Obsidian Sources in Guatemala: A Regional Approach

1978 ◽  
Vol 43 (3) ◽  
pp. 424-435 ◽  
Author(s):  
Luis Hurtado de Mendoza ◽  
William A. Jester
Keyword(s):  
Structural Features ◽  
Trade Routes ◽  
Geochemical Characterization ◽  
Regional Basis ◽  
Prehistoric Trade ◽  
Sociocultural Systems ◽  
Obsidian Source ◽  
Diverse Source

Geologic sources of obsidian are frequently treated in the archaeological literature as single, discrete flows, each being recognized as a different source as long as it can be geographically isolated. However, some recent studies show a tendency toward the correction of this misconception, and toward defining operationally the obsidian source concept on a regional basis. This work is intended to help achieve such definition for a number of obsidian sources in the central highlands of Guatemala. Geochemical characterization of samples from diverse source localities, attained by means of neutron activation analysis, is utilized for this purpose. The information thus obtained has importance to a number of fields of research in archaeology. To the now-routine studies on prehistoric trade routes, other lines of investigation can be added, namely the determination of source-specific obsidian hydration rates for dating purposes, and the reconstruction of structural features in sociocultural systems.

scholarly journals New sorbents for electrochromatography based on polymer-inorganic dielectric composites

2021 ◽  
Vol 2103 (1) ◽  
pp. 012124
Author(s):  
A Y Shmykov ◽  
S V Mjakin ◽  
N A Bubis ◽  
L M Kuztetzov ◽  
N A Esikova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Filler Content ◽  
Structural Features ◽  
Polymer Binder ◽  
Dielectric Losses ◽  
Infinite Cluster ◽  
Confocal Scanning ◽  
Scanning Electron

Abstract Oligomeric diisocyanate based coatings with different contents of barium titanate (BaTiO3) submicron sized particles as a ferroelectric filler are synthesized on poly(dimethylsiloxane) (PDMS) supports. The study of thus obtained coatings using confocal scanning electron microscopy allowed the characterization of their morphology and features of BaTiO3 particles distribution in the polymer binder, including the determination of threshold filler contents corresponding to the formation of an infinite cluster, matrix-island and chain-like structures as well as the percolation. Dielectric permittivity and dielectric losses of the composites are measured and studied depending on BaTiO3 filler content and relating structural features.

Multi-technique geochemical characterization of the Alca obsidian source, Peruvian Andes

Geology ◽  
2013 ◽  
Vol 41 (7) ◽  
pp. 779-782 ◽  
Author(s):  
Kurt Rademaker ◽  
Michael D. Glascock ◽  
Bruce Kaiser ◽  
David Gibson ◽  
Daniel R. Lux ◽  
...  
Keyword(s):  
Peruvian Andes ◽  
Geochemical Characterization ◽  
Obsidian Source

Ancient Marble Sculpture: Geochemical Characterization of Surficial Weathering Products

1988 ◽  
Vol 123 ◽  
Author(s):  
Stanley V. Margolis ◽  
Frank Preusser ◽  
W.J. Showers
Keyword(s):  
Rock Weathering ◽  
Important Goal ◽  
Ancient Greek ◽  
Carbon And Oxygen Isotopes ◽  
Electron Microscopic ◽  
Geochemical Characterization ◽  
Carbon Isotopic ◽  
Scanning Electron Microscopic

AbstractQuantitative scientific determination of the authenticity and age of marble sculpture is an important goal of geo-archaeologists and conservation scientists. Geochemical and petrographic techniques are used here to investigate rock weathering and mineral alterations responsible for the “patina” and alteration layers on marble sculpture. We present oxygen and carbon isotopic, scanning electron microscopic and electron microprobe analyses of both fresh marble and weathering crusts materials from cores taken from Cycladic and Archaic Greek sculptures and from ancient quarries, to evaluate these techniques as indicators of antiquity.Calcitic marbles exhibit an altered weathering crust of variable thickness, where calcite has been recrystallized and interpenetrated with inclusions of iron oxide, clay minerals, gypsum and other authigenic minerals. The thickness and composition of these crusts varies with soil and water chemistry as well as marble density, texture and age.Microprobe analyses indicate trace element gradients from fresh to weathered calcite. Carbon and oxygen isotopes can differentiate between insitu alteration and precipitated carbonate. Dolomitic marbles can exhibit calcitic surficial layers formed by dedolomitization, which can be confirmed by isotopic and microprobe analyses.Analyses of known forgeries, ancient quarry samples and artificially weathered marbles have further documented our criteria and show that the majority of diagnostic geochemical and mineralogical features seen on ancient Greek sculptures cannot be accurately duplicated by artificial means.

Neutron activation analysis of archaeological artefacts

1970 ◽  
Vol 269 (1193) ◽  
pp. 165-174 ◽  
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Trace Element Analysis ◽  
Element Analysis ◽  
Trade Routes ◽  
Art Objects ◽  
Prehistoric Trade ◽  
Non Destructive

The elemental compositions of archaeological artefacts, ancient and medieval coins, and metallic art objects have been determined by non-destructive neutron activation analysis. Examples are given of studies of prehistoric trade routes and cultural contacts based on the identification of the geologic origins of obsidian artefacts, of early economic systems based on the determination of debasement patterns in medieval Islamic and Western gold and silver coinage, the region of manufacture as well as authentication of ancient metallic art objects based on trace element analysis. Special procedures devised for performing these analyses are described.

scholarly journals Late Pleistocene Lithic Procurement and Geochemical Characterization of the Cerro Kaskio Obsidian Source in South-western Bolivia

Archaeometry ◽  
2018 ◽  
Vol 60 (5) ◽  
pp. 898-914 ◽  
Author(s):  
J. M. Capriles ◽  
N. Tripcevich ◽  
A. E. Nielsen ◽  
M. D. Glascock ◽  
J. Albarracin-Jordan ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Geochemical Characterization ◽  
Lithic Procurement ◽  
Obsidian Source

Understanding Structure and Electronic Properties of Extended Self-Interstitial Defects in Silicon

1998 ◽  
Vol 538 ◽  
Author(s):  
P. Alippi ◽  
L. Colombo
Keyword(s):  
Electronic Properties ◽  
Tight Binding ◽  
Structural Features ◽  
Dynamics Simulation ◽  
Formation Mechanisms ◽  
Equilibrium Configurations ◽  
Formation Energies ◽  
Atomic Stress

AbstractThe results of an atomistic investigation on the coalescence mechanisms of self-interstitial {311} defects are presented. Formation energies and equilibrium configurations of defect structures are determined by tight-binding molecular dynamics simulation. We focus on the characterization of the lattice strain field around the defect complex: By means of the determination of the atomic stress distribution, we discuss how it may influence the formation mechanisms of the planar {311} structures. We also attempt a correlation between structural features and electronic properties through the analysis of defect-related orbitals occupations and inverse participation ratios.

scholarly journals Characterization of Basalt for Conservation Use from Cultural Heritage Site of Umm El-Jimāl in Jordan

2021 ◽  
Vol 54 (1B) ◽  
pp. 12-23
Author(s):  
Wassef Al Sekhaneh
Keyword(s):  
Cultural Heritage ◽  
Major Elements ◽  
X Ray Diffraction ◽  
Trade Routes ◽  
X Ray ◽  
Ancient Trade ◽  
Heritage Site ◽  
Mineralogical Characteristics

The present study is a multi-analytical approach to the characterization of several basalt stone samples, from Umm el-Jimāl Cultural Heritage site, northern Jordan, which represents ancient trade routes between Arabian Peninsula and Syria. In particular, Micro-X-ray Fluorescence Mapping as new in the mineralogy, X-ray Diffraction Energy Dispersive X-ray spectroscopy are used for the determination of the petrological, geochemical, and mineralogical characteristics of the basalt used in this archeological site for conservation purposes. The results reveal that it belongs to the alkaline trachy-basalt to basanite-tephrite type. With predominant quartz, olivine, pyroxene, and plagioclase (albite) as major elements, the vesicular texture is occupied with secondary minerals such as biotite, gypsum, and calcite.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Ultrastructural identification of three types of sensory setae on copepod antennae

1995 ◽  
Vol 53 ◽  
pp. 956-957
Author(s):  
T. M. Weatherby ◽  
P.H. Lenz
Keyword(s):  
Phase Locking ◽  
Membrane Surface ◽  
Reaction Times ◽  
High Sensitivity ◽  
Structural Features ◽  
Calanoid Copepods ◽  
Marine Food Webs ◽  
Dendritic Membrane ◽  
Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

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