scholarly journals Determining relative magma and host rock xenolith rheology during magmatic fabric formation in plutons: Examples from the middle and upper crust

Geosphere ◽  
2009 ◽  
Vol 5 (3) ◽  
pp. 270-285 ◽  
Author(s):  
Aaron S. Yoshinobu ◽  
Jeannette M. Wolak ◽  
Scott R. Paterson ◽  
Geoffrey S. Pignotta ◽  
Heather S. Anderson
Keyword(s):  
Host Rock ◽  
Upper Crust ◽  
Magmatic Fabric

Mesoscopic and magnetic fabrics in arcuate igneous bodies: an example from the Mandi-Karsog pluton, Himachal Lesser Himalaya

2010 ◽  
Vol 147 (5) ◽  
pp. 652-664 ◽  
Author(s):  
R. JAYANGONDAPERUMAL ◽  
A. K. DUBEY ◽  
K. SEN
Keyword(s):  
Host Rock ◽  
Magnetic Fabric ◽  
Lesser Himalaya ◽  
Himalayan Orogeny ◽  
Magnetic Fabrics ◽  
Himachal Lesser Himalaya ◽  
Shear Sense ◽  
Magmatic Fabric ◽  
Extension Fracture ◽  
Shear Sense Indicators

AbstractField, microstructural and anisotropy of magnetic susceptibility (AMS) data from the Palaeozoic Mandi-Karsog pluton in the Lesser Himalayan region reveal a concordant relationship between fabric of the Proterozoic host rock and the granite. The pluton displays a prominent arcuate shape on the geological map. The margin-parallel mesoscopic and magnetic fabrics of the granite and warping of the host rock fabric around the pluton indicate that this regional curvature is either synchronous or pre-dates the emplacement of the granite body. Mesoscopic fabric, magnetic fabric and microstructures indicate that the northern part of the pluton preserves its pre-Himalayan magmatic fabric while the central and southern part shows tectonic fabric related to the Tertiary Himalayan orogeny. The presence of NW–SE-trending aplitic veins within the granite indicates a post-emplacement stretching in the NE–SW direction. Shear-sense indicators in the mylonites along the margin of the pluton suggest top-to-the-SW shearing related to the Himalayan orogeny. Based on these observations, it is envisaged that the extension that gave rise to this rift-related magmatism had a NE–SW trend, that is, normal to the trend of the aplite veins. Subsequently, during the Himalayan orogeny, compression occurred along this same NE–SW orientation. These findings imply that the regional curvature present in the Himachal Lesser Himalaya is in fact a pre-Himalayan feature and the pluton has formed by filling a major pre-Himalayan arcuate extension fracture.

scholarly journals Host-rock deformation during the emplacement of the Mourne Mountains granite pluton: Insights from the regional fracture pattern

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 182-209 ◽  
Author(s):  
Tobias Mattsson ◽  
Steffi Burchardt ◽  
Karen Mair ◽  
Joachim Place
Keyword(s):  
Host Rock ◽  
Large Scale ◽  
Rock Fracture ◽  
Fracture Pattern ◽  
Contact Aureole ◽  
Upper Crust ◽  
Magma Body ◽  
Granite Pluton ◽  
The North ◽  
Emplacement Mechanism

Abstract The Mourne Mountains magmatic center in Northern Ireland consists of five successively intruded granites emplaced in the upper crust. The Mourne granite pluton has classically been viewed as a type locality of a magma body emplaced by cauldron subsidence. Cauldron subsidence makes space for magma through the emplacement of ring dikes and floor subsidence. However, the Mourne granites were more recently re-interpreted as laccoliths and bysmaliths. Laccolith intrusions form by inflation and dome their host rock. Here we perform a detailed study of the deformation in the host rock to the Mourne granite pluton in order to test its emplacement mechanism. We use the host-rock fracture pattern as a passive marker and microstructures in the contact-metamorphic aureole to constrain large-scale magma emplacement-related deformation. The dip and azimuth of the fractures are very consistent on the roof of the intrusion and can be separated into four steeply inclined sets dominantly striking SE, S, NE, and E, which rules out pluton-wide doming. In contrast, fracture orientations in the northeastern wall to the granites suggest shear parallel to the contact. Additionally, contact-metamorphic segregations along the northeastern contact are brecciated. Based on the host-rock fracture pattern, the contact aureole deformation, and the north-eastward–inclined granite-granite contacts, we propose that mechanisms involving either asymmetric “trap-door” floor subsidence or laccolith and bysmalith intrusion along an inclined or curved floor accommodated the emplacement of the granites and led to deflection of the northeastern wall of the intrusion.

Optimal Density Determination of Bouguer Anomaly Using Fractal Analysis (Case of study: Charak area,IRAN)

2005 ◽  
Vol 1 (1) ◽  
pp. 21-24
Author(s):  
Hamid Reza Samadi
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Host Rock ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Density Difference ◽  
Optimal Density

In exploration geophysics the main and initial aim is to determine density of under-research goals which have certain density difference with the host rock. Therefore, we state a method in this paper to determine the density of bouguer plate, the so-called variogram method based on fractal geometry. This method is based on minimizing surface roughness of bouguer anomaly. The fractal dimension of surface has been used as surface roughness of bouguer anomaly. Using this method, the optimal density of Charak area insouth of Hormozgan province can be determined which is 2/7 g/cfor the under-research area. This determined density has been used to correct and investigate its results about the isostasy of the studied area and results well-coincided with the geology of the area and dug exploratory holes in the text area

DETERMINING HOST-ROCK ENVIRONMENT OF TOURMALINITES USING LASER-INDUCED BREAKDOWN SPECTROSCOPY

2019 ◽  
Author(s):  
Shoshauna Farnsworth-Pinkerton ◽  
◽  
Barbara L. Dutrow ◽  
Darrell J. Henry ◽  
Nancy J. McMillan
Keyword(s):  
Host Rock ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown
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