Drill core structural analysis and extensional-contractional controls on the sulfide mineralization at the Ambrosia Sul zinc deposit, Vazante group, Western São Francisco craton, Brazil

Abstract Current portable X-ray fluorescence (pXRF) technology can rapidly and inexpensively yield concentrations of geologically significant elements, typically with instrument detection limits below several tens of parts per million. Based on conventional XRF whole-rock geochemical data, both the Ishikawa alteration index and the chlorite-carbonate-pyrite index increase with proximity to sulfide mineralization at Myra Falls. However, available pXRF technology is typically unable to detect all the elements required to calculate these alteration indices. As a result, there is a need to utilize the elements that are readily detectable using pXRF and apply these to hydrothermal alteration assessment. We propose that Rb/Sr ratios provide a robust proxy for the Ishikawa alteration index and demonstrate that conventional whole-rock XRF analytical results for Rb and Sr can be reproduced using pXRF analysis from drill core surfaces. At Myra Falls, the Rb/Sr ratios vary from <0.1 for least altered rocks, 0.1 to 0.5 for weakly altered rocks, 0.5 to 1.0 for moderately altered rocks, 1.0 to 2.0 for strongly altered rocks, and >2.0 for intensely altered rocks. Downhole profiles of alteration intensity generated from systematic pXRF analysis of drill core surfaces can be used to inform drilling and targeting decisions. The application of the Rb/Sr ratio as a proxy for alteration intensity extends beyond this case study and can be applied to other hydrothermal systems that produce phyllosilicate minerals as alteration products of feldspar.

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Chapter 7: Structural Analysis of Drill Core for Mineral Exploration and Mining: Review and Workflow Toward Domain-Based 3-D Interpretation

APPLIED STRUCTURAL GEOLOGY OF ORE-FORMING HYDROTHERMAL SYSTEMS ◽

10.5382/rev.21.07 ◽

2020 ◽

pp. 215-245

Author(s):

Julia Kramer Bernhard ◽

Wayne Barnett ◽

Ron Uken ◽

Russell Myers

Keyword(s):

Structural Analysis ◽

Mineral Exploration ◽

Drill Core

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The Geometry and Structural Analysis of the Gold Deposits of Chirano Mine

Ghana Mining Journal ◽

10.4314/gm.v16i2.2 ◽

2016 ◽

Vol 16 (2) ◽

pp. 10-19

Author(s):

K. Ackon-Wood ◽

J. S. Y. Kuma ◽

J. A. Yendaw

Keyword(s):

Structural Analysis ◽

Gold Deposit ◽

Shear Zone ◽

Gold Deposits ◽

Drill Core ◽

The South ◽

Complex Interplay ◽

The North ◽

Structural Deformations

The Chirano Mine gold deposit is a typical example of a structurally controlled deposit developed along the Kumasi Basin and the Sefwi Belt margin structure. The area has undergone various regimes of structural deformations. Consequently, all the Chirano deposits are intimately associated with shears and faults along a single continuous structural corridor known as the Chirano Shear Zone (CSZ). The CSZ geometry has been categorised into three major zones namely: (i) Laminated veins in shears, (ii) Breccia and (iii) Ductile to brittle ductile zones. The shear veins trend NE-SW and N-S, are laminated and occur in the sheared fabric close to the footwall. Penetrative foliated zones varying from a few centimeters to several meters constitute the ductile to brittle-ductile structures. Gold grades are much higher within this zone. Analysis of cataclasis intensity recorded in drill core confirms a semi brittle form of deformation within the mineralised domain. The CSZ has different orientations in dip and strike from the south of the mining lease to the north. The subtle changes in orientation are deposit dependent. The structure has a sinuous shape and tends to pinch and swell. The current geometry and the distribution of stratigraphy and orebodies at Chirano is a manifestation of the complex interplay of magmatic and hydrothermal events in the area. Keywords: Ductile, Brittle-Ductile, Breccia, Chirano Shear Zone, Chirano Lode Horizon

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Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077268 ◽

1983 ◽

Vol 41 ◽

pp. 738-739

Author(s):

W. H. Wu ◽

R. M. Glaeser

Keyword(s):

Electron Microscopy ◽

Surface Layer ◽

Structural Analysis ◽

High Resolution ◽

Low Dose ◽

High Resolution Electron Microscopy ◽

Optical Diffraction ◽

Surface Layer Protein ◽

Morphological Unit ◽

Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

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RNA polymerase: Preparation and structural analysis of helical polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011091x ◽

1984 ◽

Vol 42 ◽

pp. 152-153

Author(s):

E. Loren Buhle ◽

Pamela Rew ◽

Ueli Aebi

Keyword(s):

Structural Analysis ◽

Rna Polymerase ◽

Molecular Level ◽

X Ray Diffraction ◽

Helical Polymers ◽

X Ray ◽

E Coli ◽

The Past ◽

Ordered Arrays ◽

Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

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Interpreting HVEM of muscle-cell impulse networks

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012103x ◽

1992 ◽

Vol 50 (1) ◽

pp. 126-127

Author(s):

Paul DeCosta ◽

Kyugon Cho ◽

Stephen Shemlon ◽

Heesung Jun ◽

Stanley M. Dunn

Keyword(s):

Structural Analysis ◽

Muscle Cell ◽

Electron Micrographs ◽

Relative Size ◽

Automatic Classification ◽

Nerve Fibers ◽

Analysis Algorithm ◽

Structural Networks

Introduction: The analysis and interpretation of electron micrographs of cells and tissues, often requires the accurate extraction of structural networks, which either provide immediate 2D or 3D information, or from which the desired information can be inferred. The images of these structures contain lines and/or curves whose orientation, lengths, and intersections characterize the overall network.Some examples exist of studies that have been done in the analysis of networks of natural structures. In, Sebok and Roemer determine the complexity of nerve structures in an EM formed slide. Here the number of nodes that exist in the image describes how dense nerve fibers are in a particular region of the skin. Hildith proposes a network structural analysis algorithm for the automatic classification of chromosome spreads (type, relative size and orientation).

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