On improving the selection of Thellier-type paleointensity data

The selection of paleointensity data is a challenging, but essential step for establishing data reliability. There is, however, no consensus as to how best to quantify paleointensity data and which data selection processes are most effective. To address these issues, we begin to lay the foundations for a more unified and theoretically justified approach to the selection of paleointensity data. We present a new compilation of standard definitions for paleointensity statistics to help remove ambiguities in their calculation. We also compile the largest‐to‐date data set of raw paleointensity data from historical locations and laboratory control experiments with which to test the effectiveness of commonly used sets of selection criteria. Although most currently used criteria are capable of increasing the proportion of accurate results accepted, criteria that are better at excluding inaccurate results tend to perform poorly at including accurate results and vice versa. In the extreme case, one widely used set of criteria, which is used by default in the ThellierTool software (v4.22), excludes so many accurate results that it is often statistically indistinguishable from randomly selecting data. We demonstrate that, when modified according to recent single domain paleointensity predictions, criteria sets that are no better than a random selector can produce statistically significant increases in the acceptance of accurate results and represent effective selection criteria. The use of such theoretically derived modifications places the selection of paleointensity data on a more justifiable theoretical foundation and we encourage the use of the modified criteria over their original forms

Conservation Science and Ethics in the Analytical Studies of Clay Cuneiform Tablets from Ancient Near Eastern Archives

The Late Bronze Age (ca. 1500-1200 BC) constitutes the heyday of the great empires of the ancient Near East (ANE), such as Egypt, Hatti, Mitanni, Babylonia, and Assyria. Centuries of conflicts followed by peaceful relations, marked the interrelations of these superpowers. Rich literary records in the form of archives of cuneiform texts were established. These archives contain abundant tablets whose origin is unknown. Sometimes the letterhead is missing, in other cases, we may have the name of the sender and still ignore his domicile. Further, the location of many ANE countries and cities has not yet been clearly established. Hence, revealing the origin of documents has the potential of shedding new light on the history of the ANE and beyond. The paper will discuss the use of a rich array of nondestructive testing (NDT) and minimally-destructive testing (MDT) methods for studying the composition, technology and provenance of ANE cuneiform tablets. This approach opens new horizons in the interpretation of the clay documents. We applied such analyses on hundreds of tablets from el Amarna, Ras Shamra/Ugarit, Boğazköy/Hattusha, and sites in Cyprus and Israel/Palestine. The research project made during the last decade, serves as the basis for this study. The results raise a set of ethical and practical issues concerning the study and conservation of such precious artifacts

Reconstructing biblical military campaigns using geomagnetic field data.

The Hebrew Bible and other ancient Near Eastern texts describe Egyptian, Aramean, Assyrian, and Babylonian military campaigns to the Southern Levant during the 10th to sixth centuries BCE. Indeed, many destruction layers dated to this period have been unearthed in archaeological excavations. Several of these layers are securely linked to specific campaigns and are widely accepted as chronological anchors. However, the dating of many other destruction layers is often debated, challenging the ability to accurately reconstruct the different military campaigns and raising questions regarding the historicity of the biblical narrative. Here, we present a synchronization of the historically dated chronological anchors and other destruction layers and artifacts using the direction and/or intensity of the ancient geomagnetic field recorded in mud bricks from 20 burnt destruction layers and in two ceramic assemblages. During the period in question, the geomagnetic field in this region was extremely anomalous with rapid changes and high-intensity values, including spikes of more than twice the intensity of today's field. The data are useful in the effort to pinpoint these short-term variations on the timescale, and they resolve chronological debates regarding the campaigns against the kingdoms of Israel and Judah, the relationship between the two kingdoms, and their administrations

The First Catalog of Archaeomagnetic Directions From Israel With 4,000 Years of Geomagnetic Secular Variations

The large and well-studied archaeological record of Israel offers a unique opportunity for collecting high resolution archaeomagnetic data from the past several millennia. Here, we initiate the first catalog of archaeomagnetic directions from Israel, with data covering the past four millennia. The catalog consists of 76 directions, of which 47 fulfill quality selection criteria with Fisher precision parameter (k) ≥ 60, 95% cone of confidence (α95) < 6° and number of specimens per site (n) ≥ 8. The new catalog complements our published paleointensity data from the Levant and enables testing the hypothesis of a regional geomagnetic anomaly in the Levant during the Iron Age proposed by Shaar et al. (2016, 2017). Most of the archaeomagnetic directions show < 15° angular deviations from an axial dipole field. However, we observe in the tenth and ninth century BCE short intervals with field directions that are 19°-22° different from an axial dipole field and inclinations that are 20°-22° steeper than an axial dipole field. The beginning of the first millennium BCE is also characterized with fast secular variation rates. The new catalog provides additional support to the Levantine Iron Age Anomaly hypothesis

Instability of thermoremanence and the problem of estimating the ancient geomagnetic field strength from non-single-domain recorders.

Data on the past intensity of Earth's magnetic field (paleointensity) are essential for understanding Earth's deep interior, climatic modeling, and geochronology applications, among other items. Here we demonstrate the possibility that much of available paleointensity data could be biased by instability of thermoremanent magnetization (TRM) associated with non-single-domain (SD) particles. Paleointensity data are derived from experiments in which an ancient TRM, acquired in an unknown field, is replaced by a laboratory-controlled TRM. This procedure is built on the assumption that the process of ancient TRM acquisition is entirely reproducible in the laboratory. Here we show experimental results violating this assumption in a manner not expected from standard theory. We show that the demagnetization-remagnetization relationship of non-SD specimens that were kept in a controlled field for only 2 y show a small but systematic bias relative to sister specimens that were given a fresh TRM. This effect, likely caused by irreversible changes in micromagnetic structures, leads to a bias in paleointensity estimates

Instability of thermoremanence and the problem of estimating the ancient geomagnetic field strength from non-single-domain recorders.

Data on the past intensity of Earth's magnetic field (paleointensity) are essential for understanding Earth's deep interior, climatic modeling, and geochronology applications, among other items. Here we demonstrate the possibility that much of available paleointensity data could be biased by instability of thermoremanent magnetization (TRM) associated with non-single-domain (SD) particles. Paleointensity data are derived from experiments in which an ancient TRM, acquired in an unknown field, is replaced by a laboratory-controlled TRM. This procedure is built on the assumption that the process of ancient TRM acquisition is entirely reproducible in the laboratory. Here we show experimental results violating this assumption in a manner not expected from standard theory. We show that the demagnetization-remagnetization relationship of non-SD specimens that were kept in a controlled field for only 2 y show a small but systematic bias relative to sister specimens that were given a fresh TRM. This effect, likely caused by irreversible changes in micromagnetic structures, leads to a bias in paleointensity estimates

Porewater chemistry and magnetic parameters of a sediment core from SG1 station in the South-Eastern Mediterranean Sea

A 6 m long sediment core was collected from Station SG-1 using a piston corer during a cruise on the R.V. Bat-Galim in January 2017. The sediment core was sliced onboard at intervals of 30 cm within minutes of core collection. For headspace measurements of CH~4~, approximately 1.5 mL of sediment was taken from the top of each sediment slice. This sediment was transferred immediately into N~2~-flushed crimped bottles containing 5 mL of 1.5 N NaOH. Sediment samples from the top 5 cm of each sediment slice were transferred to vials under anaerobic conditions, and porewater was extracted from them on the same day by centrifugation at 4°C under an N~2~ atmosphere. The supernatant was filtered through a 0.22 μm filter and was analyzed for dissolved Fe^2+^, sulfide, and sulfate. The sediment was dried in an ambient temperate under N~2~ atmosphere, the dry sediment was analyzed for different iron minerals fractions following the sequential extraction protocol from Poulton and Canfield (2005, doi:10.1016/j.chemgeo.2004.09.003). The 30 cm core segments were split along their length and sampled for magnetic analysis by pushing non-magnetic plastic sampling boxes of 23x23x19 mm into the split halves at ~5 cm intervals. The different microbial respiration pathways cause changes in the porewater chemistry and in the sediment mineralogy due to the reduction and dissolution of iron minerals. In this study, we linked the different respiration processes to the magnetic parameters of a 6 m sediment core from the South-Eastern Mediterranean Sea. In the sulfate-methane transition zone (SMTZ), we observed a decrease in the sediment magnetic properties, due to the dissolution of detrital magnetic minerals, followed by pyrite precipitation. In the upper methanic zone, where iron-reduction occurs, we observed an increase in magnetic properties due to precipitation of authigenic ferrimagnetic minerals