NEAR-SURFACE GEOPHYSICS IN THE EXTRAMURAL AREA OF THE LATE ROMAN SETTLEMENT HALMYRIS

• Published in: International Multidisciplinary Scientific GeoConference SGEM Vol. 18; no. 1.1; pp. 909 - 916
• Main Authors: Dimitriu, Radu George, Barbu, Marius-Bogdan, Stanciu, Irina-Marilena, Nuţu, George, Pojar, Iulian
• Format: Conference Proceeding
• Language: English
• Published: Sofia Surveying Geology & Mining Ecology Management (SGEM) 01.01.2018
• Subjects: 6th century; 7th century; Archaeology; Buried structures; Chain branching; Clay; Core drilling; Coring; Ditches; Drilling; Elongated structure; Excavation; Fortresses; Geologic depressions; Geological mapping; Geophysics; High resolution; Historic artifacts; Historic buildings & sites; Holocene; Interdisciplinary aspects; Interdisciplinary research; Interdisciplinary studies; Lithology; Magnetic anomalies; Magnetic permeability; Magnetic properties; Magnetic surveys; Magnetic susceptibility; Position measurement; Sediment samplers; Sediment samples; Settlements & damages; Soil analysis; Soil investigations; Soil properties; Romania
• ISSN: 1314-2704
• DOI: 10.5593/sgem2018/1.1/S05.113

First indication of habitation on the site of the future Halmyris fortress dates back to early 6th century BC, when the region was inhabited by the Getae. The Roman fortress, constructed in 2nd century AD, was the easternmost one in the chain of fortifications built under Roman occupation along the Danubian border of the empire and was abandoned in 7th century AD after it lost its economic and strategic importance. The site is located on Murighiol-Dunavăţ promontory 2.5 km east of Murighiol village at around 1.5 km south of Danube's St. George branch. Since 1981 it is subject of a continuous and systematic archaeological research. From the geological point of view, the study area is located close to the contact of two main structural units: the North Dobrogea Folded Belt and the Pre-Dobrogea Depression. The interdisciplinary research carried out in 2016 and 2017 on the surface of the archaeological site was funded by the national program NUCLEU; through the Project PN 16 45 02 03 and one of its main objectives was the understanding of the paleoambiental evolution of the Danube Delta region during Late Holocene times. The geodynamic studies performed within the project highlight the subsident regime of the entire area [1], while the sedimentological, petrophysical, geochemical and microfaunal analyzes on sediment samples extracted by core drilling provided information regarding the structure and lithological composition of the sedimentary cover [2], [3]. Unlike the first magnetic investigation carried out in early 2000's, which only covered the intramural area of the fortress [4], the high-resolution magnetic survey performed in April 2017 covered an area of about 2400 sq. m, exclusively located in Halmyris' extramural, in an attempt to provide genuine information about possible buried cultural features possibly located towards the river and the presumed position of the ancient harbor. These last near-surface geophysical investigations consisted exclusively on high resolution magnetic gradient measurements. A brief analyze of the magnetic susceptibility was also performed on soil, rocks and artifacts samples collected form the entire study area. It highlights the significant contrast existing between the regional geological background, generally characterized by low magnetic properties and artifacts, such as bricks, baked adobe, ceramic fragments, etc., which show relatively higher magnetic susceptibilities. The maps of the local magnetic anomaly and also of the vertical gradient of the total field, clearly illustrate relatively intense magnetic anomalies in the extramural area, most likely due to excavations and wastes resulted from former archaeological field works, as well as the probable near-surface accumulation of artifacts. Several elongated and orthogonal anomalous features partly observed on the geophysical maps could be due to buried anthropic structures (e.g. walls, ditches, roads, etc.), but further archaeological excavations are required in order to validate the geophysical interpretation.