Haima Supergroup Gr
Type Locality and Naming
Haima Supergroup is a major siliciclastic-dominated unit of Cambrian to early Silurian age. The type and reference sections are combination of outcrops in the Al Huqf area and South and west Oman well sections, which are detailed in the Group and Formation entries. Column: Oman Subsurface, Oman Outcrop. "Von der Weid (unpublished, 1967), in which the Haima was originally defined as a Group for all the Paleozoic clastic-dominated formations above the Buah dolomite and below the Khuff Formation. Restricted to the Lower Paleozoic by Winkler (1975; see also Hughes Clarke, 1988) and upgraded to Supergroup by Priebe and Kapellos (1993; partly published in Boserio et al., 1995). Subsequently, revised by Droste (1997) and further revised by Droste (2001), who removed the tectonostratigraphically distinct Nimr Group from the Haima Supergroup and placed it within the Huqf Supergroup." A three-fold subdivision is made corresponding to the upward succession of the Mahatta Humaid Gr (Amin Fm, Miqrat Fm / Mahwis Fm), Andam Gr (Al Bashair Fm, Barik Fm, Mabrouk Fm Barakat Fm, Ghudun Fm), and Safiq Gr (Saih Nihayda Fm, Hasirah Fm, Sahmah Fm).
Synonym:
Lithology and Thickness
The Haima Supergroup is a major composite siliciclastic succession, locally with minor limestone development. It was deposited in both continental and marine environments. The basal part (Mahatta Humaid Gr) was deposited in arid to semi-arid, continental settings and the upper part (Andam Gr and Safiq Gr) was deposited in marine, marginal marine and marine-influenced environments, with minor dolomites and limestones. It is important to stress that when considering pre- Hasirah Fm units that continental depositional settings and sediment composition were not influenced at all by the presence of, yet to evolve, land plants. Sequence stratigraphy: The Haima Supergroup represents the AP2 and basal AP3 Megasequences of Sharland et al. (2001). Their MFS surfaces Cm30 through to O40, and possibly S10, correlate into Omani sections. The Haima Supergroup represents at least one and possibly two composite sequences commencing with the non-marine, arid to semi-arid siliciclastics of the Mahatta Humaid Group (a lowstand sequence set), and terminating with deeper-marine facies of the Safiq Group. A number of third- and higher- order sequences can be interpreted within this overall composite sequence, largely the Andam Group, including the transgressive and highstand successions of the Al Bashair Formation and the subsequent lowstand/transgressive-highstand sequence set of the Barik-Mabrouk formations (e.g. Millson et al., 2008).
[The excellent table of two-sentence summaries for each of these formations and groups on Page 177 of Forbes et al. (2010] is partly pasted below with the youngest formation at the top.]:
"Safiq Gr:
Sahmah Fm: Absent through erosion over most of Oman, occurring only in the westernmost parts of Central and South Oman, along the western edge of the Rub’ Al-Khali Basin and extending into Saudi Arabia. The Sahmah Fm is a major transgressive-regressive cycle, comprising organic-rich shales interbedded with sandstones stacked in a fining-coarsening upward trend. Recognition is based on the presence of the 1003 Palynozone (Latest Ordovician – early Silurian, Hirnantian – ?early Aeronian).
Hasirah Fm: Widespread in North, Central and southwestern regions of Oman, the Hasirah Fm is probably a major marine transgressive-regressive cycle. It commonly fills-in significant erosional topography where it is dominated by mudrocks. Elsewhere it may comprise medium- to coarse-grained, commonly thickly bedded sandstones, interstratified with dark grey organic-rich shales, which may be capped by a thick sandstone unit. Contains the O40 MFS (Sharland et al., 2001). Recognition is based on the presence of the 1005 Palynozone (Late Ordovician, Katian).
Saih Nihayda Fm: Most extensive in the northern region of Oman, but also extending into the northern part of the South Oman Salt Basin. The Saih Nihayda Fm can be eroded beneath the base Hasirah Fm unconformity. It is probably a major transgressive-regressive cycle, comprising a basal sandstone, overlain by dark grey shales which are capped by another sandy unit. Contains the O30 MFS (Sharland et al., 2001). Recognition is based on the presence of the 1098 Palynozone (Middle Ordovician, Darriwilian).
Ghudun Fm: The most widespread and thickest unit of the Haima. The Ghudun Formation is primarily a cross-bedded to laminated sandstone section, which represents fluvial channel and sheet-flood deposits in a deltaic setting. To the northwest it becomes more marine, confirmed by the presence of acritarchs and bioclasts in some horizons. Typically highly feldspathic with siltstones, occasionally intercalated with shales. Occasionally yields the 1100 Palynozone (Early-Middle Ordovician, late Floian – early Dapingian) in the Upper Ghudun. The Formation is more often barren and probably ranges down to the Floian/?Tremadocian.
Mabrouk Fm: Widespread over Central and North Oman and is dominated by shallow-marine muddy sediments that are reddish-brown interbedded with thin sandstones. Contains the O10 MFS (Sharland et al., 2001). Recognition partly based on the presence of the 1108B Palyno-subzone (Early Ordovician, Tremadocian).
Barakat Fm: Widespread over Central and North Oman, the Barakat Fm is a marine transgressive-regressive cycle, incorporating a significant maximum flooding (MFS O20 of Sharland et al., 2001). The base is typically a sandstone, overlain by reddish-brown or greenish shales, which are capped by a sandy unit. Yields the 1108C and 1108B Palyno-subzones (Early Ordovician, Tremadocian).
Barik Fm: Widespread over Central and North Oman the Barik Fm, is dominantly a braid delta complex but grades into a shallow-marine system to the north. In-situ palynomorphs have yet to be recorded, as ditch cuttings yield is probably due to caving.
Al Bashair Fm: Widespread over North Oman, the Al Bashair Fm is a shallow-marine sequence that, in its upper part comprises grey to reddish-brown mudstones intercalated with sands and in its lower part is dominated by fine-grained sandstones and argillaceous siltstones intercalated with shales and carbonates. Contains the Cm30 MFS (Sharland et al., 2001). Characterized by the 1108A Palyno-subzone (‘Late’ Cambrian*, Furongian).
Miqrat Fm/ Mahwis Fm: The Miqrat Fm is present in North and Central Oman, whilst the Mahwis Fm, which is likely to be its lateral equivalent, occurs only in South Oman. Both were deposited in arid to semi-arid continental settings. The Miqrat Fm was deposited in playa/ephemeral lake-sabkha environments with a periphery of sheet-flood alluvial deposition, whereas the Mahwis Fm may have been deposited in distal alluvial fan with local playa environments. Both formations are barren of palynomorphs and all other marine indicators.
Amin Fm: Widespread throughout Oman, the Amin Formation is a complex, arid depositional system including alluvial, fluvial and aeolian deposits. The base is a conglomeratic unit overlain by alternating sandy, conglomeratic and shaly intervals with the upper part generally a clean sandstone including some restricted aeolian units. Barren of palynomorphs and all other marine indicators."
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Huqf Supergroup Gr
Relationships and Distribution
Lower contact
"The basal Angudan unconformity of the Haima Supergroup onto the Huof Supergroup Gr reflects a major deformation/thermal event dated at about 540–520 Ma, associated with the convergence and subsequent transpressional/ transtensional continent-continent collision between East Gondwanaland and West Gondwanaland (Immerz et al., 2000; van den Berg et al., 2008). This was associated with reactivation of the Maradi Fault system, localized deformation and inversion throughout Oman with resultant salt movement and dissolution."
Upper contact
The relatively stable passive-margin phase of Cambrian through Silurian ended with the collision of Gondwana and Laurasia during the Carboniferous (‘Hercynian’ event). This truncated the Haima Supergroup and is associated with the base Haushi Gr unconformity (Konert et al., 2001; Al- Husseini, 2004; Faqira et al., 2009). The Haima Supergroup unconformably overlies the siliciclastics, carbonates or evaporites of the Huqf Supergroup and is unconformably overlain by the Haushi Gr, Misfar Gr or younger groups.
Regional extent
The Haima Supergroup is present throughout the subsurface basins of Oman, and in the Al Huqf outcrop area. The Mahatta Humaid Gr and Andam Gr are partially defined at outcrop in the northern Al Huqf area. The Amdeh Fm outcropping in the Saih Hatat region of the Eastern Al Hajar Mountains (Lovelock et al., 1981; Le Métour et al., 1986) is at least partially age equivalent to the Haima Supergroup (see also Sansom et al., 2009; Booth, 2009).
The Rann Fm (Glennie, 1974) in the northern extension of the Al Hajar Mountains in the United Arab Emirates (Hudson et al., 1954) is a clastic unit with marine fossils indicating an Ordovician age, see Rickards et al. (in preparation). It may be a lateral equivalent of the Haima sediments, but is part of an allochthonous unit of uncertain original position. The clastics-dominated Saq, Qasim Fm and Qalibah Fm in Saudi Arabia are probably lateral Haima Supergroup equivalents in essentially the same depositional regime (Sharland et al., 2001; Al Husseini, 2008; Faqira et al., 2009).
GeoJSON
Fossils
Five Palynozones with nine Palyno-subzones are applied to the Haima Supergroup. [See table with formations on Page 178 of Forbes et al. (2010)].
" The oldest interval in which biostratigraphic control exists is the Al Bashair Fm of the Andam Gr (e.g., Droste, 1997; Molyneux et al., 2006). Over the whole of the Haima Supergroup five Palynozones are recognised, four of which are divided into a total of nine Palyno-subzones (Mohiuddin et al., 2007 and Booth, 2009). The zonation is primarily based on marine acritarch content, but particularly in the Safiq Gr significant amounts of cryptospores (from primitive plants) and marine chitinozoa are also recorded. Work on the latter Group has been fundamental in assigning more robust ages to the Palynozones in the Middle Ordovician – early Silurian sections (Paris, 2002, 2005 and 2006). Many uncertainties remain in the application of this zonation and in particular the extent of missing section between formations in the Safiq Gr.
Age
Depositional setting
Oman was effectively a passive margin (Loosveld et al., 1996) throughout the early Paleozoic. However, weak extension continued throughout deposition of the Haima Supergroup into, at least, the Late Ordovician (Oterdoom et al., 1999; Worthing and Nasir, 2008). Halokenesis and its effect on sedimentation were further enhanced by this extension.
Additional Information