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The extraordinary outcrop conditions provide a unique opportunity to study the geology and tectonics of the Oman Mountains, which record a geological history of more than 800 million years. We provide a summary of the geological evolution of the Oman Mountains with the emphasis on the Jabal Akhdar and Saih Hatat domes. This Memoir comprises seven chapters. This first chapter summarizes the former studies and the tectonic framework. This is followed by a comprehensive description of all geological formations/rock units (Scharf et al. 2021a, Chapter 2, this Memoir) including the famous Semail Ophiolite, the fault and fold pattern (Scharf et al. 2021b, Chapter 3, this Memoir) and the overall structure (Scharf et al. 2021c, Chapter 4, this Memoir). Chapter 5 (Scharf et al. 2021d) explains the varied tectonic evolution of the study area, ranging from the Neoproterozoic until present, while Chapter 6 (Scharf et al. 2021e) contains the conclusions and a catalogue of open questions. Finally, Chapter 7 (Scharf et al. 2021f) provides two over-sized geological maps (1 : 250 000 version available online) and a correlation chart, providing an overview of the geological units/formations. This volume is of interest for all geoscientists, geoscience students and professionals studying the Oman Mountains on the surface as well as in the subsurface because it represents a comprehensive and detailed reference.

The geology of the Oman Mountains, including the Jabal Akhdar and Saih Hatat domes, is extraordinarily well-exposed and diverse, spanning a geological record of more than 800 Ma. The area is blessed with first-class outcrops and is well known in the geological community for its ophiolite. The Oman Mountains have much more to offer; including, Neoproterozoic diamictites (“Snowball Earth”), fossil-rich Permo-Mesozoic carbonates and metamorphic rocks. The arid climate and deep incision of wadis allow for nearly complete rock exposure which can be investigated in all three dimensions. The diverse geology is also responsible for the breathtaking landscape. New roads and the nature of the friendly Omani people make fieldwork unforgettable. This Memoir provides a thorough state-of-the-art overview of the geology and tectonics of the Southeastern Oman Mountains, and is accompanied by an over-sized geological map and a correlation chart.

For the first time, Quaternary thrusts are documented within the Central Oman Mountains to the northwest of the Jabal Akhdar Dome. Thrusts with a throw of up to 1.1 m displace Quaternary alluvial fan conglomerates. These conglomerates have an Optical Stimulate Luminescence (OSL) age of 159 &plusmn, 7.9 ka BP and were deposited during MIS 6 (Marine Isotope Stage). The thrusts occur in two sets. Sets 1 and 2 formed during NE/SW and NW/SE shortening, respectively. Set-1-thusts correlate with the present-day stress field of NE/SW shortening which is related to subduction in the Makran Subduction Zone, and they strike parallel to the main continuous fold axis of the Jabal Akhdar and Hawasina windows. Set-2-thrusts correspond to NW/SE shortening and Plio-Pleistocene contractional structures in the southwestern Jabal Akhdar Dome. Set-2-thrusts are probably related to local variations of the present-day stress field originating from the Musandam area which is a part of the Zagros Collision Zone. Both thrust sets mimic the main thrust directions (NW/SE and NE/SW) within the Permo-Mesozoic allochthonous units (Semail Ophiolite, Hawasina napps) of the larger study area. The investigated thrusts imply some reactivation of the Hawasina and Semail thrusts due to far-field stress either from the Makran Subduction Zone and/or the Zagros Collision Zone. The ongoing tectonic activity of this part of the Oman Mountains, which has been considered of moderate activity, is for first time identified by structural data as contractional.

The changing climatic conditions are imposing a vital re-consideration on the hydro-chemical pathways for contaminants. The circumference Mediterranean countries will be possibly under imminent water stress. The present study attempts to identify the sources and the leaching capacity of Cr(VI) in a coastal alluvial fan and aeolian soil and in a serpentine soil in an area offering an aridity analogue, like Oman. Magnetic separation and different leaching media were applied along with Cr(VI) sorption experiments in daylight (open air) and in laboratory conditions (without direct sunlight). In most of the samples the released Cr(VI) concentration was higher that the drinking water standard (50 μg L−1). Magnetic soil fraction has the highest bulk Cr concentration, however, the leaching of Cr with phosphate extraction solution was high in the no-magnetic fraction. Immobilization of Cr(VI) was higher in the sunlight conditions for the serpentine soil and not for the alluvial/aeolian soils.

This work explores the uplift history of the best exposed marine terraces in the northeastern Arabian Peninsula (eastern Al Hajar Mountains). A multidisciplinary approach was employed, including a topographic survey,14C dating, thin section studies, and scanning electron microscopy analyses. Six distinctive marine terraces with widths ranging from tenth of meters to kilometers and elevations from 5 to ~400 m were studied. These terraces record an along-strike heterogeneous uplift history, while they show temporally variable uplift rates ranging between 0.9 to 6.7 mm/yr, which correlates well with other published uplift rates of marine terraces of the eastern Arabian Peninsula. We attribute the variable uplift along strike of the terraces, to a combination of uplift mechanisms: (1) during early to mid-Miocene along deep-rooted reverse faults that bound large crustal-scale blocks, (2) Pliocene or post-Pliocene uplift on the outer wall of the forebulge of the lower Arabian Plate as it bends to enter the Zagros-Makran subduction zone, and (3) a possible slowdown of subduction for the past ~40 ka.

We investigated two coral patch reefs of probably Weichselian age (Wyns et al., 1992a) which have been uplifted above sea-level in the coastal setting of uplifted marine terraces adjacent to the Oman Mountains. Uplift is also manifested in raised beach conglomerates and a wave-cut notch. We document some of the main reef features in the apprehension that building/development will preclude the study of the reefs in the near future. The reefs formed above a hardground of bioclastic limestone (mudstone to wackestone), characterized by intense bioerosion and red algae . The red algae may occur so plentiful to form (very localized) bafflestones. The diagenetic history of the rocks includes a transition from a marine environment (first cement) to meteoric conditions (dissolution and second cement). The reefs are 1.5 m thick and display planar as well as gently ocean-dipping reef tops, suggesting exposure to the wave-cut activity and, thus, shallow and nearshore deposition. The reefs are dominated by one coral species, identified as Cyphastrea serailia . On the protected side of the reefs the corals developed wavy and columnar growth forms while on the ocean facing side irregularly shaped exoskeletons developed. Our GPS-based topographic survey revealed an elevation of the two reefs of 21.5 m ± 0.06 m above sea-level. Taking into account (1) the global Holocene sea-level rise of 120 m ± 20 m (Pirazzoli and Pluet, 1991), (2) formation of the reefs slightly below sea-level (∼1.5 m) as well as (3) their present position above sea-level, we quantify the total upward transfer of the reefs to be 143 m and the average uplift rate to be 6.8 or 4.6 mm/yr depending on the correct age (either ∼21,000 or ∼31,000 yr B.P.). As the causes of uplift we mainly consider isostatic rebound following the late Cretaceous formation of the Oman Mountains (Yuan et al., 2016). The terrace development went through the following stages: (1) The patch reefs formed in shallow water. (2) Initial, gentle uplift caused abrasion of the reef tops. (3) Uplift continued and beach conglomerate 1was deposited on top of the reefs. (4) Abrasion continued, creating an abrasion platform. Uplift and creation of borings in platform required time and an interval of relatively slow uplift and tectonically and climatically stable conditions. (5) Uplift took place, and a wave-cut notch formed below the reefs. (6) Notch formation, including the borings into the notch, required time and stable conditions and was followed by deposition of beach conglomerate 2. (7) Finally, emergence/exposure of the notch and conglomerate 2 above sea-level ensued due to pronounced uplift, possibly associated with faulting and earthquakes. Formation of the reefs and the abrasion platform can be correlated with MIS 3 (Marine Isotope Stage 3) and notch formation with MIS 1.

Summarization: Submarine groundwater discharge (SGD) contributes to the physical and chemical characters of coastal waters by discharging nutrients and contaminants, significantly impacting regional marine ecosystems and contributing to ocean chemical budgets. However, such groundwater discharge varies dramatically across scales and is often not comparable due to different model assumptions and field designs. We used a hydrologic model with integration of fundamental surface and subsurface processes to simulate the coastline level fresh SGD for the Crete Island in the Mediterranean Sea. The modeled hydrological processes suggested that fresh SGD substantially contributes to water flow entering the Mediterranean Sea (2.3 × 108 m3/yr), amounting to 31% of river discharge and 14% of precipitation. Spatially, fresh SGD varied from 2.4 m3/yr/m to 13.4 × 104 m3/yr/m, with an average of 2.6 × 103 m3/yr/m. The local maxima were commonly associated with river mouths reflecting larger hydraulic gradients and higher permeable structures. Temporally, fresh SGD was impacted by episodic precipitation in a delayed and prolonged pattern. We found that fresh SGD variability at the coastline segment level was compared to point measurements and fresh SGD magnitudes summered up to the catchment level were consistent with global products. Our results suggest the coupled surface–subsurface hydrologic modeling approach is a promising strategy to quantify and partition large-scale water budgets down to point observations that typically do not capture the full range of fresh SGD dynamics. Presented on: Journal of Hydrology

Summarization: Koiliaris CZO is a European Critical Zone Observatory (CZO) typical of the Mediterranean karstic geomorphology, which represents watersheds affected by humans over the centuries. This study aims to provide information that underpins the hydrologic and geochemical processes functioning at Koiliaris CZO. Linking geomorphologic and tectonic analysis improved the delineation of a karstic area which extends outside of the Koiliaris watershed and identified how structural elements influence the regional hydrology. The fluctuation in the river flow represents processes occurring in the karst and the periodic signal is related to Earth tide stressing of the karstic reservoirs. The conceptualization of a two-reservoir, well-mixed karstic system is confirmed by both the geomorphologic and tidal analysis. The hydrologic response is fast and it is manifested especially during extreme events where 70% of the precipitation becomes surface runoff, creating major flood events. The different sampling sites in the Koiliaris CZO were geochemically clustered and the quantification of the weathering fluxes showed that 25 mm/1000 years and 39 mm/1000 years of carbonate were removed by chemical weathering for the Keramianos ephemeral river and the springs, respectively. These studies illustrate the importance of critical zone science and transdisciplinary studies on water and soil management. Παρουσιάστηκε στο: Water

In the Sultanate of Oman remnants of deteriorating terrace agricultural systems offer important insights into long-term human adaptation in the arid tropics. Irrigation and terrace agriculture in the mountainous Jabal Akhdar region reveal historic agricultural practices in a rugged, high elevation context. The present study examines soil quality and regolith provenance in abandoned agricultural soil terraces. Three soil profiles in each of the Villages of Hadash and Wijma were excavated and analyzed. Physical, chemical and mineralogical analyses were conducted for all soil horizons. In addition, six other soils, 3 possible soil parent rocks (regolith) and soil’s bedrock were collected. Soil ages were constrained by 14C assays and stable isotope, (13C and 18O) on the bulk carbonates in the calcrete (caliche). The results demonstrate that both sites display poor soil quality with very low average total organic carbon (TOC) (6.2–5.0 g kg−1) and mean weight diameter (MWD; 0.27–0.48 mm), with low water stable aggregate content (

The extent to which climate, eustacy and tectonics interact to shape the late Quaternary landscape is poorly known. Alluvial fans often provide useful indexes that allow decoding the information recorded on complex coastal landscapes, such as those of Eastern Mediterranean. In this paper we analyse and date (using optically stimulated luminescence – OSL) a double alluvial-fan system in Crete, an island straddling the forearc of the Hellenic subduction margin, in order to constrain the timing of, and quantify the contributing factors to, its landscape evolution. The studied alluvial system is unique because each of its two juxtaposed fans records individual phases of alluvial and marine incision, providing, thus, unprecedented resolution in the formation and evolution of its landscape. Specifically, our analysis shows that the fan sequence at Domata developed during the last glaciation (Marine Isotope Stage 3; 57–29 kyr) due to five distinct stages of marine transgressions and regressions and associated river incision, as a response to climatic changes and tectonic uplift at rates of ~ 2.2 mm/yr. Comparison of our results with published tectonic uplift rates from Crete shows, however, that vertical movement on Crete was minimal during 20–50 kyr BP and mot uplift was accrued during the last 20 kyr. This implies that eustacy and tectonism impacted on the landscape at Domata over mainly distinct time-intervals (e.g. sequentially and not synchronously), forming and preserving the coastal landforms, respectively.

International audience; The late-Cenozoic kinematic and late-Pleistocene paleoearthquake history of the Spili Fault is examined using slip-vector measurements and in situ cosmogenic (Cl-36) dating, respectively. The Spili Fault appears to have undergone at least three successive but distinct phases of extension since Messinian (similar to 7 Ma), with the most recent faulting resulting in the exhumation of its carbonate plane for a fault-length of similar to 20 km. Earthquake-slip and age data show that the lower 9 m of the Spili Fault plane were exhumed during the last similar to 16,500 years through a minimum of five large-magnitude (Mw > 6) earthquakes. The timing between successive paleoearthquakes varied by more than one order of magnitude (from 800 to 9000 years), suggesting a highly variable earthquake recurrence interval during late Pleistocene (CV = 1). This variability resulted to significant fluctuations in the displacement rate of the Spili Fault, with the millennium rate (3.5 mm/yr) being about six times faster than its late-Pleistocene rate (0.6 mm/yr). The observed variability in the slip-size of the paleoearthquakes is, however, significantly smaller (CV = 0.3). These data collectively suggest that the Spili Fault is one of the fastest moving faults in the forearc of the Hellenic subduction margin. (C) 2014 Elsevier Ltd. All rights reserved.

Summarization: A telemetric high-frequency hydrologic and water quality monitoring network was deployed to obtain data for the characterization of the hydrologic and bio-geochemical processes of a complex Mediterranean watershed of Koiliaris River, Crete, Greece. The network measures water level, water temperature, pH, dissolved oxygen (DO) and nitrate. Analysis of the hydrologic data suggests the existence of four hydrologic processes that operate in the watershed with distinctive characteristic response times. The response of the flow hydrograph of the upper reservoir of the Karstic system to a precipitation event had a characteristic time of 10 d while the characteristic time of the lower reservoir was 38 d. The flash flood events of Keramianos temporary river (tributary to Koiliaris) had a characteristic response time of 29 h while the diurnal variation of flow had a characteristic response time of 18 h. The diurnal fluctuation of the chemical parameters had a characteristic response time of 8 h for pH, 83 h for DO and 13 h for nitrates while the nitrate flush from the Neogene deposits to the river had a characteristic response time of 2.7 h. The diurnal fluctuation is related to in-stream biological activity. The results illustrate the importance of high-frequency sampling for accurate parameterization of processes operating in complex environmental systems with varying process response times. Presented on: Journal of Hydrology