geosciences
Review The Cenozoic Malaguide Basin from Sierra Espuña (Murcia, S Spain): An Example of Geological Heritage
Santiago Moliner-Aznar 1, Manuel Martín-Martín 1,* , Tomás Rodríguez-Estrella 2 and Gregorio Romero-Sánchez 3
1 Department of Earth and Environmental Sciences, University of Alicante, 03080 Alicante, Spain; [email protected] 2 Departamento de Ingeniería Minera, Geológica y Cartográfica, Universidad Politécnica de Cartagena, 30202 Murcia, Spain; [email protected] 3 Servicio de Patrimonio Histórico, Consejería de Educación y Cultura de la Región de Murcia, 30005 Murcia, Spain; [email protected] * Correspondence: [email protected]
Abstract: The Cenozoic Malaguide Basin from Sierra Espuña (Internal Betic Zone, S Spain) due to the quality of outcropping, areal representation, and continuity in the sedimentation can be considered a key-basin. In the last 30 years, a large number of studies with very different methodological approaches have been done in the area. Models indicate an evolution from passive margin to wedge- top basin from Late Cretaceous to Early Miocene. Sedimentation changes from limestone platforms with scarce terrigenous inputs, during the Paleocene to Early Oligocene, to the deep basin with huge supplies of turbidite sandstones and conglomerates during the Late Oligocene to Early Miocene. The area now appears structured as an antiformal stack with evidence of synsedimentary tectonics. The Cenozoic tectono-sedimentary basin evolution is related to three phases: (1) flexural tectonics during most of the Paleogene times to create the basin; (2) fault and fold compartmentation of the
Citation: Moliner-Aznar, S.; basin with the creation of structural highs and subsiding areas related to blind-fault-propagation Martín-Martín, M.; folds, deforming the basin from south to north during Late Oligocene to Early Aquitanian times; Rodríguez-Estrella, T.; (3) thin-skin thrusting tectonics when the basin began to be eroded during the Late Aquitanian- Romero-Sánchez, G. The Cenozoic Burdigalian. In recent times some works on the geological heritage of the area have been performed Malaguide Basin from Sierra Espuña trying to diffuse different geological aspects of the sector to the general public. A review of the (Murcia, S Spain): An Example of studies performed and the revisiting of the area allow proposing different key-outcrops to follow the Geological Heritage. Geosciences 2021, tectono-sedimentary evolution of the Cenozoic basin from this area. Eight sites of geological interest 11, 34. https://doi.org/10.3390/ have been selected (Cretaceous-Cenozoic boundary, Paleocene Mula Fm, Lower Eocene Espuña- geosciences11010034 Valdelaparra Fms, Middle Eocene Malvariche-Cánovas Fms, Lowermost Oligocene As Fm, Upper Oligocene-Lower Aquitanian Bosque Fm, Upper Oligocene-Aquitanian Río Pliego Fm, Burdigalian Received: 1 December 2020 Accepted: 8 January 2021 El Niño Fm) and an evaluation has been performed to obtain four parameters: the scientific value, Published: 10 January 2021 the educational and touristic potential, and the degradation risk. The firsts three parameters obtained values above 50 being considered of “high” or “very high” interest (“very high” in most of the Publisher’s Note: MDPI stays neu- cases). The last parameter shows always values below 50 indicating a “moderate” or “low” risk of tral with regard to jurisdictional clai- degradation. The obtained values allow us considering the tectono-sedimentary evolution of this ms in published maps and institutio- basin worthy of being proposed as a geological heritage. nal affiliations. Keywords: Sierra Espuña; Cenozoic; wedge-top basin; tectono-sedimentary evolution; geologi- cal heritage
Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- 1. Introduction ditions of the Creative Commons At- The Sierra Espuña area is located in the Murcia province in SE Spain (Figure1A,B). tribution (CC BY) license (https:// The area is located around the towns of Alhama de Murcia and Totana, to the south, Pliego, creativecommons.org/licenses/by/ in the center, and Mula, to the north (Figure1A). 4.0/).
Geosciences 2021, 11, 34. https://doi.org/10.3390/geosciences11010034 https://www.mdpi.com/journal/geosciences Geosciences 2021, 11, 34 2 of 24 Geosciences 2021, 11, 34 2 of 24
Figure 1. Geographical and geological location of the Sierra Espuña area (modified from [1]). (A) Geographic locations in Figure 1. Geographical and geological location of the Sierra Espuña area (modified from [1]). (A) Geographic locations in the Murcia province (SE Spain). (B) Geographic location in the framework of the western Mediterranean alpine chains. the Murcia province (SE Spain). (B) Geographic location in the framework of the western Mediterranean alpine chains. (C) (C) Paleogeographic sketch in Cretaceous times of the western Mediterranean area. (D) Geological map of the Sierra Es- D puñaPaleogeographic area including sketch Sierra in CretaceousEspuña s.s. timesand the of Mula the western-Pliego MediterraneanDepression. (E) area.Geological ( ) Geological cross-section map of of the the area Sierra located Espuña in (areaD). The including location Sierra of the Espuña sites of s.s. geological and the Mula-Pliegointerest appears Depression. in (D). (E) Geological cross-section of the area located in (D). The location of the sites of geological interest appears in (D). This area belongs to the Malaguide Complex from the Internal Betic Cordillera [2,3]. The Internal Zone of this cordillera usually shows metamorphic rocks (Nevado-Filabride
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This area belongs to the Malaguide Complex from the Internal Betic Cordillera [2,3]. The Internal Zone of this cordillera usually shows metamorphic rocks (Nevado-Filabride and Alpujarride complexes) and only the Malaguide Complex shows a sedimentary (or epimetamorphic) basement and cover. The Betic Cordillera belongs to the Alpine chains of the western Mediterranean area (Figure1B) and formed during the Cretaceous to Miocene in response to continental collisions between the Mesomediterranean Microplate and the Iberia-Europe and Africa plates. This led to the closure of seaways and subductions in the western Tethys (Figure1C) [4–11]. The area exhibits the Mesozoic-Cenozoic cover from the Malaguide Complex, struc- tured in an antiformal stack [2,12–14], in the southern part (Sierra Espuña s.s.). This is followed to the north by a synclinorium (Mula-Pliego Depression) with minor structural highs related to fold-thrust (Figure1D,E). The whole area consists of metamorphic (the lower units from the Alpujarride Complex) and sedimentary rocks (the upper two from the Malaguide Complex: Morrón de Totana and Perona units) ranging from the Paleozoic to the Miocene (Figure1B). The area has outcrops of good quality and a quite continuous sedimentary record from the Cenozoic succession so that a large number of papers have been published in the area in the last three decades (see below). In particular, the Paleocene to Early Miocene tectono-sedimentary evolution has been the subject of numerous research papers making this basin a key-site for understanding the Cenozoic tectonostratigraphic of the region. This paper has two scientific focuses: (1) the reviewing of the knowledge of the area, in general, and the Cenozoic, in particular; (2) the proposal of this Cenozoic record as geological heritage. So, this paper aims to show the Cenozoic tectono-sedimentary evolution of the Sierra Espuña as a key area and propose it as a geological heritage. This fact is already mentioned in the previous literature [2,3], and references therein) where the quality of outcropping of this tectonic complex from the Internal Betic Zone, is highlighted. To do this, eight sites of geological interest have been selected and evaluated according to recent methodologies [15,16].
2. Backgrounds Former studies in the area were carried out by [17–27]. These works introduced the “nappe tectonics” concepts in the area. The involved units were defined and the main structural features of the nappes were established. These studies also proposed a basic stratigraphy and the approximate ages of the sedimentary record. Studied of the Cenozoic Malaguide Basin in the Sierra Espuña area revived in the late nineties by [28] and related papers providing new insight into the structure and stratigraphy of the Cenozoic sediments of the area. These papers addressed the timing of deformation in the area, the stratigraphy of Cenozoic formations, and the structure of the Cenozoic sediments [29]. Detailed works were performed on the early Oligocene As Fm related to the beginning of Cenozoic deformation in the area [30] and the Paleocene Mula Fm of the Malaguide Complex [31]. More recent papers related to the structure and/or tectono-sedimentary evolution of the area include [5,6,11,12,32]. They redefine the cartographic boundaries, stratigraphy and direction of emplacement of the tectonic units. These authors classified the Cenozoic Malaguide basin of Sierra Espuña as a piggy-back. The mineralogy and petrography of Cenozoic formations were described by [2]. Most recently, the Paleocene-Early Eocene platform deposits of the Sierra Espuña area have been recently studied by [1]. Some books and papers have also been published about the area in recent times high- lighting the geological heritage of the area and presenting it to the general public [33–35]. These works pointed out some sites of geological interest and georoutes in the area but no evaluation was performed. Geosciences 2021, 11, 34 4 of 24
(Figure 2): the lower one (Paleocene to Earliest Oligocene) is considered pre-orogenic since it is deposited before the older thrusts affecting the Malaguide Complex reached the sur- face. Nevertheless, flexural tectonics due to basement folding took place during this cycle. The upper cycle (Late Oligocene to Burdigalian) is considered syn-orogenic and deposited contemporaneously to the thin-skin thrusting tectonics which affected the entire Internal Betic Zone. The pre-orogenic cycle includes six stratigraphic formations separated by lateral changes or unconformities (Figures 1 and 2). The older is the Mula Fm (Paleocene) con- sisting of marine carbonate platform and continental deposits and is separated from the underlying Upper Cretaceous deep marine Capas Blancas Fm by an erosional unconform- ity with a minor hiatus affecting the Upper Cretaceous p.p. The Mula Fm is separated from the overlying formations by a stratigraphic gap (unconformity and temporal hiatus) rep- resenting the Lower Ypresian (Ilerdian). Following this gap is the Cuisian to Lower Lute- tian Espuña Fm, representing an alveoloine-Nummelite platform, and its proximal lateral equivalent, the Valdeparra Fm, consisting of lagoon- and marsh-deposits with coal). The top of both formations is a new erosive contact with minor hiatus associated. It separates Geosciences 2021, 11, 34 the overlying Middle Lutetian to Upper Bartonian alveoline-Nummelites internal 4plat- of 24 form deposits of the Malvariche Fm. The latter (interfingers) into the marly Nummulite external platform deposits belonging to the Cánovas Fm (Lower Bartonian-Priabonian). The Canovas is unconformably overlain by the Lower Rupelian As Fm, consisting of marshy3. Stratigraphic-lagoonal Framework and deltaic ofdeposits the Cenozoic (with quartzite Malaguide rounded Basin pebbles). from Sierra The Espuñasyn-orogenic cycleAccording includes three to literature, units (deposited the Cenozoic in a syn of- thetectonic Malaguide setting) Complex (Figures in 1 and the Sierra2). The Espuña Upper Oligocenearea comprises to Aquitanian nine stratigraphic Bosque formationsFm consists arranged of deltaic into conglomerate, two main sedimentary and limestone cycles to (Figuremarly platfor2): them lower deposits, one which (Paleocene are separated to Earliest from Oligocene) the underlying is considered As Fm pre-orogenicby an erosive unconformity.since it is deposited The Bosque before theFm older fingers thrusts laterally affecting into, theand Malaguide is overlain Complex by turbidites reached of the Riosurface. Pliego, Nevertheless, which in turn flexural are overlain tectonics by due the toBurdigalian basement foldingdeep marine took placemarls, during turbidites this andcycle. silexites The upper of the cycle El Niño (Late Fm. Oligocene The latter to predate Burdigalian)s the Internal is considered-External syn-orogenic Zone Boundary and suturedeposited [31] contemporaneously; the back thrusting toof the thin-skinExternal over thrusting the Internal tectonics Zone which marks affected the end the entireof the CenozoicInternal Betic Malaguide Zone. Basin.
Figure 2. Stratigraphic framework with the chronostratigraphic range of Cenozoic formations of the Malaguide basin fromfrom Sierra Espuña (modified from [1]). Sierra Espuña (modified from [1]).
The pre-orogenic cycle includes six stratigraphic formations separated by lateral changes or unconformities (Figures1 and2). The older is the Mula Fm (Paleocene) con- sisting of marine carbonate platform and continental deposits and is separated from the underlying Upper Cretaceous deep marine Capas Blancas Fm by an erosional unconfor- mity with a minor hiatus affecting the Upper Cretaceous p.p. The Mula Fm is separated from the overlying formations by a stratigraphic gap (unconformity and temporal hiatus) representing the Lower Ypresian (Ilerdian). Following this gap is the Cuisian to Lower Lutetian Espuña Fm, representing an alveoloine-Nummelite platform, and its proximal lateral equivalent, the Valdeparra Fm, consisting of lagoon- and marsh-deposits with coal). The top of both formations is a new erosive contact with minor hiatus associated. It sep- arates the overlying Middle Lutetian to Upper Bartonian alveoline-Nummelites internal platform deposits of the Malvariche Fm. The latter (interfingers) into the marly Nummulite external platform deposits belonging to the Cánovas Fm (Lower Bartonian-Priabonian). The Canovas is unconformably overlain by the Lower Rupelian As Fm, consisting of marshy-lagoonal and deltaic deposits (with quartzite rounded pebbles). The syn-orogenic cycle includes three units (deposited in a syn-tectonic setting) (Figures1 and2). The Upper Oligocene to Aquitanian Bosque Fm consists of deltaic conglomerate, and limestone to marly platform deposits, which are separated from the underlying As Fm by an erosive unconformity. The Bosque Fm fingers laterally into, and is overlain by turbidites of the Rio Pliego, which in turn are overlain by the Burdigalian deep marine marls, turbidites and silexites of the El Niño Fm. The latter predates the Internal-External Zone Boundary Geosciences 2021, 11, 34 5 of 24
Geosciences 2021, 11, 34 5 of 24 4. Tectono-Sedimentary Evolution of the Cenozoic Malaguide Basin from Sierra Espuña sutureThe [31 study]; the backarea is thrusting made up of of the several External Malaguide over the tectonic Internal units Zone (nappes) marks the divided end of into the Cenozoiclower units Malaguide (mainly Basin. metamorphosed) and upper units (with a sedimentary character) (Figure 1D). The upper tectonic units are two: the Morrón de Totana unit, in the lower 4.position, Tectono-Sedimentary and the Perona Evolutionunit, in the of upper the Cenozoic position ( MalaguideFigures 1D Basinand 3). from In turn, the Mala- Sierraguide units Espuña (both lower and upper ones) are thrusting to the Alpujarride tectonic units (in the middleThe study position area in is madethe pile up of of nappes several of Malaguide the Internal tectonic Betic Zone). units (nappes)The Cenozoic divided geody- into lowernamic unitsframework (mainly of the metamorphosed) study area was andvery upper complex units and (with marked a sedimentary by different character)structural (Figurestages [2,6,131D). The] that upper strongly tectonic influenced units are thetwo: evolution the Morr and sedimentationón de Totanaunit, of the in basin. the lower Dur- position,ing this period, and the convergence Perona unit, took in place theupper between position the Internal (Figures Betic1D Units and3 (belonging). In turn, to the the Malaguidewestern and units southern (both margin lower and of the upper Mesomediterranean ones) are thrusting Microplate) to the Alpujarride and the External tectonic unitsBetic (inUnits the (belonging middle position to the in Iberian the pile plate) of nappes as represented of the Internal in Figure Betic 1C. Zone). The The convergence Cenozoic geodynamicstarted in the framework Latest Cretaceous, of the study and areaprogressed was very until complex the Eocene and- markedOligocene by bounda differentry structuralwith the superposition stages [2,6,13 of] the that Malaguide strongly influencedtectonic units the over evolution the lower and Alpujarride sedimentation tectonic of theunits basin. from Duringthe Internal this period,Zone (Figure convergence 3A) [6,13 took]. Later place a betweensecond superposition the Internal Betic stage Units took (belongingplace in the to Middle the western Oligocene. and southern In this margincase, the of theupper Mesomediterranean Malaguide Perona Microplate) unit was andup- thethrusted External over Betic the Morron Units (belonging de Totana to one the (Figure Iberian 3B), plate) generating as represented related in structures Figure1C. in The the convergencesouthern studied started area in as the the Latest Espuña Cretaceous, fold. During and the progressed Burdigalian, until the the westward Eocene-Oligocene displace- boundaryment of the with Internal the superposition Betic Zone and of the collision Malaguide against tectonic the External units over Zo thenes lower probably Alpujarride caused tectonicthe rotation units of from the units the Internal located Zone along (Figure with the3A) I [nternal6,13]. Later–External a second Zone superposition contact [6]. stage tookThe place Cenozoic in the Middle of this Oligocene.area was arranged In this case,into t thewo main upper sedimentary Malaguide Peronacycles [6,8 unit]). wasThe up-thrusted over the Morron de Totana one (Figure3B), generating related structures older is: Paleocene to Earliest Oligocene (preorogenic) and deposited contemporaneously in the southern studied area as the Espuña fold. During the Burdigalian, the westward to the deep tectonics (Figure 3A). The younger is Late Oligocene to Burdigalian (syn-oro- displacement of the Internal Betic Zone and collision against the External Zones probably genic) and deposited contemporaneously to the progression of thrustings in thin skin tec- caused the rotation of the units located along with the Internal–External Zone contact [6]. tonics affecting the entire Internal Betic Zone (Figure 3B).
FigureFigure 3.3. InterpretativeInterpretative tectono-sedimentary tectono-sedimentary cross-sections cross-sections of of the the Malaguide Malaguide Basin Basin from from Sierra Sierra Espuña Espuña (modified (modified from from [1]). [1]). (A) Preorogenic Cycle (Paleocene-Earliest Oligocene). (B) Syn-orogenic Cycle (Late Oligocene-Early Miocene). (A) Preorogenic Cycle (Paleocene-Earliest Oligocene). (B) Syn-orogenic Cycle (Late Oligocene-Early Miocene).
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The Cenozoic of this area was arranged into two main sedimentary cycles [6,8]). The older is: Paleocene to Earliest Oligocene (preorogenic) and deposited contemporaneously to the deep tectonics (Figure3A). The younger is Late Oligocene to Burdigalian (syn-orogenic) and deposited contemporaneously to the progression of thrustings in thin skin tectonics affecting the entire Internal Betic Zone (Figure3B). This division is accepted (with minor variation in the age) and equivalent for the Central-Western Alpine Chains (Apennines, Rif, Tell, and Betics). The mentioned evolution is due to the closure of the Tethyan Ocean [4,8]. After the tectonic inversion (from spreading to convergence), although this ocean started to close, the compressive conditions only provoked basement folding (deep tectonic) during most of the Paleogene, reflected in the surface by the rising of minor reliefs in the anticlines and the appearance of unconformities and lateral change of facies in the sedimentary record of the basins (usually synclines). This period is considered and mostly accepted in the literature as pre-orogenic. The first important and thin-skin tectonic manifestation took place at the middle Oligocene (just after the As Fm deposition in the study area) when subduction and collision of blocks should take place in the Tethyan area. So, deposition during the Late Oligocene to Miocene is contemporaneous to the nappe tectonic and considered and mostly accepted in the literature as a syntectonic cycle. Based on the interpreted tectono-sedimentary evolution, the development of the Cenozoic Malaguide Basin can be divided into three stages [12] (Figure4): (1) a flexural carbonate marine stage during almost the entire Paleogene; (2) a mixed carbonate and terrigenous marine stage during the Latest Oligocene-Earliest Aquitanian; (3) a terrigenous deep marine stage during the rest of the Aquitanian and Burdigalian. The flexural carbonate marine stage is coincident with the sedimentary pre-orogenic cycle. In this period the terrigenous sedimentation was very scarce and coming from the southern margin of the basin, while tectonics was restricted to basement folding, stacking of units at a deep level, and propagation of blind thrust not manifested at upper tectonic level (Figure4). The following two sedimentary stages coincided with the syn-orogenic evolution of the basin. Mixed carbonate and terrigenous deposition commenced as structures along the basin margins rose above sea-level, particularly in the south, where sediments were sourced from Jurassic to Cenozoic carbonate sediments. During this period, the basin was segmented and compartmentalized by the fold propagation faults, creating a series of local structural highs and subsiding local basins. Finally, the terrigenous deep marine stage clearly shows the paroxysmal tectonics in the area with the main source area from the northern boundary of the basin (basement and Triassic sediments) coincident with a nappe and superficial tectonics. After this, the Internal Zone was back-thrusted by the External at the Latest Burdi- galian, terminating the development of the Cenozoic Malaguide Basin. Geosciences 2021, 11, 34 7 of 24 Geosciences 2021, 11, 34 7 of 24
Figure 4. Tectono-sedimentary evolution of the Malaguide Cenozoic basin from Sierra Espuña area (modified from [12]). Figure 4. Tectono-sedimentary evolution of the Malaguide Cenozoic basin from Sierra Espuña area (modified from [12]). 5. Sites of Geological Interest 5. Sites of Geological Interest Eight sites have been selected in order to show the tectono-sedimentary evolution of Eight sites have been selected in order to show the tectono-sedimentary evolution of the Cenozoic Malaguide Basin from Sierra Espuña area (Figures 1D,E and 2), as follow: the Cenozoic Malaguide Basin from Sierra Espuña area (Figures1D,E and2), as follow: (1) Cretaceous-Cenozoic boundary in the Malvariche Valley; (2) the Paleocene Mula Fm (1) Cretaceous-Cenozoic boundary in the Malvariche Valley; (2) the Paleocene Mula Fm in in the Doñana sector; (3) the Lower Eocene Espuña and Valdelaparra Fms from Mal- the Doñana sector; (3) the Lower Eocene Espuña and Valdelaparra Fms from Malvariche variche Valley; (4) the Middle-Upper Eocene Malvariche and Cánovas Fms from Mal- Valley; (4) the Middle-Upper Eocene Malvariche and Cánovas Fms from Malvariche Valley; variche Valley; (5) the Lowermost Oligocene As Fm from Malvariche Valley; (6) the Upper (5) the Lowermost Oligocene As Fm from Malvariche Valley; (6) the Upper Oligocene Oligocene Bosque Fm in the Cejo de las Palomas area (Casas Nuevas); (7) the Aquitanian Bosque Fm in the Cejo de las Palomas area (Casas Nuevas); (7) the Aquitanian turbidite turbidite Río Pliego Fm in the Mula area; (8) the Burdigalian silexites from the Niño Fm Río Pliego Fm in the Mula area; (8) the Burdigalian silexites from the Niño Fm at the El at the El Niño de Mula area. Niño de Mula area.
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5.1. The Cretaceous-Cenozoic Boundary in the Malvariche Valley 5.1. ThisThe Cretaceous site is located-Cenozoic on theBoundary Malvariche in the Malvariche forest trail Valley (37◦ 52034.700 N 1◦36007.000 W) from SierraThis Espuña site (Figureis located1D,E). on the It wasMalvariche discovered forest and trail studied (37°52′34. by7 Mart″ N 1°3ín-Mart6′07.0″í nW) [28 from] and is consideredSierra Espuña the ( bestFigure outcrop 1D,E). illustratingIt was discovered the stratigraphic and studied Cretaceous-Cenozoic by Martín-Martín [28] boundaryand is inconsidered the Malaguide the best Basin. outcrop This illustrating area belongs the tostratigraphic the southern Cretaceous and most-Cenoz activeoic margin boundary of the basinin the at Malaguide this period. Basin. The areaThis appearsarea belongs structured to the southern as a vertical and ormost reversed active monoclinemargin of the series belongingbasin at this to period. the N flankThe area of appears the Espuña structured Fold (Figureas a vertical5A). or The reversed Lower monocline Eocene (Cuisian) series Espuñabelonging Fm to directly the N overliesflank of thethe UpperEspuña Cretaceous Fold (Figure Capas 5A). BlancasThe Lower Fm Eocene with a cartographic(Cuisian) unconformityEspuña Fm directly (Figure overlies5A). An the erosive Upper gapCretaceous affecting Capas the entireBlancas Paleocene Fm with a and cartographic the Ilerdian (Lowerunconformity Ypresian) (Figure is registered 5A). An erosive due to thegap syn-sedimentaryaffecting the entire deformation Paleocene and (uplifting) the Ilerdian of the margin(Lower of Ypresian) the basin. is registered The preserved due to thicknessthe syn-sedimentary of the Paleocene deformation succession (uplifting) in the of centralthe partmargin of the of the basin basin. varies. The preserved Site 1 consists thickness of anof outcropthe Paleocene with succession calcareous in conglomerates, the central marlypart of limestones, the basin varies. and limestone Site 1 consists pebbles of an (Figure outcrop5B,C) with eroded calcareous from conglomerates, the underlying marly Capas Blancaslimestones Fm., and Rounded limestone quartz pebbles grains (Figure and 5B pebbles,C) eroded (Figure from5 C)the from underlying the erosion Capas ofBlan- lower quartzitecas Fm. R levelounded of thequartz Malaguide grains and cover pebbles (Triassic) (Figure and 5C) basement from the erosion (Paleozoic) of lower can quartz- be found. Thisite level level of is the the Malaguide first evidence cover of (Triassic) terrigenous and inputbasement after (Paleozoic) the tectonic can inversion be found. in This which thelevel regional is the tectonicfirst evidence framework of terrigenous passes frominput extensionalafter the tectonic to compressional inversion in which at the the Latest regional tectonic framework passes from extensional to compressional at the Latest Cre- Cretaceous period. taceous period.
Figure 5. Site 1: Cretaceous-Cenozoic boundary from the Cenozoic Malaguide Basin from Sierra Espuña. (A) Geological Figure 5. Site 1: Cretaceous-Cenozoic boundary from the Cenozoic Malaguide Basin from Sierra Espuña. (A) Geological cross-section in the Malvariche Valley of the Cretaceous-Cenozoic boundary. (B) Conglomerate with marly limestone and cross-section in the Malvariche Valley of the Cretaceous-Cenozoic boundary. (B) Conglomerate with marly limestone and quartzite pebbles in the Cretaceous-Cenozoic boundary. (C) Detail of the conglomerate with marly limestone and quartzite pebbles in the Cretaceous-Cenozoic boundary. (D) Detail of Cretaceous marly limestone pebble.
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Geosciencesquartzite2021, pebbles11, 34 in the Cretaceous-Cenozoic boundary. (C) Detail of the conglomerate with marly limestone and quartzite9 of 24 pebbles in the Cretaceous-Cenozoic boundary. (D) Detail of Cretaceous marly limestone pebble.
5.2. The Paleocene Mula Fm in the Doñana Area 5.2. The Paleocene Mula Fm in the Doñana Area This site is located in the Doñana area next to the El Niño de Mula location ◦ 0 00 (38°0This1′34.2″ site N is 1°3 located2′14.3″ in theW) Doñanafrom the area Mula next-Plieg to theo Depression El Niño de Mula (Figure location 1D). It (38 was01 discov-34.2 N ◦ 0 00 ered1 32 14.3and studiedW) from by the Martín Mula-Pliego-Martín Depression [28] and Martín (Figure-Martín1D). It waset al. discovered [1,31] and and it has studied been selectedby Martí n-Martas an exampleín [28] and of Martthe Paleoceneín-Martín etevolution al. [1,31] of and the it hasbasin. been The selected bedding as anin examplethe area dipsof the gently Paleocene towards evolution NW. A of rhythm the basin.ic succession The bedding is made in the of area greyish dips gentlylimestones towards and NW.sandy A marlsrhythmic outcrops succession (Figure is made 6A,B) of representing greyish limestones several and environments sandy marls (from outcrops the lagoon (Figure 6toA,B) the externalrepresenting platform) several of environmentsa classic ramp (from platform the lagoonwith the to dominance the external of platform) larger foraminifera of a classic ramp platform with the dominance of larger foraminifera and patch corals. This platform and patch corals. This platform was oriented SE-NW from shallow to deep (Figure 6C). It was oriented SE-NW from shallow to deep (Figure6C). It belongs to the beginning of the belongs to the beginning of the preorogenic cycle of the sedimentation in the basin [2] preorogenic cycle of the sedimentation in the basin [2] when the flexural stage of the basin when the flexural stage of the basin took place and the antiformal stack and Espuña Fold took place and the antiformal stack and Espuña Fold were created (Figures3A and4)[ 12]. were created (Figures 3A and 4) [12].
Figure 6. Site 2: The Paleocene Mula Fm in the Doñana area. (A) Field outcrops of the Paleocene Mula Fm in the Doñana Figure 6. Site 2: The Paleocene Mula Fm in the Doñana area. (A) Field outcrops of the Paleocene Mula Fm in the Doñana area. (B) Detail of the Mula Fm in the Doñana area. (C) Interpretative paleoecological model of the Mula Fm (modified B C fromarea. [1 ( ])). Detail of the Mula Fm in the Doñana area. ( ) Interpretative paleoecological model of the Mula Fm (modified from [1]). 5.3. The Lower Eocene Espuña and Valdelaparra Fms in the Malvariche Valley 5.3. TheThis Lower site is Eocene located Espuña on the and Malvariche Valdelaparra forest Fms intrail the (37°5 Malvariche2′46.3″ Valley N 1°36′07.7″ W) from SierraThis Espuña site is(Figure located 1D, onE). the Some Malvariche papers have forest been trail published (37◦52046.3 on00 N this 1◦ 36outcrop007.700 W)[1,28 from,29] andSierra it has Espuña been (Figure selected1D,E). as an Some example papers of havethe Lower been publishedEocene evolution on this outcropof the basin. [ 1,28 The,29] areaand itappears has been structured selected with as an an example NW dipping of the as Lower part of Eocene the northern evolution flank of theof the basin. Espuña The Foldarea appears(Figure 5A). structured Espuña with Fm (massive an NW dipping of thick as stratified part of thecarbonate northern marine flank platform) of the Espuña and ValdelaparraFold (Figure5 A).Fm Espuña(lagoon) Fm are (massive two laterally of thick related stratified formations carbonate (Figure marine 1D). platform) The Espuña and FmValdelaparra consists of Fm alveolina, (lagoon) nummulite are two laterally, and relatedalgal rich formations limestones (Figure and1 calcarenitesD). The Espuña (Figure Fm consists of alveolina, nummulite, and algal rich limestones and calcarenites (Figure7A,B), while the Valdelaparra Fm is made of marshy whitish to cream marls rich in gastropods with intercalation of black lignite levels (Figure7C,D). Geosciences 2021, 11, 34 10 of 24
7A,B), while the Valdelaparra Fm is made of marshy whitish to cream marls rich in gas- tropods with intercalation of black lignite levels (Figure 7C,D). Both stratigraphic formations represent several environments (from the lagoon to the middle platform) of the ramp platform with the dominance of larger foraminifera and Geosciences 2021, 11, 34 algae. This platform was oriented SE-NW from shallow to deep (Figure 7E). During10 ofthis 24 period the flexural stage of the basin, the antiformal stack, and Espuña Fold formation were still ongoing (Figures 3A and 4) [12].
Figure 7. Site 3: The The Lower Lower Eocene Eocene Espuña Espuña and and Valdelaparra Valdelaparra fms in the the Malvariche Malvariche Valley. Valley. (A) Field outcrop of the Espuña Fm; (B) Detail of the fossils from the Espuña Fm. (C) Field outcrop of the Valdelaparra Fm. (D) Detail of the fossils from Fm; (B) Detail of the fossils from the Espuña Fm. (C) Field outcrop of the Valdelaparra Fm. (D) Detail of the fossils from the the Valdelaparra Fm. (E) Interpretative paleoecological model of the Espuña-Valdelaparra Fms (modified from [1]). Valdelaparra Fm. (E) Interpretative paleoecological model of the Espuña-Valdelaparra Fms (modified from [1]).
5.4. TheBoth Middle stratigraphic Eocene Malvariche formations and represent Cánovas severalFms in environmentsthe Malvariche (fromValley the lagoon to the middleThis platform) site is also of the located ramp on platform the Malvariche with the dominanceforest trail of in larger the Malvariche foraminifera Valley and (37°5algae.3′14. This5″ platformN 1°35′59. was8″ W) oriented from Sierra SE-NW Espuña from ( shallowFigures to1D,E deep and (Figure 8A). It7 E).was During previously this period the flexural stage of the basin, the antiformal stack, and Espuña Fold formation were still ongoing (Figures3A and4)[12].
5.4. The Middle Eocene Malvariche and Cánovas Fms in the Malvariche Valley This site is also located on the Malvariche forest trail in the Malvariche Valley (37◦53014.500 N 1◦35059.800 W) from Sierra Espuña (Figure1D,E and Figure8A). It was previously studied [28,29] and it has been selected as an example of the Middle Eocene GeosciencesGeosciences2021 2021, 11,, 11 34, 34 11 of11 24 of 24
evolutionstudied [28 of,29 the] and basin. it has The been area selected is part as ofan theexample northern of the (reversal) Middle Eocene flank evolution of the Espuña of Foldthe basin. showing The a area SE steep is part dip of (Figurethe northern5A). In (reversal) a reversed flank succession of the Espuña C ánovas Fold Fms showing upwardly a appearsSE steep with dip a(Figure gradual 5A). passage In a reversed over the succession Malvariche Cánovas Fm (Figure Fms upwardly8A). Malvariche appears Fm with repre- a sentsgradual the passage internal over and the middle Malvariche marine Fm platform, (Figure 8A). while Malvariche Canovas Fm Fm represents was deposited the inter- in the externalnal and platform.middle marine The Malvaricheplatform, while Fm Canovas consists Fm of alveolina,was deposited nummulite, in the external and algal plat- rich massiveform. The (or Malvariche thick stratified) Fm consists limestones of alveolina, and calcarenites nummulite (with, and similar algal facies rich massive to the Espuña (or thick stratified) limestones and calcarenites (with similar facies to the Espuña fm) (Figure fm) (Figure8B,C) with local marly intercalations. The C ánovas Fm is made of pinkish marls 8B,C) with local marly intercalations. The Cánovas Fm is made of pinkish marls (with (with local calcarenite level intercalations) rich in flat larger foraminifera (Figure8D,F) and local calcarenite level intercalations) rich in flat larger foraminifera (Figure 8D,F) and sol- solitary corals (Figure8E). In the marls, planktonic foraminifera appear. Both stratigraphic itary corals (Figure 8E). In the marls, planktonic foraminifera appear. Both stratigraphic formations represent again several environments (from the lagoon to the external platform) formations represent again several environments (from the lagoon to the external plat- of the ramp platform with the dominance of larger foraminifera and algae and oriented form) of the ramp platform with the dominance of larger foraminifera and algae and ori- S-N from shallow to deep). ented S-N from shallow to deep).
Figure 8. Site 4: The Middle Eocene Malvariche and Cánovas fms in the Malvariche Valley. (A) Panoramic View of the Figure 8. Site 4: The Middle Eocene Malvariche and Cánovas fms in the Malvariche Valley. (A) Panoramic View of the Malvariche Valley. (B) Field outcrop of the Malvariche Fm. (C) Detail of the fossils from the Malvariche Fm. (D) Field Malvariche Valley. (B) Field outcrop of the Malvariche Fm. (C) Detail of the fossils from the Malvariche Fm. (D) Field outcrop of the Cánovas Fm with flat larger foraminifera. (E) Solitary corals collected in the Cánovas Fm. (F) Thin section of the Cánovas Fm: flat larger foraminifera.
Geosciences 2021, 11, 34 12 of 24
Geosciences 2021, 11, 34 12 of 24
outcrop of the Cánovas Fm with flat larger foraminifera. (E) Solitary corals collected in the Cánovas Fm. (F) Thin section of the Cánovas Fm: flat larger foraminifera. 5.5. The Lowermost Oligocene As Fm in the Malvariche Area 5.5. TheThis Lowermost site is also Oligocene located A ons Fm the in Malvariche the Malvariche forest Area trail (37◦52057.600 N 1◦36043.400 W) fromThis Sierra site Espuña is also (Figure located1D). on It the was Malvariche previously forest studied trail [ 28 (37°5–30]2′ and57.6″ it hasN 1°3 been6′43. selected4″ W) fromas an Sierra example Espuña of the (Figure Lowermost 1D). It was Oligocene previously evolution studied of [2 the8–30 basin.] and it The has been area appearsselected asstructured an example with of athe reversal Lowermost SE steep Oligocene dip as partevolution of the of northern the basin flank. The ofarea the appears Espuña struc- Fold tured(Figure with5A). a This reversal stratigraphic SE steep formationdip as part is of made the northern of limestones, flank calcarenites,of the Espuña and Fold yellowish (Figure 5A).marls This with stratigraphic rounded quartz formation pebbles is made and occasionalof limestones, bivalves calcarenites (Figure, 9andA–D) yellowish outcropping marls withunconformably rounded quartz overlaying pebbles the and former occasional Eocene bivalve successions (Figure (Figure 9A–D)1 D).outcropping This formation uncon- formablyrepresents overlaying the deposits the of former an internal Eocene platform succession or lagoon (Figure with 1D). bivalves This formation (Figure 9representsB,C) and thebenthonic deposits foraminifera of an internal (Figure platform9D) or affected lagoon by with the bivalves beginning (Figure of the 9B,C) main and terrigenous benthonic foraminiferasupply in the (Figure basin fed9D) fromaffected the by incipient the begin southernning of risingthe main area terrigenous of Sierra Espuña.supply in This the basinstratigraphic fed from formation the incipient is very southern important rising since area it of belongs Sierra Espuña. to the end This of stratigraphic the pre-orogenic for- mationcycle. It is is very involved important in the since first it thrustings belongs to of the the end area of predatingthe pre-orogenic the beginning cycle. It ofis involved thin skin intectonics the first in thrustings the area [of2, 29the,30 area]. The predating deposition the beginning of this stratigraphic of thin skin formation tectonics tookin the place area [2,29,30when the]. The flexural deposition stage (Figure of this4 stratigraphic) of the basin formation was ending took [ 12 place]. This when site hasthe flexural been selected stage (asFigure an example 4) of the of basin the Lowermost was ending Oligocene [12]. This evolution site has been of the selected basin (Figure as an 3exampleB). In fact, of thethe Lowermostage of this nappeOligocene phase evolution was debated of the in basin the literature (Figure 3B). and In until fact, the the nineties age of consideredthis nappe phaseEocene was in agedebated as in in the the Pyrenees literature (Paquet, and until 1966 the [20 nineties]; Lonergan, considered 1991 [Eocene14]). This in age changed as in thewhen Pyrenees the As (Paquet, Fm, involved 1966 [ in20]; the Lonergan, nappes, 1991 was dated[14]). This as Early changed Oligocene when [the30]. As The Fm, new in- volvedcharacterization in the nappes, of the was As Fm dated allowed as Early the relocationOligocene of[30 the]. The first new nappe characterization tectonic phase of at the middle Oligocene. As Fm allowed the relocation of the first nappe tectonic phase at the middle Oligocene.
Figure 9. Site 5: The Lower Ol Oligoceneigocene As Fm in the Malvariche Valley. (A) FieldField outcropoutcrop of thethe AsAs Fm.Fm. (B) Detail of thethe fossils (bivalves)(bivalves) fromfrom the the As As Fm. Fm (C. ()C Detail) Detail of theof the rounded rounded quartzite quartzite pebbles pebbles and bivalvesand bivalves from thefrom As the Fm. As (D Fm) Thin. (D section) Thin ofsection the As of Fm:the As calcarenites Fm: calcarenites with benthonic with benthonic foraminifera foraminifera and rounded and rounded quartz pebbles.quartz pebbles.
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5.6. The The Upper Upper Oligocene Oligocene-Lower-Lower Aquitanian Bosque Fm in the Casas Nuevas Area This site is located nearnear CasasCasas Nuevas Nuevas on on the the Canal Canal del del Taibilla Taibilla forest forest trail trail (37 (37°5◦55034.65′34.00 6″N ◦ 0 00 N1 341°308.74′08.7″W) W) in in the the Mula-Pliego Mula-Pliego Depression Depression (Figure (Figure1 D).1D). This This stratigraphic stratigraphic formation formation crops out out in in the the Umbría Umbrí adel del Bosque Bosque (Figure (Figure 10A) 10 A)and and Casas Casas Nuevas Nuevas area area (Figure (Figure 10B) 10andB) itand was it previously was previously studied studied [12,28,29 [12,]28 and,29 ]it and has itbeen has selected been selected as an example as an example of the Upper of the OligoceneUpper Oligocene-Lower-Lower Aquitanian Aquitanian evolution evolution of the ofbasin. the basin.The area The is area situated is situated in a minor in a minor anti- clinalanticlinal fold fold inside inside the theMula Mula-Pliego-Pliego Depression Depression (Figure (Figure 10B). 10 B).This This stratigraphic stratigraphic formation formation is madeis made of ofconglomerates conglomerates (mainly (mainly carbonate carbonate clasts: clasts: Figure Figure 1 100C,D),C,D), limestones, limestones, calcarenites calcarenites,, and yellowish marls outcropping unconformably overlying the former succession but also postdating the tectonic phase with the stacking of the upper units from Sierra Espuña ((FigureFigure3 3B).B). This This formation formation represents represents the the deposits deposit ofs of a fana fan delta delta transitioning transitioning to anto an internal inter- nalplatform platform fed fromfed from the southernthe southern rising rising area ofarea Sierra of Sierra Espuña. Espuña. This stratigraphic This stratigraphic formation for- mationis very importantis very important since it belongssince it tobelongs the beginning to the beginning of the syn-orogenic of the syn- cycle.orogenic It postdates cycle. It postdatesthe first thrustings the first thrustings in the area in but the is area deformed but is deformed and involved and involved in the paroxysmal in the paroxysmal phase of phasedeformation of deformation of the area of [ 2the,12 ,area29,30 [2,12,29,30]. Deposition]. Deposition of this stratigraphic of this stratigraphic formation accountedformation accountedwhen mixed when carbonate mixed carbonate and terrigenous and terrigenous stage of thestage basin of the took basin place took (Figure place 4(Figure). It was 4). deposited contemporaneously to the tectonic compartmentation of the basin due to the It was deposited contemporaneously to the tectonic compartmentation of the basin due to appearance of structural highs and subsiding areas in response to the propagation of the the appearance of structural highs and subsiding areas in response to the propagation of structures from S to N (Figure3B) [12]. the structures from S to N (Figure 3B) [12].
Figure 10. Site 6: The Upper Oligocene-Lower Aquitanian Bosque Fm in the Casas Nuevas area. (A) Panoramic view of the Figure 10. Site 6: The Upper Oligocene-Lower Aquitanian Bosque Fm in the Casas Nuevas area. (A) Panoramic view of B C Bosquethe Bosque Fm Fm (limestones (limestones and and calcareous calcareous conglomerates). conglomerates) ( .) ( AnticlinalB) Anticlinal fold fold in thein the Bosque Bosque Fm. Fm ( .) ( DetailC) Detail of theof the calcareous calcare- pebbles.ous pebbles (D). Detail(D) Detail of calcareous of calcareous conglomerates. conglomerates.
Geosciences 2021, 11, 34 14 of 24 Geosciences 2021, 11, 34 14 of 24
5.7. The The Upper Upper Oligocene Oligocene-Aquitanian-Aquitanian Río Río Pliego Fm in the Mula Area This site site is is located located in in the the Río Río Pliego Pliego River River near near Mula Mula (38°0 (38◦1′0152.052.00″ N00 N1°2 17′◦2735.035.88″ W)00 W) in thein the Mula Mula-Pliego-Pliego Depression Depression (Figure (Figure 1D).1 TheD). Thearea areaexhibits exhibits a monoclinal a monoclinal and subhorizontal and subhor- succession.izontal succession. It was previously It was previously studied [12 studied,28,29] [and12,28 it, 29has] andbeen it selected has been as selectedan example as anof theexample Upper of Oligocene the Upper-Aquitanian Oligocene-Aquitanian evolution of evolution the basin of when the basin a terrigenous when a terrigenous turbiditic wedgeturbiditic was wedge deposited was ( depositedFigure 4) fed (Figure from4 the) fed northern from the margin northern that became margin the that active became one atthe this active time one [12 at]. This this timestratigraphic [12]. This formation stratigraphic consists formation of a rhythmic consists succession of a rhythmic (Figure suc- 11A)cession made (Figure of reddish, 11A) made sandstones of reddish, (Ta- sandstonese, Tb-e) (Figure (Ta-e, 11A), Tb-e) polygenic (Figure 11 conglomeratesA), polygenic (conglomeratesFigure 10B), and (Figure reddi 10shB to), yellowish and reddish pelites to yellowish (Figure 10C) pelites of turbiditic (Figure 10 origin.C) of turbiditicThe con- glomeratesorigin. The are conglomerates mainly made are of mainly greenish made Paleozoic of greenish greywackes, Paleozoic reddish greywackes, Triassic reddish sand- stonesTriassic, and sandstones, quartzose and conglomerates quartzose conglomerates,, and whitish and Mesozoic whitish limestones. Mesozoic limestones.The Rio Pliego The RmRio Pliegostratigraphically Rm stratigraphically overlies the overlies Bosque theFm. Bosque However, Fm. the However, lower part the lowerof the partRio Pliego of the FmRio exhibits Pliego Fm a lateral exhibits transition a lateral from transition the Bosque from Fm, the showing Bosque Fm, it to showing be partly it contempora- to be partly neouscontemporaneous to the latter ( toFigure the latter 1D). (FigureThe importance1D). The importanceof this stratigraphic of this stratigraphic formation is formation due to its belongingis due to its to belonging the syn-orogenic to the syn-orogenic cycle since it cycle is deformed since it isand deformed involved and in the involved paroxysmal in the phaseparoxysmal of deformation phase of deformationof the area [2,1 of2,29,30 the area] when [2,12 the,29 ,terrigenous30] when the stage terrigenous of the basin stage took of place,the basin contemporaneously took place, contemporaneously to the compartmentation to the compartmentation of the basin due of to the the basin appearance due to the of sappearancetructural highs of structural and subsiding highs andareas subsiding as the response areas as of the the response propagation of the of propagation the structures of the structures from S to N (Figure3B) [12]. from S to N (Figure 3B) [12].
Figure 11. Site 7: The Upper Oligocene- Aquitanian Río Pliego Fm in the Mula area. (A) Panoramic view of the rhythmic Figure 11. Site 7: The Upper Oligocene- Aquitanian Río Pliego Fm in the Mula area. (A) Panoramic view of the rhythmic succession of the RRíoío PliegoPliego FmFm (reddish(reddish sandstonessandstones andand pelites).pelites). (B)) DetailDetail ofof thethe polygenicpolygenic conglomerates.conglomerates. (C) DetailDetail reddish-yellowishreddish-yellowish pelites and marls.
Geosciences 2021, 11, 34 15 of 24 Geosciences 2021, 11, 34 15 of 24
5.8.5.8. The The Burdigalian Burdigalian El El Niño Niño Fm Fm in in the the Mula Mula Area Area ◦ 0 00 ◦ 0 00 ThisThis site site is located is located close close to El Niño to El de Niño Mula villagede Mula near village Mula (38 near02 51.9 MulaN (38°0 1 322′17.251.9″W N) in1°3 the2′17. Mula-Pliego2″ W) in the Depression Mula-Pliego (Figure Depression1D). The (Figure area is 1 situatedD). The inarea a minoris situated synclinal in a minor fold insidesynclinal the Mula-Pliegofold inside the Depression Mula-Pliego (Figure Depression 12A). It (Figure was previously 12A). It was studied previously [28,29] studied and it has[28 been,29] and selected it has as been an example selected ofas the an Burdigalianexample of evolutionthe Burdigalian of the basinevolution when of a the general basin deepeningwhen a general of the deepening basin took of place.the basin This took stratigraphic place. This stratigraphic formation consists formation of polygenic consists of breccias,polygenic sandstones, breccias, sandstones and greenish, and pelites greenish of turbiditic pelites origin,of turbiditic but also origin, whitish but silexite also whitish beds (Figuresilexite 12 bedsB,C). (Figure This formation 12B,C). This upwardly formation appears upwardly to the R appearsío Pliego to Fm. the A Río regional Pliego uncon- Fm. A formityregional with unconformity a minor erosive with gapa minor coincident erosive with gap thecoincident Aquitanian-Burdigalian with the Aquitanian boundary-Burdi- separatesgalian boundary both stratigraphic separates both formations. stratigraphic This stratigraphicformations. This formation stratigr isaphic very formation important is sincevery itimportant belongs since to the it endbelongs syn-orogenic to the end cycle. syn-orogenic This formation cycle. This appears formation deformed appears and de- involvedformed and in the involved paroxysmal in the phase paroxysmal of deformation phase of deformation of the area [2 of,12 the,29 ,area30] when [2,12,29,30 the terrige-] when nousthe terrigenous stage of the stage basin of took the basin place, took contemporaneously place, contemporaneo to theusly beginning to the beginning of the erosion of the oferosion the basin of the as abasin response as a toresponse the propagation to the propagation of the structures of the structures from S to Nfrom and S emersion to N and (Figuresemersion3B ( andFigures4)[12 3B]. and 4) [12].
FigureFigure 12. 12.Site Site 8: 8: The The Burdigalian Burdigalian El El Niño Niño Fm Fm in in the the Mula Mula area. area. ( A(A)) Panoramic Panoramic view view of of the the syncline syncline fold in the siliceous marls and silexites. (B) Detail of the strongly folded siliceous marls and si- fold in the siliceous marls and silexites. (B) Detail of the strongly folded siliceous marls and silexites. lexites. (C) Detail of the silexites. (C) Detail of the silexites.
Geosciences 2021, 11, 34 16 of 24
The eight sites demonstrate the tectonostratigraphic development of the basin in terms of changes to depositional environments, sediment sources, and tectonically driven topographic changes (Figures3–12).
6. Evaluation of the Sites A quantitative assessment of the sites has been performed following the methodology proposed by Brilha [15] and Aoulad-Sidi-Mend [16], where four different groups of criteria are evaluated separately: Scientific Value (SV), Potential Educational Use (PEU), Potential Touristic Use (PTU) and Degradation Risk (DR). Values 1, 2, 3, and 4 can be assigned to each criterion (in the case of SV value 3 is not used). These values are also weighted according to a percentage according to Brilha [15]. Seven criteria (Brilha, 2016 [15]) are used for the Scientific Value (SV) group: represen- tativeness (R), key locality (Kl), Scientific knowledge (Sn), Integrity (I), Geological diversity (Gd), Rarity (Ra), and Use limitations (Ul). - Representativeness is the capacity of a site to illustrate geological elements or processes. - Key locality is the importance of a site as a reference in any field of geology. - Scientific knowledge is a value related to the existence of published scientific studies. - Integrity is related to the present conservation status of the geosite, taking into account both natural processes and human actions. - Geological diversity is considered when a high number of different geological ele- ments with scientific interest can be seen at the same site. A high number of different geological elements with a scientific interest in a site imply a higher SV - Rarity is related to the presence of similar sites in the area. A small number of similar sites in the area of study increases the SV - Use limitations are related to the existence of obstacles to visit the site. The existence of obstacles that may be problematic for the regular scientific use of the geosite has impacts on the geosite’s SV Twelve criteria are used for the PEU group: Vulnerability (V), Accessibility (A), Use limitations (Ul), Safety (S) Logistics (L), Density of population (Dp), Associations with other values (Av), Scenery (Sc), Uniqueness (U), Observation conditions (Oc), Didactic potential (Dp), and Geological diversity (Gd). - Vulnerability is related to the existence of geological elements that can be destroyed by visitors. The existence of geological elements that can be destroyed by students decreases the value of the site - Accessibility is related to the ease of access. The easier and shorter walk between the means of transportation and the site increases the value of this criterion. - Use limitations is the existence of obstacles for educative purposes. The existence of obstacles that may be problematic for the development of educative activities has an impact on the site’s valorization - Safety is related to risks for the student’s safety on the site. When the field activity can be carried out under low-risk conditions for students the value of this criterion increases. - Logistics is the existence or not of facilities to receive students. The existence of facilities to receive students, such as accommodation, food, and toilets, increases the value of this criterion. - Density of population is related to the existence of a population near the site as possible visitors. The existence of a population near the site, potentially providing students who will use the site, increases its value. - Association with other values represents the existence of other natural or cultural elements associated with the site. The existence of other natural or cultural elements associated with the site may justify interdisciplinary field trips and increase the value of the site - Scenery is related to the beauty of the geological elements (including geomorphologi- cal ones) that could stimulate students’ interest in the site. Geosciences 2021, 11, 34 17 of 24
- Uniqueness concerns distinctiveness and the rarity of the geodiversity element that could promote students’ interest in the site. - Observation conditions are related to the grade of the goodness of the observation conditions. The better conditions for observation of all the geodiversity elements on the site imply a higher value. - Didactic potential is the possible use by students of different education levels of the site. The use of the site by students of different education levels increases the value of the site - Geological diversity is related to the number of different geological elements with the didactic potential of the site. A high number of different geological elements with didactic potential increase the value of the site Thirteen criteria are used for the PTU group, being ten of the criteria already cited in the PEU group (V, A, Ul, S, L, Dp, Av, Sc, U, Oc). The interpretative potential (Ip), Economical level (El), and Proximity to recreational areas (Pr) are specific criteria for PTU. - Interpretative potential is related to the capacity of a geodiversity feature to be easily understood by people with no geological background, i.e., typical members of the general public. - Economic level is related to the level of income of people living near the site. The high level of income of people living near the site suggests a higher probability of it being visited. - Proximity of recreational areas is related to the existence of well-known tourist attrac- tions in the surrounding area of the site. A touristic visit to a site may benefit from the existence of well-known tourist attractions in the surrounding area Finally, five criteria are used for the DR group: Deterioration of geological elements (Dg), Proximity to areas/activities with the potential to cause degradation (Pa), Legal protection (Lp), Accessibility (Ac), and Density of population (Dpp). - Deterioration of geological elements reflects the possibility of a loss of geological elements in the site as a consequence of (i) its fragility, namely its intrinsic charac- teristics (size of the geological element, ease of obtaining samples, the resistance of the rock, etc.) and natural actions (susceptibility to erosion, the intensity of erosional agents, etc.) and (ii) its vulnerability to anthropic actions (tourism, agriculture, urban development, vandalism, etc.). - Proximity to areas/activities with the potential to cause degradation is related to the existence of mines, industrial facilities, recreational areas, roads, urban areas, etc. - Legal protection is related to the location of the site in an area with any type of legal protection (direct or indirect). Access control refers to the existence of obstacles, such as restrictions by the owner, fences, need to pay entrance fees, mining activities. - Accessibility reflects the conditions of access to the site for the general public (not considering disabled people). A site with easy access is more likely to be damaged by visitors’ misuse than one with difficult access. - Density of the population reveals the number of persons that live near the site and that can cause potential deterioration to the site due to inappropriate use (vandalism, theft, etc.). In this case, the Ac and Dpp criteria (also used in the PEU and PTU as favorable) are considered unfavorable. For the final values of each group of criteria (SV, PEU, PTU, and DR) four thresholds are used: 0–25 low, 26–50 moderate, 51–75 high, 76–100 very high. The evaluation of the eight selected sites (Table1, Figure 13) shows that in terms of SV, PEU and PTU they score above 50, indicating “high” or “very high” interest. Moreover, in most of the cases values are above 75 and indicate “very high” interest. Contrarily, the DR shows lower values (always below 50) and the assigned threshold is a “moderate” risk of degradation. Geosciences 2021, 11, 34 18 of 24
Table 1. Detailed scoring of the eight sites of geological interest selected including scientific value (SV), potential educational use (PEU), potential touristic use (PTU), and degradation risk (DR).
Degradation Scientific Value * Potential Educational Use Potential Touristic Use Risk
Site of Geological Interest Rarity Safety Safety Scenery Scenery Integrity Logistics Logistics Scoring/Criteria Uniqueness Uniqueness Key Locality Accessibility Accessibility Accessibility Vulnerability Vulnerability Economic Level Use Limitations Use Limitations Use Limitations Legal Protection Didactic Potential Representativeness Geological Diversity Geological Diversity Scientific Knowledge Density of Population Density of Population Density of Population Interpretative Potential Observation Conditions Observation Conditions Proximity Cause Degradation Association with Other values Association with Other Values Proximity of Recreational Areas Deterioration Geological Elements Weight for the criteria (%) 30 20 5 15 5 15 10 10 10 5 10 5 5 5 5 5 10 20 10 10 10 5 10 5 5 5 15 10 5 10 5 5 35 20 20 15 10 Score 0 to 4 4 1 4 2 2 2 2 3 1 4 2 3 1 4 4 2 4 2 2 3 1 4 2 3 1 4 4 2 4 2 1 2 2 1 1 1 1 Cretaceus-Cenozoic Weight (%) 30 5 5 7.5 2.5 7.5 5 7.5 2.5 5 5 3.75 1.25 5 5 2.5 10 10 5 7.5 2.5 5 5 3.75 1.25 5 15 5 5 5 1.25 2.5 17.5 5 5 3.75 2.5 boundary Total value SV = 62.50 PEU = 62.50 PTU = 63.75 DR = 33.75 Score 0 to 4 4 2 4 4 4 4 4 4 1 4 2 4 3 3 1 2 4 2 4 4 1 4 2 4 3 3 1 2 4 2 1 1 1 1 4 1 3 Paleocene Mula Fm Weight (%) 30 10 5 15 5 15 10 10 2.5 5 5 5 3.75 3.75 1.25 2.5 10 10 10 10 2.5 5 5 5 3.75 3.75 3.75 5 5 5 1.25 1.25 8.75 5 20 3.75 7.5 Total value SV = 90.00 PEU = 68.75 PTU = 52.50 DR = 45.00 Score 0 to 4 4 4 4 4 4 2 2 4 1 2 2 3 1 4 4 3 4 2 4 4 1 2 2 3 1 4 4 3 4 3 1 2 1 1 1 1 1 The Lower Eocene Espuña-Valdelaparra Weight (%) 30 20 5 15 5 7.5 5 10 2.5 2.5 5 3.75 1.25 5 5 3.75 10 10 10 10 2.5 2.5 5 3.75 1.25 5 15 7.5 5 7.5 1.25 2.5 8.75 5 5 3.75 2.5 Fms Total value SV = 87.50 PEU = 68.75 PTU = 68.75 DR = 25.00 Score 0 to 4 4 2 4 4 4 2 2 4 1 2 2 3 1 4 4 3 4 2 4 4 1 2 2 3 1 4 4 3 4 3 1 2 1 1 1 1 1 The Middle Eocene Malvariche-Cánovas Weight (%) 30 10 5 15 5 7.5 5 10 2.5 2.5 5 3.75 1.25 5 5 3.75 10 10 10 10 2.5 2.5 5 3.75 1.25 5 15 7.5 5 7.5 1.25 2.5 8.75 5 5 3.75 2.5 Fms Total value SV = 77.50 PEU = 68.75 PTU = 68.75 DR = 25.00 Score 0 to 4 4 2 4 2 2 2 2 4 1 2 2 3 1 4 4 1 4 2 3 4 1 2 2 3 1 4 4 1 4 2 1 1 2 1 1 1 1 The Lowermost Weight (%) 30 10 5 7.5 2.5 7.5 5 10 2.5 2.5 5 3.75 1.25 5 5 1.25 10 10 7.5 10 2.5 2.5 5 3.75 1.25 5 15 2.5 5 5 1.25 1.25 17.5 5 5 3.75 2.5 Oligocene As Fm Total value SV = 67.50 PEU = 63.75 PTU = 60.00 DR = 33.75 The Upper Score 0 to 4 4 2 4 4 4 1 4 4 1 4 2 4 3 4 2 1 4 2 4 4 1 4 2 4 3 4 2 1 4 3 1 1 1 1 4 1 3 Oligocene-Lower Weight (%) 30 10 5 15 5 3.75 10 10 2.5 5 5 5 3.75 5 2.5 1.25 10 10 10 10 2.5 5 5 5 3.75 5 7.5 2.5 5 7.5 1.25 1.25 8.75 5 20 3.75 7.5 Aquitanian Bosque Fm Total value SV = 78.75 PEU = 70.00 PTU = 61.25 DR = 45.00 The Upper Score 0 to 4 4 4 4 4 4 2 4 4 3 4 2 4 4 3 1 1 4 2 3 4 3 4 2 4 4 3 1 1 4 2 2 1 1 1 4 1 4 Oligocene- Weight (%) 30 20 5 15 5 7.5 10 10 7.5 5 5 5 5 3.75 1.25 1.25 10 20 7.5 10 7.5 5 5 5 5 3.75 3.75 2.5 5 5 2.5 1.25 8.75 5 20 3.75 10 Aquitanian Río Pliego Fm Total value SV = 92.50 PEU = 81.25 PTU = 61.25 DR = 47.50 Geosciences 2021, 11, 34 19 of 24
Table 1. Cont.
Degradation Scientific Value * Potential Educational Use Potential Touristic Use Geosciences 2021, 11, 34 19 of 24 Risk
Total value SV = 67.50 PEU = 63.75 PTU = 60.00 DR = 33.75 Site of Geological The Upper Score 0 to 4 4 2 4 4 4 1 4 4 1 4 2 4 3 4 2 1 4 2 4 4 1 4 2 4 3 4 2 1 4 3 1 1 1 1 4 1 3 Interest Oligocene-Lower 3.7 1.2 3.7 Weight (%) 30 10 5 15 5 3.75 10 10 2.5 5 5 5 5 2.5 10 10 10 10 2.5 5 5 5 5 7.5 2.5 5 7.5 1.25 1.25 8.75 5 20 3.75 7.5 Rarity Aquitanian Bosque Safety 5 5 5 Safety Scenery Scenery Integrity Logistics Logistics Scoring/Criteria Uniqueness Uniqueness
Fm Key Locality Accessibility Accessibility Total value SV = 78.75 PEU = 70.00 PTU = 61.25 DR = 45.00 Accessibility Vulnerability Vulnerability Economic Level Use Limitations Use Limitations Use Limitations Legal Protection Didactic Potential
The Upper Representativeness Score 0 to 4 4 4 4 4 4 2 4 4 3 4 2 4 4 3 1 1 4 2 3 4 3 4 2 4 4 3 1 1 4 2 2 1 1 1 4 1 4 Geological Diversity Geological Diversity Scientific Knowledge Density of Population Density of Population Density of Population Interpretative Potential Oligocene- 1.2 1.2 Observation Conditions Observation Conditions Weight (%) 30 20 5 15 5 7.5 10 10 7.5 5 5 5 5 3.75 10 20 7.5 10 7.5 5 5 5 5 3.75 3.75 2.5 5 5 2.5 1.25 8.75 5 20 3.75 10 Proximity Cause Degradation Association with Other values Association with Other Values
Aquitanian Río 5 5 Proximity of Recreational Areas Pliego Fm Total value SV = 92.50 PEU = 81.25 PTU = 61.25 DR = 47.50 Deterioration Geological Elements Score 0 to 4 4 1Score 4 0 2to 4 24 21 4 42 32 2 14 3 4 1 24 42 4 33 3 31 11 4 12 4 4 32 1 44 32 4 13 43 21 41 4 3 2 31 11 11 41 24 11 13 1 1 4 1 3 The Burdigalian El TheWeight Burdigalian (%) 30El 5 5 7.5 2.5 7.5 10 7.5 2.5 5 5 5 3.753.7 3.751.2 1.251.2 1.25 10 10 10 7.5 2.53.7 5 5 5 3.75 3.75 3.75 2.5 5 5 1.25 1.25 8.75 5 20 3.75 7.5 Niño Fm Weight (%) 30 5 5 7.5 2.5 7.5 10 7.5 2.5 5 5 5 3.75 10 10 10 7.5 2.5 5 5 5 3.75 3.75 2.5 5 5 1.25 1.25 8.75 5 20 3.75 7.5 TotalNiño value Fm SV = 67.50 PEU =565.00 5 5 5 PTU = 51.25 DR = 45.00 Total value SV = 67.50 PEU = 65.00 PTU = 51.25 DR = 45.00 * SV is only scored 1. 2 and 4 (the 3 value is not used). * SV is only scored 1. 2 and 4 (the 3 value is not used).
FigureFigure 13. 13.Columns Columns representing representing thethe eight sites sites from from the the Cenozoic Cenozoic Malaguide Malaguide Basin Basin from fromSierra SierraEspuña Espuña for the obtained for the obtained values of valuesSV, PEU, of PTU, SV, PEU, and DR. PTU, and DR.
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7. The Cenozoic Malaguide Basin from Sierra Espuña as a Key-Area The Cenozoic Malaguide Basin from Sierra Espuña (Internal Betic Zone, S Spain) studied in depth in the last 30 years shows a high quality of outcrops. This together with the great areal representation and continuity in the sedimentation allow us to propose it as a key area for the study of this basin. Published models indicate an evolution from passive margin to wedge top (piggy-back) basin from Upper Cretaceous to Lower Miocene [1,2,12]. During this period, the sedimentary environment changed from limestone platforms with local terrigenous inputs (Paleocene to Lower Oligocene) to deep basin with a substantial influx of turbidites (Upper Oligocene to Lower Miocene) [2]. The area now appears as an antiformal stack (pile nappe folded) and shows abundant evidence of synsedimentary tectonics [2,6,7,12,13]. Three mechanisms (phases), successively following one another, have been proposed by Martín-Martín and Martín-Algarra (2002) [12]: (1) flexural tectonics during most of the Paleogene times to create the Cenozoic basin; (2) compartmentalization of the basin with associated formation of structural highs and subsiding areas related to blind-fault-propagation folds, deforming the basin from south to north (Upper Oligocene to Lower Aquitanian); (3) superficial thrust tectonics when the basin began to be deformed and eroded (Upper Aquitanian-Burdigalian). Based on the review of published studies and a survey of the sites, eight key-outcrops illustrating the tectonic and depositional evolution of the Cenozoic basin were selected. Moreover, an evaluation has been done in order to obtain the scientific value (SV), the educational and touristic potential (PEU and PTU, respectively), and the degradation risk (DR) following the methodology proposed by Brilha [15] and Aoulad-Sidi-Mend [16]. In this research, this methodology was applied to the tectono-sedimentary evolution of a basin. The methodology seems to be valid for this purpose since this basin evolution is followed through sites of geological interest. The obtained values allow us to propose the tectono-sedimentary evolution of this basin as a good example of geological heritage since values above 50 were obtained for SV, PEU, and PTU. These can be considered of “high” or “very high” interest (in most of the cases values are above 75 that indicate “very high” interest). In detail, SV values exceed (high quality) in all cases and sites 2, 3, 4, and 7 yielded values above 75 (very high). The scoring of the seven criteria of the Scientific Value (SV) group has been performed according to the exposed in the following lines. The Representativeness (R) is the capacity of a site to illustrate geological elements or processes. This criterion achieves tops core (4) at all sites since the selected sites illustrate the selected geological processes very well. The Key locality (Kl) is the importance of a site as a reference in any field of geology. This criterion has been scored according to the relevance of the site: local (1), national (2), or international (4). The higher scores have been obtained in sites 3 and 7 with international relevance. Scientific knowledge (Sn) is a value related to the existence of published scientific studies. It obtains the top score (4) in all the sites as the selected sites have been mentioned in numerous international SCI research papers. Integrity (I) is related to the degree of conservation of the sites. Scores were assigned according to the actual state of preservation of the sites. The lower scores appear in sites 1, 5, and 8 where some signs of degradation have been found. The Geological diversity (Gd) was assessed according to the number of different geological elements with scientific interest visible in the same site. Sites with higher scores (sites 2, 3, 4, 6, and 7) display four geological aspects (paleontological, stratigraphic, sedimentological, and petrographic). These sites merit a value of 4. The other sites obtain the value 2 since the number of geological aspects demonstrated at the site is lower (reduced to two geological elements). The Rarity (Ra), related to the presence of similar sites in the area, has been evaluated accordingly and the higher value (4) is assigned to site 2 because Paleocene sediments are very unusual in the Malaguide Complex. On the contrary, features very represented in many close sites obtain lower scores. In our case, site 6 obtains the score 1. The protected areas in the Regional Park of Sierra Espuña (sites 1, 3, 4, and 5) obtain lower values due to the existence of obstacles to visit the sites because access permission is Geosciences 2021, 11, 34 21 of 24
Geosciences 2021, 11, 34 21 of 24
Park of Sierra Espuña (sites 1, 3, 4, and 5) obtain lower values due to the existence of ob- stacles to visit the sites because access permission is needed and the forest tracks are closed needed and the forest tracks are closed with fences. It is reflected in the scoring of the Use with fences. It is reflected in the scoring of the Use limitations (Ul), criterion. limitations (Ul), criterion. In the case of PEU, the aggregate values are above 60 (high quality) and site 7 is In the case of PEU, the aggregate values are above 60 (high quality) and site 7 is scored scored as above 80 (very high). The PTU shows values above 50 in all the cases (high as above 80 (very high). The PTU shows values above 50 in all the cases (high quality) but quality) but no site is valued above 70. The values obtained in SV, PEU, and PTU show no site is valued above 70. The values obtained in SV, PEU, and PTU show that the study that the study area is of high to very high interest. Even, it can be considered excellent area is of high to very high interest. Even, it can be considered excellent taking into account thattaking this into area account belongs that to the this Internal area belongs Betic Zone, to the where Internal highly Betic deformed Zone, andwhere metamorphic highly de- materialsformed and normally metamorphic crop out. materials In this normally case, the crop assessment out. In ofthis the case, criteria the assessment Rarity (Ra) of and the Uniquenesscriteria Rarity (U) (Ra) are highand Uniqueness since in the (U) Internal are high Betic since Zone in outcrops the Internal of sedimentary Betic Zone outcrops rock are veryof sedimentary scarce and onlyrock restrictedare very scarce to the and Malaguide only restricted Complex. to the Malaguide Complex. OnOn thethe otherother hand,hand, thethe DRDR consistentlyconsistently yieldedyielded valuesvalues belowbelow 5050 indicatingindicating aa “mod-“mod- erate”erate” riskrisk ofof degradation. Even, Even, sites sites 3 3 and and 4 4 appear appear below below 25 25 indicating indicating a alo loww degree degree of ofdegradation. degradation. The The conservation conservation and and dissemination dissemination of the of the geological geological heritage heritage of an of area an area can cancontribute contribute to the to improvement the improvement of the of wealth the wealth of the of region the region [15]. Sites [15]. of Sites geological of geological interest interestwill stimulate will stimulate and encourage and encourage scientific scientific research, research, education education,, and promote and promote cultural culturaltourism tourism[16]. In the [16]. case In theof research case of, research, some areas some can areas be marketed can be marketed to the international to the international scientific scientificcommunity community so that new so thatresearch new researchcan be performed. can be performed. For education, For education, these sites these could sites be couldpart of be the part educational of the educational activities activitiesof local and of localregional and schools regional and schools universities. and universities. For tour- Forism, tourism, the development the development of sites of of geological sites of geological interest, interest,the introduction the introduction of signaling of signaling systems, systems,and the publication and the publication of guides of and guides brochures and brochures can stimulate can stimulate the visits the of visits a different of a different kind of kindtourist of touristmostly mostlyinterested interested in cultural in cultural aspects. aspects. WhenWhen consideredconsidered as as a a georoute georoute (Figure (Figure 14 14)), the, the Cenozoic Cenozoic Malaguide Malaguide Basin Basin of the of Sierrathe Si- Espuñaerra Espuña area yieldsarea yields an SV an average SV average close close to 80 to (“very 80 (“very high”), high”), a PEU a PEU close close to 70to 70 (“high”), (“high”), a PTUa PTU close close to 60to (“high”)60 (“high”) and and a DR a DR lower lower to 30 to (“moderate”). 30 (“moderate”). These These values values can give can angive idea an ofidea the of importance the importance of the basin;of the moreover, basin; moreover, taking into taking account into that account the study that areathe study belongs area to thebelongs Internal to the Zone. Internal Due Zone. to this, Due the to scoring this, the of scoring the criteria of the Rarity criteria (Ra) Rarity and (Ra) Uniqueness and Unique- (U) areness high (U) are since high in since this tectonic in this tectonic domain domain sedimentary sediment outcroppingary outcropping is very is scarce very scarce and only and restrictedonly restricted to the to Malaguide the Malaguide Complex. Complex.
FigureFigure 14.14. Polygon representation of of the the SV, SV, PEU, PEU, PTU PTU,, and and GR GR average average values values for for the the Cenozoic Cenozoic MalaguideMalaguide BasinBasin fromfrom SierraSierra Espuña.Espuña.
8.8. ConclusionsConclusions TheThe areaarea ofof SierraSierra EspuñaEspuña (Internal(Internal BeticBetic Zone,Zone, SS Spain)Spain) duedue toto thethe qualityquality ofof outcrops,outcrops, areal representation, and continuity in the sedimentation can be considered a key area for areal representation, and continuity in the sedimentation can be considered a key area for the study of the Cenozoic Malaguide Basin. the study of the Cenozoic Malaguide Basin. This basin evolved from passive margin to wedge-top basin and sedimentation changed from limestone platforms with scarce terrigenous inputs to the deep basin with huge terrigenous supply.
Geosciences 2021, 11, 34 22 of 24
The Cenozoic tectono-sedimentary basin evolution is related to three phases: (1) flexural tectonics during most of the Paleogene times to create the basin; (2) fault and fold compartmentation of the basin with the creation of structural highs and subsiding areas related to blind-fault-propagation folds, deforming the basin from south to north during Late Oligocene to Early Aquitanian times; (3) thin-skin thrusting tectonics during the Late Aquitanian-Burdigalian. Eight key-outcrops have been selected as sites of geological interest to follow the tectono-sedimentary evolution of the Cenozoic basin from this area: Cretaceous-Cenozoic boundary, Paleocene Mula Fm, Lower Eocene Espuña-Valdelaparra Fms, Middle Eocene Malvariche-Cánovas Fms, Lowermost Oligocene As Fm, Upper Oligocene-Lower Aqui- tanian Bosque Fm, Upper Oligocene-Aquitanian Río Pliego Fm, Burdigalian El Niño Fm. An evaluation has been performed to obtain four parameters: the scientific value, the educational and touristic potential, and the degradation risk. The first three parameters obtained values above 50 being considered of “high” or “very high” interest (“very high” in most of the cases). The last parameter shows always values below 50 indicating a “moderate” or “low” risk of degradation. When all sites are considered as a georoute, this area yields an SV average value close to 80 (“very high”), a PEU close to 70 (“high”), a PTU close to 60 (“high”), and a DR lower to 30 (“moderate”). The obtained values allow us considering the tectono-sedimentary evolution of this basin worthy of being proposed as a geological heritage.
9. Final Recommendations Some recommendations can be done for the proposed sites of the Cenozoic Malaguide Basin from Sierra Espuña according to the valuation outlined above. In the case of SV, PEU, and PTU only “high” and “very high” values are obtained. These values indicate that the sites are potential of interest for the respective scientific community, educational or touristic purposes. We proposed the introducing of signaling, distributing guides and brochures to visitors, and the promotion of visits to the area as it has been also recommended by several authors [33–35]. In the case of the DR thresholds that are “low” or “moderate” it only requires introducing regulatory measures in the sites with a “moderate” threshold. Our evaluation of the sites demonstrates that there is significant potential for further geological studies by the scientific community. The sites also have great educational value for use in visits for high school and university students from the region. The sites have a moderate-high value for tourists interested in nature. The moderate degradation value accommodates these uses and enjoyment and only some indications and warnings for the visitor at the sites are required to ensure proper conservation.
Author Contributions: Fieldworks by M.M.-M., T.R.-E. and G.R.-S. Valorisation of sites by S.M.-A. and M.M.-M. All authors have read and agreed to the published version of the manuscript. Funding: Research supported by Research Project CGL2016-75679-P, Spanish Ministry of Education and Science; Research Groups, Projects of the Generalitat Valenciana, Alicante University (CTMA-IGA). Acknowledgments: Authors wish to acknowledge the English revision performed by Peter Donnelly and the comments, suggestions, and corrections by two anonymous reviewers. Conflicts of Interest: The authors declare no conflict of interest.
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