ALBERT

Description: We have selected 39 gabbro samples from the Wadi Gideah Transect sample suite, representing a full coherent crustal profile from the Moho transition zone (MTZ) to the dike/gabbro transition with an average sample spacing of about 120 m along the crustal depth. All samples were taken at outcrops of fresh gabbro along the Wadi. The height above Moho (h.a.M.) was calculated with respect to the MTZ reference latitude of 22.9152N DD, assuming a generalized average dip of 28° for the layering of the lower gabbros in the Wadi Gideah area. The freshest and primary region of each hand specimen was cut into a block with a water-cooled diamond-blade saw, avoiding areas influenced by secondary weathering and hydrothermal overprint, and subsequently processed to a polished thin-section. We studied the thin-sections using a polarized light microscope to identify petrographic key parameters, which are presented here.

Description: The main part of major element concentrations was measured at the Institute of Mineralogy of the University of Hannover using a Cameca SX100 electron microprobe operated through the Cameca PeakSight software. Additional data was generated at the Institute of Geosciences at Kiel University using a JOEL JXA 8900 R electron microprobe. Results from both labs have been cross-checked, analyzing identical samples. All elements have been measured at Kα emission lines with a focused and fixed beam, an acceleration voltage of 15 kV, a beam current of 15 nA, and a signal count time per element of 10s on peak and 5s on each background. Matrix-correction according to PAP. For each of the 39 samples, repetitive measurements on multiple crystals have been carried out. We put a strong focus on reliable primitive core measurements; nevertheless, for most samples, we also acquired data for rim compositions. P-values have been calculated based on a paired, two-sided t-test to evaluate the significance of the difference between core and rim mean concentrations statistically and allow for H0 hypothesis testing. Additionally, propagation of uncertainty has been calculated for Mg# and Ca#.

Description: For in situ analysis of 29 trace elements, carried out at the LA-ICP-MS lab of the Institute of Geosciences at Kiel University, a 193nm ArF-exciplex laser ablation system (GeoLasPro HD, Coherent) coupled to an Agilent 7900s ICP-MS was used for most samples. Some samples have been measured using an older Agilent 7500s ICP-MS, and a minor portion was measured using a Thermo Scientific Element XR ICP-SF-MS. In any case, samples and reference materials were loaded to a Zuerich-type, two-volume low dispersion high capacity laser ablation cell, which was flushed with 995 ml min-1 helium carrier gas. Additionally, 14 ml min-1 hydrogen was added upstream of the cell to enhance ionization at the ICP and reduce oxide formation. Many elements in plagioclase are within the ultra-trace concentration range (〈 1 µg/g). Therefore, the laser was operated at a pulse frequency of 16 Hz and a fluence of 18 J cm-2 with a crater size of 120 µm for plagioclase. Clinopyroxene was measured at 10 Hz, 12 J cm-2, and a crater of 44 to 32µm. We could not detect any adverse effects from mass load of the ICP for the elements determined. The oxide production rate was monitored by Th/ThO and kept below 0.1%. Time-resolved data acquisition for each measurement was split into 20 s background, 40 s sample ablation, and 20 s washout monitoring time. Dwell times were optimized for the expected concentration range for each element. Where possible, we aimed to perform five proximal repetitions for five crystals of each phase per sample to evaluate crystal core heterogeneity as well as sample phase heterogeneity.

Description: Here we present a profile of 39 gabbros through the plutonic section of the Oman ophiolite paleocrust (Wadi Gideah Transect; Wadi Tayin block). Major and trace element core compositions for co-existing plagioclase and clinopyroxene progressively evolve up section from layered gabbros through foliated gabbros up to the varitextured gabbros. Calculated parental melts correspond to typical Oman MORB but reveal differences in the plagioclase-clinopyroxene equilibrium and crystallization style along the profile. Layered gabbro mineral cores have crystallized under equilibrium and stable boundary conditions. Rims show a pronounced inverse zonation of plagioclase Ca# and, to some extent, of clinopyroxene Mg#. Contrastingly, incompatible trace elements indicate progressive fractionation from the core to the rim and up section. For regression of the temperature inversion, we wrote a custom R script (https://doi.org/10.5281/zenodo.5702686) calling the MASS::rlm function to perform an iterated re-weighted least squares (IWLS) robust linear fit between REEs in the Ln(Dj)-A and Bj-1000 space calculated following Sun and Liang (2017, https://doi.org/10.1007/s00410-016-1326-9). We create an in situ crystallization-temperature depth profile through the lower Oman paleocrust. The estimated temperatures are consistent with temperatures established based on the plagioclase anorthite content, revealing a relationship of T-REE-An [°C] = 6.1 ± 0.2 * An + 706 ± 19. Crystallization temperatures of the layered gabbros cover a narrow median range of 1216 ± 14 °C. Considerable temperature variability of 1077 to 1231 °C is observed for the upper gabbros, featuring a thermal minimum within the foliated gabbros. This dataset includes petrographic descriptions for all 39 samples, average values for EPMA measurements, spot and median data for LA-ICP-MS measurements, the associated standard deviations, related quality control parameters, and calculated REE-temperatures.

Description: Multibeam bathymetry raw data was recorded in the South-West Pacific during cruise SO255 that took place between 2017-03-02 and 2017-04-14. The data was collected using the ship's own Kongsberg EM 122. A sound velocity profile (SVP) was applied on the data for calibration. SVP data are part of this dataset publication. This data has been contributed to the DAM (German Marine Research Alliance) underway research data project.

Description: The GLITTER software package was used for raw data reduction, applying initial calibration with NIST-SRM612 as the primary standard, using CaO g/100g for the internal count to mass fraction reference. Potential errors from surface contamination have been avoided by excluding the first seconds of data acquisition from integration. The signal trace over time for each element (m/z) measured was checked for its analytical and geological reasoning and excluded in case of abnormal pattern or spikes (e.g., vertical transitions into different mineral phases during ablation, mineral inclusions, sulfide micro nuggets in clinopyroxene). A second, matrix-matched calibration step was realized by correcting against mean offset factors of median values from at least three repetitive measurements on nano-particulate pressed powder tablets of reference materials USGS-BHVO-2NP, USGS-BIR-1NP, and GSJ-JGb-1NP. All reference materials were analyzed multiple times throughout each analytical session for bracketing and drift correction. Some sessions have been calibrated against the USGS glass microanalytical reference materials USGS-BHVO-2G and USGS-BIR-1G. Results of glass vs. pellet reference materials show no significant quality difference and lead to similar correction factors. Analytical measurement uncertainties were found to be in the range of 1% to 3% RMAD (1MAD) at mass fractions 〉10x LOD for most elements analyzed. For monitoring deviations from preferred or “true” values, the MPI-DING glasses GOR-128G, GOR-132G, and StHs6/80-G have been measured as unknowns. Additionally, JF-1P with extremely low mass fractions for most trace elements has been measured during most analytical sessions. Estimated deviations from preferred values of all analyzed reference materials are, for most elements, in the range of 5 to 10 RMSD% and within the uncertainties of the preferred or compiled values.

Description: Multibeam bathymetry raw data was recorded in the South-West Pacific during cruise SO255 that took place between 2017-03-02 and 2017-04-14. The data was collected using the ship's own Kongsberg EM 710. A sound velocity profile (SVP) was applied on the data for calibration. SVP data are part of this dataset publication. This data has been contributed to the DAM (German Marine Research Alliance) underway research data project.

Description: Multibeam bathymetry raw data was recorded in the Pacific during cruise SO249/1 that took place between 2016-06-06 and 2016-07-14. The data was collected using the ship's own Kongsberg EM 122. Sound velocity profiles (SVP) were applied on the data for calibration. SVP data are part of this dataset publication. Please see environmental data (zip file) and the cruise report for details.