cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3453314
title: Neogene rock uplift and erosion in northern Borneo: evidence from the Kinabalu granite, Mount Kinabalu

description: Thermochronological data from the Kinabalu granite, emplaced between <em>c</em>. 7.2 and 7.8 Ma, provide a unique record of northern Borneo’s exhumation during the Neogene. Biotite <sup>40</sup>Ar/<sup>39</sup>Ar ages (<em>c</em>. 7.32–7.63 Ma) record rapid cooling of the granite in the Late Miocene as it equilibrated with ambient crustal temperatures. Zircon fission-track ages (<em>c</em>. 6.6–5.8 Ma) and apatite (U–Th–Sm)/He ages (central age <em>c</em>. 5.5 Ma) indicate rapid cooling during the Late Miocene–Early Pliocene. This cooling reflects exhumation of the granite, uplift and erosion bringing it closer to the Earth’s surface. Thermochronological age versus elevation relationships suggest exhumation rates of more than 7 mm a<sup>−1</sup> during the latest Miocene and Early Pliocene. Neither the emplacement of the Kinabalu granite nor its exhumation is related to the Sabah orogeny, which terminated in the Early Miocene. Instead, granite magmatism was caused by extension related to subduction rollback of the Sulu Arc, and Mio-Pliocene exhumation of the Kinabalu granite was driven either by lithospheric delamination or break-off of a subducted slab beneath Sabah. Plio-Pleistocene tectonism offshore and onshore northern Borneo reflects continuing large-scale gravity-driven tectonics in the region.
DOI: 10.6084/m9.figshare.3453314.v1
title: Neogene rock uplift and erosion in northern Borneo: evidence from the Kinabalu granite, Mount Kinabalu

description: Thermochronological data from the Kinabalu granite, emplaced between <em>c</em>. 7.2 and 7.8 Ma, provide a unique record of northern Borneo’s exhumation during the Neogene. Biotite <sup>40</sup>Ar/<sup>39</sup>Ar ages (<em>c</em>. 7.32–7.63 Ma) record rapid cooling of the granite in the Late Miocene as it equilibrated with ambient crustal temperatures. Zircon fission-track ages (<em>c</em>. 6.6–5.8 Ma) and apatite (U–Th–Sm)/He ages (central age <em>c</em>. 5.5 Ma) indicate rapid cooling during the Late Miocene–Early Pliocene. This cooling reflects exhumation of the granite, uplift and erosion bringing it closer to the Earth’s surface. Thermochronological age versus elevation relationships suggest exhumation rates of more than 7 mm a<sup>−1</sup> during the latest Miocene and Early Pliocene. Neither the emplacement of the Kinabalu granite nor its exhumation is related to the Sabah orogeny, which terminated in the Early Miocene. Instead, granite magmatism was caused by extension related to subduction rollback of the Sulu Arc, and Mio-Pliocene exhumation of the Kinabalu granite was driven either by lithospheric delamination or break-off of a subducted slab beneath Sabah. Plio-Pleistocene tectonism offshore and onshore northern Borneo reflects continuing large-scale gravity-driven tectonics in the region.
DOI: 10.6084/m9.figshare.3453311
title: The gigantic Seymareh (Saidmarreh) rock avalanche, Zagros Fold–Thrust Belt, Iran

description: The Seymareh rock avalanche, first described by J. V. Harrison and N. L. Falcon in the 1930s, is the largest known subaerial non-volcanic landslide on Earth. The volume of its debris (44 Gm<sup>3</sup>) is approximately equal to that of the largest known subaerial landslide of any kind, the 100 ka collapse of Mount Shasta volcano (45 Gm<sup>3</sup>) and approaches those of gigantic landslides on Mars. Using satellite imagery, SRTM-3 data, and detailed field investigations, we gain a new understanding of the gigantic rock avalanche. The initial failure (38 Gm<sup>3</sup>), involving a dip slope consisting of a relatively weak interbedded limestone–mudrock sequence capped by resistant Asmari Limestone, had an average thickness of 410 m along a 15.5 km width of the Kabir Kuh anticline. The rockslide transformed into a rock avalanche that travelled 19.0 km with a <em>fahrböschung</em> (the angle between the highest point of the pre-landslide source area topography and the distal limit of the debris) of only 3.6°. Initial failure involved complex planar sliding dictated by four structural elements: (1) bedding-parallel shears and (2) across-bedding break-throughs combined to produce a low-angle (11°) overall sliding surface that (3) broke out through the Asmari carapace at the toe of the failed slope while (4) tectonically weakened bedding-normal joints provided lateral release surfaces. Nine discrete bedding-parallel basal sliding surfaces divided the detached mass into nine stacked plates. The upper plate (23 Gm<sup>3</sup>) included 20.7 Gm<sup>3</sup> of Asmari Limestone. Analysis of accelerator mass spectrometry radiocarbon dates from this study and by others indicates that the rock avalanche occurred between <em>c</em>. 8710 and 9800 <sup>14</sup>C years BP.
DOI: 10.6084/m9.figshare.3453311.v1
title: The gigantic Seymareh (Saidmarreh) rock avalanche, Zagros Fold–Thrust Belt, Iran

description: The Seymareh rock avalanche, first described by J. V. Harrison and N. L. Falcon in the 1930s, is the largest known subaerial non-volcanic landslide on Earth. The volume of its debris (44 Gm<sup>3</sup>) is approximately equal to that of the largest known subaerial landslide of any kind, the 100 ka collapse of Mount Shasta volcano (45 Gm<sup>3</sup>) and approaches those of gigantic landslides on Mars. Using satellite imagery, SRTM-3 data, and detailed field investigations, we gain a new understanding of the gigantic rock avalanche. The initial failure (38 Gm<sup>3</sup>), involving a dip slope consisting of a relatively weak interbedded limestone–mudrock sequence capped by resistant Asmari Limestone, had an average thickness of 410 m along a 15.5 km width of the Kabir Kuh anticline. The rockslide transformed into a rock avalanche that travelled 19.0 km with a <em>fahrböschung</em> (the angle between the highest point of the pre-landslide source area topography and the distal limit of the debris) of only 3.6°. Initial failure involved complex planar sliding dictated by four structural elements: (1) bedding-parallel shears and (2) across-bedding break-throughs combined to produce a low-angle (11°) overall sliding surface that (3) broke out through the Asmari carapace at the toe of the failed slope while (4) tectonically weakened bedding-normal joints provided lateral release surfaces. Nine discrete bedding-parallel basal sliding surfaces divided the detached mass into nine stacked plates. The upper plate (23 Gm<sup>3</sup>) included 20.7 Gm<sup>3</sup> of Asmari Limestone. Analysis of accelerator mass spectrometry radiocarbon dates from this study and by others indicates that the rock avalanche occurred between <em>c</em>. 8710 and 9800 <sup>14</sup>C years BP.
DOI: 10.6084/m9.figshare.3453308
title: Volcanoes of the Diamante cross-chain: evidence for a mid-crustal felsic magma body beneath the Southern Izu–Bonin–Mariana arc

description: Three submarine Diamante cross-chain volcanoes in the southern Mariana arc mark a magma-healed zone of along-arc (north–south) extension that allows either mafic mantle-derived basalts or felsic magmas from the middle of thickened arc crust to erupt. The largest volcano is East Diamante, with a well-developed (5×10 km) caldera that formed via violent felsic submarine eruptions beginning nearly 0.5 Ma. One or more of these eruptions also formed a giant submarine dune field extending 30 km to the NW of the volcano. Felsic igneous activity continues at least as recently as <em>c.</em> 20 000 years ago, with emplacement of resurgent dacite domes, some hot enough to power the only black smoker hydrothermal system known in the Mariana arc. In contrast, felsic eruptions do not occur on the two volcanoes to the west, implying that the mid-crustal felsic zone does not underlie the thinner crust of the Mariana Trough back-arc basin. Diamante cross-chain lavas define a medium K suite; mafic lava phenocryst assemblages show arc-like associations of anorthite-rich plagioclase with Fe-rich olivine. Magmatic temperatures for a basaltic andesite and three dacites are <em>c.</em> 1100 °C and <em>c.</em> 800 °C, respectively, typical for cool, wet, subduction-related felsic magmas. Felsic magmas formed under low-P crustal conditions. The Diamante cross-chain is the southernmost of at least seven and perhaps eight Mariana arc volcanoes in a <em>c.</em> 115 km long arc segment characterized by felsic eruptions. This is the ‘Anatahan Felsic Province’, which may have formed above a mid-crustal tonalite body that formed by fractionation or was re-melted when heated by <em>c.</em> 1200 °C mafic, mantle-derived magmas. Across- and along-arc variations suggest that felsic eruptions and dome emplacement occurred when midcrustal tonalite was remobilized by intrusions of mafic magma, while north–south extension facilitated the development of conduits to the surface.
DOI: 10.6084/m9.figshare.3453308.v1
title: Volcanoes of the Diamante cross-chain: evidence for a mid-crustal felsic magma body beneath the Southern Izu–Bonin–Mariana arc

description: Three submarine Diamante cross-chain volcanoes in the southern Mariana arc mark a magma-healed zone of along-arc (north–south) extension that allows either mafic mantle-derived basalts or felsic magmas from the middle of thickened arc crust to erupt. The largest volcano is East Diamante, with a well-developed (5×10 km) caldera that formed via violent felsic submarine eruptions beginning nearly 0.5 Ma. One or more of these eruptions also formed a giant submarine dune field extending 30 km to the NW of the volcano. Felsic igneous activity continues at least as recently as <em>c.</em> 20 000 years ago, with emplacement of resurgent dacite domes, some hot enough to power the only black smoker hydrothermal system known in the Mariana arc. In contrast, felsic eruptions do not occur on the two volcanoes to the west, implying that the mid-crustal felsic zone does not underlie the thinner crust of the Mariana Trough back-arc basin. Diamante cross-chain lavas define a medium K suite; mafic lava phenocryst assemblages show arc-like associations of anorthite-rich plagioclase with Fe-rich olivine. Magmatic temperatures for a basaltic andesite and three dacites are <em>c.</em> 1100 °C and <em>c.</em> 800 °C, respectively, typical for cool, wet, subduction-related felsic magmas. Felsic magmas formed under low-P crustal conditions. The Diamante cross-chain is the southernmost of at least seven and perhaps eight Mariana arc volcanoes in a <em>c.</em> 115 km long arc segment characterized by felsic eruptions. This is the ‘Anatahan Felsic Province’, which may have formed above a mid-crustal tonalite body that formed by fractionation or was re-melted when heated by <em>c.</em> 1200 °C mafic, mantle-derived magmas. Across- and along-arc variations suggest that felsic eruptions and dome emplacement occurred when midcrustal tonalite was remobilized by intrusions of mafic magma, while north–south extension facilitated the development of conduits to the surface.
DOI: 10.6084/m9.figshare.3453305
title: Neutron-induced <sup>37</sup>Ar recoil ejection in Ca-rich minerals and implications for <sup>40</sup>Ar/<sup>39</sup>Ar dating

description: The <sup>40</sup>Ar/<sup>39</sup>Ar dating technique requires the transformation of <sup>39</sup>K into <sup>39</sup>Ar by neutron activation. Neutron activation has undesirable secondary effects such as interfering isotope production, and recoil of <sup>39</sup>Ar and <sup>37</sup>Ar atoms from their (dominant) targets of K and Ca. In most cases, the grains analysed are large enough (&gt;50 μm) such that the amount of target atoms ejected from the grains is small and has a negligible effect on the ages obtained. However, increasing needs to date fine-grained rocks requires constraining, and in some cases correcting for, the effect of nuclear recoil. Previous quantitative studies of recoil loss focus mostly on <sup>39</sup>Ar. However, <sup>37</sup>Ar loss can affect the ages of Ca-rich minerals via interference corrections on <sup>36</sup>Ar (and, to a lesser extent, <sup>39</sup>Ar), yielding lower <sup>40</sup>Ar*/<sup>39</sup>Ar<sub>K</sub> and, thus, an age spuriously too young. New results focused on <sup>37</sup>Ar recoil by measuring the apparent age of multi-grain populations of Ca-rich minerals including Fish Canyon plagioclase (FCp) and Hb3gr hornblende, with discrete sizes ranging from 210 to &lt;5 µm. We use previous result on sanidine grains to correct for the <sup>39</sup>Ar recoil loss. For the finest fractions, FCp and Hb3gr apparent ages are younger than the <sup>39</sup>Ar recoil-corrected ages expected for these minerals, with a maximum deviation of −40% (FCp) and −21% (Hb3gr) reached for grains below 5 μm. We calculate <sup>37</sup>Ar-depletion values ranging from approximately 30 to 91% and from approximately 28 to 98% for plagioclase and hornblende, respectively. This results in <em>x</em><sub>0</sub> values (mean thickness of the partial depletion layer) of 3.3±0.4 μm (2σ; FCp) and 3.6±1.4 μm (Hb3gr), significantly higher than suggested by current models. The reason for the substantial <sup>37</sup>Ar loss is not well understood, but might be related to the radiation damage caused to the mineral during irradiation. <em>x</em><sub>0</sub> (<sup>39</sup>Ar) and <em>x</em><sub>0</sub> (<sup>37</sup>Ar) values obtained in this study, along with crystal dimensions, can be used for correcting <sup>40</sup>Ar/<sup>39</sup>Ar ages from <sup>39</sup>Ar and <sup>37</sup>Ar recoil loss. We also discuss the relevance of our results to vacuum-encapsulation studies and isotopic redistribution in fine-grained minerals.
DOI: 10.6084/m9.figshare.3453305.v1
title: Neutron-induced <sup>37</sup>Ar recoil ejection in Ca-rich minerals and implications for <sup>40</sup>Ar/<sup>39</sup>Ar dating

description: The <sup>40</sup>Ar/<sup>39</sup>Ar dating technique requires the transformation of <sup>39</sup>K into <sup>39</sup>Ar by neutron activation. Neutron activation has undesirable secondary effects such as interfering isotope production, and recoil of <sup>39</sup>Ar and <sup>37</sup>Ar atoms from their (dominant) targets of K and Ca. In most cases, the grains analysed are large enough (&gt;50 μm) such that the amount of target atoms ejected from the grains is small and has a negligible effect on the ages obtained. However, increasing needs to date fine-grained rocks requires constraining, and in some cases correcting for, the effect of nuclear recoil. Previous quantitative studies of recoil loss focus mostly on <sup>39</sup>Ar. However, <sup>37</sup>Ar loss can affect the ages of Ca-rich minerals via interference corrections on <sup>36</sup>Ar (and, to a lesser extent, <sup>39</sup>Ar), yielding lower <sup>40</sup>Ar*/<sup>39</sup>Ar<sub>K</sub> and, thus, an age spuriously too young. New results focused on <sup>37</sup>Ar recoil by measuring the apparent age of multi-grain populations of Ca-rich minerals including Fish Canyon plagioclase (FCp) and Hb3gr hornblende, with discrete sizes ranging from 210 to &lt;5 µm. We use previous result on sanidine grains to correct for the <sup>39</sup>Ar recoil loss. For the finest fractions, FCp and Hb3gr apparent ages are younger than the <sup>39</sup>Ar recoil-corrected ages expected for these minerals, with a maximum deviation of −40% (FCp) and −21% (Hb3gr) reached for grains below 5 μm. We calculate <sup>37</sup>Ar-depletion values ranging from approximately 30 to 91% and from approximately 28 to 98% for plagioclase and hornblende, respectively. This results in <em>x</em><sub>0</sub> values (mean thickness of the partial depletion layer) of 3.3±0.4 μm (2σ; FCp) and 3.6±1.4 μm (Hb3gr), significantly higher than suggested by current models. The reason for the substantial <sup>37</sup>Ar loss is not well understood, but might be related to the radiation damage caused to the mineral during irradiation. <em>x</em><sub>0</sub> (<sup>39</sup>Ar) and <em>x</em><sub>0</sub> (<sup>37</sup>Ar) values obtained in this study, along with crystal dimensions, can be used for correcting <sup>40</sup>Ar/<sup>39</sup>Ar ages from <sup>39</sup>Ar and <sup>37</sup>Ar recoil loss. We also discuss the relevance of our results to vacuum-encapsulation studies and isotopic redistribution in fine-grained minerals.
DOI: 10.6084/m9.figshare.3453302
title: Modelling effect of sericitization of plagioclase on the <sup>40</sup>K/<sup>40</sup>Ar and <sup>40</sup>Ar/<sup>39</sup>Ar chronometers: implication for dating basaltic rocks and mineral deposits

description: The <sup>40</sup>Ar/<sup>39</sup>Ar technique is the most commonly used technique to date basaltic rocks. For basaltic rocks older than about 30 Ma, the dating of plagioclase separates is preferred over groundmass as the latter is susceptible to containing cryptic alteration due to fluid circulations, difficult if not impossible to remove during sample preparation. Alteration under such metamorphic conditions progressively forms K-rich sericite after plagioclase. Owing to its transparency, plagioclase allows a distinction to be made optically between partially–completely altered grains and fresh grains. However, practice shows that grains that contain less than about 1% of sericite are hard to identify under the stereomicroscope. Owing to the high K<sub>2</sub>O content (<em>c.</em> 10 wt%) of sericite, such compromised grains can have dramatic effects on the age determination of plagioclase. Here, we investigate and quantify the effect of sericite on the <sup>40</sup>Ar/<sup>39</sup>Ar age determination of plagioclase using a numerical model with multiple variable parameters. We show that the most influential parameter is the time difference between the crystallization of plagioclase and the sericitization event. We also show that for some continental flood basalts, even 0.1 wt% of sericite can bias the apparent age of a plagioclase separate by several hundred thousand years. The presence of sericite can be identified using a combination of Ca/K ratios, age spectra, and <sup>39</sup>Ar and <sup>37</sup>Ar degassing curves obtained during a conventional <sup>40</sup>Ar/<sup>39</sup>Ar step-heating procedure. When the age of the fresh plagioclase and its Ca/K ratio are known, the percentage of sericitization and the age of the alteration event can be estimated. Ultimately, above approximately 65% of sericitization, the apparent age measured on the altered plagioclase is within ±1% of the age of the alteration event, with implications for accurately dating low-temperature metamorphism and mineral deposit formations.
DOI: 10.6084/m9.figshare.3453302.v1
title: Modelling effect of sericitization of plagioclase on the <sup>40</sup>K/<sup>40</sup>Ar and <sup>40</sup>Ar/<sup>39</sup>Ar chronometers: implication for dating basaltic rocks and mineral deposits

description: The <sup>40</sup>Ar/<sup>39</sup>Ar technique is the most commonly used technique to date basaltic rocks. For basaltic rocks older than about 30 Ma, the dating of plagioclase separates is preferred over groundmass as the latter is susceptible to containing cryptic alteration due to fluid circulations, difficult if not impossible to remove during sample preparation. Alteration under such metamorphic conditions progressively forms K-rich sericite after plagioclase. Owing to its transparency, plagioclase allows a distinction to be made optically between partially–completely altered grains and fresh grains. However, practice shows that grains that contain less than about 1% of sericite are hard to identify under the stereomicroscope. Owing to the high K<sub>2</sub>O content (<em>c.</em> 10 wt%) of sericite, such compromised grains can have dramatic effects on the age determination of plagioclase. Here, we investigate and quantify the effect of sericite on the <sup>40</sup>Ar/<sup>39</sup>Ar age determination of plagioclase using a numerical model with multiple variable parameters. We show that the most influential parameter is the time difference between the crystallization of plagioclase and the sericitization event. We also show that for some continental flood basalts, even 0.1 wt% of sericite can bias the apparent age of a plagioclase separate by several hundred thousand years. The presence of sericite can be identified using a combination of Ca/K ratios, age spectra, and <sup>39</sup>Ar and <sup>37</sup>Ar degassing curves obtained during a conventional <sup>40</sup>Ar/<sup>39</sup>Ar step-heating procedure. When the age of the fresh plagioclase and its Ca/K ratio are known, the percentage of sericitization and the age of the alteration event can be estimated. Ultimately, above approximately 65% of sericitization, the apparent age measured on the altered plagioclase is within ±1% of the age of the alteration event, with implications for accurately dating low-temperature metamorphism and mineral deposit formations.
DOI: 10.6084/m9.figshare.3453299
title: Ar diffusion and solubility measurements in plagioclases using the ultra-violet laser depth-profiling technique

description: We describe the first direct measurements of Ar diffusion and solubility in plagioclases using ultra-violet (UV) laser ablation depth-profiling and noble gas mass spectrometer analyses of experimentally treated (599–1000 °C, 50–200 MPa of Ar) crystal fragments of labradorite and oligoclase. Labradorite <sup>40</sup>Ar gain diffusion profiles were measured, yielding an activation energy of 26.72±4.58 kcal mol<sup>−1</sup> (118.0±19.16 kJ mol<sup>−1</sup>) and a frequency factor of 9.77×10<sup>−9</sup> (+8.79×10<sup>−8</sup>, −8.79×10<sup>−9</sup>) cm<sup>2</sup> s<sup>−1</sup> (95% confidence). The Ar solubility in labradorite was measured yielding a value of &lt;0.2 ppb bar<sup>−1</sup>, which is similar to or lower than many rock forming minerals. The labradorite diffusion parameters indicate Ar closure temperatures of 211 °C for a spherical diffusion geometry, and 243 °C for a planar diffusion geometry (for 100 µm-diameter grains, with cooling rates of 10 °C Ma<sup>−1</sup>). The data indicate that labradorite is less Ar retentive than K-feldspar at low temperatures, but more Ar retentive than K-feldspar at high temperatures, corroborating previous work on plagioclase. The relatively slow Ar diffusion rates in labradorite at magmatic temperatures may explain the common observation of older ages in large plagioclase grains in acidic volcanic systems.
DOI: 10.6084/m9.figshare.3453299.v1
title: Ar diffusion and solubility measurements in plagioclases using the ultra-violet laser depth-profiling technique

description: We describe the first direct measurements of Ar diffusion and solubility in plagioclases using ultra-violet (UV) laser ablation depth-profiling and noble gas mass spectrometer analyses of experimentally treated (599–1000 °C, 50–200 MPa of Ar) crystal fragments of labradorite and oligoclase. Labradorite <sup>40</sup>Ar gain diffusion profiles were measured, yielding an activation energy of 26.72±4.58 kcal mol<sup>−1</sup> (118.0±19.16 kJ mol<sup>−1</sup>) and a frequency factor of 9.77×10<sup>−9</sup> (+8.79×10<sup>−8</sup>, −8.79×10<sup>−9</sup>) cm<sup>2</sup> s<sup>−1</sup> (95% confidence). The Ar solubility in labradorite was measured yielding a value of &lt;0.2 ppb bar<sup>−1</sup>, which is similar to or lower than many rock forming minerals. The labradorite diffusion parameters indicate Ar closure temperatures of 211 °C for a spherical diffusion geometry, and 243 °C for a planar diffusion geometry (for 100 µm-diameter grains, with cooling rates of 10 °C Ma<sup>−1</sup>). The data indicate that labradorite is less Ar retentive than K-feldspar at low temperatures, but more Ar retentive than K-feldspar at high temperatures, corroborating previous work on plagioclase. The relatively slow Ar diffusion rates in labradorite at magmatic temperatures may explain the common observation of older ages in large plagioclase grains in acidic volcanic systems.