Angkor Borei and Protohistoric Trade Networks: A View from the Glass and Stone Bead Assemblage

40 pages. Published by University of Hawai'i Press: Carter, A.K., Dussubieux, L., Stark, M.T., & Gilg, H.A. (2021). Angkor Borei and Protohistoric Trade Networks: A View from the Glass and Stone Bead Assemblage. Asian Perspectives 60(1), 32-70. doi:10.1353/asi.2020.0036.Angkor Borei, Cambodia was an important urban center related to the early first millennium C.E. polity known as Funan. Excavations in the protohistoric period Vat Komnou Cemetery site uncovered over 1300 glass and stone beads, which are important material indicators of trade. In this article, we review data from earlier studies and add new previously unpublished data on glass and stone beads from this collection as well as previously unpublished glass compositional analyses from the nearby site of Oc Eo, Vietnam. Examinations of the glass beads highlight the presence of large quantities of high alumina mineral soda glass associated with Sri Lankan or South Indian bead production as well as smaller quantities of other glass types in circulation throughout Southeast Asia. Compositional and morphological studies of agate/carnelian beads show strong affinities with the Indian bead industry, while the garnet beads came from raw material sources in southern India. Overall, Angkor Borei's bead collection shows strong contacts with different regions of South Asia. Comparison with the bead assemblages of other contemporaneous sites demonstrate strong affinities with sites farther inland, such as Phum Snay and Prei Khmeng, Cambodia and Ban Non Wat, Thailand rather than other maritime coastal sites in Southeast Asia. We argue that the stone and glass beads at Angkor Borei are related to intensified interaction with South Asia and that elites at Angkor Borei used these exotic prestige goods to build alliances with sites farther inland forming an intraregional exchange network we call the Mekong Interaction Sphere.The authors wish to thank the Ministry of Culture and Fine Arts in Cambodia which facilitated the study of the beads from Angkor Borei. Thanks also to Seth Quintus for discussion of Bayesian modeling of the Vat Komnou cemetery dates and Mike Shand for assistance with Figure 2. Thanks to Pierre-Yves Manguin for providing materials from Oc Eo and information on his work at this site. Carter's research was funded by the Henry Luce Foundation/ACLS Grants in East and Southeast Asian Archaeology and Early History Dissertation Fellowship, The Bead Society of Los Angeles, The Portland Bead Society, The Bead Study Trust, Graduate Women in Science–Beta Chapter, and the Geological Society of America. SEM was undertaken at the University of Wisconsin Department of Animal Sciences Microscopy Laboratories and the University of Oregon CAMCOR laboratory

The influence of water on the strength of Neapolitan Yellow Tuff, the most widely used building stone in Naples (Italy)

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Mineralogy and geochemistry of the sedimentary kaolin deposits from Sinai, Egypt : Implications for control by the source rocks

Abstract-Mineralogical and geochemical variations among the Carboniferous and Cretaceous sedimentary kaolin deposits from Sinai provided an opportunity to examine the effect of the source area on compositions of the deposits. The Carboniferous kaolin deposits are mineralogically and geochemically heterogeneous. The Khaboba and Hasbar deposits consist of kaolinite, quartz, anatase, illite, chlorite, zircon, and leucoxene. The shale-normalized rare earth element (REE) patterns of the Khaboba deposit showed a slight LREE over HREE enrichment ((La/Yb) =1.19 1.51) with a MREE depletion (Gd/ Gd* =0.51 0.75), while the Hasbar kaolin had a MREE enrichment. The Abu Natash kaolin deposit consisted of kaolinite, anatase, and a little quartz with larger TiO, Cr, and V and smaller Zr and Nb contents compared to other Carboniferous deposits. The shale-normalized REE patterns of the Abu Natash deposit exhibited a positive Eu anomaly (Eu/Eu* =1.28 1.40) and a MREE enrichment (Gd/Gd* = 1.41 2.05). The Cretaceous deposits were relatively homogeneous in terms of mineralogical composition and geochemistry and are composed of kaolinite, quartz, anatase, rutile, zircon, and leucoxene. The Cretaceous kaolin deposits showed mostly flat shale-normalized REE patterns with a variable LREE depletion. The presence of illite and chlorite, the absence of rutile, large Zr and Nb contents, and the REE patterns suggested a component of weathered low-grade metasediments as a source for the Carboniferous deposits in the Khaboba and Hasbar areas, while the large Ti, Cr, and V, and small quartz contents indicated mafic source rocks for the Abu Natash deposit. The abundance of high-Cr rutile and the absence of illite and chlorite, and large Zr, Ti, Cr, and V contents suggested a mixture of medium- to high-grade metamafic and granitic rocks as source rocks for the Cretaceous kaolin deposits. The occurrence of alkaline rocks in the source of the deposits studied was identified by high-Nb contents and the presence of bastnaesite. The mineralogical and geochemical heterogeneity and lesser maturity of the Carboniferous deposits suggested local sources for each deposit and their deposition in basins close to the sources. The mineralogical and geochemical homogeneity and maturity of the Cretaceous deposits, on the other hand, indicated common sources for all deposits and their deposition in relatively remote basins

Petrophysical properties, mechanical behaviour, and failure modes of impact melt-bearing breccia (suevite) from the Ries impact crater (Germany).

The physical properties and mechanical behaviour of impactites are an important parameter in fluid flow models and slope stability and landscape evolution assessments for heavily impacted planetary bodies. We first present porosity, permeability, Young's modulus, and uniaxial compressive strength measurements for three suevites from the Ries impact crater (Germany). Porosity ranges from 0.18 to 0.43, permeability from 5.8 × 10−16 to 5.1 × 10−14 m2, Young's modulus from 1.4 to 8.1 GPa, and uniaxial compressive strength from 7.3 to 48.6 MPa. To explore their mechanical behaviour, we performed triaxial deformation experiments on these samples at a range of confining pressures. The brittle–ductile transition for the lowest (0.25) and highest (0.38) porosity suevite samples was at a confining pressure of ~30 and ~10 MPa, respectively (corresponding to, for example, depths respectively of ~1 and ~4 km on Mars). Microstructural observations show that the dominant deformation micromechanism during brittle deformation is microcracking, and during ductile deformation is cataclastic pore collapse. We show that a theoretically grounded permeability model for welded granular media accurately captures the permeability of the studied suevites, and we use micromechanical models to glean insight as to their mechanical behaviour. Finally, we upscale our laboratory measurements to provide physical property values for length scales more relevant for large-scale models, and we compare these data with those for basalt (a lithology representative of the surface of the inner Solar System bodies). These analyses show how macroscopic fractures serve to increase the permeability and decrease the strength and Young's modulus of suevite; for example, we find that basalt can be a factor of 2–5 stronger than suevite in the shallow crust. Our study suggests, therefore, that the rock masses comprising older, bombarded crusts are substantially weaker and more porous and permeable than the younger plains material on these bodies. These findings should be considered in large-scale fluid flow modelling and when providing crustal strength estimates or slope stability assessments for planetary bodies on which protracted records of impact bombardment are preserved

Repeated hydrothermal quartz crystallization and cataclasis in the Bavarian Pfahl shear zone (Germany)

Field and microstructural data of the Pfahl shear zone in north-eastern Bavaria (Germany) reveal the intimate spatial-temporal connection between fragmentation, fluid influx and quartz crystallization. These processes and their interaction led to complex-structured quartz units: (i) a dense network of early quartz veins, (ii) two domains of fine-grained reddish to grayish quartz masses, (iii) an extended central zone of massive white quartz, and (iv) late cross-cutting closely spaced parallel fractures and partly open quartz veins. The fine-grained quartz domains result from repeated and coeval cataclasis, fluidization and quartz precipitation. Material transport in these domains is at least partly governed by the flow of mobile fluid-quartz-particle suspensions. The complex internal meso-to microstructures of the massive white quartz are generated by repeated processes of fragmentation and grain growth. In general, the brittle part of the Pfahl shear zone represents a key example of cyclic dissolution/precipitation and fragmentation on large scale

Chrysoberyl recovered with Sapphires in the New England placer deposits, New Southwales, Australia

Mineralogical, chemical, and spectroscopic properties of chrysoberyl crystals recovered from sapphire placer deposits, related to Tertiary volcanic rocks, in the New England gem fields in New South Wales (NSW), Australia, are presented. The samples appeared yellow, yellowish brown, or brown in transmitted light, and some crystals revealed a distinct sectorial zoning between brown i (011) and yellow o (111) growth areas. In reflected light, the i sectors showed a whitish appearance, and cabochon-cut samples with larger whitish i sectors displayed chatoyancy. On the basis of morphological properties, trace-element contents, and absorption spectra, the chrysoberyl samples were subdivided into four different groups, possibly originating from different host rocks. The largest such group, comprised of samples with distinct sectorial color zoning, also revealed a pronounced variation in trace-element levels of titanium, niobium, and tantalum between the different growth sectors. Smaller variations were found for boron, magnesium, and iron, and almost no variation was observed for gallium

The age of volcanic tuffs from the Upper Freshwater Molasse (North Alpine Foreland Basin) and their possible use for tephrostratigraphic correlations across Europe for the Middle Miocene

The Middle Miocene Upper Freshwater Molasse sediments represent the last cycle of clastic sedimentation during the evolution of the North Alpine Foreland Basin. They are characterized by small-scale lateral and temporal facies changes that make intra-basin stratigraphic correlations at regional scale difficult. This study provides new U– Pb zircon ages as well as revised 40Ar/39Ar data of volcanic ash horizons in the Upper Freshwater Molasse sediments from southern Germany and Switzerland. In a first and preliminary attempt, we propose their possible correlation to other European tephra deposits. The U–Pb zircon data of one Swiss (Bischofszell) and seven southern German (Zahling, Hachelstuhl, Laimering, Unterneul, Krumbad, Ponholz) tuff horizons indicate eruption ages between roughly 13.0 and 15.5 Ma. The stratigraphic position of the Unterneul and Laimering tuffs, bracketing the ejecta of the Ries impact (Brockhorizon), suggests that the Ries impact occurred between 14.93 and 15.00 Ma, thus assigning the event to the reversed chron C5Bn1r (15.032–14.870 Ma) which is in accordance with paleomagnetic evidence. We combine our data with published ages of tuff horizons from Italy, Switzerland, Bavaria, Styria, Hungary, and Romania to derive a preliminary tephrochronological scheme for the Middle Miocene in Central Europe in the age window from 13.2 to 15.5 Ma. The scheme is based on the current state of knowledge that the Carpathian–Pannonian volcanic field was the only area in the region producing explosive calc-alkaline felsic volcanism. This preliminary scheme will require verification by more high-quality ages complemented by isotopic, geochemical and paleomagnetic data