Levant Arch and the Palaeozoic of Arabia

The Levant Arch is a pervasive structural high that runs on a north-northeast trend from eastern Egypt to Turkey, through the Levant. Its existence prompted the use of the term ‘Hercynian Orogeny’ by Gvirtzman & Weissbrod (1984) for the first time in the Middle East, and following this, the widespread use of the term ‘Hercynian unconformity’ across the Arabian Plate. This short article, part of a larger project on the Hercynian unconformity across the Arabian Plate, traces the palynology of the Hercynian unconformity from where the Levant Arch creates a very incomplete Palaeozoic succession to where the Palaeozoic succession is near continuous and without break in the thickest part of the Nafud-Ma’aniya Basin.

In the north of the Nafud-Ma’aniya Basin close to the southern margin of the Levant Arch (Fig. 1), the Hercynian unconformity is expressed as a very large hiatus between the latest Permian Umm Irna Formation and the Cambrian Umm Ishrin Sandstone Formation (Jordan), and the Permian Saad Formation, and Precambrian Zenifim Formation (Negev).

Fig. 1. The Nafud-Ma’aniya Basin and southern margin of the Levant Arch in the eastern Mediterranean. Isopachs in m are for Carboniferous-Permian clastic sedimentary rocks, indicating possible Hercynian palaeotopography. Position of KH-5/1 approximate. Modified from Faqira et al. (2009).

The Hercynian unconformity is spectacular in the cliffs on the east coast of the Dead Sea (Fig. 2), where the red beds of the Umm Irna Formation overlie the yellowish sandstones of the Umm Ishrin Sandstone Formation.

Fig. 2. The unconformity in the cliffs on the east coast of the Dead Sea, Jordan. Above the arrow is the latest Permian Umm Irna Formation and below is the Cambrian Umm Ishrin Sandstone Formation. The cliffs are around 300m High.

The palynological assemblages of the Umm Irna Formation are very variable but in general contain common non-taeniate bisaccate pollen including Falcisporites stabilis, Alisporites nuthallensis, A. indarraensis, and Cedripites priscus. The most common taeniate bisaccate pollen is Protohaploxypinus uttingii, Lueckisporites virkkiae and P. limpidus. Monosaccate pollen is rare, as are spores. The presence of the pollen Pretricolpipollenites bharadwajii, mainly recorded from the very latest Permian of the Salt Range of Pakistan and the Triassic in the Middle East and North Africa, suggests an age within the later part of that range (Changhsingian; Stephenson & Powell, 2014; Tekleva et al. 2019). The Umm Irna Formation rests on the Umm Ishrin Formation which is considered to be mid to late Cambrian by Powell et al. (2014). The Umm Ishrin Formation is faunally barren at outcrop, but sparse Cruziana traces are present.

Fig. 3. Illustration of the effect of the Levant Arch on Palaeozoic stratigraphy in the northern Nafud-Ma’aniya Basin

The Permian in the Negev is known only from the subsurface in boreholes. The succession consists of the Saad Formation overlain by the Arqov Formation, and in the Negev, it ranges between 300 and 500 m thick in total. Permian rocks in these areas unconformably overlie the Precambrian arkosic siliciclastic Zenifim Formation and are overlain conformably by marine Triassic strata (Weissbrod 2005; Korngreen et al. 2023).

Stephenson & Korngreen (2021, 2022) dated core from Ramon-1, Avdat-1, Boqer-1 and Makhtesh Qatan-2 wells. Based on the distribution  of Protohaploxypinus uttingii, Pretricolpipollenites bharadwajii, Reduviasporonites chalastus, Cedripites priscus and Indotriradites mundus, the Saad Formation is tentatively believed in part to be Wuchiapingian (Late Permian, Lopingian) in age, while the overlying Arqov Formation is likely in part latest Permian, Changhsingian in age (Stephenson & Powell 2014).

The ages of rocks above and below the Hercynian unconformity are markedly different 700km east northeast in the deeper, central part of the Nafud-Ma’aniya Basin. Borehole KH-5/1 in the western desert of Iraq was fully cored to TD at 1620m spanning the Raha Formation below the unconformity, and the Ga’ara Formation above the unconformity. The boundary between the two formations was picked as an unconformity at 670 m by Al-Hadidy (2007).

Stephenson et al. (2017) described Assemblage A between 796 and 739 m in KH-5/1, consisting of Lundbladispora species, Vallatisporites, and Spelaeotriletes (mainly S. triangulus); as well as Schopfipollenites ellipsoides, Apiculiretusispora multiseta, Rugospora sp. and Retusotriletes incohatus. Two specimens of Potonieisporites with no other recorded specimens of monosaccate pollen occur in Assemblage A in samples at 753 and 739 m.

Between 665 and 486m is the more diverse Assemblage B which is distinct from that below chiefly because it contains abundant bisaccate and monosaccate pollen in addition to common Lunbladispora (e.g. L. braziliensis). From 615.5 m taeniate bisaccate pollen also becomes quite common.

On the basis of palynology, an unconformity situated around 670m in KH-5/1 could therefore represent non-deposition or erosion of rocks corresponding approximately in age to part of the Serpukhovian and Bashkirian. However it is also true that the palynologically barren section (of maximum thickness 74 m) between 739 and 665 m, containing the unconformity, could represent part or all of this time period, depending on the duration of the hiatus related to that unconformity. Thus the hiatus related to the HU could be relatively short or even non-existent.

Thus palynology indicates the effect that the Levant Arch has on Palaeozoic stratigraphy in the northern Nafud-Ma’aniya Basin where strata are missing due either to non-deposition or erosion, or both. Based on seismic, Faqira et al. (2009) constructed an isopach map of post unconformity Carboniferous-Permian clastic sedimentary rock succession suggesting that this may indicate Hercynian palaeotopography (Fig. 1). The thickest succession of this age occurs in the Nafud-Ma’aniya Basin in the region of northern Jordan, southeastern Syria and western Iraq, in a narrow belt with a similar axis to the overall orientation of the Nafud-Ma’aniya Basin, in an area that would contain well KH-5/1. This may be the area containing the most complete Palaeozoic succession in the Nafud-Ma’aniya Basin, and perhaps on the Arabian Plate.

Prof Mike Stephenson is available for consulting on Palaeozoic stratigraphy.

References

AL-HADIDY, A., 2007. Paleozoic stratigraphic lexicon and hydrocarbon habitat of Iraq. GeoArabia 12, 63-130.

FAQIRA, M., RADEMAKERS, M. & AFIFI A. M 2009. New insights into the Hercynian Orogeny, and their implications  for the Paleozoic Hydrocarbon System in the Arabian Plate. GeoArabia, v. 14, no. 3, 2009, p. 199-228

GVIRTZMAN, G. & WEISSBROD T. 1984. The Hercynian Geanticline of Helez and the Late Palaeozoic history of the Levant. In DIXON J.E. & Robertson A.H.F. (Eds.), The Geological Evolution of the Eastern Mediterranean. Geological Society of London, Special Publication 17, p. 177-185

KORNGREEN, D., ORLOV-LABKOVSKY, O., ZILBERMAN, T.  and STEPHENSON, M H. Time Constrains and the Tectono-Sedimentary Setting of the Permian Sequence in Israel: Insights from Pleshet-1 and David-1 Boreholes, Western Israel. Stratigr. Geol. Correl. 31, 571–592 (2023). https://doi.org/10.1134/S0869593823060047

POWELL, J. H. ABED, A. M. & LE NINDRE; Y-M 2014. Cambrian stratigraphy of Jordan. GeoArabia 2014;; 19 (3): 81–134. doi: https://doi.org/10.2113/geoarabia190381

STEPHENSON M H & KORNGREEN, D 2021. Palynology of the Permian of the Makhtesh Qatan-2, Ramon-1 and Boqer-1 boreholes Arqov Formation, Negev. Rivista Italiana di Paleontologia e Stratigrafia, V. 127 NO. 3

STEPHENSON M. H. & KORNGREEN, D., 2020. Palynological correlation of the Arqov and Saad formations of the Negev, with the Umm Irna Formation of the eastern Dead Sea, Jordan, Review of Palaeobotany and Palynology, v. 274, 104153.

STEPHENSON, M H, & POWELL, J H. 2014. Selected spores and pollen from the Permian Umm Irna Formation, Jordan, and their stratigraphic utility in the Middle East and North Africa. Rivista Italiana di Paleontologia e Stratigrafia, 120, 145-156.

STEPHENSON, M. H., ZEKI A. KADER AL MASHAIKIE, S. & KURUKCHI, W. M., 2017. Palynological assemblages across the Hercynian unconformity in Western Iraq. Revue de Micropaleontologie, v. 60, p. 417–432.

TEKLEVA, M V., STEPHENSON, M H. & ZAVIALOVA, N E., 2019. The exine ultrastructure of Pretricolpipollenites bharadwajii from the Permian of Jordan. Review of Palaeobotany and Palynology 268, 19-28. DOI: 10.1016/j.revpalbo.2019.05.003

WEISSBROD, T., 2005. The Paleozoic in Israel and environs. In: Hall, J.K., Krasheninnikov, V.A., Hirsch, F, Benjamini, C, and Flexer, A. (Eds.) Geological Framework of the Levant, Vol. II, The Levantine Basin and Israel, Edition: 1, Chapter: 18B, Publisher: Historical Productions-Hall, Jerusalem, pp. 283-316