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A database of analogue models and geophysical data investigating caldera resurgence; DynamiCal project

In this dataset we provide data for 6 experimental models of caldera collapse and subsequent resurgence monitored through geophysical sensors (a force or “impact sensor”, Piezotronics PCB 104 200B02 and a Triaxial piezoelectric accelerometer, Model 356B18). The analogue modelling experiments were carried out at the TOOLab (Tectonic Modelling Laboratory), which is a joint laboratory between the Istituto di Geoscienze e Georisorse of the Consiglio Nazionale delle Ricerche, Italy and the Department of Earth Sciences of the University of Florence. The laboratory work that produced these data was partly supported by the European Plate Observing System (EPOS), by the Joint Research Unit (JRU) EPOS Italia and by the “Monitoring Earth's Evolution and Tectonics” (MEET) project (NextGenerationEU). Specifically, this work was performed in the frame of the DynamiCal project, funded by the 2° TNA-NOA call of the ILGE-MEET project.

Ring-shear test data of quartz sand SIBELCO S80 used for analogue modelling in the Tectonic Laboratory (TecLab) at Utrecht University

This dataset provides friction data from ring-shear tests on quartz sand SIBELCO S80 used in analogue modelling of tectonic processes as a rock analogue for the earth’s upper crust (e.g., Klinkmüller et al., 2016). According to our analysis the material shows a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of quartz sand S80 are µP = 0.75, µD = 0.59, and µR = 0.69, respectively (Table 5). Cohesion of the material ranges between 0-80 Pa. The material shows no rate-dependency (<1% per ten-fold change in shear velocity v). The tested bulk material consists of quartz sand SIBELCO S80 with grain size of ~0.63-355 µm (D50 = 175 µm. Bulk and grain densities are 1300 kg/m³ and 2650 kg/m³, respectively and the hardness is 7 on Moh’s scale. S80 is sold e.g., by the company SIBELCO (sibelco.com).

Rheology of PDMS silicones used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (CUP)

This dataset provides rheometric data of three PDMS silicones used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (CUP). The material samples have been analyzed at the Laboratory for Experimental Tectonics at GFZ Helmholtz Centre for Geosciences, Potsdam (HelTec) using an Anton Paar Physica MCR 301 rheometer in a plate-plate configuration at room temperature (21˚C). Rotational (controlled shear rate) tests with shear rates varying from 10^4 to 1 s^-1 were performed. According to our rheometric analysis, the material is quasi-Newtonian (n~1) at strain rates below 10-2 s-1 and weakly shear rate thinning above. The viscosities of the three materials range between 8*10^4 to 3*10^5 Pa s.

Cathodoluminescence zoning images of Lower El Cajete quartz and sanidine crystals, Valles Caldera, New Mexico, USA

The Valles Caldera, New Mexico, USA was created by two caldera-forming eruptions at ~1.6 and ~1.1 Myr. Since then, post-caldera activity has consisted of lava domes, lava flows, large explosive phases, and a hydrothermal system active today. Possibly the youngest eruption sequence, El Cajete, was emplaced 74.4 ± 1.3 ka (Zimmerer et al., 2016) and began with pyroclastic surges, followed by pyroclastic density currents (PDCs) and pumice-rich Plinian pyroclastic fall (Self et al., 1988). The objective of this project was to characterize crystal grains from the early El Cajete sequence, in terms of morphology and textures, using scanning electron microscopy (SEM). The early El Cajete differs from the later part of the sequence in its greater stratigraphic and lithologic complexity, having been formed from not only pyroclastic fall (like the later El Cajete) but also surge beds and PDCs. This dataset was collected under the national open access action at Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa SEM/EDS facility supported by WP3 ILGE – MEET project, PNRR – EU Next Generation Europe program, MUR grant number D53C22001400005. This allowed me to obtain the present dataset of 31 cathodoluminescence (CL) images of 30 quartz crystals and one sanidine crystal.

Ring-shear test data of colored quartz sand used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing)

This dataset provides friction data from ring-shear tests colored quartz sand used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.75, µD = 0.59, and µR = 0.67, respectively (Table 5). Cohesion of the material ranges between 20-90 Pa. The tested bulk material consists of blue colored quartz sand with grain size of 180-380 µm and is sold under the name "Colored Sand" with the product number A1 by the company Xinran Mineral Products (1688.com). The data presented here are derived by ring shear testing using a SCHULZE RST-01.pc (Schulze, 1994, 2003, 2008) at HelTec, the Laboratory for experimental tectonics at the Helmholtz Center Potsdam – GFZ German Research Centre for Geosciences in Potsdam, Germany. The RST is specially designed to measure friction coefficients µ and cohesions C in loose granular material accurately at low confining pressures (<20 kPa) and shear velocities (<1 mm/sec) similar to sandbox experi-ments. In this tester, a granular bulk material layer is sheared internally at constant normal stress σN and shear velocity v while shear force and lid displacement (corresponding to density and vol-ume change ΔV) are measured continuously. For more details see Klinkmüller et al. (2016).

Europaeischer Pool Informations- und Schulungsmaterialien Solartechnik (EUPOS)

Ring-shear test data of wallnut shells used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing))

This dataset provides friction data from ring-shear tests walnut shells used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the tested materials behave as a Mohr-Coulomb material characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.90, µD = 0.63, and µR = 0.68, respectively (Table 4). Cohesion of the material ranges between 0-40 Pa. The tested bulk material consists of walnut shells with grain size of 180-380 µm (Table 1) and is sold under the name "Walnut Shells" with the product number YR-98547 by the company Yiran Mineral Products (1688.com). The data presented here are derived by ring shear testing using a SCHULZE RST-01.pc (Schulze, 1994, 2003, 2008) at HelTec, the Laboratory for experimental tectonics at the Helmholtz Center Potsdam – GFZ German Research Centre for Geosciences in Potsdam, Germany. The RST is specially designed to measure friction coefficients µ and cohesions C in loose granular material accurately at low confining pressures (<20 kPa) and shear velocities (<1 mm/sec) similar to sandbox experiments. In this tester, a granular bulk material layer is sheared internally at constant normal stress σN and shear velocity v while shear force and lid displacement (corresponding to density and volume change ΔV) are measured continuously. For more details see Klinkmüller et al. (2016).

A database of analogue models testing the interaction between magmatic intrusion-related doming and caldera collapse

This dataset presents the raw data from one experimental series (named CCEX, i.e., Caldera Collapse under regional Extension) of analogue models performed to investigate the process of caldera collapse followed by regional extension. Our experimental series tested the case of perfectly circular collapsed calderas afterward stretched under regional extensional conditions, that resulted in elongated calderas. The models are primarily intended to quantify the role of regional extension on the elongation of collapsed calderas observed in extensional settings, such as the East African Rift System. An overview of the performed analogue models is provided in Table 1. Analogue models have been analysed quantitatively by means of photogrammetric reconstruction of Digital Elevation Model (DEM) used for 3D quantification of the deformation, and top-view photo analysis for qualitative descriptions. The analogue materials used in the setup of these models are described in Montanari et al. (2017), Del Ventisette et al. (2019), Bonini et al., 2021 and Maestrelli et al. (2021a,b).

Magnetochronostratigraphic data from marine sediments off Patagonia, SE Pacific – cores from expedition MR16-09 Leg 2, Japanese RV Mirai, 2017

Sediment cores PC02, PC03, and PC04 were recovered during the ship expedition MR16-09 Leg 2 of Japanese RV Mirai in 2017 (Murata et al., 2017) using piston corers. For paleo- and rock magnetic analyses clear plastic boxes with a volume of 7 cm3 were pressed into the split halves of the generally 1 m long sections of the sediment cores. X-ray fluoresence (XRF) scans were performed with an Itrax XRF Corescanner (Cox Analytical systems) at Kochi Core Center, Japan (Hagemann et al. 2024). The downcore resolution was set to 5 mm, and the scans were performed with a Mo X-ray tube at 30 kV and 55 mA for a measurement time of 15 s. The Itrax X-ray beam was set to 0.2 mm × 20 mm. Measurements of low-field magnetic susceptibility (klf same as: k-bulk) and its anisotropy (AMS) were performed with an AGICO MFK1-A susceptibility meter. The principal AMS axes Kmax, Kint, and Kmin, the three axes of the anisotropy ellipsoid, were used to calculate the degree of anisotropy, as well as the shape factor of anisotropy. The frequency dependency of magnetic susceptibility was determined with an automated MAGNON Variable Field Susceptibility Meter (VFSM) by measuring magnetic susceptibility at different frequencies with logarithmically equidistant steps at a field amplitude of 250 µT. Susceptibilities of core PC02 samples were measured at 7 frequencies F from 375 Hz to 4775 Hz. Samples from cores PC03 and PC04 were measured at 5 frequencies from 475 to 4775 Hz. The frequency dependency Dk/Dlog(F) then was determined by linear regression of susceptibility k versus the decadal logarithm of frequency F. Values are given as decay rate in percent over one frequency decade (% / decade (F)) relative to the measurement at the lowest frequency. Thus, values obtained are negative. Measurements of the natural remanent magnetization (NRM) and of the anhysteretic remanent magnetization (ARM) were performed with a 2G 755 SRM long-core cryogenic magnetometer. ARMs were produced with a 2G660 single-axis alternating field (AF) demagnetizer using 100 mT alternating field and 50 µT static field. NRMs and ARMs both were stepwise demagnetized with the in-line 3-axes AF demagnetizer of the cryogenic magnetometer. AF steps for NRM: 0, 5, 10, 15, 20, 30, 40, 50, 65, 80, 100 mT. AF steps for ARM: 0, 10, 20, 30, 40, 50, 65, 80 mT. Iso-thermal remanent magnetizations (IRM) were imparted with a 2G 660 pulse magnetizer using 1500 mT for producing a saturation magnetization (SIRM) and -200 mT for remagnetization of the low-coercive fraction. Measurements were performed with a Molyneux spinner magnetometer. Data records were turned into time series by applying the age model for PC03 (Hagemann et al., 2024), correlating PC02 to PC03, and correlating PC04 to PC03 (back to 140 ka) and further using the PISO1500 paleointensity stack (Channell et al., 2009), paleomagnetic data from the Black Sea (Liu et al., 2020, Nowaczyk et al., 2021), and paleoclimatic data from Antarctica (Jouzel et al., 2007; Bazin et al., 2013) for reference for older core sections.

Magnetochronostratigraphic data from sediments in the Drake Passage – cores from expedition PS97, German RV Polarstern, 2016

Sediment cores were recovered during the ship expedition of German RV Polarstern in 2016 (PS97) using piston corers. For paleo- and rock magnetic analyses clear plastic boxes of 20×20×15 mm were pressed into the split halves of the generally 1 m long sections of the sediment cores. In order to determine the direction of the characteristic remanent magnetization (ChRM), demagnetization results of the NRM were subjected to principal component analysis (PCA) according to Kirschvink (1980). The PCA also provided the maximum angular deviation (MAD) as a measure of the precision of the determined ChRM direction. ChRM declinations obtained by PCA were rotated around a vertical axis until the declinations of all samples falling into a circular window of 35° around the direction expected from a geocentric axial dipole (-72.9°) yielded a mean of 0°. ChRM data from core PS97-085-1 (-85-3) were tentatively tilted by +17° (-7°) around the EW axis in order to parallel the maximum in the inclination distribution with the inclination of a geocentric axial dipole field. The anhysteretic susceptibility K(ARM) is defined as the ARM intensity normalised by the static field used for producing the ARM. The anhysteretic susceptibility normalised by the low field bulk susceptibility K(ARM)/klf then is a magnetic grain size proxy with low (high) ratios indicating relatively large (small) magnetite particles. In order to discriminate samples being dominated by low-coercive minerals (magnetite, Fe3O4 and greigite, Fe3S4) from samples being dominated by high-coercive minerals (mostly hematite, Fe2O3), the S-ratio was calculated using S=0.5×(1-[IRM(-200 mT)/SIRM(1500 mT)]). S-ratios range from 0 to 1, with: dominance of magnetite/greigite: 0<<S≤1, and dominance of hematite: 0≤S<<1. As another grain size proxy the ARM intensity was normalised by the SIRM: (1000×ARM/SIRM) with low (high) ratios indicating relatively large (small) magnetite particles. The factor of 1000 is introduced in order to avoid small numbers. Relative paleointensity variations were estimated by three different proxies: slope of NRM vs. ARM of common demagnetization steps (slope(NRM/ARM)), NRM intensity demagnetized with 30 mT normalized with bulk susceptibility klf (pjk(30mT)), and NRM intensity demagnetized with 30 mT normalized with saturation magnetization SIRM (pjs(30mT)). Data records were turned into time series by correlation to dated reference records from Antarctica (Wu et al., 2021) and the Black Sea (Liu et al., 2021).

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