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2019

1077 record(s)
 
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From 1 - 10 / 1077
  • speleothem data - ICP-AES (Inductively coupled plasma atomic emission spectroscopy) , incomplete soil acidity experiments - soil water chemistry after acidification - incomplete

  • Infrasound Data collected at Volcan de Fuego (Guatemala) during three campaigns (May and November 2018, and June 2019). Associated article https://doi.org/10.3390/rs11111302

  • Sediment % coarse fraction (>63 microns), and abundance of fish teeth in coarse fraction. 2016 has been a record breaking year in terms of global temperatures. The high temperatures have resulted from a combination of elevated atmospheric pCO2 coupled with the global impacts of a strong El Nino event. There are many important components of the climate system, and the El Nino phenomenon demonstrates the importance of the low latitude Pacific Ocean. The warm pool of water in the western Pacific Ocean has not always had the same characteristics as it has today, and it has been proposed that its evolution over the past 15 million years has had a major impact on global climate. In order to understand how the warm pool might respond to future climate change, it is important to understand the drivers behind its past evolution. Did it respond simply to the changing shape of ocean basins through time? Or did it respond to other components of the climate system, such as sea level or latitudinal temperature gradients? The changes in warm pool structure may also have impacted the biological ecosystems, and hence the cycling of carbon in this region. The carbon cycle is another key component of the Earth's climate system. Understanding the causes and consequences of these long-term changes in the Pacific warm pool requires a two-pronged approach, using modelling in conjunction with proxy records for different parts of the climate system. This proposal aims to generate some key records of past high latitude temperature and ice volume that can be directly compared with changes in the warm pool through time. These records will be derived from geochemical analyses of microscopic marine fossils collected by the International Ocean Discovery Program (IODP).

  • Multi-decadal time series of groundwater levels were compiled by the authors from records of observation wells initiated and maintained by government departments and research institutions in nine countries in sub-Saharan Africa. The pan-African collation of these hydrographs was initiated at the 41st Congress of the International Association of Hydrogeologists (IAH) in Marrakech (Morocco) on 14th September 2014. All records were subjected to a rigorous review by the authors during which the integrity, continuity, duration and interpretability of records were evaluated. This process included dedicated workshops in Benin, Tanzania, and Uganda, and records failing these tests were discarded from the analysis. Procedures included taking of the first time derivative to identify anomalous spikes in records commonly associated with errors of data-entry. Where multiple records in same geographic and climate zone were available (e.g. Benin, South Africa) we prioritized records remote from potential areas of intensive abstraction. Statistical clustering of records was also used in the Limpopo Basin of South Africa to identify the representativity of employed records at Modderfontein and Sterkloop.

  • Porewaters from IODP Expedition 366 were extracted from serpentinite mud volcano sediments onboard the RV JOIDES Resolution (see Fryer et al, 2017; 2018 for details). Selected samples were then analysed at the University of Southampton for 87Sr/86Sr and boron isotopes and SUERC for stable hydrogen and oxygen isotope data. The strontium isotope data has recently been accepted for publication (Albers et al., 2019 (In Press) Fluid–rock interactions in the shallow Mariana forearc: carbon cycling and redox conditions, Solid Earth special issue "Exploring new frontiers in fluids processes in subduction zones").

  • The data set contains location (latitude and longitude), ellipsoidal height (m) and observed gravity of benchmarks at the Campi Flegrei caldera, Italy. The gravity and location data were collected between 8 and 12 July, 2015 using a Scintrex CG5 gravimeter (serial number: 572) in tandem with a TOPCON HiPer Pro Dual-Frequency GNSS base and rover system. The survey contained a total of 85 benchmarks in addition to the base station.

  • The data is presented as relative abundances of all species encountered in 300 counts on standard light microscope smear slides. Counts are presented from 64 samples, ranging from sample U1510A 48X 1W 50-51 cm (435.90 m) to U1510A 52X CC 24 cm (478.09 m). A second dataset provides semi-quantitative data from the same samples, which includes species that were not encountered during the 300 count.

  • Element maps from 5x 10 cm sections generated using the Zeiss Sigma HD Field Emission Gun Analytical SEM at Cardiff University. Maps come from sections within the early Miocene pelagic interval situated directly below the Nicobar Fan succession at IODP Site U1480 in the Eastern Equatorial Indian Ocean (for more information see published report, https://doi.org/10.1016/j.epsl.2017.07.019). These specific sections were chosen to examine the depositional environments associated with transitions from red clays to white chalk, which demonstrate distinct banding at the micro and macro scale.

  • This study explored the links between host rock composition, hydrothermal fluid composition (particularly pH), and the resulting ore minerals and deposits. The progressive water–rock reaction between 1 kg of initially acidic, condensed magmatic vapour and a series of different rock compositions was modelled with CHILLER (Reed, 1982, Reed, 1998), and follows the design of the water-rock reactions of Reed (1997). The thermodynamic data used in the numerical experiments are from the database SOLTHERM.H08 (Reed and Palandri, 2013). Data and calculations within SOLTHERM include: equilibrium constants calculated with SUPCRT92 (Johnson et al., 1992); mineral thermodynamic data for silicates, oxides, hydroxides, carbonates, gases (Holland and Powell, 1998) and sulphides (Shock, 2007). Mineral solid solutions are represented by end-member compositions that are mixed using an ideal multisite mixing scheme. Rock compositions used in the modelling represent a sub-alkaline andesitic control, and a number of alkaline compositions associated with world-class Au deposits. All starting rock compositions are derived from whole rock geochemical data, and have been recalculated to a 100% basis without TiO2 or P2O5 (excluded as minor phases with little to no effect on hydrothermal mineral assemblages). Original total Fe (as Fe2O3) has been recalculated to FeO and Fe2O3 using the method of Müller et al. (2001). The andesite is representative of calc-alkaline, silica saturated compositions, and is derived from and discussed in detail in Reed (1997). The Luise “Phonolite” (a trachyandesite using the Le Maitre et al., 1989 TAS plot; Fig. 1) and Trachyandesite are from the vicinity of the Ladolam epithermal Au deposit, Lihir Island, Papua New Guinea (Müller et al., 2001). The Porgera Mugearite and Feldspar Porphyry represent unaltered host rock compositions (Richards, 1990) from the Porgera Au deposit (Papua New Guinea). The Cripple Creek Phonolite is part of the host suite to the Cripple Creek epithermal Au deposit, Colorado (Kelley et al., 1998). The Savo trachyte (Smith et al., 2009) represents a typical host rock of the active hydrothermal system (Smith et al., 2010), on Savo island, Solomon Islands. With the exception of the Andesite, all compositions are alkaline using the total alkali versus silica definition of Irvine and Baragar (1971). The Savo sample is not associated with known epithermal Au mineralisation; this composition was selected on the grounds that it represents an evolved (SiO2-rich) silica-saturated, alkaline composition. The initial fluid composition is based on a condensate from Augustine volcano (Symonds et al., 1990) mixed 1:10 with pure water (Reed, 1997; Table 2). A single starting fluid for all models was chosen so as to demonstrate the effect of host rock alone.

  • Isotopic geochemical analysis of volcanic samples from across Ethiopia. Data are referenced in Hutchison et al., 2018: The evolution of magma during continental rifting: New constraints from the isotopic and trace element signatures of silicic magmas from Ethiopian volcanoes; https://doi.org/10.1016/j.epsl.2018.02.027