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  • PANGAEA  (229)
  • GSA (Geological Society of America)  (5)
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  • 1
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    70 Ma chemical zonation of the Tristan-Gough hotspot track (2013)
    GSA (Geological Society of America)
    In:  Geology, 41 (3). pp. 335-338.
    Details
    Publication Date: 2019-10-24
    Description: Asymmetrically zoned hotspot tracks in the Pacific Ocean are interpreted to have formed from zoned plumes originating from the large-scale, lower-mantle, low-seismic-velocity anomaly (superplume?) beneath the southern Pacific, providing direct information about lowermantle compositional heterogeneity. New trace-element and Sr-Nd-Hf-Pb isotope data from the classic Tristan-Gough hotspot track in the South Atlantic also display a bilateral, asymmetric zonation with two distinct mantle source components, making it the first zoned plume to be recognized overlying the African superplume. The plume zonation can be traced for 70 m.y., four times longer than recognized for Pacific zoned hotspot tracks. These findings confirm that the proposed zonation of Pacific hotspots is not simply a geochemical oddity, but could be a major feature of plumes derived from lower-mantle superplumes. We propose that the enriched southern Gough subtrack source with elevated 207Pb/204Pb and 208Pb/204Pb at a given 206Pb/204Pb, but low 143Nd/144Nd and 176Hf/177Hf (DUPAL-like composition), may reflect the African superplume composition, whereas the more depleted northern Tristan subtrack source could represent a mixture of the superplume with the surrounding depleted mantle. Our results strengthen arguments that the enriched signature (DUPAL anomaly) in the South Atlantic could be derived from the lower mantle.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/G33790.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Existence of complex spatial zonation in the Galápagos plume (2000)
    GSA (Geological Society of America)
    In:  Geology, 28 (5). pp. 435-438.
    Details
    Publication Date: 2019-10-24
    Description: Basalts from intraplate or hotspot ocean islands (e.g., the Hawaiian, Galápagos, and Canary Islands) are believed to be formed by mantle plumes, which emanate from mantle boundary layers such as the coremantle boundary. The long-term chemical structure of mantle plumes, however, remains poorly constrained. Spatial variation in the chemical composition has long been recognized in lavas from the Galápagos Islands: Enriched plume material forms a horseshoe-shaped region with depleted mantle, similar in composition to mid-ocean ridge basalt, in its inner part. The enriched horseshoe-shaped region can be subdivided into three distinct geochemical domains. We show that these same domains occur in the same relative positions with respect to morphology in a geochemical profile across the Galápagos hotspot track off the coast of Costa Rica, indicating that the asymmetrical spatial zonation of the Galápagos hotspot has existed for at least 14 m.y. Combined with published He isotope data, the results of this study imply that plume material can ascend from the lower mantle, possibly from the core-mantle boundary, with little stirring occurring during ascent, and that zonation in hotspot lavas may in some cases reflect spatial heterogeneity within the lower mantle source.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(2000)28〈435:EOCSZI〉2.0.CO;2
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Influence of the Galápagos hotspot on the East Pacific Rise during Miocene superfast spreading (2013)
    GSA (Geological Society of America)
    In:  Geology, 41 (2). pp. 183-186.
    Details
    Publication Date: 2019-10-24
    Description: At the present, the geochemical influence of the Galápagos hotspot (offshore South America) can be seen only along the Galápagos spreading center, north of the hotspot. It is possible, however, that Galápagos plume material also reached the East Pacific Rise in the past. Detecting such influence would be of particular importance for the interpretation of geochemical data from oceanic crust at Ocean Drilling Program (ODP) Site 1256, which formed ∼15 m.y. ago at the East Pacific Rise during a Miocene period of superfast spreading, and is considered to be a reference site for oceanic crust produced at fast-spreading ridges. Here we present geochemical data from Miocene basaltic crust (23–7 Ma) drilled at several Deep Sea Drilling Project (DSDP), ODP, and Integrated Ocean Drilling Program (IODP) sites that formed along the East Pacific Rise between 3°S and 7°N. Lavas formed between ca. 22.5 and ca. 11 Ma show enriched, Galápagos plume–like Pb and Nd isotope ratios (with a peak in enrichment between ≥18 and 12 Ma) compared to lavas created shortly before or after this time interval. Despite their enriched isotope composition, these samples generally show depletion in more-incompatible, relative to less-incompatible, trace elements. Derivation from an enriched Galápagos plume source that had experienced recent melt extraction before it melted further beneath the East Pacific Rise can explain the combined incompatible-trace-element depletion and isotopic enrichment of the 22.5–11 Ma lavas. The influence of plume material correlates with the interval of superfast spreading along the equatorial East Pacific Rise, suggesting a causal relationship. Enhanced ridge-plume interaction ("ridge suction") due to superfast spreading could have facilitated the flow of Galápagos plume material to the ridge. On the other hand, the arrival of Galápagos-type signatures took place immediately after formation of the Galápagos spreading center, which could have provided a pathway for hot plume material to spread into the main ridge network.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/G33533.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Tectonic dissection and displacement of parts of Shona hotspot volcano 3500 km along the Agulhas-Falkland Fracture Zone (2016)
    GSA (Geological Society of America)
    In:  Geology, 44 (4). pp. 263-266.
    Details
    Publication Date: 2019-10-24
    Description: In contrast to the long narrow volcanic chains in the Pacific Ocean, Atlantic hotspot tracks, in particular in the South Atlantic (e.g., Tristan-Gough, Discovery, Shona, and Bouvet), are irregular and, in some cases, diffuse and discontinuous. An important question is whether this irregularity results from tectonic dismemberment of the tracks or if it represents differences in the size, structure, and strength of the melting anomalies. Here we present new age and geochemical data from volcanic samples from Richardson Seamount, Agulhas Ridge along the Agulhas-Falkland Fracture Zone (AFFZ), and Meteor Rise. Six samples yielded ages of 83–72 Ma and are 10–30 m.y. younger than the underlying seafloor, indicating that they are not on-axis seamounts associated with seafloor spreading. The incompatible element and Sr-Nd-Pb-Hf isotopic compositions range from compositions similar to those of the Gough domain of the nearby Tristan-Gough hotspot track to compositions similar to samples from the Shona bathymetric and geochemical anomaly along the southern Mid-Atlantic Ridge (49°–55°S), indicating the existence of a Shona hotspot as much as 84 m.y. ago and its derivation from a source region similar to that of the Tristan-Gough hotspot. Similar morphology, ages, and geochemistry indicate that the Richardson, Meteor, and Orcadas seamounts originally formed as a single volcano that was dissected and displaced 3500 km along the AFFZ, providing a dramatic example of how plate tectonics can dismantle and disseminate a hotspot track across an ocean basin.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/G37582.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Hikurangi Plateau subduction a trigger for Vitiaz arc splitting and Havre Trough opening (southwestern Pacific) (2021)
    GSA (Geological Society of America)
    Details
    Publication Date: 2024-02-07
    Description: Splitting of the Vitiaz arc formed the Tonga-Kermadec and Lau-Colville Ridges (southwestern Pacific Ocean), separated by the Lau Basin in the north and Havre Trough in the south. We present new trace element and Sr-Nd-Hf-Pb isotope geochemistry for the Kermadec and Colville Ridges extending ~900 km north of New Zealand (36°S–28°S) in order to (1) compare the composition of the arc remnants with Quaternary Kermadec arc volcanism, (2) constrain spatial geochemical variations in the arc remnants, (3) evaluate the effect of Hikurangi igneous plateau subduction on the geochemistry of the older arc lavas, and (4) elucidate what may have caused arc splitting. Compared to the Kermadec Ridge, the Colville Ridge has higher more-incompatible to less-incompatible immobile element ratios and largely overlapping isotope ratios, consistent with an origin through lower degrees of melting of more enriched upper mantle in the Vitiaz rear arc. Between ca. 8 and 3 Ma, both halves of the arc (~36°S–29°S) included a more enriched (EM1-type) composition (with lower 206Pb/204Pb and 207Pb/204Pb and higher Δ8/4 Pb [deviation of the measured 208Pb/204Pb ratio from a Northern Hemisphere basalt regression line] and 87Sr/86Sr) compared to older and younger arc lavas. High-Ti basalts from the Manihiki Plateau, once joined to the Hikurangi Plateau, could serve as the enriched Vitiaz arc end member. We propose that the enriched plateau signature, seen only in the isotope ratios of mobile elements, was transported by hydrous fluids from the western margin of the subducting Hikurangi Plateau or a Hikurangi Plateau fragment into the overlying mantle wedge. Our results are consistent with plateau subduction triggering arc splitting and backarc opening.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Solid phase geochemistry of sediments from ROV push cores during Pourquoi Pas ? cruise INDEX2016, Hydrothermal Vent Outlet in the Kairei Field (2021)
    PANGAEA
    Details
    Publication Date: 2023-04-24
    Description: Deep-sea sediment samples were taken from the (wider) Kairei hydrothermal field area (25°S, 70°E) as well as a remote site (26°S, 71°E) in the Indian Ocean during the INDEX cruise 2016 with the N/O Pourquoi pas? (Ifremer, France). Push core samples from different areas of the Kairei vent field, as well as a sample from the remote site (~200 km south-east from the Kairei), were recovered with the help of the ROV VICTOR 6000 (Ifremer, France). All subsampling steps were carried out shipboard at 4 °C. With sterile syringes (nozzles removed) 3 ml of 2 cm layers of sediment were transferred into sterile falcon tubes for DNA extraction and stored at –80 °C. The remaining sediment was cut into 2 cm slices, freeze-dried, and partially milled to 〈75 mm for geochemical analyses. The sediment was analyzed for carbon chemistry, i.e. total organic carbon (TOC) and total inorganic carbon (TIC) with routine standard methods (IR-detection after combustion, ISO 10694, LECO CS 230 analyzer). Elemental composition of Kairei sediments was estimated by the accredited Actlab Laboratories, Canada (Multimethod mix called Ultratrace 3 program, using INAA, 4-Acid Digestion, ICP-OES, and ICP-MS). Sediments from the remote station were analyzed by routine WD-XRF after fusion with Li-Metaborate/Li-Bromide (XRF spectrometers Philips PW 2400 und Philips PW 1480).
    Keywords: 16S rRNA gene tags; Aluminium oxide; Area/locality; Calcium oxide; Carbon, carbonate; Carbon, organic; Carbon, total; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Element Analyser CS, LECO CS 230; Event label; geochemistry of porewaters; hydrothermal vent; INDEX2016; INDEX2016_12ROV; INDEX2016_20ROV; Indian Ocean; Iron oxide, Fe2O3; Kairei field; Magnesium oxide; Manganese oxide; metalliferous sediments; Phosphorus pentoxide; Potassium oxide; Pourquoi Pas ? (2005); Sample code/label; Silicon dioxide; Sodium oxide; Sulfur, total; Titanium dioxide; VICTOR; Victor6000 ROV
    Type: Dataset
    Format: text/tab-separated-values, 628 data points
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    DATA PANGAEA
  • 7
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    A reference section through fast-spread lower oceanic crust, Wadi Gideah, Samail Ophiolite (Sultanate of Oman): Petrographic Data Table and Mineral analyses performed by EPMA (2021)
    PANGAEA
    Details
    Publication Date: 2023-01-13
    Description: In the absence of a complete profile through fast-spreading modern oceanic crust, we established a reference profile through the paleo crust of the Samail Ophiolite (Sultanate of Oman), which is regarded as the best analogue for fast-spreading oceanic crust on land. To establish a coherent data set, we sampled hard rocks in the Wadi Gideah in the Wadi-Tayin massif from the mantle section up to the sheeted dikes. This paper reports our studies of the lower crust, a 5 km thick pile of gabbros, focusing on petrographic features and on the results of mineral analyses. We collected petrographical data from thins sections of the samples by optical microscope and performed also EPMA analyses (Electron Probe Microanalysis) of the mineral phases of the rocks. The samples have been collected during field campaigns from 2010 to 2015, and the data have been collected in a period from 2013 to 2021.
    Keywords: Electronprobe Microanalysis; Fast-spreading oceanic crust; gabbro; Mineral Analyses; Oman Ophiolite; Petrographic Data; Samail Ophiolite
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 8
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    26.000 - year-long oxygen isotope (G. ruber w.) and Mg/Ca-based estimates of SST analyzed in marine sediment cores from the Mozambique Channel (2021)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: The Mozambique Channel is a conduit of trade wind-driven throughflow that is a key component of the Agulhas Current and Agulhas leakage, a flux of warm and salty water from the tropical Indo-Pacific to the Atlantic Ocean. Agulhas leakage is thought to modulate Atlantic meridional overturning circulation variability. Previous studies from the Cape Basin suggest that enhanced Agulhas leakage played an important role in accelerating glacial terminations. The southern African monsoon response to abrupt climate changes associated with meltwater-induced reorganizations of the North Atlantic meridional overturning circulation, and its impact on the Mozambique Channel throughflow and, by extension, on the Agulhas leakage is not well understood. Here we present a high-resolution 26,000 year-long hydroclimate record of northern Madagascar, a core region of the southern hemisphere monsoon domain, and a mixed layer temperature reconstruction using sediment cores collected from the runoff-influenced eastern Mozambique Channel. The record indicates precipitation increases centered at 11.7-12.5 thousand years before present (kyr BP), 14.5-19 kyr BP, 23-24 kyr BP, 25-26 kyr BP. Considering age model uncertainties, this is the first strong evidence for southern African monsoon strengthening in response to meltwater-induced northern high latitude climate instabilities during the Younger Dryas (YD), Heinrich Stadial 1 (HS1), HS2 and the HS-like event prior to HS2, in agreement with the results of transient climate simulations. Furthermore, our study shows a reversal of the mixed layer temperature gradient between the western and eastern Mozambique Channel during Heinrich event 1 (HE1). We posit that the gradient reversal indicates a weakening of the trade wind-driven South Equatorial Current and Mozambique Channel throughflow that likely weakened the Agulhas leakage, potentially creating a feedback that may have contributed to the sustained weakening of the AMOC during HE1 by reducing the amount of heat and salt leakage into the Atlantic.
    Keywords: Agulhas Leakage; marine sediments; Mozambique Channel; Mozambique Channel throughflow; oxygen isotope data; SST
    Type: Dataset
    Format: application/zip, 5 datasets
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    DATA PANGAEA
  • 9
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    Petrographic observations and phase properties for sample sets from Wadi Somerah (OM10-Sam) and Wadi Wariyah (OM10-War), Oman (2020)
    PANGAEA
    Details
    Publication Date: 2023-02-08
    Description: As largest and best-exposed paleo-fast-spread oceanic crust on land, the Samail ophiolite in the Sultanate of Oman represents an ideal natural laboratory for investigating processes at fast-spreading mid-ocean ridges. We studied two layered gabbro sequences from different stratigraphic depths: one from the middle of the plutonic crust showing dm-scale modal layering with olivine abundance gradually decreasing from layer base to top (Wadi Somerah, Sumail block) and one located near the crust-mantle boundary showing mm-scale layers being enriched in olivine (Wadi Wariyah, Wadi Tayin block). Petrographic analyses were performed at the Institut für Mineralogie (Leibniz Universität Hannover, Germany) for thin-section description. Plagioclase and Clinopyroxene are present in all samples, most of the samples also include olivine as primary phase and are therefore described as olivine gabbro. The olivine content increases per layer towards the layer base. Grain sizes of the three primary phases olivine, plagioclase and clinopyroxene vary between 0.2 and 5 mm. Olivine usually forms the largest grains, plagioclase the smallest ones. The grain shapes are generally subhedral, their habit is prismatic or, occasionally, irregular or elongated. Some olivine grains show reaction rims or contain plagioclase chadacrysts. Poikilitic clinopyroxene also containing plagioclase as chadacrysts is very common. The described phases are only the primary minerals not taking the low to medium degree of alteration and therefore presence of secondary phases into account.
    Keywords: DEPTH, sediment/rock; Drilling/coring; Elevation of event; Event label; Feature; Formation of Layered Gabbros; Grain size, mean; Habit; Latitude of event; Layer number; Longitude of event; Lower Oceanic Crust; Main Lithology; Mode, area; Mode, grain size, description; OM10-Sam; OM10-War; Oman; Oman Ophiolite; Polarisation microscopy (Leica Leitz DMRP); Sample code/label; Shape; Wadi Somerah, Sumail block; Wadi Wariyah, Wadi Tayin block
    Type: Dataset
    Format: text/tab-separated-values, 746 data points
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    DATA PANGAEA
  • 10
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    Petrographic features of rock samples of the Wadi Gideah reference profile (2021)
    PANGAEA
    Details
    Publication Date: 2023-02-12
    Keywords: According to Gillis et al. (2014); Amphibole, altered; Amphibole, habit; Amphibole, primary original; Amphibole, shape; Clinopyroxene, altered; Clinopyroxene, grain size; Clinopyroxene, habit; Clinopyroxene, modal; Clinopyroxene, shape; Comment; Depth above Mohorovicic discontinuity; Electronprobe Microanalysis; Event label; Fast-spreading oceanic crust; gabbro; Grain size description; HAND; Iron-titanium oxides, habit; Iron-titanium oxides, shape; Latitude of event; Longitude of event; Mineral Analyses; Minerals, total alteration; Minerals, total modal primary; Olivine, altered; Olivine, grain size; Olivine, habit; Olivine, modal; Olivine, shape; OM10-A02; OM10-A03; OM10-A04; OM10-A05A; OM10-A05B; OM10-A06; OM10-A10; OM10-A11; OM10-A11-1a; OM10-A11-1b; OM10-A11-1c; OM10-A11-1d; OM10-A11-1e; OM10-A11-1f; OM10-A11-1i; OM10-A11-1j; OM10-A11-1l; OM10-A11-1m; OM10-A11-1n; OM10-A11-1o; OM10-A11-1p; OM10-A11-1q; OM10-A11-1r; OM10-A11-1s; OM10-A11-1t; OM10-A11-1u; OM10-A11-1v; OM10-A11-1w; OM10-A11-1x; OM10-A11-2; OM10-A11-3; OM10-A12-1A; OM10-A12-1B; OM10-A12-1C; OM10-A12-1D; OM10-A12-2A; OM10-A12-2B; OM10-A12-2C; OM10-A12-2D; OM10-A12-3; OM10-A13; OM10-A14; OM10-A14A; OM10-A14b; OM10-A15; OM10-A16; OM10-A17; OM10-A17-1; OM10-A17-2; OM10-A17-3A; OM10-A17-3B; OM10-A17-3C; OM10-A18; OM10-A18-1; OM10-A18-2a; OM10-A18-2B; OM10-A18-2C; OM10-A19; OM10-A20; OM10-A20A; OM10-A20B; OM10-A21; OM10-A22; OM10-A23; OM10-A23B; OM10-A24; OM10-A25; OM10-A25-1A; OM10-A25-1B; OM10-A25-1D; OM10-A25-1E; OM10-A26; OM10-A26-1; OM10-A27; OM10-A28; OM10-A29; OM10-A30; OM10-A31; OM10-A32; OM10-A33; OM10-A34; OM10-A34A; OM10-A35; OM10-A36; OM10-A37; OM11-10; OM11-9; OM11-A21A; OM11-A21B; OM11-A22; OM11-A26; OM11-A27; OM11-A27-1; OM11-A28B; OM11-A29; OM11-A29-1; OM11-A29-2; OM12-024; OM12-025; OM12-026; OM12-027; OM12-028; OM12-029; OM12-030; OM12-031; OM12-032; OM12-033; OM12-034A; OM12-034B; OM12-035; OM12-036; OM12-037; OM12-038; OM12-039; OM12-040; OM12-041; OM12-042; OM12-043; OM12-044; OM12-045; OM12-046; OM12-047; OM12-048; OM12-049; OM12-050; OM12-051; OM12-052; OM12-053; OM12-054; OM12-055; OM12-057; OM12-058; OM12-059; OM12-201; OM12-202; OM12-203; OM12-204; OM12-205; OM12-206; OM12-207; OM12-208; OM12-209; OM12-210; OM12-211; OM12-212A; OM12-212B; OM12-213; OM12-214; OM12-215; OM12-216A; OM12-216B; OM12-217; OM12-218; OM12-219; OM12-220; OM12-Hy0; OM12-Hy018; OM12-Hy023; OM12-Hy025; OM12-Hy030; OM12-Hy032A; OM12-Hy032B; OM12-Hy032C; OM12-Hy032D; OM12-Hy038; OM12-Hy039; OM12-Hy042; OM12-Hy055B; OM12-Hy058.5; OM12-Hy059; OM12-Hy059.5; OM12-Hy062; OM12-Hy068; OM12-Hy077; OM12-Hy080; OM12-Hy080.5; OM12-Hy096; OM12-Hy102; OM12-Hy103; OM12-Hy108; OM12-Hy154; OM12-Hy166; OM15-01; OM15-02; OM15-03A; OM15-03B; OM15-03E; OM15-03F; OM15-04; OM15-05; OM15-06; OM15-07; OM15-08; OM15-09; OM15-10; OM15-11; OM15-13; OM15-14; OM15-15A; OM15-15B; OM15-15C; Om15-15D; OM15-16; OM15-17; OM15-18; OM15-19A; OM15-19B; OM15-19C; OM15-20; OM15-21; OM15-22; OM15-23; OM15-24; OM15-25A; OM15-25B; OM15-26; OM15-27; OM15-28; OM15-29G; OM15-29I; OM15-29J; OM15-30; OM15-31; OM15-32; OM15-33; OM15-34; OM15-35; OM15-36; OM15-37; OM15-40; Oman; Oman Ophiolite; Orthopyroxene, altered; Orthopyroxene, grain size; Orthopyroxene, habit; Orthopyroxene, modal; Orthopyroxene, shape; Oxides, modal; Petrographic Data; Plagioclase, altered; Plagioclase, grain size; Plagioclase, habit; Plagioclase, modal; Plagioclase, shape; Plagioclase, zoning extent; Plagioclase, zoning type; Quartz; Rocks in Hydrothermal Fault Zone; Rock type; Samail Ophiolite; Sampling by hand; Texture; Texture, modified; Unit; Visual description
    Type: Dataset
    Format: text/tab-separated-values, 5809 data points
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    DATA PANGAEA
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