GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Document type
Keywords
Language
  • 11
    Publication Date: 2021-07-05
    Description: The Rhodope Metamorphic Complex (RMC) in Bulgaria has been established as a Mesozoic ultra‐high‐pressure metamorphic province by findings of microdiamond in gneisses. Additionally, Variscan ultra‐high‐pressure metamorphism has been proposed for the Ograzhden/Vertiskos Unit in the Upper Allochthon of the RMC, based on findings of coesite, graphite pseudomorphs after diamond and indirect age constraints. We confirm ultra‐high‐pressure metamorphism of eclogites in this unit using thermobarometry, phase‐equilibrium modelling and the Variscan age of metamorphism using Lu–Hf garnet–whole‐rock dating. In Belica (southern Rila Mountains), kyanite‐ and phengite‐bearing eclogite enclosed in high‐grade gneisses records P‐T conditions of 3.0–3.5 GPa and 700–750°C. Lu–Hf dating of eclogite samples from Belica and Gega (Ograzhden Mountain), where coesite was found, yielded ages of 334.1 ± 1.8 and 334.0 ± 2.2 Ma, respectively, interpreted as the age of garnet growth during post‐collisional subduction of continental crust after closure of the Rheic Ocean.
    Description: Slovak Research and Development Agency http://dx.doi.org/10.13039/501100005357
    Description: University of Bonn
    Description: VEGA http://dx.doi.org/10.13039/501100006109
    Keywords: 552.4 ; Rhodope Metamorphic Complex ; eclogite
    Type: article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 12
    Publication Date: 2021-07-26
    Description: The Tissint meteorite fell on July 18, 2011 in Morocco and was quickly recovered, allowing the investigation of a new unaltered sample from Mars. We report new high-field strength and highly siderophile element (HSE) data, Sr-Nd-Hf-W-Os isotope analyses, and data for cosmogenic nuclides in order to examine the history of the Tissint meteorite, from its source composition and crystallization to its irradiation history. We present high-field strength element compositions that are typical for depleted Martian basalts (0.174 ppm Nb, 17.4 ppm Zr, 0.7352 ppm Hf, and 0.0444 ppm W), and, together with an extended literature data set for shergottites, help to reevaluate Mars’ tectonic evolution in comparison to that of the early Earth. HSE contents (0.07 ppb Re, 0.92 ppb Os, 2.55 ppb Ir, and 7.87 ppb Pt) vary significantly in comparison to literature data, reflecting significant sample inhomogeneity. Isotope data for Os and W (187Os/188Os = 0.1289 ± 15 and an ε182W = +1.41 ± 0.46) are both indistinguishable from literature data. An internal Lu-Hf isochron for Tissint defines a crystallization age of 665 ± 74 Ma. Considering only Sm-Nd and Lu-Hf chronometry, we obtain, using our and literature values, a best estimate for the age of Tissint of 582 ± 18 Ma (MSWD = 3.2). Cosmogenic radionuclides analyzed in the Tissint meteorite are typical for a recent fall. Tissint's pre-atmospheric radius was estimated to be 22 ± 2 cm, resulting in an estimated total mass of 130 ± 40 kg. Our cosmic-ray exposure age of 0.9 ± 0.2 Ma is consistent with earlier estimations and exposure ages for other shergottites in general.
    Keywords: 549.112
    Language: English
    Type: article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 13
    Publication Date: 2022-11-28
    Description: Mass fractions of Cu, Zn, Ga, Ag, Cd, In, Sn and Tl were determined via isotope dilution quadrupole ICP-MS in twenty-one geological reference materials (RMs) and the carbonaceous chondrites Orgueil (CI1), Murchison (CM2) and Allende (CV3). The RMs comprise basaltic/mafic (BCR-2, BE-N, BHVO-1, BHVO-2, BIR-1, BRP-1, JB-2, OKUM, W-2, WS-E), intermediate/felsic (AGV-2, G-2, JA-2, RGM-1), ultramafic (DTS-2b, MUH-1, PCC-1, UB-N) and sedimentary (MAG-1, OU-6) rocks. Pressure digestion was applied for nonbasaltic samples to ensure effective sample digestion. For basaltic RMs, hot plate digestion was found to be sufficient for a quantitative recovery of the target elements. To minimise interferences and increase ion beam intensities during isotope ratio analyses by ICP-MS, separation of the target elements was carried out from single sample aliquots using a novel anion exchange procedure. The intermediate precision (2s) estimated from two to four replicate analyses was usually 〈 4% and results are in agreement with literature data, where available. Especially for Ag and Tl, the intermediate precision was compromised, likely due to low ion beam intensities and, hence, higher background and blank contributions. For ultramafic RMs, nugget effects and incomplete digestion might compromise the intermediate precision. Results for the carbonaceous chondrites Orgueil (CI1), Murchison (CM2) and Allende (CV3) agree well with previously reported data.
    Keywords: ddc:551.9 ; isotope dilution ; chalcophile elements ; geological reference materials ; chondrites ; Q-ICP-MS
    Language: English
    Type: doc-type:article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...