Detrital zircon U–Pb–Hf data from Cambrian sandstones of the Ougarta Mountains Algeria: Implication for palaeoenvironment

Abstract

We report new detrital zircon U-Pb ages and Hf isotopic signatures of detrital zircons in Cambrian sedimentary rocks from the Ougarta Mountains of Algeria in the West African Craton (WAC) in order to provide constraints on the palaeo-catchments of the Early Palaeozoic river systems draining Gondwana. The Cambrian sedimentary samples from the Ougarta Mountains have near-identical age spectra with a dominant age peak at 618 Ma and an additional age peak at 2,035 Ma. The oldest detrital zircon grain is 3,407 Ma. The εHf (t) values of the 618 Ma age peak spans from εHf (t) +12 to −25 with a dominant mode at −1; the εHf (t) of the Palaeoproterozoic zircon ranges from 6 to −27 with an average of −10; the pre-2,300 Ma zircon Hf lie along a crustal evolution trajectory (176 Lu/ 177 Hf = 0.01) back to the depleted mantle at 3,100 Ma. The maximum depositional age of the sandstones in the Sebkhet el Melah Formation is constrained by the youngest detrital zircon age of 559 ± 13 Ma and by the underlying volcaniclastic rocks dated at 555 ± 7 Ma (Late Ediacaran to the Early Cambrian). The 618 and 2,035 Ma age peaks are consistent with a proximal provenance from the WAC, and it is possible that recycling of eroded material from the Cadomian arc and Pan-African rocks may have been a potential source of the Ediacaran detrital zircons analysed herein. There were four (0.9%) Stenian detrital zircons identified in this study, and our results are consistent with the lack of WAC Stenian detrital zircon noted in previous studies, except those reported from a single Middle Cambrian sample in Morocco. Correlative sedimentary successions further to the east contain ubiquitous ca. 1.0 Ga detrital zircon that was likely supplied from the Trans-Gondwana Mountain chain. It is noteworthy that the WAC and Sahara Metacraton are surrounded on three sides by Neoproterozoic orogenic systems, with the Rokelide, Dahomeyide, Pharuside, Anti-Atlas, and Brasiliano orogens (reconstructed position from Gondwana palaeogeography) around the WAC and the Dahomeyide, Pharuside, East African orogen, and Oubangides orogens around the Sahara Metacraton. We posit these orogenic belts acted as drainage divides that controlled sediment routing pathways. Additionally, the occurrence of Stenian detrital zircon in Morocco could be explained by longshore drift coming from the east (present-day coordinates).

So close and yet so far: U–Pb geochronological constraints of the Jaibaras Rift Basin and the intracratonic Parnaíba Basin in SW Gondwana

“…The characteristics observed in the North American and North African intracratonic basins (Allen & Armitage, 2012;Armitage et al 2013;Wang et al 2020) are similar to that recorded in the Parnaíba Basin. First, it is necessary to consider that the boundary between the Jaibaras Rift Basin and the cratonic Parnaíba Basin is diachronous (Fig.…”

“…It is therefore correct to say that the initial subsidence of the Parnaíba Basin was not directly associated with the previous rift subsidence, but influenced by the reactivation of these rift structures. In this way, the available models indicate an initial evolution comparable to the North American and North African intracratonic basins (Allen & Armitage, 2012;Armitage et al 2013;Wang et al 2020). In the context of the early stages of intracratonic subsidence, a transcontinental fluvial sediment system developed, flowing from the remaining elevated areas of the Brazilian mobile belts towards the NW margin of the newly formed western Gondwana (similarly to the North African case; Wang et al 2020).…”

“…In this way, the available models indicate an initial evolution comparable to the North American and North African intracratonic basins (Allen & Armitage, 2012;Armitage et al 2013;Wang et al 2020). In the context of the early stages of intracratonic subsidence, a transcontinental fluvial sediment system developed, flowing from the remaining elevated areas of the Brazilian mobile belts towards the NW margin of the newly formed western Gondwana (similarly to the North African case; Wang et al 2020). This included the rivers responsible for the deposition of the Ipu, Cariri and Tacaratu formations (Fig.…”

“…Al Kufrah, Murzuk and Ghadames), in which the initial sedimentation zone was part of a large extensive platform or ramp during the Cambro-Ordovician interval (Allen & Armitage, 2012). Analogously to the example of the North American intracratonic basins, the North African Cambro-Ordovician palaeogeographical scenario points to the existence of a broad platform sloping gently to the north and opened to the ocean, characterizing a huge continental area covered by siliciclastic sediment deposits (Wang et al 2020). In the North African case, the initial subsidence process related to the formation of a tilted ramp was influenced by weakened lithosphere represented by the Precambrian-Cambrian rift-related basins in the original platform (Allen & Armitage, 2012).…”

Provenance of sediments from Barra del Tordo and Tesoro beaches, Tamaulipas State, northwestern Gulf of Mexico

“…Detrital zircon U-Pb age has become a common method to investigate zircon origin and to further discriminate source terranes (e.g. Lee et al 2015;McRivette et al 2019;Wang et al 2020;Armstrong-Altrin et al 2021). Zircon is a common mineral in acidic rocks, and due to its resistance capacity against weathering and thermal alteration, zircon retains U-Pb isotopic signatures related to their origin and parent rocks (Potter-McIntyre et al 2018;Dew et al 2019).…”