Geoarchaeological Evidence for the Decline of the Medieval City of Qalhat, Oman

Abstract

The medieval city of Qalhat was an important trade town along the sea routes in the Indian Ocean. The reasons for the decline of the city are unclear, as the archaeological evidence is inconclusive. Geological field work was conducted and a digital elevation model analysed to test the hypothesis that the city was destroyed by an earthquake. The study area is located along the passive continental margin of the Arabian Plate. The coast shows a set of Pleistocene marine terraces. These landforms are in indication of lithosphere uplift. Faulted terrace fill deposits and deviating fluvial streams indicate rather recent lithosphere deformation. Processes responsible for the deformation are seen as subduction related forebulge uplift, serpentinite diapirism as well as isostatic response to karstification of limestone. We conclude that earthquake activity along the most prominent structural element, the Qalhat Fault, is a plausible reason for the decline of the medieval city.

Collapse of Holocene mangrove ecosystems along the coastline of Oman

“…This is in contrast to Hoffmann et al (2013), who show that the northern part of the east coast is tectonically stable, excluding any noneustatic sea-level change. The topic of neotectonic movements in northern Oman is currently being researched (Mattern et al, 2018; Moraetis et al, 2018, 2020; Ermertz et al, 2019; Hoffmann et al, 2020).…”

Quaternary Thrusting in the Central Oman Mountains—Novel Observations and Causes: Insights from Optical Stimulate Luminescence Dating and Kinematic Fault Analyses

“…Moreover, seismic activity in the Dibba Fault Zone of the Musandam Peninsula and one historically recorded earthquake in the Central Oman Mountains (Nizwa area) reveal some limited but still detectable tectonic activity in northern Oman [4][5][6]. The Qalhat Fault near Sur (Figure 1), which belongs to a WNW-striking set of faults, seems to have triggered some recent earthquakes in the Southeastern Oman Mountains [7] (and references therein). According to [8], several faults cut through Quaternary conglomerates.…”

Oligocene/Early Miocene E/W‐Shortening in the Oman Mountains Related to Oblique Arabia‐India Convergence

“…Our results are consistent with those of Grobe et al (2018) demonstrating ∼60-75 km of shortening since 11 Ma (early Tortonian, Cohen et al, 2013;Interval II). Ongoing shortening may have reactivated the Qalhat Fault (recent seismicity; Ermertz et al, 2019), which is responsible for activity at the transpressional Coastal Parallel Shear Zone, inverted the Abat Basin, and uplifted marine terraces NW of the Qalhat Fault (Figure 12). However, further structural work and age dating are needed to confirm the GPlates results.…”

“…The rocks West of the Qalhat Fault (Tiwi Platform or Salma Plateau) mostly consist of late Paleocene to mid‐Eocene shallow‐marine limestone, now uplifted to >2,000 m above sea level. This area is still uplifting, as indicated by uplifted marine terraces (e.g., Ermertz et al., 2019; Fournier et al., 2006; Hoffmann et al., 2020; Mattern, Moraetis, et al., 2018; Moraetis et al., 2018; Wyns et al., 1992). In contrast, little to no Quaternary tectonic activity has been reported from the Central Oman Mountains (Moraetis et al., 2020; Scharf, Mattern, Moraetis, et al., 2019).…”