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The Suez Rift is the northern extension of the Red Sea Rift and is an ideal location to study young continental breakup tectonics. Yet, despite much effort to constrain the timing of rift flank uplift and extensional exhumation in this region, the emerging picture remains uncertain. Here we present new thermochronologic constraints including apatite (U–Th)/He and fission track data from a transect across the eastern flank of the Suez Rift in SW Sinai. The use of two different thermochronometers in conjunction with thermal history modeling and well constrained kinetic parameters delineates a pronounced episode of relatively rapid cooling at 25-18 Ma followed by subdued post ∼18 Ma cooling. In contrast to previous estimates, this cooling pattern suggests that the most rapid uplift and exhumation phase along the Gulf of Suez took place during the early stage of rift formation, prior to the middle Miocene, with over 2.4 km of exhumation occurring during this stage. Uplift and exhumation along the Suez Rift flank slowed substantially post ∼18 Ma, as deformation migrated to the newly formed plate boundary along the Dead Sea Transform. This finding complements and strengthens previous indications for the initiation timing of the Dead Sea Transform plate boundary. The inferred late Oligocene–early Miocene timing of rapid exhumation, associated with tectonic extension and rift flank uplift coincides with the onset of regional alkali-basalt magmatism, suggesting lithospheric heating prior to the rift formation. This observation, along with the elevated topography around the Sinai triple junction and indications for some pre-rifting uplift, supports a more active mantle plume role in the rifting process.

LA-ICPMS U-Pb geochronology of detrital rutile from North Gondwana Cambro-Ordovician sandstones is reported for the first time. Our sampling sites in Israel, Jordan and Ethiopia are situated thousands of kilometers apart thus providing a continental-scale perspective on the cooling and unroofing history of the provenance of the great Cambro-Ordovician sandstone sheet. Detrital rutiles in the Cambrian sandstone of Israel and Jordan define a unimodal age concentration at 0.59–0.58 Ga, preceding the timing of major orogenic sutures and predating the final assembly of Gondwana. Cooling to below the rutile U-Pb closure temperature followed continental-scale Pan-African granitoid intrusion at 0.63–0.60 Ga, signifying that rather than representing high-grade metamorphism the detrital rutile age spectra reflect widespread resetting, cooling and exhumation associated with late to post-tectonic igneous activity. The unimodal 0.59–0.58 Ga age spectra do not change significantly up the Cambrian sequence, implying exhumation prior to Cambrian sedimentation generated ample crustal material with an almost uniform U-Pb rutile signature that was prone to deliver immense amounts of detritus. Therefore, rather than reflecting progressive erosion of Cambrian Supermountains, the North Gondwana Cambrian sandstone represents secondary denudation of an already-exhumed metamorphic basement. Alongside the older (0.59–0.58 Ga) detrital rutile population, which dominates the Cambrian sequence, 0.55 Ga detrital rutiles first appear in the Ordovician of Jordan while 0.54 Ga rutile locally dominates the Ordovician from Ethiopia, some 2000 km upstream the Cambro-Ordovician fluvial system, close to its headwaters. The Ordovician drainage basin has thus been extended to include crustal vestiges that were exhumed coeval with Gondwana consolidation, but it is likely that most of the rock carapace that has been eroded from consolidating Cambrian orogenic sutures has been delivered to the south (modern coordinates).

The Arabian-Nubian Shield (ANS) is a province of mostly juvenile Neoproterozoic continental crust in NE Africa and Arabia, forming the northern extension of the East-African orogen. Subsequent to widespread, mostly late- to post-orogenic early-Ediacaran calc-alkaline granitoid emplacement, the latest magmatic phase in the ANS saw the intrusion of alkaline shallow plutons alongside volcanic massifs and dikes of variable compositions. While some of these intrusions were dated to 550–530 Ma by Rb-Sr and Ar-Ar, U-Pb zircon data has mostly limited ANS magmatism to no younger than ca. 580 Ma. Here we report new age and isotopic data from latest Neoproterozoic intrusions along a N-S transect within the northern ANS and its periphery, substantiating the record of a ca. 550 Ma igneous-thermal event in the area. In the northern Negev of Israel, mafic igneous rocks intruded into the subsurface late Neoproterozoic clastic wedge of the Zenifim Formation produced apatite U-Pb isochron ages between 557 and 545 Ma. In the Amram alkaline massif, 150 km to the south, an alkali-granite was dated to 605 ± 2.5 Ma by zircon U-Pb, but apatite U-Pb ages from all rocks of the massif concentrate at ca. 550 Ma indicating thermal resetting. Apatites from the zircon dated 611 ± 5 Ma Roded quartz diorite in the Elat area, south of Amram, produced a 600 ± 4 Ma U-Pb age, demonstrating that southern segments were not thermally reset at ca. 550 Ma. Nd isotopes in apatite and whole rock show the ca. 550 Ma igneous rocks to be variable in their isotopic composition, ranging between eNd(t)=(-4) – (+2), far less juvenile than typical ANS magmas. The ca. 550 Ma intrusions resemble in their age and isotopic properties Cadomian granites and volcanic rocks that are known from southern Turkey, Iran and Europe. We interpret the ca. 550 Ma igneous overprint and thermal resetting documented in the northernmost ANS as related to the superposition of Cadomian orogeny on the ANS periphery. This can be related to the late Ediacaran subduction of proto-Tethys accompanying the accretion of the Cadomian basement of the Tauride block to NE Africa and Arabia, before the area was overstepped by Cambrian platform sedimentation.

The Neoproterozoic Arabian–Nubian Shield (ANS), which comprises the northern sector of the East African Orogen (EAO), has been deeply denuded in Ediacaran times and its erosional products were deposited across NE Africa and Arabia; they are also found in a number of peri-Gondwana terranes. A vast Late Neoproterozoic clastic wedge, locally interbedded with volcanics, developed on the northern outskirts of the ANS and spread into areas currently at the foothills of the Taurus and Zagros belts to coalesce into a wide peri-Arabian-Mesopotamian basin. The southern limit of this basin is manifested in the subsurface of Israel and Jordan by a few km thick arkose sequence, the Zenifim Formation, which underlies the Cambro–Ordovician quartz-rich sandstones. The detritus stored in this formation was mostly eroded from the adjacent ANS at the cessation of Neoproterozoic orogeny. Along a ∼150 km long transect in the subsurface of Israel, the arkosic facies of the Zenifim Formation changes from a proximal alluvial fan in the south, to a sea marginal facies in the north reflecting the transgression of the proto-Tethys onto the decaying Neoproterozoic orogen. We studied the detrital zircon U–Pb–Hf from core samples of arkose from different parts of the Zenifim Formation in order to constrain the composition of its provenance and to obtain the Late-Neoproterozoic detrital fingerprint of the ANS. The proximal alluvial fan and plain facies is dominated by a remarkable concentration of U–Pb detrital zircon ages between 0.6 and 0.7 Ga with a peak around 0.63 Ga, alongside a few older grains (0.8 Ga and 0.9 Ga). Pre-Neoproterozoic detrtital zircons are absent. The youngest detrital zircon population peaks at 0.60 Ga. The entire inventory of detrital zircons yielded positive ɛHf values between +11 and +5, generally overlapping ɛHf values of Neoproterozoic rocks of the northern ANS. It is notable that little indication for the exposure of the Cryogenian rocks of the ANS is represented by the detrital zircon signal in the alluvial fan deposits, a feature indicating the prevalence of Ediacaran granitoids in the provenance. Towards the north, the youngest detrital zircons in the sea marginal facies concentrate at 0.58 Ga implying this part of Zenifim Formation is among the youngest Late Neoproterozoic sedimentary units in the northern ANS. The detrital zircon signal exhibits a preponderance of Neoproterozoic-aged detrital zircons peaking at 0.6 Ga and 0.75–0.8 Ga, but Grenvillian-like age peaks at 0.92, 1.0 and 1.1 Ga are also identified. Additionally, a small number of 1.8, 2.1 and 2.6 Ga-aged zircons, and a few Late Neoproterozoic detrital zircons with negative ɛHf values also occur. Erosion of basement rocks in the northern ANS was generally capable of accounting for most of the detrital zircon spectra in the sea marginal facies, but we point out two other potential sources. Our preliminary investigations indicate that dike swarms that invaded the northern ANS in the mid Ediacaran carry abundant inherited pre-Neoproterozoic zircons and Neoproterozoic-aged zircons with negative ɛHf values. The presence of such zircons in post −0.58 Ga sediments, subsequently to the major diking phases, can thus be accounted for, at least partly, by the erosion of dikes and associated volcanics. Likewise, a northern provenance that resided within the Cadomian realm or laterally along the Gondwana margin could also play a role in delivering zircons of this type to the sea marginal facies of Zenifim Formation.

The final stages in the evolution of the Arabian-Nubian Shield (ANS) during the late Neoproterozoic include the deposition of sub-aerial volcano-sedimentary sequence above exhumed deep-seated plutonic-metamorphic rocks. In southern Israel the sediments in this sequence, known collectively as the Elat conglomerate unit, consist primarily of immature polymictic conglomerates whose composition closely reflects their underlying basement. U–Pb dating and Hf isotopic analysis of single zircons from two samples of the Elat conglomerate is used here to gain a complementary perspective on crustal evolution processes in the northern ANS. The U–Pb age spectra of the detrital zircons bear evidence for two major magmatic cycles separated by a lull; early island-arc magmatism occurred at 880–760 Ma and peaked at ∼800 Ma, whereas post-collisional granitoids and volcanics invaded the amalgamated arc crust between 660 and 580 Ma and peaked at 610–630 Ma. Integration with previously published data from Sinai suggests the aforementioned igneous cycles and the intervening lull are of regional significance. Although island-arc igneous activity in the ANS ranged mostly between 880 and 760 Ma, the occurrence of detrital zircons with strongly positive ɛ Hf( t ) values and U–Pb ages of up to 1.0 Ga in the Elat conglomerate suggests that island-arc magmatism in the northern ANS started in the early Tonian, earlier than previously recognized. The youngest zircons in the Elat conglomerate constrain its deposition age to ∼580 Ma. No younger U–Pb zircon ages were obtained for crystalline rocks in this region, our data thus indicates that 580 Ma marks the cessation of igneous activity in the northern ANS. The great majority of detrital zircons in the Elat conglomerate display positive ɛ Hf( t ) values, in line with the overall juvenile character of the Shield. Nonetheless, the relatively wide range of ɛ Hf( t ) values in zircons representing island-arc magmatism (between +3.6 and +11.6), and the presence of zircons with pre-Neoproterozoic ages and/or negative ɛ Hf( t ) values, suggest some contamination of the arc magmas by an older crustal component. The ɛ Hf( t ) values in zircons representing the younger, post-collisional magmas are all positive (between +4.9 and 9.2) and resemble those in the preceding arc-derived zircons. This feature is consistent with both reworking of mafic island-arc crust and contribution from mantle-derived melts during the post-collisional stage. Thus, it cannot be deciphered whether the 1000–580 Ma igneous activity in the northern ANS represents continuous juvenile crustal addition from the mantle, or subsequent recycling of early-formed arc crust during a later post-collisional phase.

This paper presents laser-ablation (MC)-ICP-MS single-zircon Hf isotopic data coupled with U–Pb geochronology from a unique rock inventory in southern Israel, recording ca. 300 m.y. of Neoproterozoic crustal evolution in the northern Arabian-Nubian Shield (ANS). The early, island-arc magmatic cycle in this area is recorded by detrital zircons from arc-derived metasediments, dated between 870 and 760 Ma, and by ca. 790 and 740 Ma orthogneisses. Zircon ɛHf(t) values from these rocks are all positive, supporting previous isotopic evidence for the overall juvenile nature of northern ANS crust. Nonetheless, detrital zircons from the metasedimentary units display a wide range of ɛHf(t) values between +1 and +13. The lower values in this range suggest some contribution from an older crustal component. The involvement of pre-Neoproterozoic crustal component is also indicated by the occurrence of rare zircons with pre-Neoproterozoic ages and/or negative ɛHf(t) values in younger (post-collisional) magmas that intrude the arc sequence. Arc accretion was followed by a period of ∼60 m.y. of relative igneous tranquility interrupted only by the emplacement of local basic dike swarm at ca. 705 Ma. Average zircon ɛHf(t) value of +10 found in one of these dikes indicates a depleted mantle source possibly implying a mid-Neoproterozoic extensional phase. The later, post-collisional magmatic cycle marks the transition of the accreted arc complexes into a mature continental crust. It consists of voluminous 680–600 Ma granitoid plutons of calc-alkaline affinity, and subordinate 610–580 Ma intrusions of alkaline affinity. Average zircon ɛHf(t) values in these post-collisional rocks are all positive and range between +6 and +9, compatible with both mantle source and juvenile crust reworking.