Southeastern Oman Research Articles

Tectonic transition from thrusting to polyphase non-confining deformation within the Semail Ophiolite along the sinistral, transtensional Issmaiya Fault Zone (Sultanate of Oman)

• The Oman Mountains record the transition between shortening during the obduction of the Semail ophiolite . • At least three extensional events: affected the autochthonous and allochthonous units after obduction: two between the latest Cretaceous and early Eocene and one after the mid-Eocene. • Allochthonous units underwent major extensional shearing immediately after the emplacement of the ophiolite. • The allochthonous units underwent two further extensional events: One between the latest Cretaceous and early Eocene, and the other one after mid-Eocene. Obduction of the Semail Ophiolite and deep-sea basin-derived rocks represent a major tectonic event during Late Cretaceous evolution of the Oman Mountains. These allochthonous units were thrust SW-ward onto the passive Arabian margin and platform, followed by the main uplift of the Saih Hatat Dome and minor uplift of the Jabal Akhdar Dome. We present new structural data that indicate major extensional and transtensional deformation affecting the ophiolite unit after its emplacement. The studied area is in the southeastern Oman Mountains and hosts the brittle “Issmaiya Fault Zone” (IFZ; ∼3 km in wide and ∼ 30 km long). Field work and satellite image analysis show that most faults affected the Semail Ophiolite and only a few faults cut through latest Cretaceous to Paleogene sedimentary rocks of the Ibra Basin. These constraints allow us to date most faulting to immediately after the Late Cretaceous emplacement of the Semail Ophiolite, lasting to the post-Paleogene. The IFZ strikes ∼NW-SE at an acute angle of ∼30° to the WNW-ESE oriented southern margin of the Saih Hatat Dome. Northwestward, the IFZ terminates at the southern boundary fault of the Saih Hatat Dome. Fault kinematics based on shear-fracture slip-indicators reveal vertical to steep NW/SE-striking fault planes with occurrence of mainly sinistral strike-slip and some extensional dip-slip faults. This highlights a latest phase in a constrictional strain field with N/S-extension, perpendicular to E/W-oriented and vertical shortening axes of a sinistral transtensional fault zone. We suggest that SW-ward thrusting of the Semail Ophiolite was followed by mainly sinistral transtension.

Osmium isotope evidence for rapid melt migration towards the Moho in the Oman ophiolite

The oceanic crust, covering two-thirds of the Earth's surface, is formed along mid-oceanic ridges by crystallization at shallow levels of melts formed at depth by partial melting of mantle peridotite. Yet, the process of melt transport to the ridge axis remains poorly understood. Ophiolites, which provide a window into the uppermost mantle, contain dunite bodies often interpreted as relics of melt flow conduits, formed by pyroxene dissolution during melt-peridotite interaction. Here, we present structural and geochemical data on peridotites from the southeastern Oman ophiolite where three types of dunite, corresponding to the Moho transition zone (MTZ), the main and basal mantle sections, are identified. We focus on osmium isotopes, which are particularly well-adapted to tracing melt flow through peridotites. Osmium isotope signatures from host harzburgites accord with abyssal peridotite values and do not vary systematically with setting. In contrast, dunite Os compositions depend on structural context. Basal dunites display compositions similar to harzburgite values, while MTZ dunites have highly radiogenic compositions similar to those of the overlying crust, requiring extensive interaction with melts more radiogenic than MORB. Modeling shows that melts percolating through and equilibrating with dunite channels would acquire unradiogenic compositions, inconsistent with the observed Os signatures of MTZ dunites and lower crust. Thus, our findings require melt transport without equilibration with dunite or harzburgite, arguing for rapid or at least chemically isolated melt migration from the mantle source to the Moho.

Vegetation and cloud cover shape semi‐arid carbonate landform development

AbstractWe study the relationships among precipitation, vegetation, and morphological characteristics of watersheds draining either side of the Dhofar Mountains in southeastern Oman to understand the geomorphic signature of water availability in a semi‐arid carbonate landscape. Water availability is expressed in terms of vegetation and cloud cover. The integral and the statistical moments of the hypsometric curve were used to determine whether hyper‐arid, inland‐draining watersheds are significantly different from seasonally wet watersheds on the coast side of the mountain range. We demonstrate that the vegetation and cloud cover are correlated, with locations with longer cloud periods also having a longer period with a vegetation canopy. The analysis shows that the hypsometric curve and its statistical moments capture the morphological difference between wet watersheds shaped by groundwater sapping and dry watersheds with fluvial morphology. Specifically, the curves exhibit two shapes: watersheds with more vegetation and cloud cover are characterized by higher convexity, and those with less vegetation and cloud cover are characterized by higher concavity. A variance analysis of cloud cover, vegetation, and hypsometric integral shows that they are significantly different between the wet and dry watersheds. The link between hydrology and morphology is not strong at the scale of a single watershed, but it is significant when the watersheds are aggregated in zones. The statistical moments of the hypsometric curve in the range of values of the integral and skewness show good separation between watersheds dominated by sapping and fluvial erosion processes. We can separate the watersheds draining the mountain range in two distinct groups on the basis of their bimodal hydrological and morphological characteristics. Our findings support other studies that hypothesize a trade‐off from chemical‐ to mechanical‐dominated denudation in carbonate terranes as precipitation decreases.

Chapter 4 Large-scale structure of the study area

Abstract The Southeastern Oman Mountains are dominated by two major culminations: the Jabal Akhdar and Saih Hatat domes, surrounded by allochthonous and/or neo-autochthonous rocks. In the cores of both domes, folded autochthonous and par-autochthonous pre-Permian metasedimentary rocks are exposed, subjacent to the ‘Hercynian’ Unconformity. Above the unconformity are Permo--Mesozoic shelfal sedimentary rocks, characterized by carbonates. These sedimentary rocks were openly folded. The open folds are large-scale elongate structures that define the shapes of both domes. The main elongation direction is NW--SE. Doming is syn- to post-obductional. Most margins of the domes are marked by major post-obductional, extensional faults. Reactivated basement faults along the eastern margin of the Jabal Akhdar Dome may be responsible for the straight NNE-striking eastern margin which is perpendicular to the main elongation direction of the domes. The deep structure of both domes is poorly known. However, the Moho depth below the centre of the Jabal Akhdar Dome is at 50 km. We present a geological map of both domes, depicting the main faults and folds, and schematic cross-sections, parallel and perpendicular to the Oman Mountains.

Chapter 6 Conclusions, differences between the Jabal Akhdar and Saih Hatat domes and unanswered questions

Abstract This chapter provides the conclusions/outlines of the tectonics, affecting the Southeastern Oman Mountains, including the Jabal Akhdar and Saih Hatat domes. The main tectonic events include amongst others (1) Neoproterozoic rifting, (2) two distinct early Paleozoic compressive events, (3) large-scale open ‘Hercynian’ folding and formation of a pronounced unconformity during the late Paleozoic, (4) rifting preceding the opening of the Neo-Tethys Ocean during the late Paleozoic, (5) late Cretaceous obduction of the Semail Ophiolite and the response of the Arabian lithosphere as well as (6) post-obductional tectonics. Also of major geological significance are the three major glaciations (Sturtian, Marinoan and Late Paleozoic Gondwana glaciation) which have been recorded in the rocks of northern Oman. Moreover, major lithological, structural and metamorphic differences exist between the Jabal Akhdar and Saih Hatat domes. It appears likely that a major fault, striking parallel to the eastern margin of the Jabal Akhdar Dome, probably originating during Neoproterozoic terrain accretion, acted as a divide between both domes until present. This fault was multiple times reactivated and could explain the differences between the two domes. A catalogue of unanswered questions is included in chronological order to express that many geological aspects need further investigation and future research projects.

Chapter 2 Tectonostratigraphy of the eastern part of the Oman Mountains

Abstract This chapter provides comprehensive descriptions of 52 numbered formations/rock units of the Southeastern Oman Mountains, based on available literature. The oldest eight siliciclastic and carbonate formations are positioned below the ‘Hercynian’ Unconformity. The overlying formation (9–16) mostly represent carbonates which accumulated in a passive margin platform setting during or after the opening of the Neo-Tethys Ocean. The passive margin slope and platform collapsed during the late Cretaceous because of the obduction of the Semail Ophiolite along with the deep marine Hawasina sedimentary rocks. The collapsing passive margin interval was recorded within the syn-obductional Aruma Group (17; Muti Formation). Above this formation are the allochthonous units (18–42) of the tectonically lower Hawasina deep-sea basin and the structurally overlying Semail Ophiolite. The former contains Permian to Upper Cretaceous formations, while the latter is Cenomanian in age. Above the allochthonous rocks, the Neo-autochthonous formations were deposited, starting with the post-obductional uppermost Cretaceous Aruma Group (43; Al-Khod Formation) until the Quaternary deposits (52). All these formations/rock units are depicted on an accompanying map and stratigraphic chart.

About this title - The Geology and Tectonics of the Jabal Akhdar and Saih Hatat Domes, Oman Mountains

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.

Chapter 3 Thrusts, extensional faults and fold patterns of the major units

Abstract This chapter is concerned with the main faults and folds within the Southeastern Oman Mountains based on available literature. The main, best and most widely exposed thrusts are those related to the SW-directed late Cretaceous obduction of the allochthonous nappes onto the Arabian platform and margin. These thrusts are related to obduction of rocks, which had formed hundreds of kilometres offshore Oman. The thrusts were active from the Cenomanian to the Campanian. Obduction-related thrusts and folds are spectacularly exposed within the rocks of the Arabian platform in the eastern part of the Saih Hatat Dome, including large-scale recumbent cylindrical folds and sheath folds. At least six fold sets can be studied in the Southeastern Oman Mountains. At least two of them had formed prior to obduction and are exposed in the Pre-Permian formations of the Jabal Akhdar Dome. At least three fold sets formed in the course of obduction, while at least one fold set is postobductional in age. Besides the compressional structures, the Oman Mountains expose major post-obductional extensional faults, mostly at the margins of the Jabal Akhdar and Saih Hatat domes. The throw of these faults amounts to a few to several kilometres. Finally, this chapter provides an overview of the enigmatic Batinah Mélange which consists of slivers of Hawasina rocks, resting (unusually) structurally above the Semail Ophiolite.

Chapter 5 Tectonic evolution of the Oman Mountains

Abstract The tectonic evolution of the Oman Mountains as of the Neoproterozoic begins with a major extensional event, the Neoproterozoic Abu Mahara rifting. It was followed by the compressional Nabitah event, still during the Neoproterozoic, in Oman but possibly not in the study area. During the earliest Cambrian, the Jabal Akhdar area was affected by the Cadomian Orogeny, marked by NE--SW shortening. It is unclear, whether the Saih Hatat area was exposed to the Cadomian deformation, too. Still during the lower Cambrian, the Angudan Orogeny followed, characterized by NW--SE shortening. An episode of rifting affected the Saih Hatat area during the mid-Ordovician. During the mid-Carboniferous, both dome areas were deformed by tilting and large-scale open folding in the course of the ‘Hercynian’ event. As a consequence, a major unconformity formed. As another Late Paleozoic event, the Permian break-up of Pangaea and subsequent formation of the Hawasina ocean basin, are recorded in the Southeastern Oman Mountains. As a result, a passive margin formed which existed until the mid-Cretaceous, characterized by deposition of mostly shelfal carbonates. This interval of general tectonic quiescence was interrupted during the early Jurassic by uplift and tilting of the Arabian Platform. The platform collapsed during the late Cretaceous, related to the arrival of the obducted allochthonous nappes including the Semail Ophiolite, transforming the passive margin to an active margin. The Semail Ophiolite formed most likely above a subduction zone within the Neo-Tethys Ocean during the Cenomanian while parts of the Arabian Plate were subducted to the NE. Formation of oceanic lithosphere and SW-thrusting was broadly coeval, resulting in ophiolite obduction onto the Hawasina Basin. The Semail Ophiolite and the Hawasina rocks combined were thrust further onto the Arabian Plate. Their load created a foreland basin and forebulge within the Arabian Platform. Once the continental lithosphere of the Arabian Platform was forced into the subduction zone, a tear between the dense oceanic lithosphere and the buoyant continental lithosphere developed. This led to rapid uplift and exhumation of subducted continental lithosphere of the Saih Hatat area, while obduction was still going on, causing in multiple and intense folding/thrusting within the eastern Saih Hatat Dome. Exhumation of the Saih Hatat Dome was massive. The emplacement of the ophiolite was completed during the Campanian/Maastrichtian. For completeness, we also present alternative models for the developmental history of the Semail Ophiolite. Immediately after emplacement, the Arabian lithosphere underwent intense top-to-the-NE extensional shearing. Most of the Saih Hatat Dome was exhumed during the latest Cretaceous to Early Eocene, associated with major extensional shearing at its flanks. Further convergence during the late Eocene to Miocene resulted in exhumation of the Jabal Akhdar Dome and some gentle exhumation of the Saih Hatat Dome, shaping the present-day Southeastern Oman Mountains. In the coastal area, east and SE of the Saih Hatat Dome, some late Cretaceous to present-day uplift is evident by, e.g., uplifted marine terraces. The entire Oman Mountains are uplifting today, which is evident by the massive wadi incision into various rock units, including wadi deposits which may form overhangs.

Exploring the potential of solar, tidal, and wind energy resources in Oman using an integrated climatic-socioeconomic approach

This study presents - for the first time-a comprehensive assessment of the potential renewable energy resources in Oman, with a particular focus on solar, wind, and tidal energy resources. This study adopts a novel approach to assess the potential of these energy resources, in which information from multiple climatic indicators is coupled with socioeconomic drivers of energy development. Specifically, based on a daily dataset of the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), three climate indicators were employed to characterize the frequency, intensity and duration of solar radiation and wind speed. Then, we introduced a new overall assessment index (OAI) based on these three climatic indicators to explore the best localities – from a climatic perspective-for generating solar and wind energies. The validity of the recommended sites was discussed in the context of important physiographic, environmental, and socioeconomic constraints (e.g. population density, urban settlements, distance to water bodies, transportation network, etc.). Results demonstrate that both solar radiation and wind can be seen as promising and substantial alternative sources of fossil fuel resources in Oman, with almost 3.2% and 4.4% of the Omani territory being valid for a sustainable use of wind and solar radiation, respectively. The most recommended sites for wind generation are located mainly along Al-Jazir and Duqum coasts of southeastern Oman, where a promising wind energy center can be constructed. The best localities for the development of hybrid solar radiation generation centers are likely to be placed in Sohar and Thumrayt, where solar intensity approaches 8.1 kWh/m2, with a high frequency of occurrence throughout the year. In contrast, Oman showed low potential to generate tidal power, mainly due to a low tidal range (<2 m) along the majority of the Omani coastline. This study provides a solid base for national and local decision makers in Oman for a reliable assessment, monitoring, and sustainable exploitation of clean and renewable energy resources, especially with high population growth, accelerated urbanization, and rapid economic growth over the past few decades, which can pose more challenges to future energy demand in this country.

Timing of Magnetite Growth Associated With Peridotite‐Hosted Carbonate Veins in the SE Samail Ophiolite, Wadi Fins, Oman

AbstractCarbonate‐altered peridotite are common in continental and oceanic settings and it has been suggested that peridotite‐hosted carbonate represent a significant component of the carbon‐cycle and provide an important link in the CO2 dynamics between the atmosphere, hydrosphere, and lithosphere. The ability to constrain the timing of carbonate and accessory phase growth is key to interpreting the mechanisms that contribute to carbonate alteration, veining, and mineralization in ultramafic rocks. Here we examine a mantle section of the Samail ophiolite exposed in Wadi Fins in southeastern Oman where the peridotite is unconformably overlain by Late Cretaceous‐Paleogene limestone and crosscut by an extensive network of carbonate veins and fracture‐controlled alteration. Three previous 87Sr/86Sr measurements on carbonate vein material in the peridotite produce results consistent with vein formation involving Cretaceous to Eocene seawater (de Obeso &amp; Kelemen, 2018, https://doi.org/10.1098/rsta.2018.0433). We employ (U‐Th)/He chronometry to constrain the timing of hydrothermal magnetite in the calcite veins in the peridotite. Magnetite (U‐Th)/He ages of crystal sizes ranging from 1 cm to 200 μm record Miocene growth at 15 ± 4 Ma, which may indicate (1) fluid–rock interaction and carbonate precipitation in the Miocene, or (2) magnetite (re)crystallization within pre‐existing veins. Taken together with published Sr‐isotope values, these results suggest that carbonate veining at Wadi Fins started as early as the Cretaceous, and continued in the Miocene associated with magnetite growth. The timing of hydrothermal magnetite growth is coeval with Neogene shortening and faulting in southern Oman, which points to a tectonic driver for vein (re)opening and fluid‐rock alteration.

New Steamflooding Techniques Pay Off in Mukhaizna Field

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 190478, “Steamflooding Heavy Oil in a Naturally Fractured Carbonate Reservoir in Sultanate of Oman: A Case Study,” by Sanjeev Malik, SPE, Mohammed Al Balushi, SPE, Salim Al Salmi, Aamer Al Belushi, Faris Al Ismali, and Fahad Al Qassabi, Occidental Petroleum, prepared for the 2018 SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 26–28 March. The paper has not been peer reviewed. An operator has faced a number of challenges producing heavy oil (8000–20 000 cp) from the Khuff and Kahmah carbonate reservoirs at the Mukhaizna field since their discovery in 2010. The large, low-productivity reservoirs have few analogs in the world, so the operator established new approaches to bring these reserves to market. This paper covers the staged field-development methodology, including analysis and evaluation of various development concepts, that enabled the company to optimize both completion design and artificial-lift selection, reducing downtime and lowering operating costs by nearly 50%. Introduction The Mukhaizna field, located in the eastern part of central Oman, was discovered in 1975 by Petroleum Development of Oman. The Kahmah Group consists of shelf carbonate deposits of Cretaceous age, whereas the Khuff formation is of Permian age, with a major unconformity between the lower Kahmah and Khuff formations. The lower Kahmah units are believed to have been either eroded away or not deposited in this area. The Mukhaizna field is relatively close to the Huqf axis in southeastern Oman. The Kahmah and Khuff reservoirs are more representative of the interior of Oman than of either northern or southwestern Oman. The field structure consists of two structural highs, the North structure and the South structure, separated by a saddle in the middle. The first well was drilled in the Khuff reservoir and proved its productivity. Because the shallower Kahmah B reservoir has even more stock-tank original oil in place, the operator decided to assess its productivity while delineating the reservoir by drilling four wells. These wells were drilled in the northern, middle, and southern areas of the North structure in northeast/southwest and east/west directions to acquire information about the fractures throughout the 20,000-acre field. A coring program was initiated at the same time. The results from the wells and cores helped form the Phase 1 field-development plan. The two reservoirs have different geological properties. Khuff is highly fractured and has low matrix permeability, whereas Kahmah B is less fractured, has higher permeability, and has been dolomitized to varied levels across the field, which has had a significant effect on production performance. Reservoir-Development Strategy Steam-enhanced recovery of oil from heavy-oil reservoirs results from reduction in viscosity and residual oil saturation and from distillation. In fractured reservoirs, imbibition may play a significant role in improving recovery. If the crude has more resins and asphaltenes (i.e., more polar compounds), it tends to make the rock more oil-wet. Applying high-temperature steam can alter the wettability, making the rock more water-wet. This helps improve recovery because of imbibition. In addition to the complicated geology of Mukhaizna’s naturally fractured, vuggy, and dolomitized carbonate reservoirs, identifying the right steam-injection method and selecting the best artificial-lift system were critical to the success of the project.

Fluid rock interactions on residual mantle peridotites overlain by shallow oceanic limestones: Insights from Wadi Fins, Sultanate of Oman

In the southeastern Oman Mountains the mantle section of the Samail ophiolite is unconformably capped by large units of Maastrichtian to Eocene limestones deposited in a shallow marine environment after ophiolite emplacement. In the vicinity of the town of Fins, a deep canyon carved by a stream has exposed mantle sections of the ophiolite. This section is composed of altered peridotites with high concentrations of calcium and small enrichments of silica compared to the Samail mantle protolith suggesting that the peridotites reacted with a hydrous fluid derived from interaction of seawater with the overlying sediments composed of limestones with minor amounts of chert. This is further affirmed by average δ13C (−0.25‰VPDB) δ18O (−5.53‰VPDB) and 87Sr/86Sr (0.70788) in the carbonate veins, consistent with values in the sediments. Clumped isotope thermometry on calcite veins in peridotite establish that they formed at 25–60 °C. Reaction path modeling of carbonate-quartz derived fluids with peridotite reproduces the observed mineral assemblage composed of carbonate and serpentine with similar Mg# and MgO/SiO2 at high water to rock ratios, with carbon, H2O and silica added to the rock by the reacting fluid.

Tectono-sedimentary evolution of the eastern Gulf of Aden conjugate passive margins: Narrowness and asymmetry in oblique rifting context

Here, we focus on the yet unexplored eastern Gulf of Aden, on Socotra Island (Yemen), Southeastern Oman and offshore conjugate passive margins between the Socotra-Hadbeen (SHFZ) and the eastern Gulf of Aden fracture zones. Our interpretation leads to onshore-offshore stratigraphic correlation between the passive margins. We present a new map reflecting the boundaries between the crustal domains (proximal, necking, hyper-extended, exhumed mantle, proto-oceanic and oceanic domains) and structures using bathymetry, magnetic surveys and seismic reflection data. The most striking result is that the magma-poor conjugate margins exhibit asymmetrical architecture since the thinning phase (Upper Rupelian–Burdigalian). Their necking domains are sharp (~40–10km wide) and their hyper-extended domains are narrow and asymmetric (~10–40km wide on the Socotra margin and ~50–80km wide on the Omani margin). We suggest that this asymmetry is related to the migration of the rift center producing significant lower crustal flow and sequential faulting in the hyper-extended domain. Throughout the Oligo-Miocene rifting, far-field forces dominate and the deformation is accommodated along EW to N110°E northward-dipping low angle normal faults. Convection in the mantle near the SHFZ may be responsible of change in fault dip polarity in the Omani hyper-extended domain. We show the existence of a northward-dipping detachment fault formed at the beginning of the exhumation phase (Burdigalien). It separates the northern upper plate (Oman) from southern lower plate (Socotra Island) and may have generated rift-induced decompression melting and volcanism affecting the upper plate. We highlight multiple generations of detachment faults exhuming serpentinized subcontinental mantle in the ocean-continent transition. Associated to significant decompression melting, final detachment fault may have triggered the formation of a proto-oceanic crust at 17.6Ma and induced late volcanism up to ~10Ma. Finally, the setting up of a steady-state oceanic spreading center occurs at ~17Ma.

The Sawqirah contourite drift system in the Arabian Sea (NW Indian Ocean): A case study of interactions between margin reactivation and contouritic processes

The relationships between oceanic circulation in the Arabian Sea and Late Cenozoic climate changes, including variations in monsoon intensity at the million year time-scale, remain poorly investigated. Using multibeam and seismic data, we provide the first description of a contourite drift in the Arabian Sea, along the south-eastern Oman margin. This contourite drift is referred as the “Sawqirah Contourite Drift System”. Late Miocene reactivation of the south-eastern Oman margin resulted in the formation of a complex anticline system, which shaped the seafloor topography above which the Sawqirah Drift subsequently developed. The drift resulted from the circulation of bottom currents within the North Intermediate Indian Water. Major seismic unconformities identified within the Sawqirah Drift were tied to Ocean Drilling Program (ODP) drill holes, and allowed defining distinct episodes of drift construction. At least two of these unconformities record reorganizations of the oceanic circulation at ~4.5–4.8Ma and ~2.4Ma. The 4.5–4.8Ma-old unconformity is coeval with the onset of upwelling of deep and cold waters in the Owen Basin. The 2.4Ma-old unconformity records a major episode of Indian monsoon intensification (at the million year time scale) over the Arabian Sea, indicating strong coupling between oceanic and atmospheric circulation processes.

Multiple methods increase detection of large and medium-sized mammals: working with volunteers in south-eastern Oman

AbstractWe compared the effectiveness of various methods for surveying medium and large wild mammals in southern Oman. Working with volunteers recruited by Biosphere Expeditions, wildlife professionals and local rangers, we used direct observation, camera traps, sign surveys (tracks and/or dung) and molecular scatology to study 66 sampling units of 2 × 2 km (grid cells) in an area of 32 × 36 km during a 4-week period in February–March 2011. Sixteen mammal species were recorded, and the largest numbers of species were recorded by sign surveys and camera traps (both n = 9); sign surveys, direct sightings and DNA scatology recorded species across the largest number of grid cells. For species with a sample size large enough for comparison (i.e. detected in ≥ 8 grid cells), DNA scatology proved most effective for detecting caracal Caracal caracal, signs for hyaena Hyaena hyaena, ibex Capra nubiana, porcupine Hystrix indica and hyrax Procavia capensis, and signs and direct sightings for mountain gazelle Gazella gazella. Clustering, in which records from multiple methods are either adjacent or overlapping, was highest (≥ 76%) for the wolf Canis lupus, porcupine, ibex and gazelle. Our results indicate the best methods to detect and record the distributions of individual species in the study area, and demonstrate the advantage of using multiple methods to reduce the risk of false absences or partial detections. Our findings also highlight the potential of clustering as a means of cross-checking results of observations that are skill-dependent, which is particularly useful when employing a large workforce.

A modelling implementation of climate change on biodegradation of Low-Density Polyethylene (LDPE) by Aspergillus niger in soil

Aim: To model the areas becoming and remaining highly suitable for Aspergillus niger growth over the next ninety years by future climate alteration, in relation to the species’ potential enhancement of Low Density Polyethylene (LDPE) biodegradation in soil.Location: Global scaleMethods: Projections of A. niger growth suitability for 2030, 2050, 2070 and 2100 were made using the A2 emissions scenario together with two Global Climate Models (GCMs): the CSIRO-Mk3.0 (CS) model and the MIROC-H (MR) model through CLIMEX software. Subsequently the outputs of the two GCMs were overlaid to extract common areas in each period of time, providing higher certainty concerning areas which will become highly suitable to A. niger in the future. Afterwards, GIS software was employed to extract sustainable regions for this species growth from present time up to 2100.Results: Central and eastern Argentina, Uruguay, southern Brazil, eastern United States, southern France, northern Spain, central and southern Italy, southern Hungary, eastern Albania, south western Russia, central and eastern China, eastern Australia, south east of South Africa, central Zambia, Rwanda, Burundi, central Kenya, central Ethiopia and north eastern Oman will be highly suitable for A. niger growth from present time up to 2100.Main conclusions: Accurately evaluating the impact of landfilling on land use and predicting future climate are vital components for effective long-term planning of waste management. From a social and economic perspective, utilization of our mapped projections to detect suitable regions for establishing landfills in areas highly sustainable for microorganisms like A. niger growth will allow a significant cost reduction and improve the performance of biodegradation of LDPE over a long period of time, through making use of natural climatic and environmental factors.

Guadalupian brachiopods from western Taurus, Turkey.

Here we describe 41 brachiopod species belonging to the orders Productida, Orthotetida, Orthida, Rhynchonellida, Athyridida, Spiriferida, Spiriferinida, and Terebratulida coming from the Guadalupian lower-middle part of the Pamucak Formation at Curuk Dað, Antalya (Western Taurus, Turkey). Associated conodonts are also reported and illustrated. The brachiopod taxa are either pedicle attached genera, with one genus also stabilized by penetration of its elongate umbo, or free living concavo-convex semi-infaunal genera; this indicates that the energy of the environment was never very high, as in settings just below the fair weather wave-base or in a back-reef, more protected inner platform. The brachiopods from the Pamucak Formation are very similar to the Wordian fauna of southeastern Oman, and they are similar to the Guadalupian assemblages of Chios, North Iran, South Thailand, and Salt Range. In comparison they share only a few taxa with the Guadalupian faunas of Central Afghanistan and Karakorum. Therefore the biotic affinity of the Guadalupian brachiopods of the Pamucak Formation is clearly peri-Gondwanan. The brachiopod record at Curuk Dað has implications for understanding the pattern of the end-Guadalupian (pre-Lopingian) biotic crisis. The pre-Lopingian crisis assemblages are quite diverse and nearly totally consist of Guadalupian genera and species except for a single Lopingian incomer. Their stratigraphic range terminates rather abruptly and the following 120 metres of shallow water limestones are barren of brachiopods, after which there is the first occurrence of Lopingian brachiopod taxa, which show a much lower biodiversity. This pattern is different from that observed in South China and it shows that the end-Guadalupian crisis is not only characterized by taxonomic selectivity, but also by a strong local control on the extinction/recovery pattern of some groups.

Incidence of tarsonemid mites on Cocos nucifera L. (Arecaceae) from Oman with description of a new species of Nasutitarsonemus Beer and Nucifora (Acari: Tarsonemidae)

Coconut is an important crop grown in the coastal plain of the Dhofar region, south-eastern Oman, on the edge of the Arabian Peninsula desert. It holds a particular place in the landscaping of the region and is also of great interest for the production of coconut drinking water. One of the main pests of coconut in this region is the coconut mite (Aceria guerreronis Keifer). In surveys conducted to understand the dynamics of that mite and its association with other arthropods, the incidence of tarsonemid mites was determined. Steneotarsonemus furcatus de Leon was the most commonly found tarsonemid on fruits as well as on growing tips of coconut seedlings, always at low levels. A few representatives of an undescribed tarsonemid species were also found. That new species is here described as Nasutitarsonemus omani Lofego and Moraes, sp. nov. A key to the species of this little-known genus is provided.

PERMIAN CRINOIDS FROM THE SAIWAN AND KHUFF FORMATIONS,SOUTHEASTERN OMAN

Early Permian (Sakmarian) crinoids are described from six horizons in the Saiwan Formation of the Huqf area of southeastern Oman. Each horizon yielded only one to three taxa. All specimens lived in a shallow water environment characterized by mixed siliciclastic or siliciclastic-carbonate sedimentation. Disarticulated arm plates of an indeterminate articulate crinoid are described from a tempestite bed in the Khuff Formation (Wordian) of the Haushi area. The Saiwan Sakmarian crinoids are some of the earlier, although not the earliest Permian crinoids known. Representatives of both primitive (sycocrinids) and advanced (scytalocrinids, blothrocrinids, texacrinids, and cromyocrinids) cladids and articulates are present in the Saiwan crinoids that are dominated by advanced dendrocrinids and belong to families previously reported from the Carboniferous or Permian. They show greatest affinity to the late Sakmarian/early Artinskian fauna from the Callytharra Formation of Western Australia. New taxa described herein double the number of genera (three) previously reported from the same area. The diversity of the Saiwan crinoids is relatively low when compared to the large faunas reported from Timor, Western Australia, Russia, and North America. However, they show affinity with each of the larger faunas. New taxa described are Coeliocrinus arenaceous n. sp., Moapacrinus ? omanensis n. sp., Huqficrinus biserialis n. gen. and sp., and Campbellicrinus nodosus n. sp.