Geodiversity Assessment Through the Évora–Montemor-o-Novo Region: on the Scope of Valorising the Mining Heritage of the Ossa-Morena Zone (SW Iberia, Portugal)

The SW of Iberia registers diverse examples of mining remnants from activities that ceased during the twentieth century, namely in the Ossa-Morena Zone. Such activities exposed outcrops that are part of the mining heritage of the Alentejo region (Portugal), and examples of that are found throughout the Évora–Montemor-o-Novo region at the ancient Montemor-o-Novo iron mines. GeSologically, the area is comprised within the Évora Massif and, besides displaying an important mining and quarrying heritage, also exhibits important geomorphological, structural and lithological features that are a key to understand the geodynamic evolution of the Variscan Orogeny at the SW of Iberia. This work intends to evaluate the geodiversity throughout the region and propose routes that integrate geodiversity features along with the mining heritage of selected ancient mines from the Montemor-o-Novo iron district. Furthermore, the region is characterised by immense cultural, historical and archaeological assets that, together with the geodiversity of this region, have been successfully used for scientific, formal and informal educational purposes. Mining heritage can contribute to the understanding of the role of mineral resources on the past, present and future of society as we know it. The proposal herein disclosed, although intending to promote geoconservation strategies regarding the mineral resources of the Ossa-Morena Zone, does not aim to make exploration and mining unfeasible in these locations. On the contrary, this work intends to promote strategies in which industry and geoheritage can work together on the knowledge transfer to society, contributing to the increase of geological literacy.


Introduction
Society, as we know it, emerged and has been shaped by the necessity of life quality enhancement and, with it, the indissociable increasing need for mineral resources. To achieve such goals, the pursuit for raw materials, many of which provided by mineral deposits, has promoted human migrations and territorial occupation throughout history, such as the well-known Punic and Roman occupancy of the Iberian Peninsula which is an uttermost example of mineral resources exploration and mining. Diverse examples of Roman occupation are found in the Iberian territory, mainly in what concerned gold and tin exploration. Remnants of the Roman mining activities can be found throughout Iberia, with some of those sites having been studied for their geological, educational and scientific values, such as the Tresminas, Valongo and Castromil Roman gold mines in NW Portugal (e.g. Lima et al. 2010;Matías 2014;Fonte et al. 2017;Cruz et al. 2018) and the Las Miédolas Roman gold mines in NW Spain (e.g. Matías and Llamas 2021). This intricate relation between mineral resources and historical, cultural and archaeological heritage should be considered in a geodiversity assessment and geoconservation strategy, since they could be used to widen the audience range to these geodiversity sites. The Évora-Montemor-o-Novo region is one of the regions that can benefit from such strategies, as it comprises a complex geological evolution which is a key to reconstruct the geodynamic evolution of Iberia through the Cadomian and Variscan orogenies. The geological complexity is allied with the fact that human settlements in the area go back as far as the Palaeolithic, and due to the metallogenic characteristics of the region, it has also been the target of iron exploitation during Roman times. The iron mining history continues up to the twentieth century, marking an important era of industrial development. Furthermore, the potential for future exploration still exists, particularly at the Escoural area, which has been the target for several scientific research and mineral exploration projects focusing on gold mineralisation (Ribeiro et al. 1993;Inverno 2001;Maia et al. 2022).
Throughout this work, the assessment of 10 locations with the potential for geodiversity and geosite classification is provided. We intended to propose a geodiversity route between Évora and Montemor-o-Novo municipalities that focuses on the relevant mining heritage of the Montemor-o-Novo ancient iron mining area.
These mining areas are located in the vicinity of the Santiago do Escoural village, at approximately 13 km west of the Évora Municipality, classified by UNESCO as a World Heritage City since 1986. Some of the locations described throughout this work have already been considered for previous geoconservation strategies, and two of them are already catalogued as geosites, such as the Herdade Monte das Flores Quarry (Brilha et al. 2008 and the Escoural caves (Brilha et al. 2008Brilha and Pereira 2020). Unfortunately, the potential of the region is still not fully taken advantage of, lacking the existence of a common framework for the geodiversity between both municipalities.
The work here presented is motivated by the necessity to increase the awareness about mineral resources usage and their applications to everyday life, and their importance in achieving the 2030 Sustainable Development Goals proposed by the United Nations Organization, as well as in developing a consistent strategy for the beneficiation of geodiversity of mining heritage in the Ossa-Morena Zone, with an integrative approach that considers other geological, cultural and historical heritage sites. Through the last decades, a notorious effort has led to the definition of the Geosite Frameworks of Portugal (Brilha et al. 2005(Brilha et al. , 2008. Unfortunately, the mining areas of the Ossa-Morena Zone were not considered, with exception to the framework xxviii) Gold Mineralizations (Brilha et al. 2008), applicable to all Portuguese territories. Nevertheless, several crucial frameworks for geoconservation in the Ossa-Morena Zone have been defined, such as the framework iv) Silurian of the Portuguese Ossa-Morena Zone and the framework xxiv) Pre-Mesozoic granitoids (Brilha et al. 2008).
Despite mining heritage is usually left out of the geological heritage and geosite definition umbrella (Brilha 2016), several authors argue in favour of its consideration (López-García et al. 2011;Prosser, 2018;Mazadiego et al. 2019;Gioncada et al. 2019), as it should be considered an important part of those definitions since mining activities provide sites with proven scientific and educational values (Hellqvist 2019), and such is the case of the Montemor-o-Novo ancient iron mines.

The Geology of the Ossa-Morena Zone
The SW border of the Iberian Massif is the outermost terrane of the European Variscides, which separates the tectonostratigraphic terranes of the Ossa-Morena Zone (OMZ) and South Portuguese Zone (SPZ) (Julivert et al. 1972;Farias et al. 1987). The geodynamic evolution of OMZ is conditioned by the Rheic Ocean opening and closure, which are part of the Variscan cycle (Ribeiro et al. , 2010, and which can be simplistically framed in the light of the Wilson cycle (Wilson et al. 2019) as follows: stage 1, early stages of continental rifting at northern Gondwana (Middle Cambrian) marking the beginning of the Variscides evolution that will significantly overprint structures from a previous orogeny (Cadomian Orogeny); stage 2, Rheic Ocean opening (500-470 Ma) marking the detachment of Avalonia from Gondwana; stage 3, the achievement of a mature passive margin when Rheic becomes a wide ocean ); stage 4/5, the beginning of the compressional regime and oceanic crust subduction under the Gondwana terrain (425-410 Ma); stage 5, as compression continues, the Avalonia-Gondwana approximation culminates in an oblique collision (390-370 Ma) that marks the beginning of the continental orogen, and the suture of this collision is preserved within the contact between OMZ and SPZ; and stage 6, the final stages of the Variscan Orogeny are achieved by the dextral transpression between Avalonia and Gondwana (approx. 290 Ma; Ribeiro et al. 2007).
The OMZ is limited at NE by the Tomar-Badajóz-Córdoba shear zone, which is interpreted as a Cadomian suture between the OMZ terrains and Central Iberian Zone (CIZ) later reactivated during the Variscan Orogeny as a transpressive shear zone (Ribeiro et al. 2010;Araújo et al. 2013). The SW limit, between OMZ and SPZ, is materialised by the Beja-Acebuches Ophiolitic Complex, which corresponds to an abducted oceanic crustal fragment during Rheic closure (Ribeiro et al. 2010), and by the Beja Igneous Complex which marks the emplacement of mafic to intermediate magmatic bodies (Jesus et al. 2020).
The basement of OMZ is characterised by a thick Neoproterozoic metasedimentary sequence that results from the dismantlement of a Cadomian magmatic arc, referred as Série Negra in Iberia.
The Rheic closure marks the beginning of intense tectonism with metamorphic conditions being ubiquitously kept at the greenschist and amphibolitic facies. The compressional regime led to the oblique collision between Avalonia and Gondwana (390-370 Ma; Ribeiro et al. 2007), triggering the thrusting of autochthonous and allochthonous terrains over the metasedimentary basement in the inner domains of Iberia (Araújo 1995;Ribeiro et al. 2010). Such events are promoted by the transcurrent collision between Avalonia and Gondwana, which also marks the beginning of several tectono-metamorphic and magmatic events, such as those that form the Évora Massif.

The Évora Massif
The complexity and geological heterogeneity of the region are expressed by the wide and extensive Évora Massif terrains, situated between Évora and Montemor-o-Novo municipalities. The Évora Massif is located at the NW of the Montemor-Ficalho sector (Oliveira et al. 1991;Araújo 1995), which corresponds to the Évora-Beja-Aracena domains (Chacón et al. 1983;Apalagueti et al. 1990), marking the suture of a continental collision (Ribeiro et al. , 2010. The Évora Massif was internally subdivided into three main metamorphic domains: (i) the Montemor-o-Novo Shear Zone (MNSZ), (ii) the high-grade metamorphic terrains and (iii) the Évora mid-grade metamorphic terrains (Pereira et al. 2003(Pereira et al. , 2006Chichorro 2006;Moita et al. 2009;Moita 2007; Dias da Silva et al. 2018). The Évora Massif, particularly the high-grade metamorphic terrains, is evidence of the complex geodynamic context of the SW of OMZ, with reflections of the transcurrent continental collisional stages controlling the intense WNW-ESE deformation and the calc-alkaline magmatic activity throughout the suture zone. This magmatic activity is interpreted as being triggered by oceanic plate subduction during the Rheic Ocean closure and subsequent slab break-off mechanisms, leading to the emplacement of several calc-alkaline plutons during Early Carboniferous (e.g. Beja Igneous Complex; Jesus et al. 2016Jesus et al. , 2020. Throughout the Évora Massif, evidence for such activity is materialised at the high-grade metamorphic terrains, where the Hospitais tonalite and the Alto the São Bento granitic suites have been emplaced. i) The MNSZ is part of the hanging wall of the Évora Massif (Dias da Silva et al. 2018) (Carvalhosa 1983;Carvalhosa and Zbyszweski 1994), suggests that during the Upper Cambrian-Ordovician?, the basic volcanic events intensified and later metamorphosed into the greenschist and amphibolitic facies. ii) The high-grade metamorphic terrains shown in Fig. 1b correspond to a 15-20-km belt composed by the Gneiss-Migmatite Complex (GMC; Carvalhosa and Zbyszewski 1994) and intruded by several magmatic complexes (tonalites and granites) targeted for several geochemical and geochronological studies (Chichorro 2006;Moita 2007;Moita et al. 2009Moita et al. , 2015Pereira et al. 2007Pereira et al. , 2015; Dias da Silva et al. 2018). These studies focused on the genesis of some of the intrusive magmatic bodies (Hospitais Tonalite Massif and Alto de São Bento Granitic Suite), as well as in identifying the complex conditions in which migmatisation occurred at the Gneiss-Migmatite Complex (e.g. migmatites at the Almansor River; GMC).
This complex corresponds to a diatexitic-anatetic migmatite complex which, at the contact with the Hospitais Tonalite Massif, displays an extremely heterogeneous structure with individualisation of several migmatisation textures such as diatexites and metatexites and amphibolerich restites with geochemical signatures that suggest crustal anatexy of the Neoproterozoic metasediments. The ages for GMC were constrained around 341 Ma , indicating that migmatisation events should slightly precede the elongated WNW-ESE Hospitais Tonalite Massif installation with 337-336 Ma and characterised by an ubiquitous medium-to coarse-grained tonalite, which displays sparse mafic enclaves with diorite affinity (Moita 2007;Moita et al. 2015).
The Alto de São Bento Granitic Suite is a suite of plutonic rocks characterised by two-mica leucogranite and porphyritic granites with mafic enclaves, similar to the ones described for the Hospitais Tonalite Massif , with ages around 336.7 ± 3.2 Ma . The leucogranites are strongly peraluminous with calc-alkaline signatures coherent with the geodynamic settings that triggered magmatism in the SW of OMZ. The porphyritic granites are characterised by large crystals of alkali feldspar, with sparse large mafic enclaves and by several pegmatitic veins (Moita et al. 2009).
iii) The Évora mid-grade metamorphic terrains is part of the hanging wall at the NE of the Évora Massif ; Dias da Silva et al. 2018) and corresponds to a wide sector affected by amphibolitic facies metamor-phism and composed of metasedimentary rocks (schists, amphibolites) and gneisses, intruded by the Divor and the Pavia Carboniferous plutons (Dias da Silva et al., 2018). Our work focus on the Montemor-o-Novo Shear Zone terrains, which comprise a complex metallogenic setting responsible for the formation of several iron and gold deposits, some of which are part of the Montemor-o-Novo iron mining district.

The Montemor-o-Novo Iron Mining District
The ancient mines that are part of the Montemor-o-Novo iron district ( Fig. 1) are located at the SW of the Ossa-Morena Zone, close to the Montemor-o-Novo  Pereira et al. 2003Pereira et al. , 2015Moita et al. 2009). c Geological map of the Santiago do Escoural area and Montemor-o-Novo iron mines (Andrade et al. 1949), with delimitation of the mining areas (grey dashed rectangles). The map results from the reinterpretation and adaptation from seven geological mining maps at the scale of 1:5000 (n°0/-126; n°0/-124; n°-2/-122; n°-2/-124; n°-4/-122; n°-6/-120; n°-6/-122; Serviço de Fomento Mineiro 1960) and from previous geological mapping works (Silva et al., 1988;Chichorro 2006). Municipality, which gives the name to the mining complex, and to the Santiago do Escoural village, in the Monfurado Mountain range (441 m). Evidence for human occupation in the area dates back to the Palaeolithic Age based on wall paintings and artefacts (100,000 bC-10,000 bC; Silva et al. 2017), and therefore, the use of mineral resources (including those for the pigments used on the wall paintings) for human well-being is assumed to have occurred in the area from those times up to the Roman occupation of Iberia, later succeeded by modern mining in the twentieth century.
Such a long mining history has produced not only landscape transformations (e.g. the presence of mine tailings and open pits), but also the cultural and historical heritage of the region. Examples of this are recognised in the toponymy of the Monfurado Mountain and the Santiago do Escoural village. The name of the mountain range (Monfurado) derives from the agglomeration of Monte (= range/ small mountain) Furado (= bored/excavated/with cavities), owing its name to the ubiquitous excavations seen throughout the mountain which are attributed to Roman mining works. Another explanation for this name could be related to the karst morphologies associated with the limestones and marbles of the Monfurado range, such as the ones observed at the Escoural caves (see the section "Geodiversity Assessment"). The Monfurado range corresponds to an area protected under the "Natura 2000" network, considered as a Special Conservation Zone aiming to protect and preserve important natural habitats.
The Santiago do Escoural village name is considered to have its origin related to the iron exploration and beneficiation during Roman times. The Escoural name could have derived from Escorial, which means "a field of slag", due to the findings of several tailings of slag along the area, which are considered to have been produced during Roman iron mining works.
Long after the Roman occupation, the Montemor-o-Novo area was the target for iron exploitation throughout ten concessions along a 10-km NW-SE belt (Fig. 1c), in which open-pit and, to a lesser extent, underground mining was carried out from 1865 until 1929 (Andrade et al. 1949).
The first and most productive mine of the Montemoro-Novo iron deposits was the Monges mine ( Fig. 1c), with the first mining concession dating back to 1867 (Andrade et al. 1949). The mining activity was ignited by the demand from the British steel industries and reached its peak production between 1869 and 1879 (Andrade et al. 1949). Throughout the end of the nineteenth century and the beginning of the twentieth century, the Monges mine has had several owners, of which the first owner was the Cartaxo Street & C. a and the last the Burnay Bank (Andrade et al. 1949).

Ore Deposit Geology
The geodynamic evolution of the SW Iberian Variscides sustained conditions suitable for the formation of ore deposits associated with rift-related submarine volcanism during the opening of the Rheic Ocean. Example of such metallogenic systems is the Montemor-o-Novo iron deposits (Salgueiro 2011;Salgueiro et al. 2012;Mateus et al. 2013), to which a classification as SEDEX-VMS deposits were attributed due to their geological settings, the presumable time of formation and ore assemblage, mainly constituted by massive magnetite bodies and massive sulphide layers (Maia et al. 2022). Sedimentary exhalative (SEDEX) deposits are formed near seafloor submarine hydrothermal vents that promote the precipitation of metals (Cu, Pb, Zn) in stratiform bodies, usually hosted by shales and siltstones. The conditions that lead to the formation of SEDEX deposits are intrinsically related to rift-related events, in which rifting promotes the formation of hydrothermal vents that leach metals from the surrounding host rocks (Hannington 2021;Wilkinson 2014).
The volcanogenic massive sulphide (VMS) term refers to deposits formed in a submarine environment near large episodes of submarine volcanisms many times triggered during the rifting stages of an orogen. The VMS deposits are usually rich in base metals (Cu, Zn, Pb) and found in massive sulphide lenses composed of more than 60% of sulphides (Hannington 2014), mostly pyrite and pyrrhotite.
The iron ores from the Montemor-o-Novo deposits are mainly hosted as massive lenticules in the Monfurado Formation marbles, although disseminated and massive magnetite is also found at depth (intersected by drill cores; Maia et al. 2022). The host carbonate units display intense amphibole development close to the ore horizons, which is, in some cases, the reflection of the metamorphism in the greenschist to amphibolitic facies. The relation of the iron ores and the host rocks has led to the interpretation that consider them as being syngenetic, and therefore, magnetite formation should be contemporaneous of the Cambrian sedimentary carbonate formation.
The continental orogen stage of the Variscan Orogeny (390-370 Ma; Ribeiro et al. 2007) promoted the formation of several deposits related to such geodynamic context, such as the Escoural Orogenic gold deposits (Ribeiro et al. 1993;Inverno 2001;Maia et al. 2022) found near the study area. These deposits mainly occur in the vicinity of the Boa-Fé fault, within the MNSZ, and are hosted in quartz veins crosscutting the Escoural Formation metasedimentary succession, in which gold-arsenopyrite-loellingite-maldonite assemblages have been identified. Gold mineralisation is structurally controlled by the Variscan MNSZ activity (356-322 Ma; Pereira et al. 2015), with vein development mainly associated with a brittle-ductile transition. The spatial relation between the iron ores and gold mineralisation has been discussed in recent works (Maia et al. 2022).

Geodiversity Assessment
The fragile geological literacy, particularly in Portugal, is in part due to the inappropriate and unproportional teaching of geology through middle and high school, when compared to other natural sciences (Reis et al. 2014). This inefficiency leads to a deficient awareness of the role of mineral resources in society. Hence, this becomes a problem when it is necessary to grasp environmentally responsible exploration and mining projects, leading to problems with local communities and, therefore, in acquiring the necessary social license to operate. Geologists have their share of responsibility in this problem, since normally, it is quite difficult to deconstruct some of the concepts of geology (sensu lato), and particularly, the ones related to exploration and mining, to a non-specialised public. For this, the assessment of geodiversity and mining heritage by cataloguing and promoting the scientific and educational value of key locations is of major importance.
The Évora-Montemor-o-Novo districts comprise attractive and didactic geosites and geodiversity sites that display a strong relationship with several cultural and historical values of the region that could, and should, be used in informal and formal teaching activities focusing on the local and regional geology. A total of ten sites, both outside and inside the ancient iron mining area (Fig. 2), are outlined as being able to integrate a geological and cultural route between Évora and Montemor-o-Novo (Fig. 2). Limelight will be focussed on the mining heritage located in the Montemoro-Novo Municipality, near the Santiago do Escoural village, since geodiversity characterisation and assessment within these areas raises more concerns in terms of geoconservation due to the rapid deterioration of some of the mining heritage sites.
The description of geodiversity is herein addressed for both the outside and the inside of the ancient Montemor-o-Novo mining district, aiming to propose a geodiversity route that interlinks the Évora and Montemor-o-Novo municipalities. A qualitative assessment (Brilha 2016;Brilha et al. 2018) of individual potential location is provided through the next sections, as well as a tentative quantitative assessment of geodiversity regarding the scientific value (SV), educational value (EV) and touristic value (TV) of the locations proposed to integrate the geodiversity route, allied with the degradation risk assessment following the criteria defined by Brilha (2016). The quantitative assessment results can be consulted in Supplementary Material A. A score from 1 to 4 is attributed to each site selected to integrate the geodiversity route, with exception of the Almendres Dolmen Complex since it does not meet the criteria to be considered a geodiversity location. Nevertheless, the Almendres Dolmen Complex was most probably constructed using local granitic stones and, due to its significant archaeological and cultural heritage, is herein considered as an important asset for the route. The numbering of the sites is shown in accordance with Fig. 2 and does not represent the sequence of visitation for the potential geodiversity route (see section "Geodiversity Route Between Évora and Montemor-o-Novo"). The list of the sites both inside and outside of the ancient mining area can be found in Table 1.

Alto de São Bento Granitic Suite (Ancient Quarry)
The Alto de São Bento area is a geomorphological feature of the Évora landscape, located at around 3 km from the city centre, and corresponds to an elevation (approx. 360 m) that contrasts with the surrounding characteristic Alentejo plains. At the area, outcrops of two-mica leucogranite and porphyritic granites (Fig. 3a) were exposed by quarrying activities during the twentieth century and are now accessible to the public. The contrasting altitude of Alto de São Bento with the surrounding landscape was an important factor for the construction of several windmills used for seed processing.
The geological, biological and cultural assets of the area are currently musealised (Brilha and Carvalho 2010) by the Évora Municipality, which developed a museum that offers several educational and touristic activities, allied with the fact that the Alto de São Bento area offers one of the most beautiful sight-seeing sceneries over UNESCO Évora city (Fig. 3b).
Several geological features are displayed at the outcrop, such as the ubiquitous course-grained porphyritic granite with abundant K-feldspar phenocrysts which display concentric zoning (Fig. 3a) and a medium-grained two-mica leucogranite. The porphyritic granite facies also exhibit large mafic enclaves of igneous material (biotite-rich; Fig. 3a) that put in evidence of fractional crystallisation processes (Moita et al. 2009).
Considering the described characteristics, it is evident that the substantive scientific, educational and even touristic values of the area, with scores of 3.1, 3.3 and 2.9, respectively, flag it as a potential geosite location, benefiting from the musealisation and conservation already developed in the area. Furthermore, the Alto de São Bento Granitic Suite could easily be integrated in the Pre-Mesozoic granitoid framework of the Portuguese Geosite Inventory (PGI; Brilha et al. 2005Brilha et al. , 2008, and for this reason, this site is herein considered a mandatory geodiversity stop in the geodiversity route proposed through the section "Geodiversity Route Between Évora and Montemor-o-Novo".

Herdade Monte das Flores Quarry
The Monte das Flores Quarry is an example of geodiversity in the Évora Municipality, located at circa 6 km from the city centre, and it is part of the PGI framed on the Pre-Mesozoic granitoids (Brilha et al. 2008 and publicised on the ProGEO -Portugal website. The quarry is located at the Évora Massif, and extraction is devoted to the Évora granite/granodiorite facies for industrial uses (industrial rocks). The quarry was classified as a geosite due to its geological, economic, cultural, archaeological and educative values. The most relevant features are associated to the use of the Évora granites as building stones from the megalithic period until  Fig. 1). Location of the Évora and Montemor-o-Novo municipalities is provided, as well as the selected locations for the presented geodiversity assessment the present days. Evidence of that is the Almendres Dolmen Complex (see the next section).

Almendres Dolmen Complex
The Almendres Dolmen Complex corresponds to a cromlech archaeological structure located at circa 7 km of the UNE-SCO Évora city and is composed of 95 Neolithic granitic monoliths (Fig. 3c), arranged in an ellipse. The site was classified as a national monument in 2015, and besides being an example of archaeological heritage, the geological aspects of the monument, like the nature of the rock utilised in the construction, can also be used for educational purposes.
Although the Almendres Dolmen Complex does not fit the criteria for geological heritage, if inserted in the geodiversity route, this site could be used as an example of the societal and cultural evolution associated with the use of geological resources. This monument is part of the megalithic route, promoted by the Évora Municipality, and although tourists intensely visit the area, it lacks proper interpretative communication, better road access, infrastructures and visitation circuits.

Migmatites at the Almansor River
The Almansor area corresponds to an outcrop that displays the perfect conditions for the observation of the high-grade metamorphic terrains from the Variscan Gneiss-Migmatite Complex, which is part of the Évora Massif.
The area is located along the left and right margins of the Almansor River that contours the Montemor-o-Novo Municipality (ca. 2 km from the city centre). At the outcrop scale, several petrogenetic features have been individualised by several authors, such as diatexites, weakly foliated granitoids and trondhjemitic veins (Moita et al. 2009). The high-grade metamorphic terrains register the effects of intense migmatisation of the metasedimentary country rocks (Escoural Formation), in which partial fusion, a consequence of crustal anatexy, is evidenced by the presence of diatexites, metatexites, restites and numerous mafic enclaves observed through the area, revealing variable fusion rates. The diatexites and metatexites outline the migmatisation flow (Fig. 3d) commonly exhibiting centimetric to metric restites of metamorphic origin (Moita 2007;Moita et al. 2009), possibly reflecting metasedimentary host rock blocks, from the Escoural Formation, that did not undergo total fusion and in which pre-migmatisation textures are sometimes preserved (Fig. 3e).
The diatexites and metatexites are composed of leucosome and melanosome components (Fig. 3e), and the relation between the GMC and the adjacent Hospitais Tonalite Massif is evidenced by the weakly foliated granitoids present in the area (Moita et al. 2009).
As gathered from the previous description and reinforced by the SV, EV and TV scores ( Supplementary   Fig. 3 Main geodiversity and landscape features from the geodiversity and geosites excluding the mining heritage and located around the Évora and Montemor-o-Novo municipalities. a Representative photography of the porphyritic granite facies of the Alto de São Bento Granitic Suite, with characteristic K-feldspar phenocrysts commonly showing concentric zoning (zoomed-in photo also shown), large biotitic enclaves and thin pegmatitic veins (photo from the authors). b Scenery over the UNESCO Évora city at the Alto de São Bento area (photo from the authors). c Drone imagery over the Almendres Dolmen Complex (photo from the authors). d Overview of the migmatite outcrop at the Almansor riverbed (photo from the authors). e Example of the diatexite, metatexite and restite structures individualised in the Gneiss-Migmatite Complex at the Almansor River (photo from the authors). f Photography showing geological features characteristic of the karst system inside of the Escoural Cave. This photography is a courtesy from the Direção Regional de Cultura do Alentejo (DRCA; Regional Direction of Alentejo's Culture) Material A) of 3.6, 3.1 and 2.65, respectively, it is here suggested that the area has the potential to be classified as a geosite framed in the Pre-Mesozoic Framework of the PGI (Brilha et al. 2008. Furthermore, there has been a previous proposition for the creation of two ecotrails along the Almansor River margins (Dias da , which contemplates the geological, cultural and landscape characteristics of the area. The geoconservation strategies that could possibly be implemented should focus on the implementation of interpretative centres focusing on the representative and rare geological processes displayed through the outcrops. Besides the proposals from other authors, we believe that contemplating this site in a geodiversity route is extremely important in interpreting regional geological settings.

Nogueirinha and Serrinha Mines
The Nogueirinha and Serrinha mines were two of the main open-pit exploitation areas corresponding to two of the 10 mining concessions which are part of the ancient Montemor-o-Novo iron district (Fig. 1). Both mines are located approximately at 26 km and 21 km from Évora and Montemor-o-Novo municipalities, respectively. Mining activities were sustained from 1876 until 1929, and the total amount of exploited iron ores is estimated at around 137,406 tons (Andrade et al. 1949), which, at the face of current societal supply and demand, is considered insignificant.
Currently, the open-pit mining areas are abandoned and have not been the target of any geoconservation proposals. They are both located inside private owned lands, although access is usually granted for educational and scientific purposes. From a visitation point of view, these proposed locations are the ones that raise more concerns regarding security and accessibility to the outcrops, but nevertheless, field work is possible.
Remnants of the ancient mining works are ubiquitously denounced by large volumes of tailings in both Nogueirinha and Serrinha mines. At the Serrinha mining area, the access to the outcrop is easier, and primary magnetite ± primary pyrite mineralisation can be observed.

Escoural Cave
The Escoural caves is a geosite framed in the "Karst Systems of Portugal" classified by the PGI (Brilha et al. 2008Brilha and Pereira 2020) and corresponds to a typical carbonate karst system, located at approximately 15 km from the Montemor-o-Novo Municipality (Fig. 2). The cave was accidentally discovered in 1963 during quarrying works in the area, which focused operations on marble extraction for ornamental purposes. The marbles belong to the Cambrian Monfurado Formation (Chichorro 2006). Allied with the karst, other geological features are identified, such as stalactites and stalagmites (Fig. 3f).
Besides the described geological features that classify the Escoural Cave as a geosite, carvings and paintings found on the cave walls demonstrate that the karst system was used as a shelter for human settlements since the Palaeolithic Age (Silva et al. 2017). The discovery of these findings has classified the cave as a national monument due to its major archaeological value.
Hence, the Escoural Cave has been the aim of several conservation interventions and academic research in a wide range of scientific fields (e.g. Caldeira et al. 2021). Visitation is currently possible, although prior booking with the Montemor-o-Novo Municipality is mandatory. The guided tour through the small cave takes approximately 30 min and can be organised in groups of up to 10 persons. Although the cave displays interesting geodiversity features, the visitation currently only focuses on the pre-historic archaeological features of the monument. The geodiversity quantitative assessment of the Escoural Cave revealed SV, EV and TV scores of 3.1, 3.3 and 3.25, respectively, supporting the geological significance of the monument. We believe that since the area is already classified as a geosite, the guided tour in the Escoural Cave should also focus on the geological features of the karst system and, if so, should integrate the herein suggested geodiversity route.

Serra do Conde Quarry
The Serra do Conde area corresponds to a differential erosion relief (439 m) that is part of the Monfurado Mountain range, located at approximately 23 km from Évora Municipality and 21 km from the Montemor-o-Novo Municipality.
Amphibolites from the Carvalhal Formation outcrop at the Serra do Conde area ( Fig. 1; Fig. 4a), occurring in the core of a synclinal structure ( Fig. 4c; Chichorro 2006). The amphibolites display a nematoblastic texture, and two main metamorphic deformation fabrics are present: one parallel to an S 0 foliation with a 325° N direction and subvertical dipping, strongly marked by the development of epidote (Fig. 4b). Primary foliation is transposed by a generally folded S 1 mylonitisation (145° N direction; Fig. 4b). The rock quality and weak fracturing fomented the extraction of several blocks as ornamental stone, and therefore, the outcrops at the Serra do Conde area were exposed by the quarrying activity.
The area contributed to scientific research that focused on the interpretation of the regional and structural geological settings (Chichorro 2006) reinforcing the scientific value score of 3.2 (Supplementary Material A). Access to the area can be done by foot or by vehicle through a dirt road (approximately 1.5 km from the nearest paved road). The described characteristics of the Serra do Conde Quarry resulted in EV and TV scores of 1.95 and 2.05, respectively, although we believe that the educational value is far greater than the touristic value. Fig. 1. a Wall of the front of quarry exploration in which exceptional outcrops of the green amphibolites of the Carvalhal Formation are observed (photo from the authors). b Closeup photography of the Carvalhal Formation amphibolites at the Serra do Conde Quarry, with clear epidote development marking the S 0 foliation, later folded, and marking a second stage of deformation (S 1 ) (photo from the authors). c An A-B cross section representative of the Serra do Conde area. The A-B profile is shown in Fig. 1 as was adapted from Silva (2013)

Vale da Arca Mine
Vale da Arca Mine is located at circa 16 km and 25 km from the Montemor-o-Novo and Évora municipalities and contributed with a minor amount of ore production to the overall tonnage of the Montemor-o-Novo iron district, although concrete numbers are not known (Andrade et al. 1949). The mine was abandoned during the early twentieth century, although it was later used for quarrying activities that focused on the extraction of the marbles. The quarry is presently abandoned, but both the mining and quarrying activities exposed outcrops that allow for the characterisation of geodiversity features related to the geodynamic and structural settings of the MNSZ.
For the present work, the digital elevation model (DEM) was constructed using drone imagery collection in the Vale da Arca area (Fig. 5), and five geological features of the outcrops are outlined (Fig. 5): 1) Observation of marbles with olivine and disseminated magnetite ± pyrite mineralisation. This lithotype belongs to the Monfurado Formation marbles, and here, it is possible to understand that the disseminated textures and low tonnage were probably the reasons why the mine was abandoned; 2) Boudinage structures of a silicious layer interbedded within the olivine marbles (Fig. 6a) resulting from the different mechanical/rheological competencies between the marbles, with a ductile behaviour, and the silicious layer which has a brittle behaviour, generated due to the overall NW-SE deformation associated to the MNSZ activity. Boudinage structures such as chocolate tablet boudinage and interboudin (Fig. 6c) and necking structures (Fig. 6d) are observed in this site; 3) At the area, beds of massive pyrite ± magnetite layers can be observed (Fig. 6b) and usually exhibit surficial oxidation (Fig. 6b). These beds are overthrusted (355° N; 40° E) by a pristine course-grained marble lithotype, which correspond to point 4 in Fig. 5;  4) The upper unit of the Monfurado Formation marks the initial stages of Cambrian basic volcanism, with abundant intercalations of metavolcanic coarse-grained rocks, which can be observed in this point. These rocks exhibit large crystals of amphibole, epidote and feldspar (Fig. 6e).
The pin-pointed geological features (Fig. 2) show the relevance of these outcrops for a possible geodiversity route, which favour the accessibility conditions of the Vale da Arca Mine. The SV, EV and TV scores (2.1, 2.5 and 2.4, respectively; Supplementary Material A) reinforce the proposition of the Vale da Arca area as a geosite that would easily be integrated in a geodiversity route.
Ongoing research focusing on trace element composition of magnetite (Maia et al., submitted) found evidence for the Quarry area, which is the result of drone aerial imaging and later 2.5D model construction using the QGIS plugin QGIS2ThreeJS. The pinpoints on the model correspond to locations where several geodiversity features can be observed. These locations are described throughout the manuscript deposition of sphalerite (ZnS) along late stages of magnetite deposition. The textures found on magnetite crystals indicate that sphalerite is associated with the porous rims (Fig. 6f), where they occur as inclusions along with pyrite (Fig. 6g, Zn distribution in green). Such findings might be good indications for future mineral exploration in the area, which should not be constrained by future geoconservation strategy because the mining potential of the area should be an ally of the use of the area for scientific, formal and informal education activities.

Monges Mining Complex
The Monges Mining Complex corresponds to the biggest mining works that are part of the Montemor-o-Novo iron district. The area is located approximately 10 km from the Montemor-o-Novo and 35 km from the Évora cities. Mining works were mostly performed in open pit, although locally underground mining was adopted, with ore production estimated around 206,783 tons, which correspond to 60% of the iron production in the sector (Andrade et al. 1949). The Monges mine (Monges = Monks) owes its name to the existence of an Abbey (Fig. 7a) which construction dates back to 1738 and served hermit monks that inhabited the Abbey until 1834. After the abandonment, and with the discovery of the iron ores, the Abbey was used to lodge many of the miners that worked at the mine site (Andrade et al. 1949). Currently, the beautiful building is in ruins (Fig. 7a) due to an unfortunate lack of architectonic conservation strategies.
The remnant open-pit mining activities are currently dominated by intense vegetation which outlines nature restoration promoted by natural processes combined with human abandonment. Even though access is difficult, at the area, large mine tailings can be observed, as well as in situ ore bodies. As previously described, mining activities in the region are thought to date back to the Roman period, and at the time, iron ores were found due to the intense leaching capping, i.e. gossan zone, that are an evidence of intense iron oxide surficial alteration (Fig. 7c).
The massive ore bodies are mainly constituted by magnetite (± pyrite ± chalcopyrite), and perfect crystallisation of magnetite is ubiquitously observed (Fig. 7b). The effects of pyrite exposure to atmospheric conditions are observed at the outcrop scale, and the oxidation of pyrite results in sulphate and native sulphur formation, denounced by its characteristic yellow colour (Fig. 7d). Microscopic examination of magnetite samples collected at the Monges open pits (Fig. 7e,f) revealed euhedral magnetite crystals with porous textures and homogenous chemical compositions (Fig. 7f), but with sparse silicate inclusions.
The examination of the Monges Mining Complex indicates that this is one of the prime examples of mining heritage in the region and is herein proposed to integrate a list of Portuguese geosites, although a framework that considers the mining heritage of the Ossa-Morena Zone would have to be proposed. This proposition is supported by the obtained SV and EV quantitative assessments (Supplementary Material A). Although some accessibility conditioning is identified, such as the access by an earth road and by foot, the area also displays the necessary conditions for a trekking route, taking advantage of the Monfurado Mountain habitats and characteristic vegetation (Quercus suber).

Proven Educational Value
Proven educational and scientific value of the Évora-Montemor-o-Novo region is recognised by the many scientific papers, thesis (e.g. Moita et al. 2009Moita et al. , 2015Chichorro et al. 2008;Salgueiro 2011;Pereira et al. 2003Pereira et al. , 2006Pereira et al. , 2015Dias da Silva et al. 2018;Maia et al. 2022) and educational activities continuously being developed, addressing both the lithological and metallogenic diversity of the area.
Most of the educational activities carried out throughout the area are dedicated to geology bachelor and master's degree students, and one of the reasons why this is continuously done is the proximity to the University of Évora. During the last 4 years, the dynamisation of several activities in the area was done by the project "ZOM3D: 3D Metallogenic Modelling of the Ossa-Morena Zone The activities were targeted to a geoscientific audience, and examples of that were the 2018 Spring Course and the recent 2021 accredited field course devoted to the upgrading of geological concepts targeted to professors from the basic and high-school educational levels. Additionally, the Montemor-o-Novo iron district was the theme for a geoscience communication and divulgation webseries, also promoted by the ZOM3D project and targeted to a Portuguese non-specialised audience. The webseries are dedicated to the iron deposits of the Fe-Zn-(Pb) Montemor-Ficalho belt, with special dedication to the mining heritage of the Montemor-o-Novo ancient iron mines. This webseries is composed of five episodes with lengths between 3 and 5 min, promoting the use of virtual teaching resources inside the classroom. The videos were scientifically revised by the researchers of the ZOM3D project and are currently allocated in the ZOM3D project YouTube channel (https:// www. youtu be. com/c/ ZOM3D/ videos), in which several other webseries dedicated to other geological concepts and mineral resources of the Ossa-Morena Zone can be found.

Geodiversity Route Between Évora and Montemor-o-Novo
The proposal of a geodiversity route between Évora and Montemor-o-Novo municipalities was conceptualised to take advantage of several sites that have already proved their geological value, some already having been classified as geological heritage (e.g. Escoural Cave) and aiming for the beneficiation of the Alentejo mineral resources, in particular the mining heritage of the region (Montemor-o-Novo ancient iron mines).
This geodiversity route would serve as a geological link between the two municipalities, tightening their relationship and reinforcing that geology has no administrative borders. The qualitative and quantitative assessment of geodiversity reveals a great potential for geoconservation purposes of some of the sites, particularly the Alto de São Bento Granitic Suite; Serra do Conde Quarry and Monges Mining Complex display the best scores for considering them key locations of geodiversity in the Évora-Montemor-o-Novo transects and are therefore proposed to be classified as geosites.
Besides the geological aspects of the geodiversity route, it additionally displays important archaeological and cultural features that enrich its intrinsic value, such as the proximity to the UNESCO World Heritage Évora city.
From another perspective, the geological diversity of the route covers several fields of Earth sciences, from mineral resources to structural geology, and geological ages, from the Neoproterozoic up to the Carboniferous. Such features offer the possibility to travel through different stages of the evolution of the Iberian Variscan Belt, presenting it at the light of the Wilson Cycle, and therefore, are immensely favourable for educational and scientific purposes. The proximity to the University of Évora and its state-of-theart institutes (Institute of Earth Sciences (ICT); HERCU-LES Laboratory) is a key factor for the viability of this route, to which the scientific know-how of these institutions could provide unique inputs.
As described, some of the locations are currently used as educational and touristic attractions (e.g. Almendres Dolmen Complex; Escoural Cave) and were intervened by successful conservation strategies (e.g. Alto de São Bento), but the state of conservation of some of them is debatable and their touristic and economic beneficiation seems to fall short (e.g. Almendres Dolmen Complex) from their true potential. For this reason, the geodiversity promotion proposed in this work could favour both the reinforcement of investment in the already classified areas and the beginning of a regional geoconservation strategy focusing on the Montemor-o-Novo ancient iron mining area.
Nevertheless, some of the proposed locations have aspects that could be detractors of a possible beneficiation for touristic and even educational uses of this route, such as the difficulty to access some of the locations (e.g. Nogueirinha and Serrinha mines; Serra do Conde Quarry), private property location (e.g. Herdade Monte das Flores Quarry) and safety issues related to ancient mining areas. Such questions could be addressed with protocols between the municipalities and landowners for the use of private access roads to the geodiversity sites, as well as the common geoconservation strategy of the sites.

Conclusions
There are still many efforts to be done in what concerns the beneficiation and geoconservation of mining and quarrying heritage in Alentejo, particularly in the Ossa-Morena Zone, aiming for the use of such geosites in proper geoscience communication and awareness of the importance of mining on the economic and social development of society.
In many of the mining areas of the Ossa-Morena Zone, such as the Montemor-o-Novo ancient iron mines (Fig. 1), beneficiation could provide assets for local communities by the means of geotourism, with the proposition of geotouristic routes that could combine geodiversity, mining history, history and other cultural assets (e.g. archaeological).
Many of the geodiversity sites and mining heritage, besides their geological value, display landscape sceneries that complement their significance and can attract more public to the sites, increasing the possibility of geoscience communication being effectively delivered.
As previously stated, mining is usually perceived by the public as only being connected to negative key factors, such as acid mine drainage and landscape degradations, and therefore tends to be demonised. Such negative opinion is undeniably related to ancient mining, in which exploitation was performed under lax environmental regulation and with insufficient or absent oversight. Even though current environmental and economic regulations in Portugal are strict, the public perception is stained by the poor examples. This brings us to one of the major problems that present exploration and mining projects face, the social license to operate. This issue can only be overcome through effective and attractive geoscience communication strategies and transparency of the exploration and mining projects and by involving the local communities in the projects. Geodiversity assessment can be a powerful ally in the awareness for the necessity and importance of mining for the society. On the reverse, mining and quarrying works can be powerful allies of geodiversity and geoconservation, as they expose geological features that would otherwise be inaccessible (Prosser 2018).
We believe that the geodiversity assessment herein presented for the geodiversity route between the Évora and Montemor-o-Novo municipalities should not be used as an Fig. 8 Proposal of geodiversity routes between the Évora and Montemor-o-Novo municipalities. The proposed routes are idealised to create a geodiversity "bridge" between these two historical cities. The marked locations correspond to the geodiversity sites and geosites described throughout the manuscript; the base map was constructed from QGIS using the ortophotomap from Open Street View argument to detain future exploration, mining and quarrying projects; on the other hand, we propose that in the future, such projects could provide fruitful cooperation for the catalogue of important geological features and, by fomenting scientific and educational activities, further promote the bridges between academia and industry and society. In sum, the existence of a territorial geoconservation strategy interplayed with responsible mining of mineral resources does and cannot mean the unfeasibility of future exploration, mining and quarrying projects.