Al Hajar Research Articles

The complex continental margin of NE Oman: Fault-gouge dating of the Wadi Kabir Fault at the northern margin of the Saih Hatat window, Sultanate of Oman, and its wider implications

The complex structural geometry along the northern continental margin of Oman formed during polyphase deformation from the mid-Cretaceous to the Miocene. We focus on the kinematics and tectonics of the Wadi Kabir Fault, which represents an eastern segment of the large-scale, composite Frontal Range fault system that forms the northern boundary of the central Al Hajar Mountains. The most exhumed rocks outcrop in the Saih Hatat window of the Al Hajar Mountains, which occurs in the footwall of the Wadi Kabir Fault. To better understand the tectonic history of the Wadi Kabir Fault, we report three K-Ar illite fault-gouge ages. Sample FG16-1 from a shallowly north-dipping gouge zone of the eastern segment of the Wadi Kabir Fault yielded two consistent ages that overlap within 2σ uncertainties at ∼90 Ma. Sample FG16-2 from the central segment of the fault yielded a K–Ar age of 57.9 ± 2.0 Ma (2σ uncertainties), which is interpreted as a late Paleocene faulting event as it perfectly matches the cooling history of the high-pressure rocks of the Saih Hatat window in the footwall of the Wadi Kabir Fault. We present two tectonic interpretations for the ∼90 Ma fault-gouge age and prefer a synchronous kinematic relationship with the parallel and contractional mid-Cretaceous Yenkit Shear Zone that was active at the distal Arabian Platform since 114 Ma. Because the 57.9 ± 2.0 Ma age is associated with pronounced footwall cooling, we interpret this age to be related to the formation of the Bandar Jissah Basin in the hanging wall of the Wadi Kabir Fault. We conclude that the Frontal Range fault system likely formed during the Paleocene and that its young (≤∼43 Ma) history was accommodated along the western segment of the fault, as there is no evidence of this Eocene fault interval at the Wadi Kabir Fault.

Trends and variability in methane concentrations over the Southeastern Arabian Peninsula

Methane (CH4) is a potent greenhouse gas with an important contribution to global warming. While national and international efforts have been put in place to reduce methane emissions, little is known about its variability, especially in hotspot regions where natural and anthropogenic emissions are compounded. In this study, the current state of CH4 concentrations and their trends over the United Arab Emirates (UAE) and surrounding region are investigated with satellite and reanalysis data. CH4 concentrations have increased over the last 5 years, with a trend in the satellite-derived column values (XCH4) of about 9 ppb/year. A clear annual cycle is detected in XCH4, with an amplitude of up to 75 ppb and peak values in the warmer months. The largest concentrations are found in coastal sites, where sabkhas and landfills are present, and along the Al Hajar mountains, where agricultural activities and microhabitats that may host CH4-producing microbes occur and where advection by the background flow is likely an important contributor. The reanalysis data shows a good agreement with the satellite-derived estimates in terms of the spatial pattern, but the magnitudes are smaller by up to 50 ppb, due to deficiencies in the data assimilated. Surface CH4 concentrations in the reanalysis data account for more than 50% of the corresponding XCH4 values, and exhibit a seasonal cycle with the opposite phase due to uncertainties in the emissions inventory. Our findings provide an overview of the state of CH4 concentration in the UAE and surrounding region, and may aid local authorities to propose the appropriate emission reduction strategies in order to meet the proposed net-zero greenhouse gas emission target by 2050. This study highlights the need for the establishment in the Arabian Peninsula region of a ground-based observational network for greenhouse gas concentrations which is still lacking to date.

Anatomy of a Summertime Convective Event over the Arabian Region

Abstract This study investigates the structure and evolution of a summertime convective event that occurred on 14 July 2015 over the Arabian region. We use the WRF Model with 1-km horizontal grid spacing and test three PBL parameterizations: the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme; the Asymmetrical Convective Model, version 2, (ACM2) scheme; and the quasi-normal scale-elimination (QNSE) scheme. Convection initiates near the Al Hajar Mountains of northern Oman at around 1100 local time (LT; 0700 UTC) and propagates northwestward. A nonorographic convective band along the west coast of the United Arab Emirates (UAE) develops after 1500 LT as a result of the convergence of cold pools with the sea breeze from the Arabian Gulf. The model simulation employing the QNSE scheme simulates the convection initiation and propagation well. Although the MYNN and ACM2 simulations show convective initiation near the Al Hajar Mountains, they fail to simulate the development of the convective band along the UAE west coast. The MYNN run simulates colder near-surface temperatures and a weaker sea breeze, whereas the ACM2 run simulates a stronger sea breeze but a drier lower troposphere. Sensitivity simulations using horizontal grid spacings of 9 and 3 km show that lower-resolution runs develop broader convective structures and weaker cold pools and horizontal wind divergence, affecting the development of convection along the west coast of the UAE. The 1-km run using the QNSE PBL scheme realistically captures the sequence of events that leads to the moist convection over the UAE and adjacent mountains.

Observing the pre-convective environment and convection initiation with Doppler Lidar and cloud radar in the Al Hajar Mountains of the United Arab Emirates

Observing the pre-convective environment and convection initiation with Doppler Lidar and cloud radar in the Al Hajar Mountains of the United Arab Emirates

A multi-isotopic evaluation of groundwater in a rapidly developing area and implications for water management in hyper-arid regions

Management of water resources in hyper-arid areas faces vital challenges in a global climate change context. Consequently, understanding the effects on groundwater sources can help mitigating the problem of water scarcity and the negative impact of human intervention on the environment. A case study area in the hyper-arid climate of the United Arab Emirates, was tackled here with the focus on applying stable isotopes as tools for evaluating groundwater sources and quality assessment. The results of major ions indicate variable increase in groundwater salinity moving away from Al Hajar Mountains recharge areas to the discharge areas (Arabian Gulf coast). The data of stable isotopes (δ18OH2O, δ2HH2O, δ18ONO3, δ15NNO3, δ18OSO4, δ34SSO4, δ11B) suggest impact of paleo-groundwater in the abstractions of the wells nearest to the coast. Nitrate isotopes indicate farming activities sources that can be masked due to the contribution from the nitrate-poor paleo-groundwater. Nitrate reduction processes are expected near to the recharge front. Sulphate and boron isotopes further suggest that influence of ancient evaporite dissolution in salinization. Management efforts should be focused on the diffuse sources of quality mitigations that can be vital in fingerprinting local and regional (transboundary) effects.

Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates

Abstract. Aerosol and cloud microphysical measurements were collected by a research aircraft during August 2019 over the United Arab Emirates (UAE). The majority of scientific flights targeted summertime convection along the eastern Al Hajar Mountains bordering Oman, while one flight sampled non-orographic clouds over the western UAE near the Saudi Arabian border. In this work, we study the evolution of growing cloud turrets from cloud base (9 ∘C) up to the capping inversion level (−12 ∘C) using coincident cloud particle imagery and particle size distributions from cloud cores under different forcing. Results demonstrate the active role of background dust and pollution as cloud condensation nuclei (CCN) with the onset of their deliquescence in the subcloud region. Subcloud aerosol sizes are shown to extend from submicron to 100 µm sizes, with higher concentrations of ultra-giant CCN (d>10 µm) from local sources closer to the Saudi border, compared with the eastern orographic region where smaller CCN are observed. Despite the presence of ultra-giant CCN from dust and pollution in both regions, an active collision–coalescence (C–C) process is not observed within the limited depths of warm cloud (<1000 m). The state-of-the-art observations presented in this paper can be used to initialize modeling case studies to examine the influence of aerosols on cloud and precipitation processes in the region and to better understand the impacts of hygroscopic cloud seeding on these clouds.

Aquatic Coleoptera of North Oman, with description of new species of Hydraenidae and Hydrophilidae

Abstract We report the aquatic Coleoptera (families Dryopidae, Dytiscidae, Georissidae, Gyrinidae, Heteroceridae, Hydraenidae, Hydrophilidae and Limnichidae) from North Oman, mostly based on the captures of fourteen localities sampled by the authors in 2010. Four species are described as new, all from the Al Hajar mountains, three in family Hydraenidae, Hydraena (Hydraena) naja sp. nov., Ochthebius (Ochthebius) alhajarensis sp. nov. (O. punctatus species group) and O. (O.) bernard sp. nov. (O. metallescens species group); and one in family Hydrophilidae, Agraphydrus elongatus sp. nov. Three of the recorded species are new to the Arabian Peninsula, Hydroglyphus farquharensis (Scott, 1912) (Dytiscidae), Hydraena (Hydraenopsis) quadricollis Wollaston, 1864 (Hydraenidae) and Enochrus (Lumetus) cf. quadrinotatus (Guillebeau, 1896) (Hydrophilidae). Ten species already known from the Arabian Peninsula are newly recorded from Oman: Cybister tripunctatus lateralis (Fabricius, 1798) (Dytiscidae), Hydraena (Hydraena) gattolliati Jäch & Delgado, 2010, Ochthebius (Ochthebius) monseti Jä ch & Delgado 2010, Ochthebius (Ochthebius) wurayah Jäch & Delgado, 2010 (all Hydraenidae), Georissus (Neogeorissus) chameleo Fiká č ek & Trá vní č ek, 2009 (Georissidae), Enochrus (Methydrus) cf. tetraspilus Régimbart, 1903, Laccobius (Hydroxenus) leucaspis Kiesenwetter, 1870, Paracymus relaxus Rey, 1884 (all Hydrophilidae), Dryops lutulentus (Erichson, 1947) (Dryopidae), and Augyles flavidus (Rossi, 1794) (Heteroceridae). A total of 73 species of aquatic Coleoptera are presently known from Oman, although this number is expected to increase substantially with further sampling. A checklist of the species of aquatic Coleoptera from the Arabian Peninsula is provided.

Assessment of seasonal cloud properties in the United Arab Emirates and adjoining regions from geostationary satellite data

The present study mainly focuses on the United Arab Emirates (UAE) and adjoining areas, in the Arabian Peninsula, coming under the arid/semi-arid climatic conditions. The extremely intermittent rainfall strongly hinders the economic growth of this region. The freshwater primarily comes from the desalination of seawater along with other resources such as groundwater in the UAE region. Nevertheless, the declining groundwater reserves and expensive desalination approach have made to search for alternative sources for rain enhancement and one such approach is through the cloud seeding. However, there are barely few studies concentrated on the occurrence frequency of clouds and seasonal variability including their natural microphysics and dynamics that is crucial for precipitation augmentation through cloud seeding. Hence, the present study uses two geostationary satellites, namely, Meteosat-8 and Meteosat-10, due to their higher spatiotemporal observations in this region. The two geostationary satellites scan the UAE and adjoining regions in different view angles due to their positioning in different longitudes. Therefore, the Meteosat-8 has more advantage than Meteosat-10 in terms of the biases associated with the angular view and spatial resolution over the UAE and adjoining regions. Hence, the present study also evaluates the biases related to cloud occurrence due to different view angles.The winter (February–March) and summer (June–August) seasons indicate the frequent occurrence of clouds with distinct spatial distribution in these arid/semi-arid areas. The Arabian Gulf shows a higher percentage of clouds during winter while frequent convective clouds are noticed during summer over the Al Hajar Mountains. The evaluation of liquid and ice clouds also indicates that the warm cloud percentage is higher over the mountainous regions. However, the ice cloud distribution is higher over the Arabian Gulf during winter while they are highly confined along the Al Hajar Mountains in summer. The evaluation of cloud cover from Meteosat-10 and Meteosat-8 indicates the former shows higher occurrence percentage than the later. The significant biases are noted in warm cloud occurrence along the mountainous regions from both the satellites. The fractional occurrence of rain is also estimated for different seasons based cloud liquid water path that provides key information to the seedable convective clouds. Therefore, the present study finds significant implications to the rain enhancement over arid and semi-arid regions in the Arabian Peninsula.

Jabal Hafit anticline (UAE and Oman) formed by décollement folding followed by trishear fault-propagation folding

Creating three-dimensional (3D) models to replicate geological structures is crucial in discerning the geometry and kinematics of an orogen. The Jabal Hafit anticline, in the foreland of the Al Hajar Mountains, extends through Oman and the United Arab Emirates and is a relatively simple and well exposed structure. Surprisingly, previous studies of this anticline have presented conflicting interpretations regarding the strain field and the timing of deformation. In this study a structural 3D geological model of the Jabal Hafit anticline is constructed and demonstrates that the anticlines geometry can be reproduced by a two-phase model: (1) flexural slip folding, followed by (2) trishear fault-propagation folding. The trishear mode occurred due to a west-dipping backthrust that propagated from the décollement, to accommodate WSW–directed shortening. The different geometries of the various biostratigraphic layers indicate that anticline growth occurred during the late Oligocene to early–middle Miocene. This timing supports the recently established age for uplift of the Al Hajar Mountains.

Neogene to Quaternary uplift history along the passive margin of the northeastern Arabian Peninsula, eastern Al Hajar Mountains, Oman

AbstractThis 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.

Effects of climate change on niche shifts of Pseudotrapelus dhofarensis and Pseudotrapelus jensvindumi (Reptilia: Agamidae) in Western Asia.

Genus Pseudotrapelus has a wide distribution in North Africa and in the Middle East. In the present study, we modeled the habitat suitability of two Omani species of the genus (Pseudotrapelus dhofarensis and Pseudotrapelus jensvindumi) to evaluate the potential effects of climate change on their distribution. Mean diurnal range and precipitation of wettest quarter are the most highly contributed variables for P. jensvindumi and P. dhofarensis, respectively. The potential distribution for P. dhofarensis in the current time covers the southern coastal regions of Oman, Yemen, the Horn of Africa, and Socotra Island, but the suitable regions were reduced in the future prediction and limited to Yemen, Socotra Island, and Oman. There have not been any records of the species outside of Oman. Analysis of habitat suitability for P. jensvindumi indicated that the species is restricted to the Al Hajar Mountain of Oman and the southeast coastal region of Iran, but there are no records of the species from Iran. Because mean diurnal range will not be influenced by climate change in future, the potential distribution of the species is not expected to be changed in 2050. All predicted models were performed with the highest AUC (more than 0.97) using the Maxent method. Investigation to find unknown populations of these two species in Iran, Yemen, and Socotra Island is essential for developing conservation programs in the future.

Mineral Exploration in Rough Mountainous Area Using Geospatial Technology (Case Study of Al Hajar Area)

As acknowledged that the exploration is the first step before reaching the discovery of profitable economic raw materials. However, it is also representing a high risk financially because it is possible that the areas discovered is not economically worthwhile, at that time the stakeholder will confront difficult return their exploration expenses. Therefore, the exploration process executed in multiple stages before increasing expenses for the detection. The business of mineral exploration, one of high cost investment especially if it was in rugged mountain areas, which is difficult to reach and has a very high cost of access, consequentially increased the exploration costs. The reasons for doing this research in rough mountainous area using geospatial technology, can be justified to be valuable, time-saving and cost-reducing. Therefore, we can see that one of the solid factors that helped the study is using of GIS technology in the rough terrain area, which strongly and effectively contributes to the display of spatial information and linking the study, and analysis of the information collected by using GIS programs. Subsequently, its benefits minimizing exploration costs, and selecting targets with confidence and effective field work. Most of the data related to the operations of mineral exploration have a spatial nature. So, GIS has the capability for storage, updating, revising, displaying, retrieving, processing, manipulating and integrating of different geo-spatial data. By ending of this study, we will be able to save time and money and increase profitability and efficacy.

Late Eocene Uplift of the Al Hajar Mountains, Oman, Supported by Stratigraphy and Low‐Temperature Thermochronology

AbstractUplift of the Al Hajar Mountains in Oman has been related to either Late Cretaceous ophiolite obduction or the Neogene Zagros collision. To test these hypotheses, the cooling of the central Al Hajar Mountains is constrained by 10 apatite (U‐Th)/He (AHe), 15 fission track (AFT), and four zircon (U‐Th)/He (ZHe) sample ages. These data show differential cooling between the two major structural culminations of the mountains. In the 3 km high Jabal Akhdar culmination AHe single‐grain ages range between 39 ± 2 Ma and 10 ± 1 Ma (2σ errors), AFT ages range from 51 ± 8 Ma to 32 ± 4 Ma, and ZHe single‐grain ages range from 62 ± 3 Ma to 39 ± 2 Ma. In the 2 km high Saih Hatat culmination AHe ages range from 26 ± 4 to 12 ± 4 Ma, AFT ages from 73 ± 19 Ma to 57 ± 8 Ma, and ZHe single‐grain ages from 81 ± 4 Ma to 58 ± 3 Ma. Thermal modeling demonstrates that cooling associated with uplift and erosion initiated at 40 Ma, indicating that uplift occurred 30 Myr after ophiolite obduction and at least 10 Myr before the Zagros collision. Therefore, this uplift cannot be related to either event. We propose that crustal thickening supporting the topography of the Al Hajar Mountains was caused by a slowdown of Makran subduction and that north Oman took up the residual fraction of N‐S convergence between Arabia and Eurasia.

The diversity and distribution of freshwater macrophytes in the wedian of the mountainous northern Oman

The paper reports the first study of diversity and distribution of freshwater macrophytes in the wedian (plural of wadi = seasonal river) of the northern Al Hajar Mountain range in Oman. Fifteen lentic habitats in the wedian were surveyed. The number of species, their growth forms and abundance were recorded in the studied habitat of each wadi. In all, 41 species belonging to 14 families and 32 genera were collected. Of these 37 species were emergent and four were submergent. Poaceae was the most diverse emergent family with 17 species. Phragmites australis was the most common emergent followed by Typha domingensis. Among submerged macrophytes, Chara vulgaris had higher frequency of occurrence with low abundance followed by Potamogeton distinctus with relatively high abundance. Floristic diversity was estimated using species richness (Margalef’s D), general diversity (Shannon–Wiener H′), evenness (Pielous’s EH), and dominance (Berger–Parker d) indices for each study habitat. Principal component analysis was used to evaluate the variability using four indices. PC1 and PC2 explained 98.18% of the variability. Some habitats in different watersheds exhibited similar species diversity, but some in the same watershed were different. Baseline data on the freshwater macrophytes in northern Oman are provided here.

Darriwilian shallow-marine deposits from the Sultanate of Oman, a poorly known portion of the Arabian margin of Gondwana

AbstractThe Amdeh Formation is a 3.4 km stack of sparsely fossiliferous quartzites and shales which crops out in the Al Hajar mountains near Muscat. Here we describe the uppermost member (Am5) that can be dated biostratigraphically as Darriwilian and which is the outcrop equivalent, and probably the seaward continuation, of the Saih Nihayda Formation in the Ghaba Salt Basin of northern Oman. The outcrops at Wadi Daiqa and Hayl al Quwasim consist of 690 m of quartzitic sandstones, shales and bivalve-rich shell beds. Trace fossils referable to theCruzianaandSkolithosichnofacies abound. The member comprises storm-dominated shelf, shoreface and delta deposits. A number of new discoveries have been made in the outcrops: fragments of the arandaspid fishSacabambaspis, ossicles and moulds of the early disparid crinoidIocrinus, two new genera of conodont, an occurrence of the rare trinucleid trilobiteYinpanolithus, and palynological and sedimentological evidence of more continuous Floian–Darriwilian deposition than is usual in the region. Sea levels during Middle Ordovician time are estimated to have been 50–200 m above present levels and a wide, low-gradient shelf covered much of Arabia. Similar trace fossils and storm-dominated, micro-tidal, sedimentary rocks occur throughout the region. Small changes of sea level, possibly caused by the growth and melting of polar ice sheets, could lead to substantial seaward or landward shifts of facies belts. The Am5 deposits are thick compared to most equivalents in Arabia implying active subsidence and a ready supply of sediment.

New picobuthoid scorpions (Scorpiones: Buthidae) from Oman

Five new species of diminutive buthid scorpions are described from Oman. Two belong to Microbuthus Kraepelin, 1898, a genus with heavily sclerotized, smooth, strongly pitted posterior metasomal segments, abbreviated telson, and pedipalps with 9 femoral and 6–7 external patellar trichobothria: M. gardneri, sp. nov., from the Al Hajar Mountains, and M. kristensenorum, sp. nov., from the Dhofar Mountains and Hadhramaut of Yemen, which was long misidentified as M. pusillus Kraepelin, 1898. Two additional new species are placed in a new genus Picobuthus, gen. nov., differentiated by granular posterior metasomal segments, elongate telson, pedipalps with 7–9 femoral and 5 external patellar trichobothria: type species P. wahibaensis, sp. nov., from the Wahiba Sands, and P. dundoni, sp. nov., from sand deserts in central Oman. A second new genus, Femtobuthus, gen. nov., is monotypic with type species F. shutuae, sp. nov., from the southern coast and plateau of Jiddat Al Harasis, differentiated by enlarged, granular, dentate metasomal segments, abbreviated telson, and pedipalps with 6 femoral and 5 external patellar trichobothria. The relationship of Microbuthus and the two new genera to other buthid scorpions is discussed, and their trichobothrial homologies are addressed. These three genera are hypothesized to represent a monophyletic ‘picobuthoid’ lineage that originated in the Arabian Peninsula.

A new species of Odontobuthus (Scorpiones: Buthidae) from northern Oman

The Asian buthid genus Odontobuthus is newly recorded from the Arabian Peninsula where is represented by O. brevidigitus sp. nov. from the Batínah coast and foothills of the Al Hajar mountains of northern Oman. The new species is characterized by short pedipalp fingers, long pectines with narrow basal middle lamella, 2–3 enlarged denticles on ventrosubmedian carinae of metasoma II–III, stout metasoma IV with 10 anterior transverse granules, 3 lateral anal lobes, and enlarged dentition on the ventral anal arch. A model is proposed for the speciation of Odontobuthus by westward dispersal of an ancestral population on the Indus floodplain, followed by vicariant tectonic events in the Miocene and Pliocene that led to divergence of four species in temporal sequence: O. odonturus, O. doriae, O. bidentatus and O. brevidigitus sp. nov.

Two new Hemiscorpius Peters, 1861 (Scorpiones: Hemiscorpiidae) from northern Oman

Two new species of Hemiscorpius, H. falcifer, sp. nov. and H. flagelliraptor, sp. nov., are described from the Al Hajar Mountains of northern Oman. Although both are lithophilic or ultralithophilic scorpions beautifully adapted for living in rock crevices, they exhibit divergent morphologies and may not be closely related. H. falcifer is distinguished by: smaller size, relatively short compact metasoma, bulbous telson, relatively distal placement of lamellar double hook of hemispermatophore, pedipalp chela with wide, sub-triangular manus and exceptionally elongated fingers with single file dentition along distal half of movable finger (in adults); H. flagelliraptor is distinguished by: extremely elongated, sexually dimorphic metasoma, slender telson, proximal placement of lamellar double hook of hemispermatophore, slender pedipalp chela with double denticle rows along the distal half of movable finger. Although orthobothriotaxic, in other respects H. flagelliraptor appears most similar to the neobothriotaxic species H. enischnochela Monod et Lourenço, 2005 and H. gaillardi (Vachon, 1974) from Iran.

A new lithophilic Compsobuthus Vachon, 1949 (Scorpiones: Buthidae) from northern Oman

A new species of Compsobuthus is described from the Al Hajar mountains of northern Oman. It is distinguished by a strongly dorsoventrally compressed body, reduced carination on the carapace and tergites, extreme elongation of legs and pedipalps, lack of external accessory denticles on the pedipalp fingers, chelal trichobothrium est placed closer to dt than db, heavy setation on the ventral metasoma, and 28–34 pectine teeth. It is an ultralithophilic scorpion, highly adapted to life in narrow rock fissures.

The Convictions Some Jurisprudence Cases Related to Al Hajar As-Aswad (The Black Stone) and Al Rukn Al Yamani

The Convictions Some Jurisprudence Cases Related to Al Hajar As-Aswad (The Black Stone) and Al Rukn Al Yamani