Partition coefficients of chalcophile elements between sulfide and silicate melts and the early crystallization history of sulfide liquid: LA-ICP-MS analysis of MORB sulfide droplets
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Chalcophile element partitioning among base-metal sulfide, oxide and silicate phases during magmatic processes is poorly constrained in part because there are very few studies of reliable sulfide melt–silicate melt partition coefficients (Ds) and because the crystallization history of the sulfide liquid is ignored in most studies. Here we present laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of sulfide droplets and their host fresh mid-ocean-ridge basalt (MORB) glasses. The compositions of the sulfide droplets suggest that they formed in magma chambers beneath the mid-ocean ridges and equilibrated with their host silicate melt , enabling us to calculate new Ds for chalcophile elements. These are Co (45 ± 4.5), Ni (776 ± 98), Cu (1334 ± 210), Zn (3.5 ± 0.9), Se (345 ± 37), Ag (1138 ± 245), Cd (107 ± 47), Sn (11 ± 1.6), Te (4478 ± 1146), Pb (57 ± 10) and Bi (316 ± 38). The contents of the highly siderophile elements in the glasses were too low to be determined using LA-ICP-MS. The whole rock values were used as a proxy for the glass and these allow an estimate of minimum Ds in the 10 000 to 40 000 range for the platinum-group elements (PGE) and 870 for Re. Partition coefficient values are affected by oxygen fugacity; comparison of our values with those from experimental studies suggests that oxygen fugacities of the MORBs considered here were between FMQ and FMQ-1. From the determined D values we calculate the contribution of the sulfides to bulk partition coefficient during mantle melting. Considering these values in combination with what is known about the behavior of the chalcophile elements during mantle partial melting, we suggest that Co, Ni, Zn, Te, PGE and Au behave as compatible elements during mantle melting, with Ni, Co and Zn being controlled mainly by the silicate and oxide minerals and the PGE, Au and Te being controlled mainly by the sulfides (or other discrete metallic phases). Copper, Se, Ag, Cd, Sn, Re, Pb and Bi are slightly to strongly incompatible during mantle melting. MORB sulfide droplets consist mainly of monosulfide solid solution (MSS), which is the first mineral to crystallize from a sulfide liquid, and intermediate solid solution (ISS), which crystallizes from the remaining liquid. The distribution of the chalcophile elements within the sulfide droplets shows that Co and Re have a slight preference for MSS, whereas the Cu, Zn, Ag, Cd, Sn, Te, Au, Bi and Pb partition into ISS. Selenium is present in approximately equal amounts in both MSS and ISS, and Pt and Pd are also present in both phases. Previous experimental and empirical studies have shown that Os, Ir, Ru and Rh partition into MSS and a portion of these elements exsolve from the sulfides as platinum-group minerals (PGM) during cooling. The same studies show that most of the Pt and Pd partition into the liquid and eventually crystallize from the late fractionated liquid as PGM. We examined our MORB sulfide droplets closely for platinum group-minerals (PGM) but none were found. We suggest that because the rocks sustained rapid cooling PGM were unable to exsolve from the sulfide minerals and the liquid did not fractionate sufficiently to permit the crystallization of the Pt or Pd minerals. Thus the PGE are present in MSS and ISS.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it