A new approach to palynostratigraphy of the middle–late Famennian Gafo Formation, southern sector of the Pulo do Lobo Domain, SW Iberia (Portugal and Spain)

Abstract New palynological results from the Gafo Formation (southern sector of the Pulo do Lobo Domain, South Portuguese Zone) are integrated with recently studied sections and drillholes from the Portuguese and Spanish sectors. A total of 44 samples were studied, 27 of which were positive for palynomorph taxonomy. This research revealed well preserved palynological assemblages, including 73 spore species allocated to 28 genera, four acritarch genera, three prasinophyte algae genera plus common chitinozoan remains. Some additional forms were retained under open nomenclature. From this, the first complete age determination for the Gafo Formation in Portugal and Spain was achieved, indicating a middle Famennian (Grandispora gracilis–Grandispora famenensis, GF Biozone) to a late Famennian (Grandispora echinata, VH Biozone) age. A greywacke sample from the same Gafo Formation was dated by U–Pb zircon geochronology and a maximum depositional age of 369 ± 2.5 Ma was obtained. A correlation between these palynological and U–Pb zircon data and the palynoflora assemblages of previous authors was made, as well as with the ages of felsic volcanic rocks found intercalated in the Gafo Formation, confirming the complex stratigraphy of Pulo do Lobo Domain. The results are consistent with stratigraphic mapping and structural interpretations, allowing a middle–late Famennian age (GF and VH Biozone) to be assigned to the Gafo Formation sedimentary rocks. This work has also contributed to a reinterpretation of Gafo Formation depositional facies correlatives (e.g. the Santa Barbara Group in Spain) as being the same lithological unit.

Four main domains are identified in the SPZ, namely: the PLD, Iberian Pyrite Belt (IPB), Baixo Alentejo Flysch Group (BAFG) and the SW Portuguese Sector (Oliveira, 1990;Oliveira et al. 2019). This research focuses on the PLD anticlinal structure (Fig. 1), particularly the southern sector, which comprises clastic formations including the Atalaia and Gafo formations. The Gafo Formation is characterized by flysch facies in turbiditic sedimentary rocks. While its petrographic and paleogeographic setting is known, the definition of stratigraphic units for field mapping, the lateral correlation of the facies and depositional age all remain contentious.
This paper discusses the Late Devonian miospore assemblages of the Gafo Formation, southern PLD, comprising palynostratigraphic analysis from drillhole and outcrop samples collected in both the Portuguese and Spanish sectors of the PLD (see location in Fig. 1 and online Supplementary Material, available at http://journals.cambridge.org/geo).
The Gafo Formation was previously studied by PA Lake (unpubl. Ph.D. thesis, University of Southampton, 1991), Rodríguez González (1999) and Pereira et al. (2006aPereira et al. ( , b, 2008, who attributed a Givetianearly Famennian age, late Frasnianlate Famennian age and early Frasnian age, respectively (Figs 2, 3). An attempt is made to integrate and correlate these data with new biostratigraphic records based on spores and chitinozoans in order to achieve an accurate age of the Gafo Formation, as well as an understanding of the microfloral assemblages of the PLD and the SPZ, thus confirming an affinity with the Avalonian Terrane (Oliveira et al. 1979;Loboziak & Streel 1981;Korn 1997;Clayton et al. 2002;Higgs et al. 2013). Newly obtained U-Pb detrital zircon data are also included and discussed.
This research was a co-sponsored geological mapping project supported by the Portuguese (LNEG) and Spanish (IGME) geological surveys of the South Portuguese Zone, 1:200 000 scale (GEO_PFI Project), including the Pulo do Lobo and Iberian Pyrite Belt domains. Based on this project, recent palynostratigraphy studies were developed to constrain the sedimentary sequence of the southern PLD, particularly the Gafo Formation, and to test correlations with the Santa Bárbara Unit, as defined in the Spanish sector.

Geological setting
The PLD E-W-trending complex antiform structure crops out both in Portugal and Spain, in a sigmoidal shape bound to the north by the OMZ (the Beja-Acebuches Ophiolite Complex in particular) and the south by the IPB, and is part of the SPZ (Fig. 1).The domain is divided into a northern sector, represented by the Ferreira-Ficalho Group (including the Ribeira de Limas, Santa Iria and Horta da Torre formations; Fig. 2) and the southern limb, characterized by the Chança Group (including Atalaia and Gafo formations; Fig. 2), the latter being the focus of this work. In the core of this domain, the Pulo do Lobo Formation (Late Devonian, middle Frasnian in age; Pereira et al. 2006aPereira et al. , b, 2018Pereira et al. , 2019 crops out and is well exposed in the Guadiana and Chança river sections, including strongly deformed chloritic and sericitic phyllites and quartzites with minor intercalations of felsic volcanic rocks (Pfefferkorn, 1968;Oliveira, 1990).
In the PDL northern sector, three formations are recognized in the Ferreira-Ficalho Group, including the Ribeira de Limas, Santa Iria and Horta da Torre formations (Fig. 2;Carvalho et al. 1976;Oliveira et al. 1986;Giese et al. 1988;Oliveira, 1990;CP Eden, unpubl. Ph.D. thesis, University of Southampton, 1991;Silva, 1998). In Spain, the northern sector of the PLD includes, from bottom to top: the Peramora Mélange, the Ribeira de Limas Formation (Frasnian age), Santa Iria Formation and Horta da Torre Formation (both late Famennian age) , and the Alájar Mélange (Fig. 2). In the northern part of the PLD, the stratigraphy and age of the formations are described in detailed in Pereira et al. ( , 2019 and Oliveira et al. (2019).
a similar fashion to the Pulo do Lobo Formation (Pfefferkorn, 1968;Carvalho et al. 1976;Oliveira 1982Oliveira , 1990Oliveira et al. 2006). However, it has not yet been dated . Pereira et al. (2017) provided a U-Pb zircon maximum depositional age of 390.5 ± 4.7 Ma (Eifelian age) for a quartzite within the Atalaia Formation. The Gafo Formation represents a sequence of greywackes and interbedded shales, with minor intercalations of fine volcaniclastic sediments, intruded by metre-thick felsic and mafic volcanic rocks (veins and pipes structures) that are several hundred metres long . Felsic volcanic rocks are generally (sub)intrusive (Rosa et al. 2008). The age of this unit has been considered Middle Devonian -(?)early Frasnian to Late Devonian (PA Lake, unpubl. Ph.D. thesis, University of Southampton, 1991) and middle Frasnian -BM Biozone (Pereira et al. 2006a(Pereira et al. , b, 2008 based on palynostratigraphy (Fig. 3).
The Gafo Formation shows three main episodes of tectonic deformation and associated cleavages (Silva et al. 2013). The second-phase deformations exhibit an E-W-aligned trend in Spain, a WNW-ESE to NW-SE-aligned trend in Portugal, and tectonic vergence to the south or SSW. The structural thickness may reach 500 m . Metamorphism is low greenschist facies (Pereira et al. 2006a, b).
In Spain, the stratigraphic equivalent unit of the Gafo Formation is the Santa Bárbara Group, which includes: (1) in the northern sector, the Gafo Formation itself, including greywackes and interbedded shale successions with minor tuffite intercalations, intruded by felsic and mafic veins  of late Frasnian age (Late Devonian; Rodríguez González, 1999), and (2) in the south, the Santa Bárbara Unit, comprising an interbedded shale succession with siltite lamination, intruded by felsic veins of late Famennian (Late Devonian) to probably earliest Tournaisian age (early Carboniferous; Rodríguez González, 1999;Matas et al. 2015

Previous palynostratigraphic and geochronological studies of the Gafo Formation
The first reference to miospores in the Gafo Formation in PLD was provided by PA Lake (unpubl. Ph.D. thesis, University of Southampton, 1991), who recorded the presence of dispersed and poorly preserved assemblage of miospores. In three samples located in the vicinity of Paymogo, the author considered a late Givetianearly Famennian age for the Gafo Formation (Fig. 3). Rodríguez González (1999) and Matas et al. (2015) have also dated the Gafo Formation and Santa Bárbara Unit (included in the Santa Bárbara Group), and also obtained long-ranging ages, spanning middle Frasnianlatest Famennian and to probably earliest Tournaisian age (Fig. 3). Reworked palynomorph taxa seem to be persistent in the described palynoassemblages (Matas et al. 2015). Rodríguez González (1999) also identified chitinozoan remains, interpreted by the author as being reworked Fungochitina pilosa, characteristic of Givetian sediments. Pereira et al. (2006aPereira et al. ( , b, 2008 recognized 12 specimens in two sections from Mértola to Corte Gafo de Cima (Cemetery section) and along the Chança River (Volta Falsa section). The assemblage provided for the first time a BM Biozone marked primarily by zonal species Verrucosisporites bulliferus, of Frasnian age (Fig. 3). The age and geological interpretation of the Gafo Formation and Santa Bárbara Unit are therefore still poorly understood; further research is required.
Recent U-Pb zircon dating of a rhyodacite intrusive rock in the Pego do Altar sector (westernmost Gafo Formation in the NNW IPB region in Portugal; Matos et al. 2018) indicates an age of 346.5 ± 1.6 Ma (Díez-Montes et al. 2020b). This age is in general accordance with those reported above, defining an age interval of c. 346-356 Ma for the (sub)volcanic rocks in the Gafo Formation. Additional data on the Gafo greywacke sedimentary units indicate a maximum depositional age of 384 ± 6 Ma based on the two youngest concordant grains (Pereira et al. 2017).
In this work, new U-Pb zircon age data were obtained from the greywacke units in the Volta Falsa section of the Gafo Formation (see Fig. 1).

4.a. Gafo Formation palynology and U-Pb zircon geochronology
A total of 44 samples (20 outcrop samples and 24 drill core samples) collected from the Gafo Formation sediments were subjected to standard palynological laboratory procedures to extract and concentrate the palynomorphs (Wood et al. 1996). Oxidation of the palynomorphs was carried out using Schultze solution. Oxidation time varied according to the degree of carbonization, ranging from 30 min to 2 hours, and resulted in 27 productive samples for palynology studies (19 outcrop samples and 8 drill core samples), yielding moderate to well-preserved palynomorphs.
A sample list with geographic coordinates is provided in the online Supplementary Table S1 (available at http://journals. cambridge.org/geo). The selected productive residues were mounted on slides and examined with a Nikon Eclipse Ci transmitted light microscope. All samples, residues and microscope slides are stored at the Portuguese Geological Survey (LNEG). The standard western Europe miospore biozonal scheme was followed (Loboziak & Streel, 1981, 1989Streel et al. 1987;Pereira et al. 2008;Higgs et al. 2000Higgs et al. , 2013. The studies of Clayton et al. (2000) and Loboziak (2000) were used to correlate the palynoflora with Saudi Arabia assemblages.
The palynomorph assemblages recovered from the drillholes and outcrop samples are presented in Figures 3, 4. Important stratigraphic taxa are illustrated in Figures 5-8. A list of all taxa recovered or mentioned in this work is also available in the online Supplementary Material.
A representative sample from Gafo Formation greywacke unit (PL 18) was collected for U-Pb zircon geochronology (see Fig. 1 for location). Zircon grains were separated from whole-rock samples using standard crushing and mineral separation techniques

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M Mendes et al. ( Mange & Maurer, 1992). The handpicked zircons were mounted in resin and ground and polished to half-thickness. Zircon U-Pb isotopic data were generated at the Department of Geology, Trinity College Dublin, Ireland. A Photon Machines Analyte Excite 193 nm ArF excimer laser-ablation system with a HelEx 2-volume ablation cell, coupled to an Agilent 7900 mass spectrometer, was used for the analyses. Line scans on NIST612 standard glass were used to tune the instruments by obtaining a Th/U ratio close to unity and low oxide production rates (i.e. ThOþ/Thþ typically < 0.15%). A circular laser spot of 24 μm was used, with a repetition  and 9 s of washout time. The latter portions of the washout time were used for baseline measurements. The reduction of the raw U-Th-Pb isotopic data was undertaken using the freeware IOLITE package (Paton et al. 2011), with the VizualAge data reduction scheme (Petrus & Kamber, 2012). Conventional sample-standard bracketing was applied to account for both downhole fractionation and long-term drift in isotopic or elemental ratios by normalizing all ratios to those of the U-Th-Pb reference materials. The primary U-Pb calibration standard was the 91500 zircon

4.b. Gafo Formation drillholes
In this study two AGC Company exploration drillholes were sampled (Figs 1, 9). These holes were drilled at the IPB Chança massive sulphide deposit in 2006 by AGC Minas de Portugal.  the full depth of the drillhole (650 m). In both drillholes, minor mafic and felsic dykes occur in the Gafo Formation, and stockwork mineralization was intersected in the VSC felsic rocks (rhyolites and rhyodacites). Seven palynomorph-bearing samples were recovered from the CH0601 drillhole (from 37.5 m to 218.0 m) and one from the CH0602 drillhole (121.1 m). Figure 9 shows the WNW Chança section based on the CH0601 drillhole data and surface mapping.  (Fig. 1). An alternation of quartz wackes and slate forms the outcrop, a brownish colour with greenish tones. Some thin levels of impure quartzites can also be observed. Samples H-336 and H-337 (= H-405) were collected to the SE of Paymogo, on the route to Los Peros. The outcrops are formed by a succession of quartz wackes, lithic arenites and slate. Samples H-314, H-318 (= H-378) and H-321 were collected in the Albahacar creek. The outcrops are formed by a succession of quartz wackes, quartzite and black slate. Sample H-325 was taken from the riverbed of the Corte creek. The outcrop is formed by an alternation of black slate, greywackes, quartz wackes and occasional quartzite beds.

4.c.3. Paymogo SE sector
Sample H-339 was collected SE of Paymogo, on the Rivera Aguas de Miel. This outcrop is an alternation of black slate, lithic arenites, greywackes and quartz wackes.

4.c.4. Santa Bárbara section
Samples H-398, H390 and H-395, collected from the Santa Bárbara section, are all negatives. Sample H-390 was collected east of Santa Bárbara de Casa from a horizon of slate with an intense schistosity. Sample H-395 was collected from an outcrop consisting of greenish slate, sandstones and quartzites along the road from Cabezas Rubias to El Mustio. Sample H-398 was collected north of Santa Bárbara de Casa, on the road that leads to El Mustio. The outcrop comprises slate and sandstones. S-C-type textures are observed throughout the outcrop, which show thrust movement towards the south.

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4.c.5. South of Gil Márquez Unit section
Sample H-420 was collected south of Gil Márquez, in the Rivera de Olivarga. A succession of slate and sandstones forms this outcrop, which is very close contact with the Pulo de Lobo thrust.

Gafo Formation palynology results
The Gafo Formation palynoflora comprises a diverse and abundant set of 73 spore types (including 28 different genera), five acritarch types, five prasinophyte specimens and some chitinozoans and graptolite remains, enabling the identification of three different assemblages. The poor preservation of some specimens did not allow specific identification; these specimens were left as open nomenclature (Figs 3, 4). These assemblages are characterized by the first occurrence (FO) of key taxa and the relative abundance of prominent taxa. The palynomorph assemblages and biozones identified are described in stratigraphic order in the following sections.
The identified species Camarozonotriletes sp., Dictyotriletes cf. emsiensis and Retusotriletes cf. maculatus of Early Devonian age, and Grandispora cf. megaformis, Grandispora cf. protea and Grandispora protea of Middle Devonian age, are interpreted as reworked miospores. Chitinozoans and scolecodont fragment remains are very common in the samples studied in the Spanish sector sections (Fig. 7).
Acritarchs and prasinophytes are rare and assigned to Leiosphaeridia sp., Maranhites mosesii, Maranhites sp., Veryhachium downiei and Veryhachium trispinosum. Similar to the lowermost samples from the Gafo Formation, chitinozoan fragments are common. The presence of the taxa Grandispora cf. megaformis is interpreted as reworked upper Emsianmiddle Givetian strata.

Gafo Formation chitinozoan results
Eight samples were studied for chitinozoans, four of which were productive (H-314, H-318, H-321 and H-378). It was possible to recognize some chitinozoans from the observations made, but the preparations mostly included other groups, namely prasinophytes algae and spores. Most of the chitinozoan specimens observed show evidence of transport, as most of them are broken, incomplete and worn on their surface.
Focusing on the Spanish outcrop samples, the chitinozoan taxa recovered in palynology samples of middle-late Famennian age were carefully documented. Two main subfamilies were identified -Lagenochitininae and Angochitininae (Paris & Verniers, 2005)with the recognized species Lagenochitina sp. and Angochitina sp. (Fig. 8) assigned a Middle-Late Devonian age. Some additional forms or fragments of low preservation are retained under open nomenclature.

U-Pb age results
Sampled PL 18 greywacke (north of the VSC Chança structure, Fig. 1) yielded 149 zircon grains, 119 of which are concordant and comprising Palaeozoic (33%), Neoproterozoic (34%), Mesoproterozoic (11%), Palaeoproterozoic (19%) and Archean (3%) grains. Within the Palaeozoic population, the largest population is of Devonian (28%), particularly Late Devonian (22%) and Middle Devonian (9%) age; there were also single zircons of Early Devonian (1%) and Carboniferous (348 Ma) (1%) age, interpreted as representing minor lead loss (Fig. 10). Based on probability distribution and kernel density estimator plots, a major Late Devonian peak at c. 374 Ma was identified. Within this Late Devonian peak, 10 grains occur in the 371.4-367.3 Ma age range (early Famennian) and 16 zircon ages within the 381.9-373. A Concordia age was obtained using the youngest five (out of 10) late Famennian grains with favourable statistics, yielding an age of 369.1 ± 2.5 Ma (mean squared weighted deviation and probability of concordance of 0.019 and 0.89, respectively). This age is proposed as the maximum depositional age for the greywackes of the Gafo Formation.

8.a. Miospores
This study was undertaken on a regional basis, based on both exploration drillholes and reference geological sections of the turbiditic sequences of the Gafo Formation in the Portuguese and Spanish PLD southern sector (Fig. 1). The miospore content was qualitatively considered, first and last occurrences were established, and common distinctive taxa presented (Figs 3, 4).
The Gafo Formation samples cropping out in the south Chança River section yielded an assemblage from a (?)latest Givetianearly Frasnian age based on the occurrence of Verrucosisporites cf. bulliferus. The palynoassemblage is complemented by frequent Cristatisporites Cristatisporites triangulatus and Ancyrospora ancyrea, and by the most frequent Frasnian taxa, Cristatisporites Cristatisporites cf. inusitatus and Lophozonotriletes sp. Since the association is uncertain, it is not possible to constrain the age considering the poorly preserved and long-ranging palynomorphs.
Nevertheless, these preliminary age constraints have redefined the Gafo Formation as a greywacke and interbedded shale unit, previously interpreted as Culm facies in the Spanish literature and assigned to the BAFG and an early Carboniferous age (typically Visean; Matas et al. 2015).
The Gafo Formation data sampled in drillholes (Portugal) and several outcrops (Spain) show a very consistent GF Miospore Biozone, assigned a middle Famennian age. The microflora observed contain similar miospore taxa as recorded by Streel (2009) and Higgs et al. (2013), specifically Grandispora gracilis, Grandispora famenensis and Grandispora cf. microseta. According to Higgs et al. (2013), the GF Miospore Biozone can be characterized by the first occurrence of Grandispora famenensis and of Grandispora microseta, which appear in the middle of the GF Biozone. Common occurrences of Grandispora gracilis are also observed in this biozone, suggesting a middle GF Miospore Biozone of middle Famennian age.
In Spain, the Santa Bárbara Group crops out in the south Paymogo road section, where the Gafo Formation (to the north) and the Santa Bárbara Unit (to the south) are separated by the Santa Bárbara Fault (Fig. 1). The Santa Bárbara Unit has yielded a middle Famennian age (GF Biozone) based on palynomorphs for the first time. The same palynomorph assemblage is recognized in the Gafo Formation, both in Portuguese and Spanish outcrops and drillholes, allowing lithological and age correlation (Figs 2, 3). The Santa Bárbara Unit in Spain and the Gafo Formation are therefore reinterpreted in the present work as representing the same unit (Figs 2, 4; Díez-Montes et al. 2020a).
A late Famennian palynomorph assemblage (VH Miospore Biozone) was also identified in the easternmost part of the Spanish sector, indicating a probable younger age for the Gafo Formation in the SPZ region, suggesting a probable sedimentary progradation from the west to the east sector. Nevertheless, more detailed palynostratigraphic studies are needed to confirm this hypothesis. A similar age and palynoassemblage are found in the Represa and Phyllite-Quartzite Formations of the IPB Phyllite-Quartzite Group (Cunha & Oliveira, 1989;Pereira et al. 2008Pereira et al. , 2014Pereira et al. , 2021Oliveira et al. 2013).
In the PLD northern sector, common Early Devonian reworked spore assemblages were reported by  within the Pulo do Lobo and Ribeira de Limas formations (sections located ESE of Serpa). Reworking is also confirmed by the presence of graptolite fragments.
When we consider the palynoassemblages described by PA Lake (unpubl. Ph.D. thesis, University of Southampton, 1991), Rodríguez González (1999), and Pereira et al. (2006aPereira et al. ( , b, 2008, the following conclusions can be drawn. Despite the complex tectonics, the small number of samples studied, the low biodiversity and the long-ranging species associated with the reworking processes, the age interval is broad and unclear, or else corresponds to the age of reworked miospores (Fig. 3).
However, examining the new data with the palynoassemblage described by Rodríguez González (1999) in Castillo de las

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Guardas (Fig. 3), an age correlation can be made based on the abundance of miospores and chitinozoans remains; however, the age is not constrained as it is mainly based on long-ranging species taxa.

8.c. Chitinozoans
The occurence of several fragments of Lagenochitina sp. and Angochitina sp. (Fig. 8) indicates a Middle and Late Devonian age. These taxa are common in assemblages showing erosion of the main processes. Chitinozoan biostratigraphic schemes for the Middle-Late Devonian are scarce for Europe and Iberia (Paris et al. 2000), and few previous studies have been undertaken (Askew & Russell, 2019). In this research, the occurrence of moderately to well preserved chitinozoans can be helpful for stratigraphic correlations with other Devonian chitinozoan biozonal schemes (e.g. North Africa, Brazil, Argentina and Poland; Grahn et al. 2006), confirming a Middle-Late Devonian age.
In Santa Barbara unit (PLD), Rodríguez González (1999) identified chitinozoan assemblages that included reworked Fungochitina pilosa, a late Givetian -Frasnian key species globally (Paris, 1996). Other uncertain fragments were interpreted as reworked, probably from close to the Middle-Late Devonian boundary (Rodríguez González, 1999). In this complex stratigraphic context, the occurrence of chitinozoan taxa in the assemblages studied, including reworked graptolite remains and reworked Early-Middle Devonian miospore taxa, reinforces the importance of reworking processes. This is highlighted by the first documented chitinozoan specimens in the IPB and PLD (Rodríguez González, 1999). However, more detailed studies are needed to improve knowledge of the chitinozoan assemblages and the importance of identified in situ and reworked taxa.

8.d. Comment on depositional environment
The palaeoecology of chitinozoans and scolecodonts indicates deposition in marine nearshore to offshore environments. However, moderate to good preservation of specimens of these fossil groups in the flysch sediments of the Gafo Formation suggests a short time gap from their reworking on the continental platform and transport in turbidity currents to deep-sea fans.
From the discussion above, the Gafo Formation was deposited during middle-late Famennian time (c. 368-363 Ma), corresponding to the GF and VH palynomorph biozones.

Conclusions
This study of the Gafo Formation from the southern sector of the Pulo do Lobo Domain allows the following conclusions to be made.
-The Gafo Formation yielded an abundant and diverse palynomorph assemblage assigned to the GF Miospore Biozone of middle Famennian (Late Devonian) age, both in Portugal and in Spain. In the easternmost sector of the basin (Spain), a VH Miospore Biozone of late Famennian age was also attained. -The palynological results obtained for the Gafo Formation, both in Portugal and Spain, are consistent and in agreement with the stratigraphic, structural and mapping interpretations. -In Spain, these data show that the Santa Bárbara Unit corresponds to the same lithostratigraphic unit as the Gafo Formation (Fig. 1). -In the south Chança River section, an assemblage probably of (?) latest Givetianearly Frasnian (Late Devonian) age was recovered based on a poorly preserved assemblage. Further studies will be developed in this section to improve the accuracy of the age. However, this preliminary study allowed identification of a greywacke and interbedded shale unit previously interpreted as culm (BAFG; of Visean age) as being part of the Gafo Formation (Late Devonian age) (Fig. 1).

-The consistent occurrence of Lagenochitininae and
Angochitininae chitinozoans indicates a Middle-Late Devonian age, consistent with the miospore age determination. -Common graptolite fragments, poorly preserved chitinozoans fragments and the common occurrence of Early-Middle Devonian miospores represent strong evidence of reworking processes in the basin. -A maximum U-Pb depositional age of 369 ± 2.5 Ma from detrital zircons was obtained for the Gafo Formation greywackes. -This work highlights the importance of palynostratigraphy and detrital zircon geochronology for an integrated understanding of the depositional age and paleoenvironmental models, confirming the field-based interpretations of the complex stratigraphy of the southern sector of the Pulo do Lobo Domain.