Results 11 to 20 of about 2,536 (164)

Rapakivi K‐Feldspar Megacrysts in Monzogranitic Porphyry: Evidence for Magma Recharge and Mush Rejuvenation

Geochemistry, Geophysics, Geosystems
The formation, storage, and evolution of granitic magmas are fundamental processes driving the growth of continental crust. While traditionally attributed to crystal fractionation in high‐melt fraction magma chambers, the model invoking low‐melt fraction
Wang Li, Xuxuan Ma, Roberto Weinberg, Liang Qiu, Zhiyong Zhu, Haibing Li   +5 more
doaj   +2 more sources

Sediment Characteristics in Stonewort <i>Chara Tomentosa</i> Assemblages. [PDF]

Ecol Evol
The study investigated sediment characteristics associated with Chara tomentosa. The results show that sediment grain size and the concentration of the dissolved phosphate in the porewater differ in the seafloor areas characterised by C. tomentosa from adjacent areas at similar depth, but without charophytes.
Puttonen I, Raitanen H, Nystrand M, Salovius-Laurén S.   +3 more
europepmc   +2 more sources

Geologia e Geoquímica do Batólito Rapakivi Rio Branco, SW do Craton Amazônico - MT [PDF]

Geologia USP. Série Científica, 2007
O Batólito Rapakivi Rio Branco está inserido no Domínio Tectônico Cachoeirinha, parte da Província GeocronológicaRio Negro-Juruena, localizado na porção sudoeste do Craton Amazônico em Mato Grosso.
Larissa Marques Barbosa de Araújo-Ruiz, Antonio Misson Godoy, Amarildo Salina Ruiz, Maria Zélia Aguiar de Sousa, Luiz Fernando de Mello Montano   +4 more
doaj   +3 more sources

A specialized topaz-bearing rapakivi granite and associated mineralized greisen in the Ahvenisto complex, SE Finland [PDF]

Bulletin of the Geological Society of Finland, 1991
The Ahvenisto rapakivi complex is a satellite northwest of the large Wiborg rapakivi batholith in Southeastern Finland. The rapakivi rocks are surrounded by rapakivi-age gabbros, anorthosites, monzodiorites and diabases.
P. Edén
doaj   +1 more source

On the direction of remanent magnetization of the quartz porphyry dikes in SE Finland [PDF]

Bulletin of the Geological Society of Finland, 1986
Attempts are made to determine the direction of remanent magnetization of the rapakivi varieties belonging to the Wiborg (Viipuri) rapakivi massif and its satellites in the precambrian Baltic Shield. Hard and stable remanence was found only in the quartz
K.J. Neuvonen
doaj   +1 more source

Hydrogeological Characterization of Crystalline Bedrock Using Borehole Magnetic Resonance

Groundwater, Volume 61, Issue 6, Page 793-815, November/December 2023., 2023
This study is one of the first to test the applicability of the borehole magnetic resonance (BMR) method in crystalline “hard rock” environment. The aim was to investigate whether the BMR measurements could constitute an effective method for investigating detailed permeability variations in the crystalline bedrock of the two study sites: Sakatti mining
Salla Eeva, Aino Karjalainen, Emilia Koivisto, Kirsti Korkka‐Niemi, Anne Rautio, Olli Räisänen, Ryan Gee, Benjamin Birt   +7 more
wiley   +1 more source

The Shahewan rapakivi-textured granite-quartz monzonite pluton, Qinling orogen, central China: Mineral composition and petrogenetic significance [PDF]

Bulletin of the Geological Society of Finland, 2002
The Mesozoic Shahewan pluton consists of four texturally different types of biotite-hornblende quartz monzonite. In the porphyritic types alkali feldspar occurs as euhedral or ovoidal megacrysts that are often mantled by one or more plagioclase shells ...
X. Wang, T. Wang, I. Haapala, X. Lu
doaj   +1 more source

The interplay of bedrock fractures and glacial erosion in defining the present‐day land surface topography in mesoscopically isotropic crystalline rocks

Earth Surface Processes and Landforms, Volume 48, Issue 10, Page 1956-1968, August 2023., 2023
In this paper, we link natural fractures with outcrop morphologies and apply the findings in understanding the glacial erosion signatures in crystalline rocks. Abstract This paper addresses the effect of fractures within crystalline bedrock on glacial erosion processes in fast flowing hard bed glacier environments. In particular, we examine (i) whether
Pietari Skyttä, Nicklas Nordbäck, Antti Ojala, Niko Putkinen, Ismo Aaltonen, Jon Engström, Jussi Mattila, Nikolas Ovaskainen   +7 more
wiley   +1 more source

Induced Earthquake Source Parameters, Attenuation, and Site Effects From Waveform Envelopes in the Fennoscandian Shield

Journal of Geophysical Research: Solid Earth, Volume 128, Issue 4, April 2023., 2023
Abstract We analyze envelopes of 233 and 22 ML0.0 to ML1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. We separate source spectra and site terms and determine intrinsic attenuation and the scattering strength of shear waves in the 3–200 Hz frequency range using radiative transfer based synthetic ...
Tom Eulenfeld, Gregor Hillers, Tommi A. T. Vuorinen, Ulrich Wegler   +3 more
wiley   +1 more source

Secular Evolution of Continents and the Earth System

Reviews of Geophysics, Volume 60, Issue 4, December 2022., 2022
Abstract Understanding of secular evolution of the Earth system is based largely on the rock and mineral archive preserved in the continental lithosphere. Based on the frequency and range of accessible data preserved in this record, we divide the secular evolution into seven phases: (a) “Proto‐Earth” (ca. 4.57–4.45 Ga); (b) “Primordial Earth” (ca. 4.45–
Peter A. Cawood, Priyadarshi Chowdhury, Jacob A. Mulder, Chris J. Hawkesworth, Fabio A. Capitanio, Prasanna M. Gunawardana, Oliver Nebel   +6 more
wiley   +1 more source