Results 101 to 110 of about 59,128 (262)

Variable Sr Diffusion and Implications for Rb–Sr Biotite Geochronology

Journal of Metamorphic Geology, EarlyView.
ABSTRACT The rubidium–strontium (Rb–Sr) system has a long pedigree as a geochronological tool that relies on the application of an isochron approach. In particular, biotite contains strongly radiogenic Rb–Sr isotopes, and thus can yield meaningful crystallisation or cooling ages via this approach. However, the response of the Rb–Sr system in biotite to
Riley Rohrer, Christopher L. Kirkland, Hugo Olierook, Tim Johnson, Katy Evans   +4 more
wiley   +1 more source

Magmatic and Amygdaloidal Plagioclases [PDF]

Geological Magazine, 1955
AbstractThermal metamorphism of zeolites in amygdales of basaltic rocks is shown to give glomero-porphyroblastic aggregates of plagioclase crystals. Plagioclase phenocrysts in basic rocks are shown to undergo but little change during similar degrees of metamorphism.
openaire   +2 more sources

Siberian flood basalt magmatism and Mongolia-Okhotsk slab dehydration [PDF]

, 2008
Experimental data combined with numerical calculations suggest that fast subducting slabs are cold enough to carry into the deep mantle a significant portion of the water in antigorite, which transforms with increasing depth to phase A and then to phase ...
Alexei V. Ivanov, Konstantin D. Litasov
core   +1 more source

Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina [PDF]

, 2018
The A-type Huaco granite pluton of the Velasco range (Sierras Pampeanas of northwest Argentina) is formed by three coeval granitic facies and contains subordinate coeval-to-late facies, as well as enclaves, dikes and stocks that show different temporal ...
Grosse, Pablo, Lozano Fernández, Rafael Pablo, Murata, Mamoru, Sardi, Fernando Guillermo   +3 more
core   +2 more sources

P–T Modelling Constrains the Depth of Emplacement of the Porto Azzurro Pluton and Implies Minor Exhumation Caused by the Zuccale Fault (Island of Elba, Italy)

Journal of Metamorphic Geology, EarlyView.
ABSTRACT Understanding the pressure of emplacement of granitic intrusions is crucial to understanding the exhumation history of plutons and constraining the tectonic setting of magma emplacement. However, P–T and geochronological constraints from exhumed plutons are often characterized by large uncertainties, especially in shallow crustal settings with
Samuele Papeschi, Marco Bonini, Matteo Lupi, Chiara Del Ventisette, Domenico Montanari   +4 more
wiley   +1 more source

Strumble-Preseli ancient communities and environment study (SPACES); Sixth report 2007-08 [PDF]

, 2009
This paper reports the results of field surveys and geophysical surveys in the eastern Preseli Hills of Pembrokeshire, Wales, together with petrological descriptions of rock samples taken from key outcrops and quarry ...
Armstrong, Kayt, Darvill, Timothy, Ixer, R.A., Wainwright, Geoff   +3 more
core  

New knowledge about shock events that affected the L‐chondrite parent body from two heavily shocked L6 meteorite finds

Meteoritics &Planetary Science, EarlyView.
Abstract We report new results from a study of shock‐related features in the L6 ordinary chondrites Northwest Africa (NWA) 4672 and NWA 12841. Our observations confirm the occurrence of eight high‐pressure (HP) minerals in each meteorite, namely, ringwoodite, majorite, akimotoite, wadsleyite, albitic jadeite, lingunite, tuite, and xieite.
I. Baziotis, L. Ferrière, C. Ma, J. Hu, D. Palles, P. D. Asimow   +5 more
wiley   +1 more source

A micro-analytical approach to partition coefficients in plagioclase and clinopyroxene of basaltic sills in Serra Geral Formation, Paraná Basin, Brazil

Brazilian Journal of Geology
: In the present study, detailed micro-analytical data (major and trace elements) in minerals from sills of Serra Geral Formation represents the first attempt to evaluate the partition coefficient of Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Mo ...
Leonardo Cardoso Renner, Léo Afraneo Hartmann, Wilson Wildner, Hans-Joachim Massonne, Thomas Theye   +4 more
doaj   +1 more source

Determining impact angle from the spatial distribution of shock metamorphism: A case study of the Gosses Bluff (Tnorala) impact structure, Australia

Meteoritics &Planetary Science, EarlyView.
Abstract The majority of planetary impacts occur at oblique angles. Impact structures on Earth are commonly eroded or buried, rendering the identification of the direction and angle of impact—using methods such as asymmetries in ejecta distribution, surface topographic expression, central uplift structure, and geophysical anomalies—challenging. In this
Eloise E. Matthews, Auriol S. P. Rae, Thomas Kenkmann, Nicholas E. Timms, Aaron J. Cavosie, Marian B. Holness   +5 more
wiley   +1 more source

Vertical profiling of shock attenuation at the Rochechouart impact structure, France

Meteoritics &Planetary Science, EarlyView.
Abstract Rochechouart, south‐west France, is a complex impact structure. Here, we present the first report of shock barometry of quartz from what are likely parautochthonous basement units at depth, based on samples from the 2017 C.I.R.I.R drilling campaign. The crystallographic orientations of 725 sets of PDFs in 512 quartz grains in samples from four
P. Struzynska, S. Alwmark, C. Alwmark, M. H. Poelchau, P. Lambert   +4 more
wiley   +1 more source