Next Article in Journal
Statistical Physics of Fissure Swarms and Dike Swarms
Previous Article in Journal
Real-Time Foreshock–Aftershock–Swarm Discrimination During the 2025 Seismic Crisis near Santorini Volcano, Greece: Earthquake Statistics and Complex Networks
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Geosciences
Volume 15
Issue 8
10.3390/geosciences15080299
geosciences-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Palynostratigraphy of the “Muschelkalk Sedimentary Cycle” in the NW Iberian Range, Central Spain

by
Manuel García-Ávila
1,2,*,
Soledad García-Gil
1,2 and
José B. Diez
1,2
1
Departamento de Xeociencias Mariñas e Ordenación do Territorio, Facultade de Ciencias do Mar, Universidade de Vigo, 36310 Vigo, Spain
2
Centro de Investigación Mariña, Universidade de Vigo (CIM-UVIGO), 36310 Vigo, Spain
*
Author to whom correspondence should be addressed.
Geosciences 2025, 15(8), 299; https://doi.org/10.3390/geosciences15080299
Submission received: 29 June 2025 / Revised: 29 July 2025 / Accepted: 1 August 2025 / Published: 4 August 2025
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
Browse Figures
Versions Notes

Abstract

The Muschelkalk sedimentary cycle in the northwestern region of the Iberian Range (central Spain) lies within a transitional area between the Iberian and Hesperia type Triassic domains. To improve the understanding of its paleopalynological record, fifty samples were analyzed from ten stratigraphic sections corresponding to the Tramacastilla Dolostones Formation (TD Fm.), Cuesta del Castillo Sandstones and Siltstones Formation (CCSS Fm.), and Royuela Dolostones, Marls and Limestones Formation (RDML Fm.). Despite previous studies in the area, palynological data remain scarce or insufficiently detailed, highlighting the need for a systematic reassessment. Based on the identified palynological assemblages, the succession is assigned to an age spanning from the Fassanian to the Longobardian, with a possible extension into the base of the Julian (early Carnian). The results confirm that the siliciclastic unit (CCSS) represents a lateral facies change with respect to the carbonate formations of the upper Muschelkalk (TD and RDML). From a paleoecological perspective, the assemblages indicate a warm and predominantly dry environment, dominated by xerophytic conifers, although evidence of more humid local environments, such as marshes or coastal plains, is also observed.

1. Introduction

The Triassic of the Iberian Peninsula displays a succession of facies analogous to those of the “Germanic-type” Triassic [1], that is, consisting of a lower red clastic unit or Buntsandstein, an intermediate carbonate unit or Muschelkalk, and an upper terrigenous-evaporitic unit or Keuper.
However, at a more detailed scale, notable differences in lithofacies and biofacies allow the definition of new characteristic types with their own distinct identities. These differences are mainly due to the paleogeographic diversity resulting from the key position of the present-day Iberian Peninsula in relation to the Tethys. The “Iberian-type Triassic” [2], which includes part of the area studied in this work, corresponds to the outcrops of the Sierra de la Demanda and the central and northern parts of the Iberian Range. It is characterized by the presence of a single carbonate unit with Muschelkalk facies (M3). The “Hesperian-type Triassic” [3] includes the outcrops in which the carbonate unit of the Muschelkalk is absent or lacks individual character. The Triassic succession is composed almost entirely of terrigenous facies with some evaporites.
The study area considered here is located at the boundary between the domains of the “Iberian-type Triassic” and the “Hesperian-type Triassic” [4,5,6]. The upper carbonate unit (M3, sensu [7]) of the Iberian Range is characterized by the deposition of calcareous materials such as limestones, dolomites, and marls, showing significant lateral continuity up to the Riba de Santiuste area, where intercalations of siliciclastic materials correspond to a reduction in carbonate content.
The formations cropping out in the study area include two carbonate formations: the “Tramacastilla Dolostones Formation” (TD Fm.) and the “Royuela Dolostones, Marls and Limestones Formation” (RDML Fm.). Following a revision of the lithostratigraphic boundaries [5,6], a new siliciclastic formation was identified and named the “Cuesta del Castillo Sandstones and Siltstones Formation” (CCSS Fm.). Based on its lithological characteristics and stratigraphic position, this new formation was proposed to represent a lateral facies change, towards the NW, of the two previously described carbonate formations of the M3 unit (TD Fm. and RDML Fm.). However, this hypothesis had not been biostratigraphically confirmed.
All three formations overlie the Torete variegated Siltstones and Sandstones Formation (TvSS Fm.), which represents the M2 unit from the Muschelkalkand and has been interpreted as Fassanian (Lower Ladinian) in age (TvSS = TMMS) [8].
In this context, the objective of this article is to extensively document and illustrate the palynological content obtained from several levels of the three lithostratigraphic formations (CCSS, TD, and RDML), in order to obtain a relative age that may support the hypothesis of a lateral facies change and to infer a paleoclimatic and paleoecological reconstruction of these coastal transitional records from the Iberian and Hesperian domains during the Middle Triassic.

2. Geological Context

The studied region is located at the confluence of the Iberian Range and the Central System (Figure 1a), covering parts of the provinces of Soria and Guadalajara, close to their boundary with the province of Zaragoza. It lies between parallels 41° 3′ N and 41° 14′ N, and between meridians 2° 23′ W and 2° 50′ W, within an area whose geological context has been extracted from four sheets corresponding to the Geological Map of Spain (MAGNA) at a 1:50,000 scale [9,10,11,12] (Figure 1b).
The Alpine structure [9,11] displays a superimposed folding pattern with two main orientations: NE–SW (“Guadarrama direction”) and NW–SE (“Iberian direction”).
Some of the folds are cover folds, but others, such as the Sigüenza fold, are basement-involved structures, with the Triassic cover appearing faulted. These were originally late-Hercynian strike-slip faults that later acted as normal faults, playing a significant role in controlling the geometry and sedimentation of the Triassic basin in the study area.
From a palynostratigraphic perspective, there are few studies in this area have focused on the Middle–Upper Triassic transition (Ladinian–Carnian). The first data yielded two palynological “type” assemblages, KR-1 and KR-2 [13]. The “type” classification is applied to these assemblages to highlight the methodological constraints arising from grouping heterogeneous palynological records across multiple sections, stratigraphic levels, and facies. Although this approach has been adopted in previous studies, its implementation here demonstrably diminishes their biostratigraphic reliability.
The “KR.1 assemblage” corresponds to the samples from levels 53 and 55 in the upper half of the “tr” unit (“Lutitas y areniscas de Fraguas”, a unit representing the transition between Buntsandstein and Muschelkalk facies) from the El Robledo road section, as well as samples 299, 324, and 342 from the middle and upper levels of the “tm.2” unit (“Unidad de Dolomías y areniscas de Riba de Santiuste”, Muschelkalk facies) from the Riba de Santiuste section. This “type” assemblage is composed of trilete spores, Ovalipollis ovalis, Triadispora plicata, Plicatisaccus badius, Ellipsovelatisporites plicatus, Pityosporites sp., Striatoabietites aytugii, Cuneatisporites cerinus, Alisporites sp., Cycadopites sp., Enzonalasporites tenuis, Camerosporites secatus, Duplicisporites granulatus, Paracirculina tenebrosa, Paracirculina scurrulis, Praecirculina granifer, and tetrad-form Circumpolles. Based on a previous study [14], this assemblage was assigned a Carnian age due to the abundance of Circumpolles-type pollen grains and, in particular, the presence of Camerosporites secatus.
The “KR.2 assemblage” was identified in three sections: level 5 in the upper part of the “tm.1” unit (Arcillas y dolomías del embalse de Pálmaces, Muschelkalk facies) from the Camino de Veguillas section; level 13 at the base of the “tk” unit (Arcillas y yesos de los Gavilanes, Keuper facies) from the Fraguas section; and level 6 in the middle part of the same unit in the Los Gavilanes section. This “type” assemblage includes trilete spores, Leiotriletes sp., Ovalipollis ovalis, Ovalipollis minimus, Ovalipollis cultus, Cuneatisporites cerinus, Ellipsovelatisporites plicatus, Sulcatisporites sp., Microcachryidites fastidioides, Microcachryidites doubingeri, Striatoabietites aytugii, Camerosporites secatus, Circulina granulata, Calamospora sp., Duplicisporites granulatus, Paracirculina tenebrosa, Paracirculina scurrilis, Praecirculina granifer, Enzonalasporites tenuis, Patinasporites iustus, Paracirculina quadruplicis, tetrad-form Circumpolles, Inaperturopollenites orbicularis, and Cycadopites. Based on previous studies [15,16,17], the assemblage was assigned a Late Carnian age.
Subsequently, a KL association was described in the Riba de Saelices section [18], corresponding to level 21 of the TvSS Fm., and composed of Leiotriletes sp., Keuperisporites baculatus, Calamospora sp., Doubingeripollenites sp., Ovalipollis minimus, Triadispora aurea, Triadispora falcata, Triadispora plicata, Microcachryidites fastidioides, bisaccate pollen grains, Cycadopites sp., Camerosporites secatus, Duplicisporites granulatus, Paracirculina maljawkinae, Paracirculina tenebrosa, Paracirculina scurrilis, and Praecirculina granifer. This assemblage was assigned an Early Carnian age.
The “type” K assemblage was also defined and identified in level 56 of the Torrecilla section and level 46 of the Arroyo de San Román section. In both cases, it appears in the upper half of the “Royuela Beds” unit. It is composed of Punctatisporites sp., Sphagnites sp., Ovalipollis cultus, Ovalipollis ovalis, Parillinites sp., Triadispora vilis, Triadispora staplini, bisaccate pollen grains, Alisporites grauvogeli, Samaropollenites speciosus, Pityosporites sp., Duplicisporites granulatus, Camerosporites secatus, Praecirculina granifer, Paracirculina tenebrosa, Circumpolles sp., Enzonalasporites tenuis, and Inaperturopollenites varians. This assemblage was assigned a Carnian age based on the presence of Camerosporites secatus, following the criteria outlined in a previous study [14].
Years later, a Ladinian age was attributed to the Dolomitic Beds Unit [19], where molds of bivalves, gastropods, bone fragments, and “a palynological association characteristic of the Ladinian” were found. The original designation of Dolomitic Beds [20] was replaced by DT Fm. [21], and indirect references were made to the existence of “two palynological associations whose characteristics indicate a Ladinian to Carnian age” in the marly intervals at the base of the Royuela Beds Unit.
Based on these data and following a revision of the lithostratigraphic boundaries in the region, a new siliciclastic formation was identified and named CCSS Fm. [5,6], and the hypothesis of a lateral facies change with DT Fm. and RDML Fm. was proposed.
Taking into account the palynological data provided by the KL association in the Riba de Saelices section [18], a Late Fassanian–Early Julian age was assigned to the TvSS Fm. [22]. Subsequently, the palynomorphs from this sample were reinterpreted, and the age was revised to Late Fassanian [8].
More recently, southwest of our study area, our team conducted a palynostratigraphic analysis of several levels within Keuper facies near the “El Atance” reservoir [23]. The resulting assemblage was composed of Calamospora sp., Densoisporites sp., Verrucosisporites sp., indeterminate trilete spores, Alisporites opii, Alisporites sp., Camerosporites secatus, Chordasporites sp., Cycadopites sp., Duplicisporites granulatus, Enzonalasporites vigens, Ephedripites sp., Infernopollenites sp., Lunatisporites acutus, Lunatisporites sp., Microcachryidites fastidioides, Microcachryidites sp., Ovalipollis cultus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina scurrilis, Paracirculina sp., Patinasporites densus, Platysaccus papilionis, Platysaccus sp., Praecirculina granifer, Staurosaccites quadrifidus, Striatoabieites sp., Triadispora plicata, Triadispora suspecta, Triadispora sp., Vallasporites ignacii, and Plaesiodictyon mosellanum. Based on the palynomorph biozones, these levels were dated to the base of the Julian age, the basal substage of the two-substage division of the Carnian.
The relevance of the data from these previous studies will be evaluated in the discussion section.

3. Materials and Methods

For the palynological study, the slides prepared and analyzed during the development of García-Gil’s Ph.D. thesis [4] were re-examined. The results of this previous work were never published in detail. The preparations correspond to an extensive sampling across ten stratigraphic sections (see Supplementary Materials for details) from the TD, CCSS, and RDML formations in the area marking the junction between the Central System and the Iberian Range.
To reference the studied samples within the stratigraphic levels from which they were collected, the sections established by García-Gil [4] were used. Their locations, listed from northwest to southeast, are as follows (Figure 1b and Figure 2): RS4 (Río Alcolea, samples: RS4-1 and RS4-2), RS8 (Torredelrrabano 1, samples RS8-1 and RS8-2), RS9 (Torredelrrabano 2, samples RS9-1 and RS9-2), RS3 (Riba de Santiuste, RS3-1 to RS3-10), RS1 (Loma de la Sierra 1, RS1-1 to RS1-10), RS2 (Loma de la Sierra 2, RS2-1 to RS2-12), SS2 (Sienes 2, SS2-1 to SS2-6), TH (Túnel de Horna, TH-1 and TH-2), BU (Bujarrabal, BU-1 to BU-3), and FC (Fuencaliente de Medina 2, FC-1). For improved organization and presentation of the samples and their results, the samples were renamed; the correspondence between the original and new codes is provided in Table S1 of the Supplementary Materials.
The original sample preparation followed the standard HCl–HF–HCl method [24], and the residues were then sieved at 10 µm. The current analysis of the available slides was carried out using a Leica DM2000 LED microscope, and the palynomorphs were photographed with a Leica ICC50 W camera at 1000× magnification. The location of each specimen was recorded using the code of the corresponding slide along with coordinates obtained with an England Finder. After the study was completed, the slides were deposited in the Palynology Laboratory of the Department of Geosciences, University of Vigo.
To determine the age of the samples, the biozones defined by the presence of key taxa were taken into account, avoiding the use of absence data or relative abundance, as these may be affected by taphonomic biases.

4. Results

Of the 50 samples studied, 40 yielded palynological content (see Table S1 in the Supplementary Materials for details). Since the palynomorphs present in the different samples are similar, assemblages were established based on the stratigraphic sections and, within them, each formation. The position of the samples within each simplified stratigraphic section can be found in Figure 2, and with greater precision in the stratigraphic sections presented in the Supplementary Materials.
The palynological assemblages identified in each lithostratigraphic formation are presented below, organized according to the stratigraphic section from which they were collected. Each assemblage is the result of the samples indicated in parentheses.

4.1. Assemblage 1 (Section RS4, CCSS Fm., Sample RS4-2)

Alisporites sp., Duplicisporites granulatus, Ellipsovelatisporites plicatus, Microcachryidites fastidioides, Paracirculina scurrilis, Todisporites major, Triadispora staplinii.

4.2. Assemblage 2 (Section RS8, TD Fm., Sample RS8-1)

Camerosporites secatus, cf. Convolutispora sp.1, Duplicisporites granulatus, Microcachryidites cf. doubingeri, Microcachryidites fastidioides, Ovalipollis ovalis, Ovalipollis pseudoalatus, Platysaccus papilionis, Praecirculina granifer, cf. Punctatisporites sp.1, Triadispora spp., Triadispora plicata, Triadispora staplinii, Triadispora suspecta, indeterminate bisaccates.

4.3. Assemblage 3 (Section RS8, CCSS Fm., Sample RS8-2)

Alisporites sp., Camerosporites secatus, cf. Convolutispora sp.2, Duplicisporites granulatus, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis pseudoalatus, Paracirculina sp., Triadispora spp., Triadispora crassa, Triadispora epigona, Triadispora staplinii, Triadispora suspecta, Verrucosisporites contactus, indeterminate bisaccates.

4.4. Assemblage 4 (Section RS9, CCSS Fm., Sample RS9-2)

Alisporites grauvogeli, Alisporites sp., Angustisulcites klausii, Aratrisporites granulatus, Calamospora sp., Calamospora tener, Camerosporites secatus, Chordasporites singulichorda, Cuneatisporites radialis, Cycadopites sp.1, Cycadopites sp.2, Cyclotriletes cf. microgranifer, Deltoidospora sp.1, Duplicisporites granulatus, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina scurrilis, Paracirculina tenebrosa, Paracirculina sp., Platysaccus sp.3, Platysaccus sp.4, Praecirculina granifer, Punctatisporites sp.3, Punctatisporites subcarpaticus, Punctatisporites triassicus, Striatoabieites aytugii, Todisporites minor, Triadispora spp., Triadispora cf. aurea, Triadispora epigona, Triadispora falcata, Triadispora plicata, Triadispora staplinii, Triadispora suspecta, indeterminate bisaccates, indeterminate monosaccate 2, indeterminate trilete spore 3, Plaesiodictyon mosellanum.

4.5. Assemblage 5 (Section RS3, TD Fm., Sample RS3-2)

Alisporites progrediens, Calamospora sp., Camerosporites secatus, Duplicisporites granulatus, Microcachryidites fastidioides, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina tenebrosa, Praecirculina granifer, Staurosaccites quadrifidus, Triadispora spp., Triadispora suspecta, indeterminate bisaccates, indeterminate monosaccate 1, Crassosphaera sp.1, Crassosphaera sp.2, indeterminate monocolpate.

4.6. Assemblage 6 (Section RS3, CCSS Fm., Samples RS3-3 to RS3-6 and RS3-8)

Alisporites grauvogeli, Alisporites progrediens, Calamospora sp., Camerosporites secatus, Duplicisporites granulatus, Illinites sp., Microcachryidites doubingeri, Microcachryidites fastidioides, Monosulcites sp., Ovalipollis cultus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina sp., Platysaccus cf. papilionis, Platysaccus papilionis, Triadispora plicata, Triadispora suspecta, Verrucosisporites contactus, cf. Verrucosisporites sp., indeterminate bisaccates, indeterminate monosaccate 1, indeterminate trilete spore.

4.7. Assemblage 7 (Section RS3, RDML Fm., Sample RS3-10)

Camerosporites secatus, Enzonalasporites sp., Paracirculina tenebrosa, Triadispora spp., Verrucosisporites cf. contactus, indeterminate bisaccates.

4.8. Assemblage 8 (Section RS1, TD Fm., Samples RS1-1 to RS1-3)

Alisporites sp., Calamospora sp., Camerosporites secatus, Duplicisporites granulatus, Microcachryidites fastidioides, Ovalipollis sp., Paracirculina tenebrosa, Platysaccus sp.1, Reticulatisporites sp., Triadispora epigona, Triadispora plicata, Triadispora suspecta, Triadispora spp., Verrucosisporites morulae, indeterminate bisaccates.

4.9. Assemblage 9 (Section RS1, CCSS Fm., Samples RS1-5 to RS1-9)

Alisporites progrediens, Alisporites sp., Calamospora sp., Camerosporites secatus, Densoisporites sp., Duplicisporites granulatus, Duplicisporites mancus, Illinites chitonoides, Keuperisporites baculatus, Microcachryidites cf. doubingeri, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Palaeospongisporis europaeus, Paracirculina scurrilis, Paracirculina tenebrosa, Platysaccus papilionis, Praecirculina granifer, Punctatisporites fungosus, Punctatisporites sp., Triadispora epigona, Triadispora plicata, Triadispora cf. stabilis, Triadispora suspecta, Triadispora sp., Verrucosisporites morulae, Verrucosisporites thuringiacus, indeterminate bisaccates, indeterminate trilete spore 1.

4.10. Assemblage 10 (Section RS2, TD Fm., Sample RS2-1)

Indeterminate spore, indeterminate bisaccates, Triadispora sp.

4.11. Assemblage 11 (Section RS2, CCSS Fm., Samples RS2-2, 4, 6 to 8, 10, and 12)

Alisporites progrediens, Alisporites splendens, Alisporites cf. opii, Alisporites spp., Aratrisporites granulatus, Calamospora tener, Calamospora sp., Camerosporites secatus, Duplicisporites granulatus, Duplicisporites mancus, Kyrtomisporis ervii, Microcachryidites doubingeri, Microcachryidites cf. doubingeri, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis notabilis, Ovalipollis ovalis, Ovalipollis pseudoalatus, Palaeospongisporis europaeus, Paracirculina scurrilis, Paracirculina tenebrosa, Paracirculina sp., Platysaccus cf. cacheutensis, Platysaccus sp.2, Punctatisporites fungosus, Reticulatisporites sp., Staurosaccites quadrifidus, Striatoabieites sp.1, Todisporites minor, Triadispora crassa, Triadispora epigona, Triadispora falcata, Triadispora plicata, Triadispora cf. stabilis, Triadispora staplinii, Triadispora suspecta, Triadispora spp., Verrucosisporites sp., indeterminate monosaccate 1, indeterminate bisaccates, indeterminate reticulate spore, mutant bisaccate.

4.12. Assemblage 12 (Section RS2, RDML Fm., Sample RS2-11)

Camerosporites secatus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina sp., Platysaccus queenslandi, Triadispora epigona, Triadispora staplinii, indeterminate bisaccates, incertae sedis 2.

4.13. Assemblage 13 (Section SS2, TD Fm., Sample SS2-1)

Alisporites grauvogeli, Calamospora sp., Calamospora tener, Camerosporites secatus, Duplicisporites granulatus, Haberkornia parva, Ovalipollis pseudoalatus, Paracirculina tenebrosa, Punctatisporites fungosus, cf. Rewanispora sp., Todisporites major, Todisporites minor, Triadispora spp., Triadispora epigona, Triadispora falcata, Triadispora plicata, Triadispora suspecta, Verrucosisporites aff. morulae, indeterminate bisaccates, Crassosphaera sp.1.

4.14. Assemblage 14 (Section SS2, CCSS Fm., Sample SS2-3)

Alisporites progrediens, Alisporites spp., Camerosporites secatus, Duplicisporites granulatus, Microcachryidites fastidioides, Microcachryidites sp., Ovalipollis pseudoalatus, Palaeospongisporis europaeus, Paracirculina sp., Platysaccus papilionis, Triadispora falcata, Triadispora plicata, Triadispora spp., Verrucosisporites thuringiacus.

4.15. Assemblage 15 (Section SS2, RDML Fm., Samples SS2-2, SS2-5 and SS2-6)

Alisporites spp., Calamospora tener, Camerosporites secatus, Crassosphaera sp.1, Deltoidospora sp.2, Duplicisporites granulatus, Microcachryidites cf. doubingeri, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis ovalis, Ovalipollis pseudoalatus, Paracirculina tenebrosa, Paracirculina sp., Platysaccus cf. papilionis, Platysaccus sp.5, cf. Punctatisporites sp.2, Triadispora epigona, Triadispora falcata, Triadispora plicata, Triadispora suspecta, Triadispora spp., indeterminate bisaccates, indeterminate monosaccate 1, indeterminate pollen grain, incertae sedis 3.

4.16. Assemblage 16 (Section TH, RDML Fm., Samples TH-1 and TH-2)

Camerosporites secatus, Microcachryidites doubingeri, Microcachryidites fastidioides, Ovalipollis cultus, Ovalipollis pseudoalatus, Striatoabieites sp.2, Triadispora spp., Triadispora epigona, Triadispora plicata, Triadispora staplinii, Triadispora suspecta.

4.17. Assemblage 17 (Section BU, RDML Fm., Samples BU-1 to BU-3)

Alisporites sp., Camerosporites secatus, Duplicisporites cf. granulatus, Ovalipollis pseudoalatus, Platysaccus cf. papilionis, Punctatisporites sp.1, Triadispora cf. staplinii, Triadispora cf. suspecta, Triadispora spp., indeterminate bisaccates.

4.18. Assemblage 18 (Section FC, RDML Fm., Sample FC-1)

Alisporites sp., Camerosporites secatus, Chordasporites singulichorda, Duplicisporites granulatus, Microcachryidites fastidioides, Ovalipollis ovalis, Paracirculina sp., Platysaccus cf. papilionis, Punctatisporites sp.1, Staurosaccites quadrifidus, Triadispora falcata, Triadispora plicata, Triadispora suspecta, indeterminate monosaccate 1 and incertae sedis.
Figure 3, Figure 4, Figure 5 and Figure 6 show a synthesis of the palynomorphs identified in this study at a 20 µm scale. The acronym indicates section-sample_number or letter assigned to the slide_England Finder slide coordinates. For further information, the Supplementary Materials include detailed figures of each proposed assemblage (10 µm scale).

5. Discussion

5.1. Reinterpretation of Previous Data

Considering previous palynostratigraphic studies, their usefulness is often limited due to several methodological issues. Two “type” assemblages were proposed [13], that is, palynological groups common to different sections and intervals, without a detailed presentation of each assemblage individually. Although that study included illustrations of the identified palynomorphs, their precise stratigraphic position was not indicated, making it impossible to reinterpret the data. Furthermore, an inconsistency arose in assigning a similar age to materials from transitional facies (tr, between the Buntsandstein and the Muschelkalk), the Muschelkalk (Tm1), and the Keuper (Tk) in the same area.
The KL assemblage [18] includes accurate illustrations and, since it is located at a single stratigraphic level, allows for a reliable reinterpretation, as previously discussed [8], suggesting that the TvSS Fm. corresponds to the late Fassanian. However, the “type” K assemblage presents the same issues of data presentation as described above.
Later, a Ladinian–Carnian age was proposed for the marly intervals at the base of the CCSS Fm. [19], but without providing a list of palynomorphs or any illustrations. This is a consequence of it not being the main objective of that publication, and for this reason, it is not possible to verify or refute the proposed age for that unit.
Due to the proper and complete presentation of data, we refer to the levels within Keuper facies at El Atance [23] as corresponding to the base of the Julian.

5.2. Interpretation of the New Data

The analysis of the samples indicates that the three formations (CCSS, TD, and RDML) share a very similar palynomorph composition (see Table S1 in the Supplementary Materials).
Approximately 100 different palynomorphs have been identified, with the most recurrent taxa across all assemblages being Camerosporites secatus, Duplicisporites granulatus, Ovalipollis pseudoalatus, and Microcachryidites fastidioides.
Regarding taxonomic diversity, in all formations, the number of pollen species always exceeds that of spores. Additionally, in the TD and CCSS formations, some levels contain algae indicative of marine and transitional environments.
To assign an age to the formations, the biozones defined by several key taxa present in the palynological assemblages have been considered. To begin with, the First Appearance Datum (FAD) of Camerosporites secatus, in the Alpine domain of Europe, is placed in the Fassanian (lower Ladinian) [22,25,26,27,28,29].
Other relevant taxa include Microcachryidites doubingeri and Microcachryidites fastidioides, characteristic of the Early to Middle Triassic and scarce in the basal Carnian assemblages in the Mediterranean area (e.g., [30,31]), Poland (e.g., [32,33]), Israel [34], and Central and Northwestern Europe [35]. Moreover, the Last Appearance Datum (LAD) of Protodiploxypinus fastidioides (=Microcachryidites fastidioides) is situated in the middle Longobardian (upper Ladinian) [35].
Collectively, these taxa indicate an age interval spanning from the Fassanian to the end of the Longobardian, without excluding the base of the Carnian.
On the other hand, the presence of Paracirculina tenebrosa, whose first appearance in the Longobardian was recorded in the Mediterranean area [31], in the upper levels of the TD Fm. and in the rest of the studied formations, suggests that from the top of the TD Fm. (including these levels), the age of those levels could be placed in the Longobardian sensu lato or even extend up to the base of the Julian (lower Carnian).
These assemblages correspond to the secatus-dimorphus and secatus-vigens phases or the base of the vigens-densus phase [27] and the Heliosaccus dimorphus Zone plus the base of the Camerosporites secatus Zone [35].
The proposed age for TD, CCSS, and RDML formations is consistent with the ages assigned both to the underlying unit [8], dated as possibly upper Fassanian (TvSS Fm.), and to the overlying unit [23], which suggests a transition between the Ladinian and Carnian (Longobardian-Julian).
Taking into account that sedimentological analysis suggests continuity between the terrigenous formation (CCSS Fm.) and the regional Muschelkalk carbonate formations (TD Fm. and RDML Fm.), the age of the formations provided by the palynological study supports the hypothesis of lateral facies change.

5.3. Paleoecological and Paleoclimatic Interpretation and Taphonomic Bias

All assemblages are dominated by taxa of continental origin. Among these, the most common are pollen grains of conifers adapted to dry environments, especially those belonging to the Circumpolles group (e.g., genera such as Camerosporites, Duplicisporites, and Paracirculina) linked to the family Cheirolepidiaceae [36,37,38,39,40,41]. These may represent pioneer xerophytic coastal vegetation [42], indicating drier and/or more saline influences [43].
The presence of various xerophytic species of the genus Triadispora (e.g., T. staplinii, T. suspecta, T. falcata), related to Voltziales [44,45,46,47], points to the influx of inland elements originating from saline mudflats [42,48].
The occurrence of genera such as Alisporites, Ovalipollis, Platysaccus, Microcachryidites, or Striatoabieites further supports the prevalence of xerophytic gymnosperm vegetation (e.g., [49]) within a warm and arid climatic context.
However, the presence of wetter zones is indirectly inferred from the identification of spores associated with hygrophytic vegetation, such as lycophytes and ferns (e.g., Aratrisporites, Densoisporites, Deltoidospora, or Verrucosisporites), as well as sphenophytes (Calamospora) (e.g., [50,51]).
Additionally, algae identified in some samples also indicate levels closely related to humid environments. The presence of Plaesiodictyon mosellanum, a colonial alga with a stratigraphic range from the late Anisian to the latest Norian, suggests brackish to freshwater conditions [52]. This implies that the depositional environment could have been associated with marine settings influenced by freshwater influx [53,54], coastal marshes [55], or a coastal, limnic/brackish to marginal marine setting [47].
The tasmanacean green alga Crasosphaera is considered an indicator of fully marine/neritic environments [55].
From a taphonomic perspective, samples containing palynomorphs from the most distal sections (BU, FC, and TH), located in the SE of the study area and dominated by marine sediments distant from the coastline, exhibit lower average diversity and poorer preservation compared to samples from other stratigraphic sections, where continental or nearshore sediments prevail.
This observation highlights the clear taphonomic bias imposed by the sedimentological context; in our case, TD and RDML formations represent marine environments, while CCSS reflects a transitional deltaic setting.
This suggests that similar biocoenoses can yield different taphocoenoses, casting doubt on the direct application of percentage-based abundance graphs in paleoclimatic interpretations, at least for palynological records from deep time (Paleozoic, Mesozoic).

6. Conclusions

The main conclusions of the palynological study are as follows:
–
From the upper levels of the TD Fm. (inclusive) to the highest studied levels, the age of those levels can be placed within the Longobardian sensu lato, and possibly extending to the base of the Julian (Lower Carnian).
–
The contemporaneous age of CCSS, TD, and RDML formations supports the hypothesis that the termination of the two carbonate formations that constitute the upper Muschelkalk unit in the region (i.e., TD Fm. and RDML Fm.) is resolved by a lateral facies change to the terrigenous CCSS Fm.
–
The palynological assemblage indicates a warm and predominantly dry climate, dominated by xerophytic conifers adapted to arid conditions. However, the presence of hygrophytic spores and algae suggests the existence of localized wet areas, possibly associated with coastal or palustrine environments.
In this context, the new palynological data presented in this study provide valuable insights, contributing to more precise dating and stratigraphic interpretation of the CCSS, TD, and RDML formations.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/geosciences15080299/s1, Figures S1 to S57: Detailed stratigraphic sections with comprehensive representation of the palynomorphs identified in the formations of each section; Figure S58: Distribution of the stratigraphic sections and samples analyzed in the study, as well as facies correlation; Table S1: Palynomorphs referenced in the study.

Author Contributions

Conceptualization, M.G.-Á., S.G.-G. and J.B.D.; methodology, M.G.-Á., S.G.-G. and J.B.D.; investigation, M.G.-Á., S.G.-G. and J.B.D.; writing—original draft preparation, M.G.-Á., S.G.-G. and J.B.D.; writing—review and editing, M.G.-Á., S.G.-G. and J.B.D.; visualization, M.G.-Á., S.G.-G. and J.B.D.; project administration, M.G.-Á. and J.B.D.; funding acquisition, S.G.-G. and J.B.D. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partially funded by the Ministerio de Ciencia y Innovación of the Spanish Government (ref.: PID2022-141050NB-I00).

Data Availability Statement

All data obtained in this study are included in the main article and the Supplementary Materials. The studied slides are housed at the Palynology Laboratory of the Department of Geosciences, University of Vigo.

Acknowledgments

The authors thank the editors and reviewers for their time, careful reading, and helpful and constructive comments, which have helped to improve the quality and clarity of our manuscript.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Alberti, F. Ueberblick über Die Trias, mit Berücksichtigung Ihres Vorkommens in der Alpen; Verlag der J. G. Gottaschen Bachhandlung: Stuttgart, Germany, 1864; pp. 1–353. [Google Scholar] [CrossRef]
  2. Virgili, C.; Sopeña, A.; Ramos, A.; Hernando, S. Problemas de la cronoestratigrafía del Trías en España. Cuad. Geol. Ibérica 1977, 4, 57–88. [Google Scholar]
  3. Sopeña, A.; Virgili, C.; Arche, A.; Ramos, A.; Hernando, S. El Triásico. In Libro jubilar J.M. Rios, Geología de España; Instituto Geológico y Minero de España: Madrid, Spain, 1983; Volume 2, pp. 47–63. [Google Scholar]
  4. García-Gil, S. Estudio Sedimentológico y Paleogeográfico del Triásico en el Tercio Noroccidental de la Cordillera Ibérica (provincias de Gualajara y Soria). Ph.D. Thesis, Universidad Complutense Madrid, Madrid, Spain, 1989. [Google Scholar]
  5. García-Gil, S. Las unidades litoestratigráficas del Muschelkalk en el NW de la Cordillera Ibérica (España). Bol. R. Soc. Esp. Hist. Nat. 1991, 86, 21–51. [Google Scholar]
  6. García-Gil, S. The sedimentological significance of a clastic wedge in the western basin margin of the Triassic Tethys (Iberian Range, Spain). Cuad. Geol. Ibérica 1991, 15, 209–239. [Google Scholar]
  7. Virgili, C. El Triásico de las Catalánides. Bol. Inst. Geol. Mm. 1958, 69, 1–186. [Google Scholar]
  8. Dinarès-Turell, J.; Diez, J.B.; Rey, D.; Arnal, I. “Buntsandstein” magnetostratigraphy and biostratigraphic reappraisal from Eastern Iberia: Early and Middle Triassic stage boundary definitions through correlation to Tethyan sections. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2005, 229, 158–177. [Google Scholar] [CrossRef]
  9. Ardell Argilés, F.; González Lodeiro, F.; Tena-Dávila Ruiz, M. Mapa geológico de la Hoja nº 343 (Barahona). Mapa Geológico de España E. 1:50.000. In Segunda Serie (MAGNA), Primera Edición; IGME: Madrid, Spain, 1982. [Google Scholar]
  10. Lendínez González, A. Mapa geológico de la Hoja nº 435 (Arcos de Jalón). Mapa Geológico de España E. 1:50.000. In Segunda Serie (MAGNA), Primera Edición; IGME: Madrid, Spain, 1991. [Google Scholar]
  11. Ardell Argilés, F.; González Lodeiro, F.; Tena-Dávila Ruiz, M. Mapa geológico de la Hoja nº 461 (Sigüenza). Mapa Geológico de España E. 1:50.000. In Segunda Serie (MAGNA), Primera Edición; IGME: Madrid, Spain, 1981. [Google Scholar]
  12. Bascones Alvira, L.; Martínez Álvarez, F. Mapa Geológico de la Hoja nº 462 (Maranchón); Mapa Geológico de España E. 1:50.000. Segunda Serie (MAGNA), Primera Edición; IGME: Madrid, Spain, 1981. [Google Scholar]
  13. Sopeña, A. Estratigrafía del Pérmico y Triásico del noroeste de la provincia de Guadalajara. In Seminarios de Estratigrafía, Serie Monografías 5; Universidad Complutense: Madrid, Spain, 1979; p. 329. [Google Scholar]
  14. Geiger, M.E.; Hopping, C.A. Triassic stratigraphy of the Southern North Sea Basin. In Philosophical Transactions of the Royal Society of London Series B; The Royal Society: London, UK, 1968; Volume 254, pp. 1–36. [Google Scholar]
  15. Hernando, S.; Doubinger, J.; Adloff, M.C. Datos cronoestratigráficos del Triásico superior de la región Ayllón-Atienza. Cuad. Geol. Ibérica 1977, 4, 399–410. [Google Scholar]
  16. Dunay, R.E.; Fisher, M.J. The Karnian palynofloral succession in the Northern Calcareous Alps, Lunz-am-See, Austria. Pollen Spores 1978, 20, 177–187. [Google Scholar]
  17. Visscher, H.; Krystyn, L. Aspects of late Triassic palynology. 4. A palynological assemblage from ammonoid-controlled Late Karnian (Tuvalian) sediments of Sicily. Rev. Palaeobot. Palynol. 1978, 26, 93–112. [Google Scholar] [CrossRef]
  18. Ramos, A. Estratigrafía y paleogeografía del Pérmico y Triásico al Oeste de Molina de Aragón (provincia de Guadalajara). In Seminarios de Estratigrafía, Serie Monografías 6; Universidad Complutense: Madrid, Spain, 1979; p. 313. [Google Scholar]
  19. García-Gil, S.; Sopeña, A. Estratigrafía y Sedimentología del Triásico en el sector medinaceli-Somaén (Provincia de Soria). Cuad. Geol. Ibérica 1987, 11, 707–735. [Google Scholar]
  20. Hinkelbein, K. El Triásico y el Jurásico de los alrededores de Albarracín. Teruel 1969, 4, 35–75. [Google Scholar]
  21. Pérez-Arlucea, M.; Sopeña, A. Estratigrafía del Pérmico y Triásico en el sector central de la Rama Castellana de la Cordillera Ibérica. Estud. Geol. 1985, 41, 207–222. [Google Scholar] [CrossRef]
  22. Diez, J.B. Geología y Palaeobotánica de la Facies Buntsandstein en la Rama Aragonesa de la Cordillera Ibérica. Implicaciones Bioestratigráficas en el Peritethys Occidental. Ph.D. Thesis, Universidad de Zaragoza (Spain), Zaragoza, Spain, Université Paris VI (France), Paris, France, 2000. [Google Scholar]
  23. García-Ávila, M.; De la Horra, R.; de Miguel Chaves, C.; Juncal, M.A.; Pérez-García, A.; Ortega, F.; Diez, J.B. Palynological and sedimentological implications of the sauropterygian Upper Triassic site of El Atance (Central Iberian Peninsula). Rev. Palaeobot. Palynol. 2021, 295, 104541. [Google Scholar] [CrossRef]
  24. Wood, D.G.; Gabriel, A.M.; Lawson, J.C. Palynological techniques—Processing and microscopy. In Palynology: Principles and Applications; Jansonius, J., McGregor, D.C., Eds.; American Association of Stratigraphic Palynologists Foundation: Houston, TX, USA, 1996; Volume 1, pp. 29–50. [Google Scholar]
  25. Visscher, H.; Brugman, W.A. Ranges of selected palynomorphs in the Alpine Triassic of Europe. Rev. Palaeobot. Palynol. 1981, 34, 115–128. [Google Scholar] [CrossRef]
  26. Besems, R.E. Aspects of Middle and Late Triassic Palynology. 1. Palynostratigraphical data from the Chiclana de Segura Formation of the Linares-Alcaraz region (southeastern Spain) and correlation with palynological assemblages from the Iberian Peninsula. Rev. Palaeobot. Palynol. 1981, 32, 257–273. [Google Scholar] [CrossRef]
  27. Van Der Eem, J.G.L.A. Aspects of Middle and Late Triassic Palynology: 6. Palynological investigations in the Ladinian and Lower Karnian of the Western Dolomites, Italy. Rev. Palaeobot. Palynol. 1983, 39, 189–300. [Google Scholar] [CrossRef]
  28. Roghi, G. Analisi Palinologica del Trias Medio del Sudalpino. Ph.D. Thesis, University of Padova, Padova, Italy, 1995. [Google Scholar]
  29. Stockar, R.; Baumgartner, P.O.; Condon, D. Integrated Ladinian bio-chronostratigraphy and geochronology of Monte San Giorgio (Southern Alps, Switzerland). Swiss J. Geosci. 2012, 105, 85–108. [Google Scholar] [CrossRef]
  30. Doubinger, J.; Bühmann, D. Röt bei Borken und bei Schlüchtern (Hessen, Deutschland). Palynologie und Tonmineralogie. Z. Dtsch. Geol. Ges. 1981, 132, 421–449. [Google Scholar] [CrossRef]
  31. Doubinger, J.; Adloff, M.C. Triassic Palynomorphs of the Mediterranean Area; Centre de Sédimentologie et Géochimie de la Surface: Strasbourg, France, 1983. [Google Scholar]
  32. Orłowska-Zwolińska, T. Palynostratigraphy of the upper part of Triassic Epicontinental sediments in Poland. Pr. Inst. Geol. 1983, 104, 1–89. [Google Scholar]
  33. Orłowska-Zwolińska, T. Palynological zones of the Polish epicontinental Triassic. Bull. Pol. Acad. Sci. Earth Sci. 1985, 33, 107–117. [Google Scholar]
  34. Eshet, Y. The palynostratigraphy of the Permian Triassic boundary in Israel: Two approaches to biostratigraphy. Isr. J. Earth Sci. 1990, 39, 1–15. [Google Scholar]
  35. Kürschner, W.M.; Waldemaar Herngreen, G.F.W. Triassic palynology of central and northwestern Europe: A review of palynofloral diversity patterns and biostratigraphic subdivisions. In Triassic Timescale; Lucas, S.G., Ed.; Geological Society of London: London, UK, 2010; Special Publications 334; pp. 263–283. [Google Scholar] [CrossRef]
  36. Scheuring, B.W. Palynologische und palynostratigraphische Utersuschungen des Keupers im Bölchentunnel (Solothurner Jura). Schweiz. Paläont. Abh. 1970, 88, 1–187. [Google Scholar]
  37. Scheuring, B.W. Mikrofloren aus den Meridelkalken des Monte San Giorgio (Kanton Tessin). Schweiz. Paläont. Abh. 1978, 100, 1–205. [Google Scholar]
  38. Visscher, H.; Van Route, M.; Brugman, W.A.; Poort, R.J. Rejection of a Carnian (Late Triassic) “pluvial event” in Europe. Rev. Palaeobot. Palynol. 1994, 83, 217–226. [Google Scholar] [CrossRef]
  39. Roghi, G. Palynological investigations in the Carnian of the Cave del Predil area (Julian Alps, NE Italy). Rev. Palaeobot. Palynol. 2004, 132, 1–35. [Google Scholar] [CrossRef]
  40. Zavialova, N.E.; Roghi, G. Exine morphology and ultrastructure of Duplicisporites from the Triassic of Italy. Grana 2005, 44, 337–342. [Google Scholar] [CrossRef]
  41. Buratti, N.; Cirilli, S. Microfloristic provincialism in the Upper Triassic Circum-Mediterranean area and palaeogeographic implication. Geobios 2007, 40, 133–142. [Google Scholar] [CrossRef]
  42. Roghi, G.; Gianolla, P.; Minarelli, L.; Pilati, C.; Preto, N. Palynological correlation of Carnian humid pulses throughout western Tethys. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2010, 290, 89–106. [Google Scholar] [CrossRef]
  43. Kustatscher, E.; Ash, S.; Karasev, E.; Pott, C.; Vajda, V.; Yu, J.; McLoughlin, S. Flora of the Late Triassic. In The Late Triassic World; Tanner, L.H., Ed.; Springer: Berlin/Heidelberg, Germany, 2017; Topics in Geobiology; 2018; Volume 46, pp. 545–622. [Google Scholar] [CrossRef]
  44. Balme, B.E. Fossil in situ spores and pollen grains: An annotated catalogue. Rev. Palaeobot. Palynol. 1995, 87, 1–323. [Google Scholar] [CrossRef]
  45. Looy, C.V.; Brugman, W.A.; Dilcher, D.L.; Visscher, H. The delayed resurgence of equatorial forests after the Permian–Triassic ecologic crisis. Proc. Natl. Acad. Sci. USA 1999, 96, 13857–13862. [Google Scholar] [CrossRef]
  46. Kustatscher, E.; Heunisch, C.; Van Konijnenburg-Van Cittert, J.H.A. Taphonomical implications of the Ladinian megaflora and palynoflora of Thale (Germany). Palaios 2012, 27, 753–764. [Google Scholar] [CrossRef]
  47. Lindström, S.; Erlström, M.; Piasecki, S.; Nielsen, L.H.; Mathiesen, A. Palynology and terrestrial ecosystem change of the Middle Triassic to lowermost Jurassic succession of the eastern Danish Basin. Rev. Palaeobot. Palynol. 2017, 244, 65–95. [Google Scholar] [CrossRef]
  48. Brugman, W.A.; Van Bergen, P.R.; Kerp, J.H.E. A quantitative approach to Triassic palynology: The Lettenkeuper of the Germanic Basin as an example. In Sedimentation of Organic Particles; Traverse, A., Ed.; Cambridge University Press: Cambridge, UK, 1994; pp. 409–430. [Google Scholar] [CrossRef]
  49. Césari, S.N.; Colombi, C. Palynology of the Late Triassic Ischigualasto Formation, Argentina: Paleoecological and paleogeographic implications. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2016, 449, 365–384. [Google Scholar] [CrossRef]
  50. Mueller, S.; Hounslow, M.W.; Kürschner, W.M. Integrated stratigraphy and palaeoclimate history of the Carnian Pluvial Event in the Boreal realm; new data from the Upper Triassic Kapp Toscana Group in central Spitsbergen (Norway). J. Geol. Soc. 2015, 173, 186–202. [Google Scholar] [CrossRef]
  51. Hochuli, P.A.; Hermann, E.; Vigran, J.O.; Bucher, H.; Weissert, H. Rapid demise and recovery of plant ecosystems across the end-Permian extinction event. Glob. Planet. Change 2010, 74, 144–155. [Google Scholar] [CrossRef]
  52. Lindström, S.; Vosgerau, H.; Piasecki, S.; Nielsen, L.H.; Dybkjær, K.; Erlström, M. Ladinian palynofloras in the Norwegian–Danish Basin: A regional marker reflecting a climate change. GEUS Bull. 2009, 17, 21–24. [Google Scholar] [CrossRef]
  53. Hauschke, N.; Heunisch, C. Lithologie und Palynologie der Bohrung USB 3 (Horn-Bad Meinberg, Ostwestfalen): Ein Beitrag zur Faziesentwicklung im Keuper. Neues Jahrb. Geol. Paläontol. Abh. 1990, 181, 79–105. [Google Scholar] [CrossRef]
  54. Vigran, J.O.; Mangerud, G.; Mørk, A.; Worsley, D.; Hochuli, P.A. Palynology and Geology of the Triassic Succession of Svalbard and the Barents Sea; Special Publication, 14; Geological Survey of Norway: Trondheim, Norway, 2014; p. 247. [Google Scholar] [CrossRef]
  55. Duringer, P.; Doubinger, J. La palynologie: Un outil de caractérisation des faciès marins et continentaux à la limite Muschelkalk supérieur—Lettenkohle. Sci. Géol. Bull. 1985, 38, 19–34. [Google Scholar]
Geosciences 15 00299 g001
Figure 1. Study area. (a) Geographical setting; (b) Geological setting based on several sheets of the Geological Map of Spain (MAGNA) at a 1:50,000 scale [9,10,11,12].
Figure 1. Study area. (a) Geographical setting; (b) Geological setting based on several sheets of the Geological Map of Spain (MAGNA) at a 1:50,000 scale [9,10,11,12].
Geosciences 15 00299 g001
Geosciences 15 00299 g002
Figure 2. Distribution of the stratigraphic sections and samples analyzed in the study, as well as facies correlation. Modified from [4].
Figure 2. Distribution of the stratigraphic sections and samples analyzed in the study, as well as facies correlation. Modified from [4].
Geosciences 15 00299 g002
Geosciences 15 00299 g003
Figure 3. Synthesis of the palynomorphs found in the study (1/4). (1) Calamospora tener RS9-2_3_P522, (2) Calamospora sp. RS1-5_A_G504, (3) Indeterminate spore RS2-1_O232, (4) Indeterminate trilete spore RS1-8_A_B420, (5) Indeterminate trilete spore 2 RS9-2_1_V221, (6) Cyclotriletes cf. microgranifer RS9-2_3_G153, (7) Kyrtomisporis ervii RS2-12_G304, (8) Deltoidospora sp.1 RS9-2_3_N274, (9) Deltoidospora sp.2 SS2-5_C_M270, (10) cf. Rewanispora sp. SS2-1_A_V144, (11) Punctatisporites sp.1 FC-1_L420, (12) Punctatisporites sp.3 RS9-2_BIS2_Q191, (13) Punctatisporites sp.2 753A_U293, (14) cf. Punctatisporites sp.2 SS2-5_B_C264, (15) cf. Punctatisporites sp.1 RS8-1_Q434, (16) Punctatisporites triassicus RS9-2_3_G133, (17) Punctatisporites subcarpaticus RS9-2_BIS2_C333, (18) Punctatisporites fungosus RS1-8_A_S271, (19) Todisporites minor SS2-1_C_O280, (20) Todisporites major RS4-2′_V273, (21) Verrucosisporites cf. contactus RS3-10_A_D334, (22) Verrucosisporites contactus RS8-2_A_Y333, (23) Verrucosisporites sp. RS2-8_B_D283, (24) Verrucosisporites aff. morulae SS2-1_C_t164, (25) Verrucosisporites morulae RS1-1_L480, (26) Verrucosisporites thuringiacus SS2-3_C_N333, (27) cf. Verrucosisporites sp. RS3-3_H300, (28) Palaeospongisporis europaeus RS2-8_B_D411, (29) Indeterminate reticulate spore RS2-12_E381, (30) Keuperisporites baculatus RS1-8_A_Y292, (31) cf. Convolutispora sp.1 RS8-1_Q230, (32) cf. Convolutispora sp.2 RS8-2_A_F270, (33) Reticulatisporites sp. RS1-1_Q473, (34) Aratrisporites granulatus RS2-12_O211, (35) Densoisporites sp. RS1-9_A_Z310.
Figure 3. Synthesis of the palynomorphs found in the study (1/4). (1) Calamospora tener RS9-2_3_P522, (2) Calamospora sp. RS1-5_A_G504, (3) Indeterminate spore RS2-1_O232, (4) Indeterminate trilete spore RS1-8_A_B420, (5) Indeterminate trilete spore 2 RS9-2_1_V221, (6) Cyclotriletes cf. microgranifer RS9-2_3_G153, (7) Kyrtomisporis ervii RS2-12_G304, (8) Deltoidospora sp.1 RS9-2_3_N274, (9) Deltoidospora sp.2 SS2-5_C_M270, (10) cf. Rewanispora sp. SS2-1_A_V144, (11) Punctatisporites sp.1 FC-1_L420, (12) Punctatisporites sp.3 RS9-2_BIS2_Q191, (13) Punctatisporites sp.2 753A_U293, (14) cf. Punctatisporites sp.2 SS2-5_B_C264, (15) cf. Punctatisporites sp.1 RS8-1_Q434, (16) Punctatisporites triassicus RS9-2_3_G133, (17) Punctatisporites subcarpaticus RS9-2_BIS2_C333, (18) Punctatisporites fungosus RS1-8_A_S271, (19) Todisporites minor SS2-1_C_O280, (20) Todisporites major RS4-2′_V273, (21) Verrucosisporites cf. contactus RS3-10_A_D334, (22) Verrucosisporites contactus RS8-2_A_Y333, (23) Verrucosisporites sp. RS2-8_B_D283, (24) Verrucosisporites aff. morulae SS2-1_C_t164, (25) Verrucosisporites morulae RS1-1_L480, (26) Verrucosisporites thuringiacus SS2-3_C_N333, (27) cf. Verrucosisporites sp. RS3-3_H300, (28) Palaeospongisporis europaeus RS2-8_B_D411, (29) Indeterminate reticulate spore RS2-12_E381, (30) Keuperisporites baculatus RS1-8_A_Y292, (31) cf. Convolutispora sp.1 RS8-1_Q230, (32) cf. Convolutispora sp.2 RS8-2_A_F270, (33) Reticulatisporites sp. RS1-1_Q473, (34) Aratrisporites granulatus RS2-12_O211, (35) Densoisporites sp. RS1-9_A_Z310.
Geosciences 15 00299 g003
Geosciences 15 00299 g004
Figure 4. Synthesis of the palynomorphs found in the study (2/4). (1) Monosulcites sp. RS3-4_G261, (2) Cycadopites sp.1 RS9-2_1_U222, (3) Cycadopites sp.2 RS9-2_BIS1_L134, (4) Indeterminate monocolpate RS3-2_E311, (5) Duplicisporites cf. granulatus BU-1_D_AA492, (6) Duplicisporites granulatus RS1-9_E_W474, (7) Duplicisporites granulatus RS9-2_1_F314, (8) Duplicisporites granulatus RS9-2_2_Y391, (9) Enzonalasporites sp. RS3-10_A_T204, (10) Indeterminate monosaccate SS2-2_D__T223, (11) Indeterminate monosaccate RS2-12_F251, (12) Indeterminate monosaccate FC-1_D473, (13) Indeterminate monosaccate RS9-2_2_J464, (14) Camerosporites secatus RS2-12_Y434, (15) Camerosporites secatus RS1-8_A_X460, (16) Duplicisporites mancus RS1-5_A_R522, (17) Indeterminate pollen grain SS2-2_D_H393, (18) Paracirculina sp. RS2-12_AA322, (19) Paracirculina scurrilis RS2-12_E260, (20) Duplicisporites tenebrosus RS1-2_B_V251, (21) Duplicisporites tenebrosus RS1-6_G274, (22) Haberkornia parva SS2-1_A_E200, (23) Praecirculina granifer RS1-5_B_D323, (24) Ovalipollis ovalis RS2-12_O500, (25) Ovalipollis sp. RS1-1_P310, (26) Ovalipollis cultus SS2-5_A_H233, (27) Ovalipollis notabilis RS2-12_H480, (28) Ovalipollis pseudoalatus SS2-2_A_L372, (29) Staurosaccites quadrifidus RS2-12_D313, (30) Triadispora cf. stabilis RS2-12_D480, (31) Triadispora sp. RS2-8_A_E323, (32) Triadispora sp. RS2-12_O464, (33) Triadispora suspecta RS2-12_Q471, (34) Triadispora staplinii RS9-2_4_G134, (35) Triadispora plicata RS2-12_Z380, (36) Triadispora crassa RS2-12_J314, (37) Triadispora epigona RS9-2_1_W500, (38) Triadispora falcata RS9-2_BIS1_D341, (39) Triadispora cf. staplinii BU-2_A_T394, (40) Triadispora cf. aurea RS9-2_1_F103, (41) Triadispora cf. suspecta BU-1_B_Z370, (42) Triadispora sp. RS2-12_Q460, (43) Striatoabieites sp.1 RS2-12_W371, (44) Striatoabieites sp.2 TH-1_A_M290, (45) Ellipsovelatisporites plicatus RS4-2_B_X563, (46) Illinites chitonoides RS1-9_E_N492, (47) Striatoabieites aytugii (body) RS9-2_2_J424, (48) Cuneatisporites radialis RS9-2_BIS4_U233, (49) Chordasporites singulichorda RS9-2_BIS1_X370, (50) Illinites sp. RS3-4_K263.
Figure 4. Synthesis of the palynomorphs found in the study (2/4). (1) Monosulcites sp. RS3-4_G261, (2) Cycadopites sp.1 RS9-2_1_U222, (3) Cycadopites sp.2 RS9-2_BIS1_L134, (4) Indeterminate monocolpate RS3-2_E311, (5) Duplicisporites cf. granulatus BU-1_D_AA492, (6) Duplicisporites granulatus RS1-9_E_W474, (7) Duplicisporites granulatus RS9-2_1_F314, (8) Duplicisporites granulatus RS9-2_2_Y391, (9) Enzonalasporites sp. RS3-10_A_T204, (10) Indeterminate monosaccate SS2-2_D__T223, (11) Indeterminate monosaccate RS2-12_F251, (12) Indeterminate monosaccate FC-1_D473, (13) Indeterminate monosaccate RS9-2_2_J464, (14) Camerosporites secatus RS2-12_Y434, (15) Camerosporites secatus RS1-8_A_X460, (16) Duplicisporites mancus RS1-5_A_R522, (17) Indeterminate pollen grain SS2-2_D_H393, (18) Paracirculina sp. RS2-12_AA322, (19) Paracirculina scurrilis RS2-12_E260, (20) Duplicisporites tenebrosus RS1-2_B_V251, (21) Duplicisporites tenebrosus RS1-6_G274, (22) Haberkornia parva SS2-1_A_E200, (23) Praecirculina granifer RS1-5_B_D323, (24) Ovalipollis ovalis RS2-12_O500, (25) Ovalipollis sp. RS1-1_P310, (26) Ovalipollis cultus SS2-5_A_H233, (27) Ovalipollis notabilis RS2-12_H480, (28) Ovalipollis pseudoalatus SS2-2_A_L372, (29) Staurosaccites quadrifidus RS2-12_D313, (30) Triadispora cf. stabilis RS2-12_D480, (31) Triadispora sp. RS2-8_A_E323, (32) Triadispora sp. RS2-12_O464, (33) Triadispora suspecta RS2-12_Q471, (34) Triadispora staplinii RS9-2_4_G134, (35) Triadispora plicata RS2-12_Z380, (36) Triadispora crassa RS2-12_J314, (37) Triadispora epigona RS9-2_1_W500, (38) Triadispora falcata RS9-2_BIS1_D341, (39) Triadispora cf. staplinii BU-2_A_T394, (40) Triadispora cf. aurea RS9-2_1_F103, (41) Triadispora cf. suspecta BU-1_B_Z370, (42) Triadispora sp. RS2-12_Q460, (43) Striatoabieites sp.1 RS2-12_W371, (44) Striatoabieites sp.2 TH-1_A_M290, (45) Ellipsovelatisporites plicatus RS4-2_B_X563, (46) Illinites chitonoides RS1-9_E_N492, (47) Striatoabieites aytugii (body) RS9-2_2_J424, (48) Cuneatisporites radialis RS9-2_BIS4_U233, (49) Chordasporites singulichorda RS9-2_BIS1_X370, (50) Illinites sp. RS3-4_K263.
Geosciences 15 00299 g004
Geosciences 15 00299 g005
Figure 5. Synthesis of the palynomorphs found in the study (3/4). (1) Microcachryidites cf. doubingeri RS1-8_A_O300, (2) Microcachryidites sp. SS2-3_C_H342, (3) Microcachryiditesdoubingeri RS2-2_E501, (4) Microcachryidites fastidioides SS2-6_B_D143, (5a) Platysaccus sp. SS2-5_B_L334, (5b) Camerosporites secatus SS2-5_B_L334, (6) Platysaccus sp. RS9-2_1_X320, (7) Platysaccus cf. cacheutensis RS2-12_F284, (8) Angustisulcites klausii RS9-2_BIS1_S322, (9) Platysaccus sp.1 RS1-3_C313, (10) Platysaccus queenslandi RS2-11_P472, (11) Platysaccus cf. papilionis SS2-5_A_N410, (12) Platysaccus papilionis RS8-1_S363, (13) Alisporites grauvogeli RS3-8_K280, (14) Alisporites sp. RS9-2_BIS4_Z360, (15) Alisporites splendens RS2-10_A_P480, (16) Alisporites sp. RS9-2_BIS3_W420, (17) Alisporites cf. opii RS2-8_B_M323, (18) Alisporites progrediens RS2-10_A_Q300.
Figure 5. Synthesis of the palynomorphs found in the study (3/4). (1) Microcachryidites cf. doubingeri RS1-8_A_O300, (2) Microcachryidites sp. SS2-3_C_H342, (3) Microcachryiditesdoubingeri RS2-2_E501, (4) Microcachryidites fastidioides SS2-6_B_D143, (5a) Platysaccus sp. SS2-5_B_L334, (5b) Camerosporites secatus SS2-5_B_L334, (6) Platysaccus sp. RS9-2_1_X320, (7) Platysaccus cf. cacheutensis RS2-12_F284, (8) Angustisulcites klausii RS9-2_BIS1_S322, (9) Platysaccus sp.1 RS1-3_C313, (10) Platysaccus queenslandi RS2-11_P472, (11) Platysaccus cf. papilionis SS2-5_A_N410, (12) Platysaccus papilionis RS8-1_S363, (13) Alisporites grauvogeli RS3-8_K280, (14) Alisporites sp. RS9-2_BIS4_Z360, (15) Alisporites splendens RS2-10_A_P480, (16) Alisporites sp. RS9-2_BIS3_W420, (17) Alisporites cf. opii RS2-8_B_M323, (18) Alisporites progrediens RS2-10_A_Q300.
Geosciences 15 00299 g005
Geosciences 15 00299 g006
Figure 6. Synthesis of the palynomorphs found in the study (4/4). (1) Indeterminate bisaccate RS9-2_1_F460, (2) Indeterminate bisaccate RS8-2_B_V240, (3) Indeterminate bisaccate RS9-2_1_W194, (4) Indeterminate bisaccate RS1-1_E314, (5) Indeterminate bisaccate RS2-2_W390, (6) Indeterminate bisaccate RS9-2_BIS3_U350, (7) Mutant bisaccate RS2-12_H303, (8) Indeterminate bisaccate RS2-12_H250, (9) Indeterminate bisaccate RS2-10_B_Z411, (10) Indeterminate bisaccate RS8-1_T330, (11) Plaesiodictyon mosellanum RS9-2_BIS2_E140, (12) Crassosphaera sp.2 RS3-2_H531, (13) Crassosphaera sp.1 RS3-2_C280, (14) Crassosphaera sp.1 SS2-2_D_S513.
Figure 6. Synthesis of the palynomorphs found in the study (4/4). (1) Indeterminate bisaccate RS9-2_1_F460, (2) Indeterminate bisaccate RS8-2_B_V240, (3) Indeterminate bisaccate RS9-2_1_W194, (4) Indeterminate bisaccate RS1-1_E314, (5) Indeterminate bisaccate RS2-2_W390, (6) Indeterminate bisaccate RS9-2_BIS3_U350, (7) Mutant bisaccate RS2-12_H303, (8) Indeterminate bisaccate RS2-12_H250, (9) Indeterminate bisaccate RS2-10_B_Z411, (10) Indeterminate bisaccate RS8-1_T330, (11) Plaesiodictyon mosellanum RS9-2_BIS2_E140, (12) Crassosphaera sp.2 RS3-2_H531, (13) Crassosphaera sp.1 RS3-2_C280, (14) Crassosphaera sp.1 SS2-2_D_S513.
Geosciences 15 00299 g006
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

García-Ávila, M.; García-Gil, S.; Diez, J.B. Palynostratigraphy of the “Muschelkalk Sedimentary Cycle” in the NW Iberian Range, Central Spain. Geosciences 2025, 15, 299. https://doi.org/10.3390/geosciences15080299

AMA Style

García-Ávila M, García-Gil S, Diez JB. Palynostratigraphy of the “Muschelkalk Sedimentary Cycle” in the NW Iberian Range, Central Spain. Geosciences. 2025; 15(8):299. https://doi.org/10.3390/geosciences15080299

Chicago/Turabian Style

García-Ávila, Manuel, Soledad García-Gil, and José B. Diez. 2025. "Palynostratigraphy of the “Muschelkalk Sedimentary Cycle” in the NW Iberian Range, Central Spain" Geosciences 15, no. 8: 299. https://doi.org/10.3390/geosciences15080299

APA Style

García-Ávila, M., García-Gil, S., & Diez, J. B. (2025). Palynostratigraphy of the “Muschelkalk Sedimentary Cycle” in the NW Iberian Range, Central Spain. Geosciences, 15(8), 299. https://doi.org/10.3390/geosciences15080299

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop