Papers by Nikolaos Zacharias
Optical Materials, 2008
The work pertains to the application of solid-state luminescence as a characterization tool for g... more The work pertains to the application of solid-state luminescence as a characterization tool for glassy ceramic cultural artefacts. An archaeological glass bead collection excavated at the city of Thebes, Greece and considered as unique in terms of typological variety and time span was examined with the application of luminescence techniques (thermoluminescence, optically stimulated luminescence). Additionally, X-rays fluorescence (XRF) was used to provide non-destructively the elemental concentration profile of the samples. The thermoluminescence signals following laboratory irradiation provided distinct groups of spectra types according to the color classification of the samples. For each sample, the signal sensitivity and growth were examined using both thermoluminescence and optically stimulated luminescence recording. The study provides evidence for the usefulness of the combined application of luminescence and non-destructive, XRF-based, elemental analysis for the characterization of glass assemblages. Finally, due to the satisfactory level of radiation-induced signal intensity, the work suggests the possibility of chronological estimation of ancient glass beads using luminescence dating protocols.
ΠΕΡΙΛΗΨΗ Η συντήρηση απολιθωμάτων και κυρίως απολιθωμένων δασών in situ αποτελεί έναν όχι διαίτερ... more ΠΕΡΙΛΗΨΗ Η συντήρηση απολιθωμάτων και κυρίως απολιθωμένων δασών in situ αποτελεί έναν όχι διαίτερα ανεπτυγμένο κλάδο. Αναζητώντας απαντήσεις σε ερωτήματα όπως ποιοι είναι οι κύριοι παράγοντες φθοράς των απολιθωμένων δασών, ποια πρέπει να είναι η ενδεδειγμένη μεθοδολογία εξέτασής τους για σκοπούς συντήρησης και ποιοι είναι οι βέλτιστοι τρόποι συντήρησης πυριτιωμένων απολιθωμένων δέντρων στο φυσικό τους περιβάλλον, στο εργαστήριο Αρχαιομετρίας του Πανεπιστημίου Πελοποννήσου διενεργείται έρευνα με αντικείμενο μελέτης το πάρκο του απολιθωμένου δάσους του Τακ στην Ταϋλάνδη. Πρόκειται για μία πρόσφατα ανεσκαμμένη απολιθωματοφόρα θέση, που παρουσιάζει τάχιστο ρυθμό διάβρωσης. Ο σκοπός της έρευνας είναι η κατανόηση του υλικού των απολιθωμάτων, η κατανόηση της παθολογίας τους και η πρόταση μεθόδων για τη συντήρησή τους. Οι προκλήσεις του τροπικού κλίματος, της ευαισθησίας των συγκεκριμένων απολιθωμάτων και η έως τώρα απουσία δράσης συντήρησης, καθιστούν το υλικό μελέτης μοναδικό και την έρευνα πρωτοποριακή, αφού ενδέχεται να ανοίξει νέους δρόμους για την επιστήμη της συντήρησης.
Optical Materials, 2008
The work pertains to the application of solid-state luminescence as a characterization tool for g... more The work pertains to the application of solid-state luminescence as a characterization tool for glassy ceramic cultural artefacts. An archaeological glass bead collection excavated at the city of Thebes, Greece and considered as unique in terms of typological variety and time span was examined with the application of luminescence techniques (thermoluminescence, optically stimulated luminescence). Additionally, X-rays fluorescence (XRF) was used to provide non-destructively the elemental concentration profile of the samples. The thermoluminescence signals following laboratory irradiation provided distinct groups of spectra types according to the color classification of the samples. For each sample, the signal sensitivity and growth were examined using both thermoluminescence and optically stimulated luminescence recording. The study provides evidence for the usefulness of the combined application of luminescence and non-destructive, XRF-based, elemental analysis for the characterization of glass assemblages. Finally, due to the satisfactory level of radiation-induced signal intensity, the work suggests the possibility of chronological estimation of ancient glass beads using luminescence dating protocols.
Geochronometria, 2006
TL dating of archaeometallurgical kiln remains provides information about the chronological perio... more TL dating of archaeometallurgical kiln remains provides information about the chronological period of the corresponding activities. Due to the high temperature this material
has usually been subjected to, changes in the TL sensitivity of the quartz grains and also indications of mineralogical alterations, can be present. The study provides absolute ages for kiln assemblages from two prehistoric sites on the island of Seriphos (Cyclades, Greece). Additionally, as the study highlights sources of potential errors, a methodological approach for luminescence dating of similar material is presented.
Mediterranean …, 2010
A more exact dating of the Chiemgau meteorite impact in Bavaria, southeast Germany, that produced... more A more exact dating of the Chiemgau meteorite impact in Bavaria, southeast Germany, that produced a large strewn field of more than 80 craters sized between a few meters and several hundred meters, may provide the indispensable fundament for evaluating its cultural implications and thus enable an extraordinary case study. A straightforward answer has not yet been provided due to e.g. scarce existence of diagnostic material, lack of specialised micromorphologists, absence of absolute dating data etc. Here we report on a first OSL dating applied to a catastrophic impact layer that features both impact ejecta and tsunami characteristics attributed to proposed falls of projectiles into Lake Chiemsee in the impact event. The OSL dating was conducted on a quartzite cobble and four sediment samples collected from an excavated archaeological stratigraphy at Lake Chiemsee that comprised also the impact layer.
The Portable Unit for the Care, Analysis and Conservation of Movable Cultural Objects (MoCaCu) is... more The Portable Unit for the Care, Analysis and Conservation of Movable Cultural Objects (MoCaCu) is an innovative, interdisciplinary project aiming at protecting and recording cultural heritage assets in remote areas of Greece. It is run under the coordination of the Laboratory for Archaeometry of the University of the Peloponnese, following a generous financial support by the Federal Office for Culture of the Swiss State. The team is comprised by archaeomaterial scientists, conservation experts and two Greek SMEs. It follows a comprehensive methodology including evaluation of the needs and state of preservation of the assets, analysis and characterization of the artefacts, collection of historical and archaeological data of the assets as well as of their context, interventive or preventive conservation and finally digitization of the assets and of all the relevant information. For the latter purpose Time Heritage and Diadrasis have undertaken the task the creation of an electronic database, in compliance with the European standards and rules, as well as of an informed internet site in two languages, Greek and English (www.onsitepreservation.eu).
So far two missions have been accomplished, one in 2013-14, on the remote mountainous area of Alagonia in Messenia, and one in 2014-15 in the village of Kalarrytes on the rough Tzoumerka mountains in Epirus. The results of these two missions were very satisfying. Over 60 works of ecclesiastic art, coming from the religious endowments of these regions, have been recorded, cleaned and preserved, whereas for selected items material characterization, analyses and selective absolute dating were applied.
The digitization part involved careful photographing not only of the assets as a whole but also of all the details of their vulnerabilities and damages; detailed photographing of all the phases of conservation completed the project and created a digital thesaurus for preventive and interventive conservation step-by-step. The innovative part of the digital database built in the course of the project is that the information on the objects themselves (dating, description, artist, location etc is backed by information on their historical and archaeological context as well as on their former state of preservation and by a detailed recording of all conservation measures applied on them.This approach has a double aim: recording otherwise unknown and "forgotten" little treasures of post-Byzantine art, in constant threat of theft and illicit trafficking, and tracking their conservation history in the future, in order to chose compatible solutions in future conservation. Needless to say, the enhancement of these collections and of the monuments and regions which constitute their context is an important step towards the sustainability of the mountainous and remote regions of Greece, as their cultural (and natural) heritage becomes widely known in Greece and abroad.
Twenty five glass artefacts, mostly fragmented beads, recovered from the north side of the Kameir... more Twenty five glass artefacts, mostly fragmented beads, recovered from the north side of the Kameiros citadel of Rhodes (Greece) and dated from the 640 to 600 BC period are probed by Raman spectroscopy for the purpose of evaluation of processing temperatures according to Colomban's method [Ph. Colomban, J. Non-Cryst. Solids 323 and also by X-ray fluorescence (XRF) spectroscopy, for the determination of essential compositional trends. Artefact compositions are more in line with archaic recipes prevailing in East Mediterranean between 15th and 7th century BC. The Raman spectroscopy approach suggests relatively low processing temperatures (from well below 1000°C to well below 600°C), while additional useful conclusions are possible through a comparison of Raman and XRF data.
Journal of Archaeological Science, 2005
Recent mineralogical studies on archaeological pottery samples report significant variations in a... more Recent mineralogical studies on archaeological pottery samples report significant variations in alkali metal concentrations due to environmental alterations during burial. Here we examine the effects of potassium (K) leaching on luminescence dating. The effect on the estimation of the dose rate is studied by considering four models of leaching (exponential, linear, early and late) and their impact on fine-and coarse-grain dating are calculated. The modeling approaches are applied to two cases of pottery in which evidence for alteration was found. Additionally, TL dating performed on pottery of one of the studied cases, indicates the importance of leaching effects on absolute dating measurements.
Journal of Archaeological Science, 2006
A set of 122 ceramic vessels found mostly in Hellenistic tombs in Boeotia, Greece, has been analy... more A set of 122 ceramic vessels found mostly in Hellenistic tombs in Boeotia, Greece, has been analysed using neutron activation analysis. The samples had been found during excavations of ancient cemeteries in the towns of Akraiphnion and Aliartos situated, respectively, at the eastern and south-western shores of the ancient lake of Copais (north-western part of Boeotia), as well as at Tanagra and Thebes in the eastern part of the same region. The analyses resulted in a clear separation between the Copaic and eastern samples. Several of the samples also showed compositions already found among Bronze Age samples from the same region indicating a local origin. Especially with regard to the samples from the Theban tombs, the results point to an import from different origins, in some cases as distant as Asia Minor.
Archaeometry, 2004
From 38 sherds with 'corroded' surfaces, two samples per sherd were examined using Neutron Activa... more From 38 sherds with 'corroded' surfaces, two samples per sherd were examined using Neutron Activation Analysis, one from the surface and one from the core of each sherd, in order to analyse post-depositional alterations of minor and trace elements. The most striking effect was that a leaching of Ca could be found at the surface. Another group of elements that is severely affected are the alkali metals, with Cs and Rb showing the strongest changes. A third conspicuous group of elements are the Rare Earth Elements. Finally, the effect of such alterations on a statistical data evaluation to classify pottery according to provenance is investigated.
Geological Society, London, Special Publications, 2006
A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained n... more A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained nine ware groups formed by visual examination covering the Late Neolithic, Bronze Age and Punic Periods (c. 3000 -218 BC). Despite this diversity and long time range, seven of these ware groups, including the 'Thermi Ware', all have a similar chemical composition and, therefore, have been made from the same clay. This points most probably to a local origin. One group from the Punic Period, containing only Bricky Red cooking ware, is chemically separate and represents a second distinct pattern probably assignable to a local production. Five amphora sherds also from the Punic Period, and consisting of a micaceous fabric, all have different chemical characteristics and are probably imports from overseas production sites of unknown location.
A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained n... more A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained nine ware groups formed by visual examination covering the Late Neolithic, Bronze Age and Punic Periods (c. 3000 -218 BC). Despite this diversity and long time range, seven of these ware groups, including the 'Thermi Ware', all have a similar chemical composition and, therefore, have been made from the same clay. This points most probably to a local origin. One group from the Punic Period, containing only Bricky Red cooking ware, is chemically separate and represents a second distinct pattern probably assignable to a local production. Five amphora sherds also from the Punic Period, and consisting of a micaceous fabric, all have different chemical characteristics and are probably imports from overseas production sites of unknown location.
Geomorphology, 2009
Within the framework of an ongoing geoarchaeological project undertaken in the area of Istron, Gu... more Within the framework of an ongoing geoarchaeological project undertaken in the area of Istron, Gulf of Mirabello, eastern Crete, sediment dating using optical stimulated luminescence (OSL) was employed to provide information on the landscape evolution of the area. In addition to detailed field-survey, geophysical prospection, and archaeological excavations, drilling of five boreholes provided undisturbed and light protected sediments to depths up to 12 m below sea level. OSL dating using blue-light stimulation was undertaken on pure quartz grain samples from two cores. In addition, chemical and spectrometric studies on selected deltaic deposits are enlightening for paleoenvironmental differentiations that prevailed at neighboring sites. The reported ages, with a span of 770 to ca. 15,000 a, along with the results of field work and chemical analysis provide insight for landscape evolution, influenced mainly by environmental changes at an area occupied by the man since Neolithic onwards.
Journal of Archaeological Science, 2006
A set of 122 ceramic vessels found mostly in Hellenistic tombs in Boeotia, Greece, has been analy... more A set of 122 ceramic vessels found mostly in Hellenistic tombs in Boeotia, Greece, has been analysed using neutron activation analysis. The samples had been found during excavations of ancient cemeteries in the towns of Akraiphnion and Aliartos situated, respectively, at the eastern and south-western shores of the ancient lake of Copais (north-western part of Boeotia), as well as at Tanagra and Thebes in the eastern part of the same region. The analyses resulted in a clear separation between the Copaic and eastern samples. Several of the samples also showed compositions already found among Bronze Age samples from the same region indicating a local origin. Especially with regard to the samples from the Theban tombs, the results point to an import from different origins, in some cases as distant as Asia Minor.
Journal of Archaeological Science, 2007
In luminescence dating, the potassium concentration significantly contributes to the dose rate va... more In luminescence dating, the potassium concentration significantly contributes to the dose rate value in the age estimation. Within this study, fine-grain thermoluminescence dating has been applied on sherds of calcareous pottery of known age, excavated at a Roman site in Mallorca, Spain. For those of the samples that showed signs of severe potassium leaching, according to chemical and mineralogical examination, the thermoluminescence analysis provided overestimated dates. By using the known archaeological age of the samples, a corrected dose rate value can be estimated which provides the potassium concentration averaged for the burial period. Finally, a step-like model can then be used to estimate the fraction of the burial period after which most of the alteration effects took place.
Archaeometry, 2004
From 38 sherds with 'corroded' surfaces, two samples per sherd were examined using Neutron Activa... more From 38 sherds with 'corroded' surfaces, two samples per sherd were examined using Neutron Activation Analysis, one from the surface and one from the core of each sherd, in order to analyse post-depositional alterations of minor and trace elements. The most striking effect was that a leaching of Ca could be found at the surface. Another group of elements that is severely affected are the alkali metals, with Cs and Rb showing the strongest changes. A third conspicuous group of elements are the Rare Earth Elements. Finally, the effect of such alterations on a statistical data evaluation to classify pottery according to provenance is investigated.
Geological Society, London, Special Publications, 2006
A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained n... more A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained nine ware groups formed by visual examination covering the Late Neolithic, Bronze Age and Punic Periods (c. 3000 -218 BC). Despite this diversity and long time range, seven of these ware groups, including the 'Thermi Ware', all have a similar chemical composition and, therefore, have been made from the same clay. This points most probably to a local origin. One group from the Punic Period, containing only Bricky Red cooking ware, is chemically separate and represents a second distinct pattern probably assignable to a local production. Five amphora sherds also from the Punic Period, and consisting of a micaceous fabric, all have different chemical characteristics and are probably imports from overseas production sites of unknown location.
Archaeometry, 2006
The approaches of comparative studies and profile measurements, often used in order to detect pos... more The approaches of comparative studies and profile measurements, often used in order to detect post-depositional alterations of ceramics, have been applied simultaneously to two sets of Roman pottery, both of which include altered individuals. As analytical techniques, Neutron Activation Analysis and X-Ray Diffraction have been used. Both approaches lead to substantially different results. This shows that they detect different levels of alteration and should complement each other rather than being used exclusively. For the special process of a glassy phase decomposition followed by a crystallization of the Na-zeolite analcime, the results suggest that it changes high-fired calcareous pottery rapidly, and so fundamentally that the results of various archaeometric techniques can be severely disturbed.
Journal of Archaeological Science, 2005
Recent mineralogical studies on archaeological pottery samples report significant variations in a... more Recent mineralogical studies on archaeological pottery samples report significant variations in alkali metal concentrations due to environmental alterations during burial. Here we examine the effects of potassium (K) leaching on luminescence dating. The effect on the estimation of the dose rate is studied by considering four models of leaching (exponential, linear, early and late) and their impact on fine-and coarse-grain dating are calculated. The modeling approaches are applied to two cases of pottery in which evidence for alteration was found. Additionally, TL dating performed on pottery of one of the studied cases, indicates the importance of leaching effects on absolute dating measurements.
Posters by Nikolaos Zacharias
The petrified forest of Tak, northwestern Thailand, dating back to more than 800,000 years ago co... more The petrified forest of Tak, northwestern Thailand, dating back to more than 800,000 years ago covers an area of approx. 20 km2 and was partially excavated in 2003-’05. It features the longest known intact in situ fossil tree trunk in the world, measuring 69m in length. The Park is visited by up to 100,000 visitors annually and is expected to become a major eco- and geo-touristic destination, providing the possibility for sustainable development for the area and its habitants. Among the aims of the park is its entry to the Global Geoparks Network and its recognition by the UNESCO.
The excavated trunks, within the ten years of their discovery, have suffered severe deterioration, erosion, disintegration, loss of material, detachments, fragmentations, mechanical damages, discolourations, biological colonisations, etc. The pathology of the fossil tree trunk is connected to the unstable environmental parameters such as intense T and RH variations, human-made damages and natural phenomena including intense rainfalls, annual forest fires, flooding etc.
For the study and submission of proposals regarding the conservation treatment of the Tak petrified trees, a research collaboration has commenced, involving Thai and Greek institutes [Northeastern Research Institute of Petrified Wood and Mineral Resources (NRIPM), Nakhon Ratchasima Rajabhat University (NRRU), University of the Peloponnese, National Technical University of Athens, etc.]. Within the context of the research collaboration, a study is being made to determine the composition, properties and pathology of the petrified material, the identification of the causes, rates and speed of its deterioration, and the realisation of tests for cleaning, consolidation, filling and hydrophobiation, in order to submit proposals for the treatment of fossils and sustainable development of the area. In parallel, seminars, educational and volunteer programmes are being organised, aiming to raise the awareness of the scientific community and the public in issues of fossil conservation treatments.
The above research and the actions it involves is pioneer in the field of fossil wood conservation and is expected to bring a number or research benefits such as the recording of the pathology of fossilised material, and proposals on conservation treatment, interpretation and management for sustainable development.
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Papers by Nikolaos Zacharias
has usually been subjected to, changes in the TL sensitivity of the quartz grains and also indications of mineralogical alterations, can be present. The study provides absolute ages for kiln assemblages from two prehistoric sites on the island of Seriphos (Cyclades, Greece). Additionally, as the study highlights sources of potential errors, a methodological approach for luminescence dating of similar material is presented.
So far two missions have been accomplished, one in 2013-14, on the remote mountainous area of Alagonia in Messenia, and one in 2014-15 in the village of Kalarrytes on the rough Tzoumerka mountains in Epirus. The results of these two missions were very satisfying. Over 60 works of ecclesiastic art, coming from the religious endowments of these regions, have been recorded, cleaned and preserved, whereas for selected items material characterization, analyses and selective absolute dating were applied.
The digitization part involved careful photographing not only of the assets as a whole but also of all the details of their vulnerabilities and damages; detailed photographing of all the phases of conservation completed the project and created a digital thesaurus for preventive and interventive conservation step-by-step. The innovative part of the digital database built in the course of the project is that the information on the objects themselves (dating, description, artist, location etc is backed by information on their historical and archaeological context as well as on their former state of preservation and by a detailed recording of all conservation measures applied on them.This approach has a double aim: recording otherwise unknown and "forgotten" little treasures of post-Byzantine art, in constant threat of theft and illicit trafficking, and tracking their conservation history in the future, in order to chose compatible solutions in future conservation. Needless to say, the enhancement of these collections and of the monuments and regions which constitute their context is an important step towards the sustainability of the mountainous and remote regions of Greece, as their cultural (and natural) heritage becomes widely known in Greece and abroad.
Posters by Nikolaos Zacharias
The excavated trunks, within the ten years of their discovery, have suffered severe deterioration, erosion, disintegration, loss of material, detachments, fragmentations, mechanical damages, discolourations, biological colonisations, etc. The pathology of the fossil tree trunk is connected to the unstable environmental parameters such as intense T and RH variations, human-made damages and natural phenomena including intense rainfalls, annual forest fires, flooding etc.
For the study and submission of proposals regarding the conservation treatment of the Tak petrified trees, a research collaboration has commenced, involving Thai and Greek institutes [Northeastern Research Institute of Petrified Wood and Mineral Resources (NRIPM), Nakhon Ratchasima Rajabhat University (NRRU), University of the Peloponnese, National Technical University of Athens, etc.]. Within the context of the research collaboration, a study is being made to determine the composition, properties and pathology of the petrified material, the identification of the causes, rates and speed of its deterioration, and the realisation of tests for cleaning, consolidation, filling and hydrophobiation, in order to submit proposals for the treatment of fossils and sustainable development of the area. In parallel, seminars, educational and volunteer programmes are being organised, aiming to raise the awareness of the scientific community and the public in issues of fossil conservation treatments.
The above research and the actions it involves is pioneer in the field of fossil wood conservation and is expected to bring a number or research benefits such as the recording of the pathology of fossilised material, and proposals on conservation treatment, interpretation and management for sustainable development.
has usually been subjected to, changes in the TL sensitivity of the quartz grains and also indications of mineralogical alterations, can be present. The study provides absolute ages for kiln assemblages from two prehistoric sites on the island of Seriphos (Cyclades, Greece). Additionally, as the study highlights sources of potential errors, a methodological approach for luminescence dating of similar material is presented.
So far two missions have been accomplished, one in 2013-14, on the remote mountainous area of Alagonia in Messenia, and one in 2014-15 in the village of Kalarrytes on the rough Tzoumerka mountains in Epirus. The results of these two missions were very satisfying. Over 60 works of ecclesiastic art, coming from the religious endowments of these regions, have been recorded, cleaned and preserved, whereas for selected items material characterization, analyses and selective absolute dating were applied.
The digitization part involved careful photographing not only of the assets as a whole but also of all the details of their vulnerabilities and damages; detailed photographing of all the phases of conservation completed the project and created a digital thesaurus for preventive and interventive conservation step-by-step. The innovative part of the digital database built in the course of the project is that the information on the objects themselves (dating, description, artist, location etc is backed by information on their historical and archaeological context as well as on their former state of preservation and by a detailed recording of all conservation measures applied on them.This approach has a double aim: recording otherwise unknown and "forgotten" little treasures of post-Byzantine art, in constant threat of theft and illicit trafficking, and tracking their conservation history in the future, in order to chose compatible solutions in future conservation. Needless to say, the enhancement of these collections and of the monuments and regions which constitute their context is an important step towards the sustainability of the mountainous and remote regions of Greece, as their cultural (and natural) heritage becomes widely known in Greece and abroad.
The excavated trunks, within the ten years of their discovery, have suffered severe deterioration, erosion, disintegration, loss of material, detachments, fragmentations, mechanical damages, discolourations, biological colonisations, etc. The pathology of the fossil tree trunk is connected to the unstable environmental parameters such as intense T and RH variations, human-made damages and natural phenomena including intense rainfalls, annual forest fires, flooding etc.
For the study and submission of proposals regarding the conservation treatment of the Tak petrified trees, a research collaboration has commenced, involving Thai and Greek institutes [Northeastern Research Institute of Petrified Wood and Mineral Resources (NRIPM), Nakhon Ratchasima Rajabhat University (NRRU), University of the Peloponnese, National Technical University of Athens, etc.]. Within the context of the research collaboration, a study is being made to determine the composition, properties and pathology of the petrified material, the identification of the causes, rates and speed of its deterioration, and the realisation of tests for cleaning, consolidation, filling and hydrophobiation, in order to submit proposals for the treatment of fossils and sustainable development of the area. In parallel, seminars, educational and volunteer programmes are being organised, aiming to raise the awareness of the scientific community and the public in issues of fossil conservation treatments.
The above research and the actions it involves is pioneer in the field of fossil wood conservation and is expected to bring a number or research benefits such as the recording of the pathology of fossilised material, and proposals on conservation treatment, interpretation and management for sustainable development.