estimating cognitive models typically requires large hierarchical data sets that need to be accommodated by an appropriate statistical structure within the model. Secondly, statistical inference needs to appropriately account for model uncertainty to avoid overconfidence and biased parameter estimates. In the present work, we show how these challenges can be addressed through a combination of Bayesian hierarchical modeling and Bayesian model averaging. To illustrate these techniques, we apply the popular diffusion decision model to data from a collaborative selective influence study.

Unlike the chemical composition and diagenetic modification of buried bones, subaqueous archaeological bone diagenesis has not been studied in detail. This observational work presents a macroscopic and microscopic characterization of 11 variably preserved archaeological terrestrial mammalian bones submerged in seawater and/or surrounded by marine sediment for 169–347 years. In situ trace element analysis was undertaken to identify geochemical fingerprints of diagenesis. The analyzed bones belong to a collection of underwater archaeological faunal materials excavated from four shipwreck sites. With one exception, all archaeological bones were fragmented, some were also heavily stained, and in two samples, the damage to the cortical layer was extensive. Bioerosion was assessed by scanning electron microscopy (SEM), and bone trace element chemistry (by laser ablation inductively coupled mass spectrometry—LA-ICP-MS) was compared with that of an unsubmerged modern sheep bone control. In the control, several trace elements were low in concentration (weighted mean concentration <1 ppm; Cr, Co, Ni, Cu, Y, rare earth elements, Th, U). In the submerged archaeological bones, the weighted mean concentration of Li, Cr, Cu, and U was enriched relative to the modern sheep bone, whereas Rb and Ba were depleted. The best-preserved bone, recovered from Batavia, showed less variation in trace element patterns compared with the more poorly preserved bones. The only archaeological bone with preserved macroscopic structure and cortex showed a gradual decrease in trace element concentration from the outer surface towards the medullary cavity, whereas in samples where more cortical damage was noted, the distribution of these elements is more irregular. With the exception of Cu and Cr, the elements focused on in this work (Li, U, Rb, and Ba) are nonessential to life, supported by their low concentration in the modern sheep bone (with the exception of Ba). The results suggest that early macr

Contains fulltext : 226718.pdf (Publisher’s version ) (Open Access), Despite the increasing popularity of Bayesian inference in empirical research, few practical guidelines provide detailed recommendations for how to apply Bayesian procedures and interpret the results. Here we offer specific guidelines for four different stages of Bayesian statistical reasoning in a research setting: planning the analysis, executing the analysis, interpreting the results, and reporting the results. The guidelines for each stage are illustrated with a running example. Although the guidelines are geared towards analyses performed with the open-source statistical software JASP, most guidelines extend to Bayesian inference in general.

Samples from fresh and propylitically altered rocks from the Black Mountain porphyry Cu-Au deposit were used to study the suitability of apatite as an indicator of the source, chemistry, and evolution of magma and hydrothermal fluids. The rocks all showed homogeneous textures but distinct luminescence. Apatite in the altered rocks had distinct compositions of Cl, Mn, Fe, Mg, Sr, and Pb and a slightly different delta O18 value, suggesting mobilisation during hydrothermal alteration. This suggests that apatite texture, chemistry, and isotopes can be modified by hydrothermal fluids. Altered and magmatic apatite had comparable concentrations of REEs, Y, U,, Th, and Zr and also Nd isotope signatures, indicating retention of some primary magmatic characteristics during alteration. The study showed that cathodoluminescence, elemental compositions, and Sr-O isotope signatures in apatite can be modified during hydrothermal alteration, whereas other components (REE, Y, U, Th, and Zr) and the Nd isotope composition are preserved. It is concluded that these features can be used to constrain the origin, chemistry, and evolution of the primary magma and ore-forming hydrothermal fluids., Samples from fresh and propylitically altered rocks from the Black Mountain porphyry Cu-Au deposit were used to study the suitability of apatite as an indicator of the source, chemistry, and evolution of magma and hydrothermal fluids. The rocks all showed homogeneous textures but distinct luminescence. Apatite in the altered rocks had distinct compositions of Cl, Mn, Fe, Mg, Sr, and Pb and a slightly different delta O18 value, suggesting mobilisation during hydrothermal alteration. This suggests that apatite texture, chemistry, and isotopes can be modified by hydrothermal fluids. Altered and magmatic apatite had comparable concentrations of REEs, Y, U,, Th, and Zr and also Nd isotope signatures, indicating retention of some primary magmatic characteristics during alteration. The study showed that cathodoluminescence, elemental compositions, and Sr-O isotope signatures in apatite can be modified during hydrothermal alteration, whereas other components (REE, Y, U, Th, and Zr) and the Nd isotope composition are preserved. It is concluded that these features can be used to constrain the origin, chemistry, and evolution of the primary magma and ore-forming hydrothermal fluids.

Despite the increasing popularity of Bayesian inference in empirical research, few practical guidelines provide detailed recommendations for how to apply Bayesian procedures and interpret the results. Here we offer specific guidelines for four different stages of Bayesian statistical reasoning in a research setting: planning the analysis, executing the analysis, interpreting the results, and reporting the results. The guidelines for each stage are illustrated with a running example. Although the guidelines are geared towards analyses performed with the open-source statistical software JASP, most guidelines extend to Bayesian inference in general.

Pentlandite can sometimes form as the result of peritectic reaction between early formed monosulphide solid solution (MSS) and residual Ni-Cu–rich sulphide liquid during differentiation of the sulphide melt. This suggests that at least some loop textures may be genuinely magmatic in origin. Microbeam X-ray fluorescence mapping has been used to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits including slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), and extrusive komatiite-hosted ores from low and high metamorphic-grade terranes. Laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite was also carried out. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulphide liquid and early crystallised MSS. The wide range of Pd contents in pentlandite reflects a continuum of processes between peritectic reaction and grain boundary exsolution. The presence of loop textures can be taken as evidence of a lack of penetrative deformation and remobilisation at submagmatic temperatures., Pentlandite can sometimes form as the result of peritectic reaction between early formed monosulphide solid solution (MSS) and residual Ni-Cu–rich sulphide liquid during differentiation of the sulphide melt. This suggests that at least some loop textures may be genuinely magmatic in origin. Microbeam X-ray fluorescence mapping has been used to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits including slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), and extrusive komatiite-hosted ores from low and high metamorphic-grade terranes. Laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite was also carried out. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulphide liquid and early crystallised MSS. The wide range of Pd contents in pentlandite reflects a continuum of processes between peritectic reaction and grain boundary exsolution. The presence of loop textures can be taken as evidence of a lack of penetrative deformation and remobilisation at submagmatic temperatures.

Pre- and syn-mineralised rocks at the Black Mountain porphyry Cu-Au deposit preserve magmatic and hydrothermal minerals spanning the complete paragenesis of the deposit. Variation in Sr isotope profiles suggest there are two types of plagioclase grains present at the deposit: Type-I show homogeneous Sr isotope compositions, indicating crystallisation from a stable felsic magma chamber; Type-II have a wider range of Sr isotope compositions, consistent with recharge of mafic and/or felsic magmas. Late magmatic titanite shows slightly increased Nb/Ta but decreased Zr/Hf and Y/Ho values. Hydrothermal titanite and epidote have ratios similar to those in the whole rock. These patterns reflect crystallisation effects imposed during the magmatic stage but an absence of differentiation during the hydrothermal stage. The consistent gradual decrease in total rare earth element, Y, Zr, and U contents in titanite and epidote from early to late stages indicates the effect of hydrothermal fluid evolution with decreasing temperature. The variation of 87Sr/86Sr values indicates the addition of mafic magma-derived fluid into the felsic magma-derived fluid. One extra source of fluid (probably derived from wall-rock limestone) was required to generate the highly radiogenic 87Sr/86Sr values of some epidote. It is concluded that in situ elemental and Sr isotope variation in minerals from different paragenetic stages can be used to interpret formation process and source for both magmas and hydrothermal fluids., Pre- and syn-mineralised rocks at the Black Mountain porphyry Cu-Au deposit preserve magmatic and hydrothermal minerals spanning the complete paragenesis of the deposit. Variation in Sr isotope profiles suggest there are two types of plagioclase grains present at the deposit: Type-I show homogeneous Sr isotope compositions, indicating crystallisation from a stable felsic magma chamber; Type-II have a wider range of Sr isotope compositions, consistent with recharge of mafic and/or felsic magmas. Late magmatic titanite shows slightly increased Nb/Ta but decreased Zr/Hf and Y/Ho values. Hydrothermal titanite and epidote have ratios similar to those in the whole rock. These patterns reflect crystallisation effects imposed during the magmatic stage but an absence of differentiation during the hydrothermal stage. The consistent gradual decrease in total rare earth element, Y, Zr, and U contents in titanite and epidote from early to late stages indicates the effect of hydrothermal fluid evolution with decreasing temperature. The variation of 87Sr/86Sr values indicates the addition of mafic magma-derived fluid into the felsic magma-derived fluid. One extra source of fluid (probably derived from wall-rock limestone) was required to generate the highly radiogenic 87Sr/86Sr values of some epidote. It is concluded that in situ elemental and Sr isotope variation in minerals from different paragenetic stages can be used to interpret formation process and source for both magmas and hydrothermal fluids.

Despite the increasing popularity of Bayesian inference in empirical research, few practical guidelines provide detailed recommendations for how to apply Bayesian procedures and interpret the results. Here we offer specific guidelines for four different stages of Bayesian statistical reasoning in a research setting: planning the analysis, executing the analysis, interpreting the results, and reporting the results. The guidelines for each stage are illustrated with a running example. Although the guidelines are geared towards analyses performed with the open-source statistical software JASP, most guidelines extend to Bayesian inference in general.

Exhumation of plutonic systems is driven by a range of mechanisms including isostatic, tectonic, and erosional processes. Variable rates of plutonic exhumation in active subduction systems may be driven by idiosyncrasies of regional geology or by first‐order tectonic features. We report new age, isotope, and low‐temperature thermochronology constraints of granitoids from the Hida Mountains of central Japan that constrain the highest rates and magnitude of plutonic rock exhumation within the Japan and one of the highest worldwide. This extreme exhumation is centered on the apex of a lithospheric scale anticlinorium associated with the subduction of the Izu‐Bonin oceanic arc. The spatial and temporal relationship between the exhumation of these Pleistocene plutons and the subducting/accreting Izu‐Bonin oceanic arc links the plate‐scale geodynamics and regional exhumation patterns. Identifying thermochronological anomalies within magmatic arcs provides an opportunity to identify ancient asperities previously subducted and responsible for rapid exhumation rates within ancient subduction systems.

Studies of a micaceous pegamitatic ore from the waste dump at Lepidolite Hill (Western Australia) showed that the majority of Li, grading 1.5 wt% Li, was found to be associated with particles made up of: intergrowth of micas with varying Li composition; inclusions of muscovite with low Li content disseminated in large lepidolite particles; and minor content of Mg rich areas, some associated with Fe, along grain boundaries and where fractures occur. Liberation and possible separation of Li muscovite grains within the large lepidolite particles required a grind size of less than 90 microns. The gangue material, 20% of the sample, was predominately quartz and albite which were readily separated from the majority of Li micas at the size fractions examined. The concentration of Ta and Nb minerals in the sample was of no economic value. It is concluded that a staged crushing/grinding and screening approach would yield optimum Li liberation. The extraction processes would have to consider the influence of the liberation and treatment of F from both a safety and environmental view. In addition to the 6000 t of Li resource from the waste dump, the recovery of Rb (9200 t) and Cs (920 t) from micaceous minerals could also be considered in the process development., Studies of a micaceous pegamitatic ore from the waste dump at Lepidolite Hill (Western Australia) showed that the majority of Li, grading 1.5 wt% Li, was found to be associated with particles made up of: intergrowth of micas with varying Li composition; inclusions of muscovite with low Li content disseminated in large lepidolite particles; and minor content of Mg rich areas, some associated with Fe, along grain boundaries and where fractures occur. Liberation and possible separation of Li muscovite grains within the large lepidolite particles required a grind size of less than 90 microns. The gangue material, 20% of the sample, was predominately quartz and albite which were readily separated from the majority of Li micas at the size fractions examined. The concentration of Ta and Nb minerals in the sample was of no economic value. It is concluded that a staged crushing/grinding and screening approach would yield optimum Li liberation. The extraction processes would have to consider the influence of the liberation and treatment of F from both a safety and environmental view. In addition to the 6000 t of Li resource from the waste dump, the recovery of Rb (9200 t) and Cs (920 t) from micaceous minerals could also be considered in the process development.