Ocean Crust & Mountains of Mantle
MUSCAT TO MUSCAT
2 - 11 March 2021
10 Days/9 Nights
Exclusive small group tour, number of participants : 4 - 12
Prices are per person, based on 2 people sharing a room, bed & breakfast accommodation, and picnic lunches. Single supplement applies please make contact for details.
The geology of Oman is spectacular. Exceptionally well exposed rocks offer a fascinating outcrop experience, second to none. The scenery is unique and often breathtaking. The Semail Ophiolite (former sea floor you can walk on), mountain ranges of more than 3000 m altitude and deeply incised canyons, with turquoise-coloured perennial streams, contrast with dry but golden sand deserts. In addtional to all this, the coastal areas also have kilometres of white beaches and the country as a wholeboasts great archaeology and several world heritage sites.
James Cresswell pointing to the Moho in Wadi al Abyad (Day2)
Tropical dolomites (cap carbonates) overlying Snowball Earth glacial deposits(Day 2)
Our local driver and the vent of a fossilized Black Smoker (Day 3)
The 'Geotimes' pillow basalts at Wadi al Jizzi (Day 3)
A copper mine that has been mined for most of the last 4,000 years (Day 3)
Boudin and moullion structures in marinesediments of the Hawasina nappe (Day 4)
The Grand Canyon of Arabia, Wadi al Nakhr (Day 5)
Giant Triassic aged fossil bivalves. These bivalves were up to 30cm across and belong to the extinct bivalve family Megalodontidae. (Day 5)
Jebel Misht mountain in the background. This mountain was asubmarine volcano with an atoll on top of it. In the foreground is the Al Ayn beehive tombs World Heritage Site. (Day 5)
A cave formation which resembles a lion inside Al Hoota Cave (Day 6)
“The Aflaj Irrigation System of Oman” World Heritage Site (Day 6)
Our group at sunset in the Wahiba Sands (Day 6)
The 'Mother of All Outcrops' folds in radiolarian cherts (Day 7)
Wadi Shab, one of the most beautiful wadis in Oman (Day 8)
Stacked up tsunami boulders (Day 8)
A large fold (Day 9)
Day 1. Arrive in Muscat, Oman. We will stay at a hotel within easy reach of the International Airport.
Day 2. The Moho, Snowball Earth and Precambrian stromatolites. Our first stop today is one of Oman's greatest geosites. We travel to Wadi al Abyad to see the world's best outcrops of the Moho. The Moho is another name for the Mohorovičić discontinuity and is the boundary between the Earth's crust and mantle. The Moho is visible here because a spreading ridge plate boundary (a place where the Moho is near the surface) was obducted onto the Arabian continent as part of the Semail Ophiolite. The Semail Ophiolite is the best exposed ophiolite anywhere in the world. To reach Wadi al Abyad we must drive off-road on a river bed, and the wadi is about an hour from Muscat. Once we arrive at our site can see mantle rock (peridotite) at the base of a cliff with a clear line separating them from layered gabbros above. We then move on to Wadi Haslan for our first picnic lunch and examine Snowball Earth deposits. These deposits formed at a time when it is thought that the whole Earth was glaciated. At this site we see 712ma tillites and glacial lake deposits with drop-stones (rocks that fall out of icebergs) immediately overlain by tropical dolomites. These tropical dolomites are known as the cap carbonates and can be found all over the world on Snowball Earth deposits, demonstrating the climate very rapidly warming at the end of Snowball Earth. Our final site of the day is an unconformity between Precambrian rocks and Permian rocks. The Precambrian rocks contain stromatolites while the Permian rocks showed a marine transgression from a beach to limestone. From here we drive to the coast where we spend the night in the luxury Millennium Resort. Total drive time: 3 hrs 30 mins.
Day 3. Mid-ocean ridge rocks of the Semail Ophiolite. Today is all about seeing rocks that formed at a mid-ocean spreading ridge, but have now been obducted on the continent surface as part of the Semail Ophiolite. We start the day by visiting a fossilised Black Smoker that was once on the ocean floor at a mid-ocean ridge plate boundary. At the smoker we view copper mineralisation and interesting umber sediments which are rich in metals. At our next stop, we see hexagonal cooling structures in thick sill, before having our picnic lunch at part of the sheeted dyke complex, which is so characteristic of ophiolites. These dykes were the feeders of lava that was erupting out onto the sea floor at the mid-ocean spreading ridge. Next, we visit one of Oman's most famous geosites, the incredible "Geotimes" Pillow Basalts at Wadi al Jizzi. It is considered to be the best pillow basalt outcrops in the world. These basalts were erupted out on to the seabed, and formed pillow structures as they were cooled by the sea water. We finish the day with a visit to a copper mine that had been mined for most of the last 4,000 years, and see what may be the only ziggurat (stepped pyramid) in Arabia, built by early copper miners from Mesopotamia. We spend the night back on the coast in the town of Sohar. Drive time: 2.5 hrs
Day 4. Oceanic crustal rocks, the metamorphic sole of the ophiolite, and sediments of the Hawasina nappe. The first stop of our day is fossilised White smoker near to a place called Al Ghizayn. At Al Ghizayn we see pillow basalts, sills, dykes and a site of ancient copper smelting. Next we stop at the hospital in Wadi Hawasina. Here there is a fantastic view – mantle peridotites of the Semail ophiolite nappe behind us, and in front of us heavily folded marine sediments of the Hawasina nappe. The Hawasina nappe had first thrust over the Arabian continent and the Semail ophiolite nappe then thrust over both of them. The boundary between the two nappes is now thought to have been a former subduction zone, with the Semail ophiolite having formed at the spreading ridge of a back-arc-basin. A little further along the road we see granulite facies rocks known as the “metamorphic sole”. These rocks formed in the subduction zone. Furthermore, at this contact we see a hill made of marble. This was once an atoll which got jammed into the subduction zone! Soon after this stop we examin some beautiful chevron folds in the Hawasina sediments, that were deposited by turbidites. We continue on to our lunch stop, where we see shallower water sediments that show incredible boudins and moullion structures. The final geological stop is a multi-coloured outcrop of Hawasina sediments in a road cut, that were also very tightly folded. We then drive on via Ibri, where we have a comfort stop, to reach Bahla. We spend the next two nights in Bahla. Total drive time: 4 hrs.
Day 5. Jebel Shams and the Grand Canyon of Arabia, fossil Megalodonts and the Al Ayn UNESCO World Heritage Site. Our first stop today is an archaeological one, to observe important Neolithic rock engravings, at Hasat Bin Salt also known as Coleman’s Rock. The next stop is a view over the ruined town of Ghul which lies on Cretaceous limestone, and from our viewpoint it may be possible to find a few fossils preserved in pebbles. The next site is a viewpoint of Jebel Shams, Oman’s highest peak (3,028m) and of Wadi al Nakhr, which is also known as the “Grand Canyon of Arabia”. The cliffs of the canyon are 1,500m high and are made of Jurassic and Cretaceous marine sedimentary rocks. We then drive, via a windy mountain track, to our picnic lunch stop near the village of Sint. Here we also see giant Triassic-aged fossil bivalves. These bivalves were up to 30cm across and belong to the extinct bivalve family Megalodontidae. They lived as semi-infaunal suspension feeders. Our next stop is a large chevron fold near Al Hayl. The folded rocks were late Triassic/early Jurassic in age and were part of the Hawasina nappe. We travel a short distant further on for a view of the beautiful Jebel Misht mountain. This mountain is made up of Triassic aged limestone and dominate sitting on top of volcanic rock. It is known as an ‘Oman exotic’ because it was actually a submarine volcano with an atoll on top of it, which was scraped on to the continent as part of the Hawasina nappe! Our final stop of the day is the nearby Al Ayn beehive tombs World Heritage Site. Here we not only observe the early Bronze Age tombs, but also the Hawasina sediments on which they stand. We then returned to Bahla for a second night. Total drive time: 3 hrs 50 mins.
Day 6. Bahla Fort World Heritage Site, Al Hoota Cave, Falaj Daris World Heritage Site and the Wahiba Sands. We start the day with a visit to the Bahla Fort World Heritage Site, which was built between the 12th and 15th centuries by the Banu Nebhan tribe who were known for controlling the frankincense trade at the time. The fort also sits on an outcrop of ophiolitic rock and it is possible to see peridotite cut by gabbro dykes. The next stop is Al Hoota Cave in the Hajar Mountains. The cave is the largest show cave in Arabia and sits in mid-Cretaceous aged limestones and dolomites. The cave has been formed by water flowing through tectonic fractures, and it contains beautiful stalactites and stalagmites. Our lunch stop is at another World Heritage Site, “The Aflaj Irrigation System of Oman”. This irrigation system is up to 4,500 years old and is seen as one of the driving forces behind the formation of Oman as a nation as it provided the reason for nomadic societies to settle down. After lunch we have a longer drive to the Wahiba Sands. En route we stop at a site where we have a distant view of the Moho on a mountainside, with the bulk of the mountain made of peridotite and the top capped by gabbro. Once we reach edge of the Wahiba Sand dunes we leave the road, and drive through the sand to reach a desert tented camp where we spend the night. Here we discuss dune formation and Bedouin culture. Total drive time: 3 hrs 30 mins.
Day 7. Precambrian basement, Kimberlite, the ‘Mother of All Outcrops’, and Climate Change. The first thing we do this morning is drive back through the desert dunes to reach the road. We then visit a site where we see rocks of the Precambrian crystalline basement (800-1,000 million years old). Here we see granites that formed as terranes, were accreted together and then cut by huge gabbro dykes that were intruded as the basement went through a later period of extension. All these rocks are themselves intruded by granitic pegmatite (containing large crystals) dykes. Our next stop is to see an ultramafic rock outcrop on the beach, which contained volcanic fragments (lapilli) that formed due to the ascent of magma. Some authors have called the rock a kimberlite, which is the deepest mantle derived volcanic rock of all, and sometimes contains diamonds, although this outcrop contains no diamonds. After our picnic lunch, we then visit one of Oman’s most photogenic outcrops, informally known as the ‘Mother of All Outcrops’. Here, red radiolarian chert is interbedded with white porcellanite. These sediments were deposited in water 4,000-4,500 metres deep, and were thrust onto Arabia as part of the Batain Nappe (along with Oman’s other ophiolite, the Masirah Ophiolite), 15-20 ma after the emplacement of the main Semail Ophiolite. Our next stop is nearby and is to see an outcrop of manganese ore which contained crystals of pyrolusite (MnO2). This is followed by an outcrop of carbonitite volcanic rock, which contains beautiful veins of amethyst. Our final stop on the edge of Sur, is a site 3.7m above current sea level, where marine erosion and marine organisms have carved a pitted notch into Eocene conglomerate. This level represents the high tide level in the Eemian interglacial (127,000 to 106,000 years ago), when global temperatures were several degrees warmer than today (and, for example, hippos lived in the River Thames in London). Today we have already exceed Eemian CO2 levels, so this outcrop is a stark warning of what sea level rise is to come. We spend the night in Sur. Total drive time: 4 hrs.
Day 8. Fossil Corals, Wadi Shab, the Bimmah Sinkhole and the World’s largest Sheath Fold. The first stop of the day is a series of Miocene wave-cut platform terraces which are overlain by Quaternary fossil corals. The terraces have formed due to tectonic uplift. We then arrive at Wadi Shab, a magnificent canyon cut into Eocene limestone, which is considered by many to be Oman’s most beautiful Wadi. We spent three hours hiking in the wadi enjoying the wonderful scenery, and have the opportunity to swim in the natural pools there. We also had our picnic lunch here. We then visit a fascinating site with a tsunami deposit. Here huge boulders are seen on top of a cliff. Some of the boulders are even stacked up, or ‘imbricated’, showing that they had been washed into place by a giant wave! Our next stop is the Bimmah Sinkhole a popular stop for geologists and the general public alike. The sinkhole is actually a doline. The surface rock is not soluble but the layer beneath is and, when a cave formed in it, the surface rock crashed through leaving a doline. There is the further opportunity for a swim here. Our final stop of the day is at Wadi al Mayh to see the world’s largest sheath fold, which also contains many smaller isoclinal folds. Sheath folds are associated with shear zones, in this case the plate boundary along which the Semail ophiolite obducted. They are normally only centimetre to metre in scale but this one is 15 km long! We then return to Muscat, where we began our tour and will spend the next two nights here. Total drive time: 2 hrs 30 mins.
Day 9. Mantle rocks of the Semail Ophiolite and the As Sifah Eclogite. Today is the final day of the tour and we spend it visiting sites in the Muscat area. Our first stop is in the harbour in the old city. Here we take a steep walk up to a viewpoint (600m in each direction with a 100m climb). On the walk we examine the rocks which are peridotites that originated in the mantle and are part of the Semail ophiolite. We then drive past the Sultan’s Palace and on to another viewpoint where we see a beautiful coastline of drowned valleys. From here we reach the beach of As Sifah, known to be one of the most beautiful beaches in Oman. Here you can relax on the beach or take an optional (difficult) walk, 500 m each way, over large boulders to get to another beach where high-pressure low temperature metamorphic rock can be seen. This rock is eclogite, and formed as the Semail ophiolite was obducted onto Arabia. We then stop at a site where a large fold can be viewed. This fold is part of the same complex as the mega-sheath fold we saw on the proceeding day. Our final stop is a viewpoint over south-west Muscat. From here we can also see a strike slip fault, that may still be active, and of Eocene rocks lying unconformably upon the mantle rocks. We then return to our hotel for our final night.
Day 10. Today we depart, but if you wish to see Muscat’s cultural sites, we recommend that you stay on an extra day. Our logitiscs company is able to arrange you a Muscat City tour as a one-day extension.
Geological guiding from James Cresswell
Local guide and driver
Transportation from destination to destination
Breakfast in the hotels
Shuttles to and from airport
Alcohol and soft drinks
CARBON GENERATED BY THIS TOUR
= 0.353 TONNES OF C02
(calculated at https://www.carbonfootprint.com/calculator.aspx)
At no additional cost to you, GeoWorld Travel will offset the Carbon created by this tour using carbon offsetting company Carbon Footprint. A certificate for this offset will be supplied to you after the tour is completed.
It is your responsibility to book your travel to and from the start and finish of the tour, so if you would like to also carbon offset this cost please use our carbon offset calculator here.
Trip diaries, photo galleries and reviews of previous trips
TRIP DIARY 2020
contains lots of captioned photos
TRIP DIARY 2019
contains lots of captioned photos
OMAN - OCEAN CRUST AND MOUNTAINS OF MANTLE (2020)
"There were eight of us on this tour from four different English-speaking countries. Luckily we completed the tour and all of us got home just before the Coronavirus pandemic shut down tourist travel worldwide. James led us to one world-class geosite after another and presented them in a way that we could all understand and appreciate. James’ explanations of the sites that we visited left us all well-informed and he was very patient in explaining basic geological concepts to those in the group that didn’t have a background in geology. Geology aside, Oman is a beautiful and amazing country and this tour took us through remote places that the average tourist just isn’t going to see. Travel was in comfortable Toyota 4WD Land Cruisers. James drove one and a local Omani drove the other one. Our Omani driver Nasser was a pleasant man who spoke English well and was glad to tell us as much about Oman as we wanted to know. We stopped at six or seven geosites every day and had a nice leisurely picnic lunch in the shade I never felt like we were being rushed. The drives between stops weren’t too long and I never got tired of the mountain and desert scenery. Accommodations ranged from a five-star beach resort to tents at a Bedouin desert camp – which was by far my favorite overnight stop. My only regret is that I didn’t plan an extra day or two to spend in Muscat after the tour. James has a special thing going with GeoWorld Travel and I hope that this Coronavirus pandemic runs its course before much longer so that he can continue to offer us these unique tours."
Joseph M., Utah, USA
Review was posted to TripAdvisor, January 2020
OMAN - OCEAN CRUST AND MOUNTAINS OF MANTLE (2019)
"I was impressed by the trip, including the overall standard of the travel and accommodation. As ever, I enjoyed your company and will be viewing your website for future options."
Dennis C., Essex, UK,
Review sent to us by email, March 2019
OMAN - OCEAN CRUST AND MOUNTAINS OF MANTLE (2019)
"Thanks for the well-organised, informative, and very enjoyable tour around the geological highlights of Oman."