Universität zu Köln

Ageby, Lucas ORCID: 0000-0002-2496-3413 (2024). Investigating and applying rock surface luminescence dating in archaeological and geomorphological contexts. PhD thesis, Universität zu Köln.

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Abstract

Rock surface luminescence dating is a developing geochronological method which utilises the zeroing of the dose-dependent, optically sensitive luminescence signal at rock surfaces. Extended exposure to daylight resets the signal from the rock surface deeper inwards. If the surface is subsequently covered from daylight, then the luminescence signal will increase due to ionising radiation, forming a luminescence signal-depth profile. This depth profile is demonstrative of sufficient signal resetting before a potential burial, and hence, the method is increasingly often used for burial dating of rock surfaces. Exposure dating of rock surfaces is also, in some cases, possible if the rate of signal zeroing with depth is known for a specific lithology and geographical location. This study focuses on investigating rock surface luminescence dating in archaeological environments or in environments of importance for archaeological research since significant methodological and practical limitations apply to this kind of research. This work specifically addresses (i) the application of rock surface luminescence to date various open-air sites; (ii) the direct dating of stone structures of varying states of degradation; as well as (iii) the methodological impact for successfully dating with regard to lithology. This study explores the possibility of dating rock surfaces at various locations, either directly connected to human activities in pre-history or in environments associated with archaeological research. Open-air sites are notoriously difficult to date. Ages from covered rock surfaces from gneissic stones from archaeological horizons in Val di Sole, Italy, provide insights into site development and human use of the site from the Early Bronze Age until the Medieval period, including humans using fire. In contrast, exposed granite and vein quartz cobbles from desert pavements in the Eastern Desert, Egypt, proved difficult to date because of insufficient signal resetting resulting in too short signal-depth profiles in the granites, or due to bad signal characteristics with significant input of slow luminescence signal components in the quartz. Work from the upland landscape of Val di Sole demonstrates that novel geochronological data can be obtained from gneissic rocks collected directly from rock structures. Direct dating of these structures using buried rock surfaces dates construction and degradation cycles from the Bronze Age (1000 BC) until the Early Modern Period (19th century). It is unlikely that any other dating method could resolve such a complex record. Regrettably, the dating of exposed rock surfaces caused severe age underestimations due to shorter-than-expected signal-depth profiles. A key result of this study is the importance of lithology for the successful application of rock surface luminescence dating. Dating of shorelines in the coastal Atacama Desert, Chile using cobbles of various lithologies demonstrates that despite good bleaching conditions, many samples suffered from insensitivity to luminescence stimulation, or the luminescence signal-depth profiles were affected by high dose rates and low signal saturation limits. Also, investigations into calcarenites rocks from the Mula Valley, Spain, demonstrated it is possible to date deposits which lack silica-rich rocks. The luminescence signal is sufficiently bright for the dating of at least two cobbles. However, the rock surface burial ages (10--15 ka) currently underestimate the chronological understanding of the site. In summary, the research from this thesis further demonstrates the usefulness of rock surface luminescence dating for archaeological research. The chronological data related to site development and human activity that are accessible using this method are challenging to acquire with other methods for many settings. However, the chosen lithology for dating is consequential for a successful application, perhaps more so than other site-related factors such as bleaching conditions.

Item Type:	Thesis (PhD thesis)
Translated title:	Title Language UNSPECIFIED German
Creators:	Creators Email ORCID ORCID Put Code Ageby, Lucas UNSPECIFIED orcid.org/0000-0002-2496-3413 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-727000
Date:	2024
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Geographisches Institut
Subjects:	Earth sciences History of ancient world
Uncontrolled Keywords:	Keywords Language Luminescence dating; rock surface luminescence dating; OSL; IRSL; geochronology; geoarchaeology English
Date of oral exam:	18 October 2023
Referee:	Name Academic Title Brückner, Helmut Prof. Dr. Reimann, Tony Prof. Dr.
Projects:	CRC806 - Our Way to Europe; subproject F2
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/72700