Introduction

The numerous provincial states of Pakistan are fortunate to have many great examples of unique geological and geomorphologic landscapes that band together to from its rich geoheritage. Unfortunately, development processes over time have destroyed many of the spectacular features that help geoscientists unravel the geological process that form the pristine scenery of Pakistan. Geoheritage measures to conserve these important sites have been limited or non-existent in Pakistan’s landscape. This is particularly noted in the Khyber Pakhtunkhwa area (KP). Fortunately, two unique and geologically important sites in this domain, known as the Nowshera Reef Complex and Gohati Rhyolite Deposits (Gaju Ghundai), respectively, have been shortlisted for consideration for conservation. The Silurian-Devonian age (Mawson et al. 2003) Nowshera Reef Complex is a rare example of complete reef deposit bearing all the three parts of a reef system. The Gohati Rhyolite deposit in Gaju Ghundai is another unique geosite in the Peshawar Basin that shows all the features of a volcano system (Ahmad et al. 2013) in a relatively small area. These two sites are deemed very important for both their unique geological characteristics and ease of access by the public both local people and international academic institutes (Fig. 1). In other countries around the world, the concept of geoheritage and geoparks is well established and maintained. This allows for properly protected large sections of biodiverse landscape that act as successful tourism destinations with economic benefits.

Fig. 1
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Tectonic map of north Pakistan with the location of the Peshawar Basin highlighted, following the topographic and geologic map of Peshawar Basin. Location of the proposed geoheritage points are marked on the map (modified after Hussain et al. 2004; Bibi et al. 2019a, b)

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Outside the educational forums of academia and the mining industry, there is little awareness about the significance of the geological heritage not only in the Khyber Pakhtunkhwa area but also in the broader Pakistan region. This certainly highlights the need to develop, implement, and maintain conservation regulations for the unique features and landforms and their scientific merit. Government’s geoconservation groups, in collaboration with the tourism department and the tourism industry, could generate economic opportunities by becoming the major investors in protecting the geosites, and promoting their spectacular value as a tourist destination.

This study presents the detailed geological field results of the Nowshera Reef Complex (NRC) and Gohati Rhyolite deposits (GRD) located in Gaju Ghundai in the Peshawar Basin of Pakistan, and outlines their potential mining destruction and recommendation for their conservation. The geological field assessment concludes that most of the geosites have encountered extensive blasting and gradual destruction over the past few years. This destruction certainly highlights the need to identify and convince appropriate organizations and/or individuals who will actively protect these geopark sites and bring forth their potential to local administrations, tourism departments, and the public. Simple, but effective measures such as assigning geoconservation protection status and conveying their significant value and uniqueness to the general public can make a huge difference to help protect these geosites. Although a seemingly difficult task, it is predicted that many geoheritage sites will be recognized and the necessary protection measures implemented during the course of development. With much effort, hopefully some of these sites can make the UNESCO list of protected geoparks. It is envisioned that this study will certainly help to bring to light the geological importance of these sites and promote their protection. Furthermore, protection of the designated geological sections can be the first step towards the geological heritage status of the entire Peshawar Basin. It is thought that this status can be made possible through reforming rigid regional laws based on the subjective and barely acknowledged criteria for geodiversity valuation. This geoheritage status can also be achieved through public awareness and initiatives aimed at local residents. It is thought that most effective awareness campaigns will outline not only the educational importance but also the pristine landscapes and the potential social and tourism benefits that these can bring to the different areas of Khyber Pakhtunkhwa, Pakistan. Furthermore, this study emphasizes on creating more public awareness for local inhabitants regarding the geological value, unique landscapes, and diversity of the geosites in the Khyber Pakhtunkhwa, Pakistan.

Methods

The primary step in any geoconservation approach is the inventory and quantification of geological and geodiversity sites, irrespective of the dimensions of the area under analysis. One reliable geoconservation strategy outlined by Brilha (2005) is to establish the number of existing and succeeding phases, which include inventory, quantitative assessment, conservation, interpretation and promotion, and lastly, monitoring of geosites. The current inventory of geosites warrants an initial general survey based on detailed geological fieldwork and analyzed literature reports, which allows for the identification of geosites of interest. A comprehensive description of the geosites follows Ferreira et al. (2018) and presents a basic catalogue form outlining the measuring factor and the functioning constituent parameters. Additionally, Hossain and Nahar (2014) outlined the study dealing with the identification, characterization, and evaluation of the Jaflong, Eocene Sylhet Limestone (Bangladesh) as a geoheritage as well as a potential Geopark.

In order to apply quantification factors to the geosites of interest, this study has adopted the methodology of Pereira and Pereira (2010) and the review article of Brilha (2016), which are both currently used in the inventory of geodiversity by São Paulo State. Brilha (2016) divides the sites into two categories: geosites and geodiversity sites. However, the category separation is subjective and highlights that the scientific value holds more significance than the other criteria, such as cultural, educational, intrinsic, or tourism values. Furthermore, the methodology of Pereira and Pereira (2010) has been highly favored because of the four valued category systems (i.e., intrinsic, scientific, tourism, and management values), and its potential further subdivision of parameters, which can be applied to a particular study area. Each geosite is ranked 1, 2, or 4 points in accordance with the indicators for each criterion. The final scientific value (SV) is a weighted sum of all the ten criteria each holding 7 points which are presented in Tables 1 and 2. Weight distribution is an intricate matter for discussion and will not be conferred further as it is beyond the aim of this study.

Table 1 Geosite classification criteria used for the Peshawar Basin sites in this study
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Table 2 Criteria, indicators, and parameters applied to the selected geosites in this study
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The scientific formulas expressed below (Eqs. 1–4) are used here to calculate the arithmetic mean value of each assigned parameter value for each category. X, Y, Z, and M show the different station values within the geosites.

$$ \mathrm{Intrinsic}\ \mathrm{value}\ \left(\mathrm{IV}\right)=\mathrm{X1}+\mathrm{X}\mathrm{2}+\mathrm{X}\mathrm{3}+\mathrm{X}4/4 $$
(1)
$$ \mathrm{Scientific}\ \mathrm{value}\ \left(\mathrm{SV}\right)=\mathrm{Y1}+\mathrm{Y}\mathrm{2}+\mathrm{Y}\mathrm{3}+\mathrm{Y}3/4 $$
(2)
$$ \mathrm{Tourist}\ \mathrm{value}\ \left(\mathrm{TV}\right)=\mathrm{Z1}+\mathrm{Z}\mathrm{2}+\mathrm{Z}\mathrm{3}+\mathrm{Z}4/4 $$
(3)
$$ \mathrm{Management}\ \mathrm{value}\ \left(\mathrm{MV}\right)=\mathrm{M1}+\mathrm{M}\mathrm{2}+\mathrm{M}\mathrm{3}+\mathrm{M}4/4 $$
(4)

Following the above mathematic mean value calculation, an additional set of final score equations are applied below (Eqs. 5–8) to all.

$$ \mathrm{Scientific}\ \mathrm{usage}\ \mathrm{value}\ \left(\mathrm{SUV}\right)=\left(2\times \mathrm{IV}+3\times \mathrm{SV}\right)/5 $$
(5)
$$ \mathrm{Touristic}\ \mathrm{usage}\ \mathrm{value}\ \left(\mathrm{TUV}\right)=\left(3\times \mathrm{TV}+2\times \mathrm{MV}\right)/5 $$
(6)
$$ \mathrm{Conservation}\ \mathrm{value}\ \left(\mathrm{CV}\right)=\left(3\times \mathrm{IV}+\mathrm{SV}+\mathrm{MV}\right)/5 $$
(7)
$$ \mathrm{Relevance}\ \mathrm{ranking}\ (R)=\left\{2\times \left[\left(\mathrm{CV}/19\right)\times 100\right]+\left[\left(\mathrm{TUV}/19\right)\times 100\right]\right\}/3 $$
(8)

Geological Setting and General Characteristics of the Geosites

The Peshawar Basin is a ~ 8300-km2 intermontane basin bordered by a Main Mantle Thrust (MMT) in the north, and Main Boundary Thrust (MBT) in the south (Fig. 2). The basin is suggested to have formed due to tectonic uplift of the Attock-Cherat Range approximately 2.8 My ago. The northern part consists of metamorphic successions, while the southern part is predominantly metasedimentary. The basin fill is composed of Pliocene to Pleistocene age sediments and a rarely exposed Paleozoic succession (Fig. 2). Martin et al. (1962) classified the successions using lithostratigraphy. Davies and Ahmad (1963) for the first time reported Paleozoic rock in south of Swabi from orthoconic nautiloid fossils. Following this, Teichert and Stauffer (1965) discovered a Devonian reef complex near Nowshera and recorded age-specific fossils. Stauffer (1968) marked all the locations with possible Paleozoic succession in Peshawar. In 1975, Fuchs tried to integrate the Paleozoic succession of Peshawar Basin in the Himalayan stratigraphic framework. The most significant breakthrough in the Nowshera Formation was by Molloy (1979) who found evidence of conodonts. This discovery redefined the stratigraphy of the Peshawar Basin based on the new biostratigraphic information.

Fig. 2
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A geological map of the Peshawar Basin study area (modified after Ahmad et al. 2013) illustrating the regional tectonic structures, associated igneous suites, and deposit localities set over the Gaju Ghundai and Nowshera Reef background

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Pliocene to Pleistocene sediments cover much of the Peshawar Basin. According to Burbank and Tahirkhcli (1885), the sequences can be up to 300 m thick (e.g., southern basin) and generated by sedimentation rates ranging between 2 cm/1000 to 15 cm/1000 years during late Pliocene. In the middle part of the basin, interbedded lacustrine and alluvial sediments are present and thought to have formed due to small local ponds. Burbank and Tahirkhcli (1885) also reported that the deposit patterns are consistent with tectonically controlled drainage. These deposit types are observed both in the south and north basin, while the center is mainly composed of lake and alluvium type deposition. This sedimentation ended early Brunhes chron. 0.6 My with a recent uplift episode of the Attock-Cherat range, which changed the dynamics of the area. Sediments cover much of the older Paleozoic formation with the exception of a few rare outcrops such as the Nowshera Reef Complex and Gohati Rhyolite deposits (GRD). These small outcrops are geologically significant by providing rare stratigraphic exposure into the basin subsurface.

Gohati Rhyolite Deposits

The Gohati Rhyolite deposits (GRD) are part of the Gohati Rhyolite formation and form distinct, isolated volcanic-bearing outcrops both south of the Ambela Complex and in the southeastern Shewa-Shahbazgarhi igneous complex (34° 6′ 16.81″ N; 72° 23′ 11.42″ E). The deposits presented here predominantly consist of ignimbrite/rhyolite rocks that are suggested by Rafiq (1987) to be related to the initial intrusions of the Permian Shewa intrusive complex. Geological features of these deposits include flow banding, 1–2-mm vesicles, and ranges a mineralogy predominately composed of plagioclase, alkali feldspar, euhedral quartz, and biotite set in an aphanitic groundmass (Fig. 3c). Rare clear zircon grains are also present that have both elongated prismatic and rounded shapes. However, some zircon grains are cracked and are associated with radiation halos within biotite. Also noted were hydrothermally altered vesicles partially occupied by epidote and quartz, veinlets of manganese oxide dendrites, and sericitized feldspar phenocrysts (Fig. 3c–f).

Fig. 3
figure 3

Representative photomicrographs of rhyolites with a porphyritic texture—PPL, b manganese dendrites, c porphyritic texture—CPL, d sphene, epidote, and oxide minerals, e monazite present in phenocryst of quartz, and f tourmaline—reproduced after Nawaz et al. (2013)

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A volcanic ash bed and a basaltic dyke are also present in the Gaju Ghundai deposits, which indicates that an extrusive volcanic event occurred at this point in time. Ahmad et al. (2013) record a deposit age of 26.6 + 1.32/0.51 Ma (Oligocene) constrained from seven U-Pb analyses within two zircon grains. This Oligocene age is significant as it differentiates the Gaju Ghundai deposits from all other igneous rocks in not only the Peshawar Basin but also the Himalaya region. The Gohati Rhyolite deposits appear to be coeval with the documented Late Cenozoic eruption–related and intrusive rocks adjoining the Swat, Indus syntaxis, Karakorum, Hindu Kush Mountains, and the Nanga Parbat-Haramosh Massif (Figs. 4, 5 and 6; Maluski and Matte 1984; Zeitler 1982; Zeitler et al. 1993). Furthermore, this recently confirmed Cenozoic age for an extrusive volcanic rock in the Peshawar Basin provides significant igneous support for the continued progression of the Himalayan mountain chain and volcano hotspot origin suggested by Ahamad et al. (2013).

Fig. 4
figure 4

Representative field and microscopic photos of the Nowshera Reef Complex. Significant features include a, b fine grain reef carbonate with examples of stromatoporoid and crinoids, c, d reef core with complex colonies of Rogus Corals, e, f brecciated fossil debris found within back reef settings, and g, h microscopic images of Ozarkodian sp. of conodont (g; Mawson et al. 2003) and Belodella resima sp. of conodonts (h; Mawson et al. 2003)

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Fig. 5
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Representative field images of the Gaju Ghundai volcanic deposits and current excavation activity. The important geological features include (1) a mafic dyke in the rhyolite host rock, (2) contact of the rhyolitic lava flow and volcanic ash deposit, (3) a pyroclastic debris layer, (4) close-up images of the rhyolite lava flow, (5–7) differing views of the deposit excavation, (8) an igneous dyke intruding through a rhyolitic body, and (9) regional view of the deposits

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Fig. 6
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A series of Landsat images showing the gradual excavation of the Gaju Ghundai volcanic deposits with time (years 2010 to 2018). Numbers 1 to 9 in these pictures represent geological sites. The details are explained in Fig. 5

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Petrographic Studies of Gohati Rhyolite Deposits

The Gohati Rhyolite deposits (GRD) mainly comprise volcanic rocks including rhyolites, dacites, and microporphyries. The porphyritic texture of the rhyolites (Fig. 3a) indicates a volcanic origin with a composition consisting of ~ 70–80% quartz phenocrysts in a fine-grained matrix (Fig. 3b), ~ 14–17% alkali feldspar, and ~ 9–14% plagioclase. Other accessory minerals include rutile, tourmaline, garnet, epidote, and monazite (Fig. 3c–f). Manganese dendrites are also observed and appear as brown-colored tree-like patterns in both the field and petrographic examples (Fig. 3f). These dendrites have also been documented by Nawaz et al. (2013) and Potter and Rossman (1979).

Nowshera Reef Complex

A Paleozoic reef belt has been recognized adjacent to the town of Nowshera (34° 00′ N, 72° 00′ E) in Khyber Pakhtunkhwa. This belt comprises nine distinct hills that are situated in a 15-mile-long, east-west-orientated band which protrudes out of the Peshawar alluvial plain. Each separate hill geologically consists of one or more reef cores that range between ~ 100 and 700 ft in thickness. The Nowshera Reef Complex (NRC) was initially documented by Teichert and Stauffer (1965) as one of the first unique reef deposit examples in the Indo-Pakistan subcontinent. This unique NRC hosts fauna that were previously undiscovered in the geological strata of the Gondwanan Indian and Pakistan region Fuchs (1975) (Fig. 4). These fauna are regarded by Stauffer (1968) to be Early Devonian to Late Silurian (Ludlovian to Gedinnian) in age. The initial carbonate reef deposits hosting the fauna are thought to be Silurian in age and found both in rare localities within the state, and southernmost Devonian sediments in West Pakistan (Shah 2009). Prior to the discovery of both Teichert and Stauffer (1965), and Stauffer (1968), the NRC was thought to be the part of the Attock Slates and was assigned a Precambrian age. However, Molloy (1979) redefined the new stratigraphy of Peshawar Basin by documenting late Devonian (Frasnian) conodont fauna in the carbonate rocks north of the NRC. Following this, Pogue and Hussain (1986) were able to redefine the broader stratigraphy of the Peshawar Basin. Significance of this reef is that it represents all three parts of a reef complex. The stromoporoids and crinoids of front reef setting (Fig. 4 a and b) and reef core are represented by complex colonies of Rogus corals (Fig. 4 c and d) and back reef setting with brecciated fossil debris (Fig. 4 e and f). Conodonts recovered from these rocks have a color alteration index (CM) value of 5, which indicates peak metamorphic temperatures of 300 °C (Fig. 4 g and h; Pogue et al. 1992).

Cooperation between the International Association of Promoting Geoethics in Pakistan (IAPG Pakistan Chapter) and the Department of Geology, Abdul Wali Khan University Mardan, allowed for detailed geological fieldwork in Peshawar Basin. The aim of the fieldwork was to collect data for the assessment of the geosite in relation to its potential Geoheritage status. Excavation of marble in the study area has been taking place for many years with the excavated limestone products used both for building as construction material and for calcination processes. Although the marble deposits exhibit nice pink color and have red-gray ferruginous bands and calcite veins and cavities of interests, the mining of this marble is unfortunately intertwined with the partly metamorphosed NRC. According to Geological Survey of Pakistan (GSP) reports as mentioned by Shah (2009), these marble deposits associated with the NRC are of substandard quality with estimated reserves up to 3,84,000 ft3. By contrast, the rosy and gray-colored marble deposits of the Pir Sabak area are of good quality (limited impurities) and have estimated reserves of 9,70,000 ft3 (Figs. 7 and 8; Stauffer 1968). Consequently, these marbles are excavated on a large scale (e.g., blocks measuring 6 × 2 ft) by private miners and traded at a high market value.

Fig. 7
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A series of Landsat images illustrating the gradual excavation of Nowshera Reef Complex with time (years 2002 to 2017)

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Fig. 8
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Representative field photographs that document (1) the initial important geological features of the Nowshera Reef Complex, and (2, 3) the extensive excavation activity of the complex that occurred shortly after

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The Scientific and Educational Values of the Exposure

The current geological stratigraphy of the entire Peshawar Basin is based on the Nowshera Reef Complex strata. Strata sequences that form the base or higher sections of the stratigraphy are poorly age constrained and have been assigned an assumed to be of Devonian (Frasnian) age based on the principle of relative superposition and conodonts found within the Nowshera Formation. These conodonts are important geological markers that possess a color alteration index that represents a thermal clock to help unravel and reconstruct the history of the Peshawar Basin. Another significant factor of the unique modal Nowshera Reef Complex is that it is the only known example in the stratigraphy of Pakistan to exhibit all reef aspects (i.e., front, back, and core), and hosts some rare and beautiful coral fossils found nowhere else in Pakistan (Fig. 4). The Gohati Rhyolite represents another unique geological episode in Geological history of Peshawar Basin. Confined to a relatively small area of < 500 m2, the Gohati sequence provides insight into the fascinating geological processes of a volcano. Lava flows of rhyolite and ignimbrite, followed by a layer of pyroclastic debris and tuff, and a late-stage mafic dyke are thought to represent an eruption model in the Peshawar Basin tectonic history (Figs. 4 and 5). Recent isotope data by Ahmad et al. 2013 reveals that this volcanic sequence potentially represents the first Cenozoic volcanic hotspot activity in Pakistan after the Indian plate collision.

Both NRC and GRD preserve excellent examples of past geological processes to qualify for educational, scientific, and tourism geoconservation. These sites are located very close to national-provincial capitals and the major educational institute for earth science in Pakistan, which creates readily available access for members of the public and scientific community. Table 2 presents the detail analysis of these geosites and their evaluation to international standards. The outcomes in Table 2 highlight that both geosites are highly qualified for geoconservation based on their criterion. Unfortunately at present, both of these sites are at high risk of destruction due to their extensive excavation/mining for construction materials. This study aims to emphasize and promote the rare and important geological heritage and educational significance of the Nowshera Reef Complex (NRC) and Gohati Rhyolite, and their need for geoconservation.

Geodiversity and geoheritage maintenance projects contribute to help resolve the issues surrounding species existence and the reliability of ecological systems. Geoheritage is a vital aspect of world heritage in general as it characterizes the exceptional record of the entire progression of the geoworld. Human disturbance of the Earth’s surface has led to the accelerated devastation of many key geosites in the geological record (e.g., European countries such as Germany and Poland). As a result, geoconservation has been developed to systemically deal with the conservation of geological heritage, hence its geology and geomorphological significance, by identifying, protecting, and managing important sites and landscapes (Hose 2000; Francesco et al. 2015). The choice of geoconservation is the conservation of geosites, as elementary components of the geological heritage of the Earth by means of definite inventory, evaluation, conservation, valuing, and monitoring procedures (Brilha 2005; Brilha 2010, Henriques et al. 2011). Taking into account the geological and geomorphological significance of current geoconservation sites, the rare fossils of the Nowshera Reef Complex and the pyroclastic bed sequences of the Gohati Rhyolite make an excellent case for geoconservation. These eye-catching geosites would be beneficial not only for local residents to visit and study but also for the broader international scientific community and tourism/geotourism industry

Limited consideration for the geoconservation of the Nowshera Reef Complex and Gohati Rhyolite has been given, which is unfortunate for the education of upcoming earth scientists, as well as established international researchers. Continuous environmental devastation threatens the reef complexes and volcano model sequences, which are truly great treasures of nature. Elsewhere in the world, like Europe for example, similar geosites are well protected and have a geoconservation status formed under specified propagated laws and strict codes. This begs the question why the spectacular Nowshera Reef Complex and Gohati Rhyolite are not yet also placed under a geoconservation status. At the current rate of destruction due to mining, by year 2025, the Nowshera Reef Complex and Gohati Rhyolite will become nothing more than a quarry waste dump. This of course will provide a great hindrance to local and international geoscientists who wish to study the rare and significant fossil records documented by Stauffer (1968), and/or the tectonic history of the volcanic extrusive rocks. Exposure of these geosites is already limited in Pakistan and will be significantly reduced if the geoconservation status is not applied. Future alternatives may involve spending large amounts of time and money on digging rubble and concrete from nearby roads, which seems unnecessary if conservation authorities act quickly. It is therefore proposed that the great geological treasures of the Nowshera Reef Complex and Gohati Rhyolite must be preserved as a National Park for the education of future generations.

Conclusions

Placing emphasis on the important geological heritage of the Peshawar Basin geosites and outlining their inventory and qualification parameters has been the focal point of this paper. Each geologically exposed geosite was assessed and underwent a systemic valuation of its scientific, educational, and tourist merits. The preliminary characterization of the geosites was performed in the field with bibliographic support and involved thorough inventory characterization and tabulations. Through this, a comprehensive catalogue with specific detailed information for each geosite has been achieved.

Geosite results illustrate that both the Nowshera Reef Complex and Gohati Rhyolite deposits retain their international significance in the relevance score (IR), i.e., 5/7P. Adding to the significant relevance score, both geosites hold high tourist potential due to their esthetic and intrinsic value. However, concerns regarding the scientific usage value and effect on the areas have been raised. These issues were warranted since the geosites possess a final relevance score of 4/7P which is above the minimal and zero relevance, i.e., 2/7P and 1/7P. This above average score for the Nowshera Reef Complex and Gohati Rhyolite deposits indicate a high representation of important geological and geomorphological processes which are present and should be taken into account for geosite preservation. With regard to the scientific usage value (SV), the result outcomes based on ten criteria produce a final score of 28/70P for station A and 25/70P for station B with overall 53/70P for the NRC and consecutively the 25/70P and 28/70P for GRD stations A and B, respectively, which is above the average value of 35/70P.

In addition to the above, facts documented in this study aim to highlight the importance of geoconservation for the Peshawar Basin geosites. Geological management and municipal town governments have the responsibility to safeguard the geodiversity and geoheritage for sustainable development. Great emphasis is placed on a dire need to develop protection measures and apply these to conserve the unique and scientifically significant geological features and landforms of the Peshawar Basin geosites.

To date, unfortunately limited attention has been paid to protect these geologically fascinating sites of nature. Elsewhere in the world, similar reef complexes and rare volcanic deposits are currently protected for educational purposes under specified propagated laws with a strong code of practice. As a result of the protection laws, these sites will be able to be scientifically studied and enjoyed by future generations. Furthermore, due to their distinctive nature, exceptional geological phenomena, and historic and educational values, these rare deposit locations are frequently visited by large groups of fascinated tourists. The flow on the effect of tourism not only provides social economic benefits for the municipal areas but also acts as an educational focal point for international exposure in the scientific community. Consequently, this study highlights the need for a conservation policy and educational interpretive services (e.g., information panels, visitor centers, public scientific forums) that are currently limited or non-existent in the Peshawar Basin geosite areas. Taking into account all of the above factors, it becomes clear that the great geological treasures of the Nowshera Reef Complex (NRC) and Gohati Rhyolite deposits (GRD) must be preserved as a National Park that caters for education of future generations.