Introduction

The Göbekli Tepe is located in southeastern Anatolia (Türkiye) and is one of the most important Neolithic sites, dating back to the early Holocene (9500–8200 cal years BC). During the early Holocene, there were Neolithic sites with iconography similar to the Göbekli Tepe iconography, such as Nevali Çori and Karahan Tepe (Şanlıurfa, S Türkiye), Hallan Çemi (Batman, SE Tükiye), and Çayönü (Diyarbakır, SE Türkiye) in the Upper Euphrates-Tigris Basin (Fig. 1). However, Göbekli Tepe has attracted attention for its well-preserved monumental structures and remains (Schirmer 1990; Rosenberg and Redding 2000; Çelik 2011; Schmidt 2011; Tobolczyk 2016). In the Göbekli Tepe, monolithic T-shaped pillars with carvings of animals and humans and a variety of animal sculptures were discovered in these sanctuaries during excavations. These pillars range in size from several meters in height (Schmidt 2000; 2011). Although the meaning of symbolic carvings on T-shaped pillars is a matter of debate today, these figures must have had a ‘communal and collective’ meaning to their builders, who are hunter-gatherer communities (Watkins 2010, 2017). This common interest may have provided early Holocene hunter-gatherer populations with the necessary motivation for the construction of the Göbekli Tepe (Watkins 2010, 2017; Dietrich et al. 2012). Moreover, during the early Holocene, there must have been enough food sources in the area to attract these populations (Schmidt 2012; Clare 2020). Hunter-gatherers are known to have collected and feasted throughout the Epipaleolithic (ca. 20–10,000 BCE) and Early Neolithic periods for social and ritualistic purposes (Munro & Grosman 2010; Byrd 2005; Twiss 2008). The presence of numerous grinding tools and hand stones in Göbekli Tepe indicates familiarity with the processing of cereals (Dietrich et al. 2019; Dietrich 2021). The use of drinking beer prepared from fermented wild crops demonstrated that grains are one of the main food sources and are actively used in Göbekli Tepe (Dietrich et al. 2012). Based on phytolith analysis and morphological examinations of the samples taken from grinding equipment, Hordeum (barley) and Triticum (wheat) plants were processed and consumed in the Göbekli Tepe (Dietrich et al. 2019). The transition from hunter-gathering to agriculture in the early Holocene was possible only with collective memories and working harmoniously with nature (Çıvgın 2016). Archaeobotanical studies from the Fertile Crescent (i.e., Southeast Anatolia) are among the regions where the first domestication attempts began worldwide and early farming sites were established (Lev-Yadun et al. 2000; Aurenche et al. 2001; Diamond 2002; Brown et al. 2009). Domestication of wild grains such as barley, einkorn wheat, emmer wheat, and rye during the Neolithic period is a challenging process that began with the showing of wild seeds and was identified with the agricultural benefits of some mutations (Nesbitt and Samuel 1996; Heun et al. 1997, 2008; Lev-Yadun et al. 2000; Özkan et al. 2002; Luo et al. 2007; Dietrich et al. 2012; Weiss and Zohary 2011; Abbo and Gopher 2017). The earliest signs of cereal processing in the Fertile Crescent are thought to have occurred in the Levant Basin in the Late Epipaleolithic (Hillman et al. 2001; Liu et al. 2018; Eitam et al. 2015). The emergence of the farming lifestyle through the use of various domestication and cultivation techniques is most clearly observed in the Pre − Pottery B (PPNB) period (Cauvin 2000; Byrd 2005).

Fig. 1.
figure 1

1) Several Neolithic settlements in Southeast Anatolia, the Göbekli Tepe and sampling locations within the scope of the study. 2) The location of the Göbekli Tepe in the fertile crescent (modified from Özdoğan 2022)

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In southeastern Anatolia, the presence of domestic emmer and einkorn has been demonstrated since the early PPNB period in the Cafer Höyük (Malatya), Çayönü (Diyarbakır), and Nevali Çori (Şanlıurfa) settlements (Nesbitt 2002; Willcox 2005; Willcox and Savard 2011; Çıvgın 2016). Until recently, the prevailing belief was that the Göbekli Tepe lacked any indications of agricultural activity or domestication (Neef 2003; Schmidt 2012; Clare 2020). However, a reevaluation of this viewpoint became necessary following phytolith analyses of samples recovered from grinding tools (Dietrich et al. 2019). While the southern Levant had hunter gatherers during the Younger Dryas, the lack of evidence of human activity in southeastern Anatolia and the northern Levant until the early Holocene should be correlated with the availability of climatic conditions and natural vegetation (Willcox and Savard 2011; Palmisano et al. 2021) . Pollen analysis is a significant proxy that can provide insights into past vegetation and climatic changes. Additionally, information about past populations and which the type of plants consumed for their daily diet can be obtained. Palynological studies have been conducted in different geographic regions to better understand the climatic changes and vegetation dynamics that have occurred in Anatolia since the late Pleistocene and Holocene. Following moister climate conditions during the Bolling Allerod (late Glacial interstadial), southeastern Anatolia experiences steppe vegetation at the cold and dry Younger Dryas (cal. 12,900 to 11,700 years BP) with limited precipitation in the late Pleistocene (Eriş et al. 2018; Biltekin et al. 2018). Although signs of human-induced land cover change in Anatolia have been observed since the early Holocene, the most prominent anthropogenic impacts and agricultural activity indicators were identified during the Beyşehir Occupation Phase between 3500 and 1300 cal. years BP (van Zeist et al. 1975; Bottema and Woldring. 1984; Asouti and Hather 2001; Eastwood et al. 2007). Even if there are similarities between paleoclimatic studies related to different parts of Anatolia, each region must be evaluated in its unique geomorphological, climatic, and cultural characteristics. An Itrax μ-XRF (micro X-ray fluorescence) scanner is for identifying multiple elements that may be indicators of paleoenvironmental conditions in the study region, and total organic carbon (TOC) is an important proxy for determining organic productivity together with the Ca/Ti elemental ratio (Rothwell and Croudace 2015). This study pioneers the examination of fossil pollen data in the vicinity of the Göbekli Tepe. The absence of pollen data represents a significant gap, and this work addresses this issue by incorporating new palynological insights into the environmental and human history of the region. By utilizing fossil pollen analysis, this work aimed to provide a comprehensive understanding of the plant communities that existed around the Göbekli Tepe before and during the early Holocene periods. This contributes valuable information about the biodiversity and vegetation dynamics in the region. This will be undertaken through elemental analysis of sedimentary cores, specifically μ-XRF and total organic carbon (TOC)/total inorganic carbon (TIC), and examination of fossil pollen data extracted from the region, which can provide insights into paleoenvironmental and paleoclimatic conditions. Additionally, investigating the effects of human-made changes during the early Holocene and Younger Dryas on paleoenvironmental and paleoclimatic conditions also provides a significant advantage. This aspect of the study adds depth to the understanding of anthropogenic influences on local environments, contributing to broader discussions on human impacts on climate. This study aimed to examine paleoenvironmental proxy data to reconstruct past vegetation and climate conditions before and during the early Holocene (from 12,795 to 11,184 cal years BP) and provide insight into the following questions: 1) What plant communities persisted in the surrounding landscape of the Göbekli Tepe?, 2) What impact did human-induced activity within the region exhibit during the early Holocene and Younger Dryas, epochs marked by noteworthy paleoenvironmental and paleoclimatic alterations?

Study area

Şanlıurfa Province, located in southern southeastern Anatolia and east of the Taurus Region, is a bridge between the Syro-Mesopotamian lowlands and Anatolian highlands as shown in Fig. 1. The Harran, Suruç, and Ceylanpınar depression plains formed due to tectonic ruptures in the southern plateau expanding from north to south in Türkiye. The Göbekli Tepe study area is located in the transition area of the ​​Şanlıurfa Plateau to the Harran Plain (southern Türkiye). Administratively, this place is within the border of Örencik village in the Şanlıurfa Haliliye central district. Since the study area is at the meeting point of the Mediterranean and continental climate regimes, both climatic conditions are characteristic of the region. Dry summers are followed by winter months with a continental-Mediterranean precipitation regime, where frost conditions are not very intense (Kuzucuoğlu et al. 2019). According to the statistics from 1929–2021, the annual average highest temperature in the Şanlıurfa district was 38.8 °C in July, and the average lowest temperature was 2.1 °C in January; however, according to meteorological records, the highest temperature record in the region was 46.8 °C in July, and the lowest temperature value was -12.4 °C in February (https://www.mgm.gov.tr/).

Göbekli Tepe, located at the highest point (800 m high) of the Germuş mountain range, has agriculturally inefficient soil cover with steep slopes and Neogene limestone bare ground. The soil structure, arid climatic conditions, and other factors in the vicinity of the Göbekli Tepe correspond to steppe forest vegetation dominated by large grasslands and shrubs. Hordeum spontaneum (wild barley), Bromus sp., Stipa sp., Aegilops sp., Avena sp. (wild oats), Astragalus sp., and Teucrium polium are commonly found in the surrounding grass steppe (Neef 2003). The open herb-rich steppes are accompanied by xeric woodlands consisting of Quercus sp. (oaks), Pistacia sp. (pistachio), Rosaceae (family with shrubs and trees), and P. brutia. The abundance of wild cereal species in Upper Mesopotamia, which covers the Euphrates and Tigris Rivers and their fertile tributaries, was a major factor that led people to prefer this location in the early Neolithic period during the transition from hunter-gathering to early agricultural societies (Willcox 2005; Kuzucuoğlu et al. 2019).

Figure 2 demonstrates that the oldest unit of the Sayındere Formation in the Adıyaman Group in the study area is located on the Southeast Anatolian autochthon. The Middle-Upper Campanian Sayındere Formation was deposited in a deep-sea environment. Belonging to the Şırnak Group, the late Campanian-middle Maastrichtian Bozova Formation builds from clayey limestone and marls and was deposited on the Sayındere Formation (Güven et al. 1991; MTA 2014). In the northern part of the study area, the late Maastrichtian-Paleocene Germav Formation conformably overlying the Bozova Formation was deposited in a submarine slope-deep marine environment (Duran et al. 1988; 1989; Güven et al. 1991; Herece 2008). Composed of clayey limestone and chalky limestone, the Gaziantep Formation is Eocene‒Oligocene in age and laterally passes to the Hoya Formation. The Hoya Formation is made from colored neritic limestone and covers the Adıyaman Group units together with the Gaziantep Formation (Duran et al. 1989). The Fırat Formation (early Miocene), consisting of shelf edge-bank/reef-type carbonates, displays a transgressive character from north to south and conformably overlies the Gaziantep Formation (Çoruh et al. 1997). Moreover, according to Kazancı and Lopes (2022), Limestones of the Fırat Formation were used in the production of T-shaped pillars in the Göbekli Tepe due to their thick bedding, high water content, and high porosity which facilitates shaping. During the middle Miocene (Langhian-Serravallian), the Arabian and Eurasian plates collided along the Bitlis-Zagros suture belt. As a result of this collision, mountain belts along the suture rose. The southeastern Anatolian region has also transitioned into a shallow marine environment basin. Stratigraphic studies have revealed that the deposition of terrestrial material on the Eastern Anatolian and Arabian platforms began 15 million years ago (Okay et al. 2010; Okay et al. 2020). Late Miocene deformation in the Southeast Anatolian region, Tektek in the east of the north‒south trending fracture line, Çaykuyu horst in the west, and the Harran graben area in the middle of the two were formed (Güzel 2020). The youngest units in the study area are Quaternary alluvium units consisting of pebbles, sand, and mud deposits that accumulated in riverbeds and depression plains (Nykamp et al. 2021). Many water resources have emerged around the city of Şanlıurfa through tectonic movements and subsurface karstification created as a result of severe pressure from the South (Eroskay 1982). These include Göbekli Tepe, Edene, Diphisar, Uyuzpınarı, Balıklıgöl, Direkli, Cavsak, Aşık, Dağeteği (Germuş) and Okrasuyu and regional karstic springs. Important and historical settlements were established on these water resources.

Fig. 2.
figure 2

1) Geological map of the study area (modified from MTA 2014 and Kazancı and Lopes 2022), 2) and 3) photos of the Göbekli Tepe indicating the sampling locations

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Materials and methods

Chronology

Accelerated mass spectrometry (AMS) radiocarbon 14C dating of the soil samples (paleosol samples) was performed at the TÜBİTAK-MAM (Marmara Research Center) laboratory facility. The chronology of the samples, their culture and climate periods and their radiocarbon 14C dating results are given in Fig. 3 and Table 1. Seven samples with a high organic content were collected from three distinct locations and subjected to 14C aging and calibration. The ages of the samples taken from the SK-1 location ranged between 12,795 ± 58 and 8948 ± 42 cal BP. The age of the sample retrieved from the SK-2 location was determined to be 12,839 ± 54 cal BP. The samples taken from the SK-3 location were aged 1177 0 ± 48 and 12,357 ± 51 cal BP, respectively. The age of the sample at the 10 m level of the section at the SK-3 location was considered to be incorrect and was not included in the study. Because different fractions of the organic matter in the soil result in different mean residence times (MRTs), there may be some deviations in the ages of the paleosol samples (Birkeland 1999).

Fig. 3
figure 3

Chronology of the samples during different culture and climate periods

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Table 1 AMS radiocarbon ages for SK-1, SK-2 and SK-3 samples
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Total organic carbon (TOC) and total inorganic carbon (TIC)

The total organic carbon (TOC) content in the freeze-dried samples was analyzed by using a Shimadzu TOC/TIC Analyzer at the ITU-EMCOL Geochemistry Laboratory. For TOC analysis, seven samples taken from the topsoil horizons near the Göbekli Tepe were used. Total carbon (TC) analysis is based on measuring the amount of CO2 generated by burning samples at 900 °C with the detector of the analyzer in the presence of purged oxygen and a platinum catalyst. The total inorganic carbon (TIC) contents of the samples were determined by treating the samples with 85% phosphoric acid, heating the sample to 200 °C and quantifying the produced CO2. The TOC content was calculated by subtracting the TIC content from the total carbon (TC) content. The precision of the TOC analysis is better than 2% at the 95% confidence level. TOC is used to reveal organic matter production and preservation (Burdige 2007).

Itrax micro XRF (X-ray Fluorescence) core scanner

XRF core scanning has developed into a widely adopted analytical technique for quickly assessing elemental, density, and textural variations in various sediments and materials, allowing rapid, non-destructive acquisition of elemental variations at sub-millimeter resolution for a wide range of materials (Löwemark et al. 2019). Paleosol samples taken from the Göbekli Tepe vicinity at 1 and/or 2 m intervals were analyzed for multielement composition (e.g., K, Ca, Ti, and Fe) using an Itrax XRF Core Scanner equipped with an optical camera system, an X-ray line camera and an XRF detection system at the ITU-EMCOL Core Analyses Laboratory. Prior to analysis, the soil samples were powdered with an agate mortar. Then, the samples were placed into boxes (size of boxes: 1 cm × 1 cm). The accuracy of these measurements was ensured by multiple measurements on each sample. Subsequently, the averages of these measurements were calculated. XRF measurements were obtained without disturbing the sample and were performed without contacting the sample surface. The XRF elemental detection limits are robust for a range of medium-heavy and lighter elements, including Si, Al, S, Cl, K, Ca, Ti, Fe, As, Pb, Zn, Br, Rb, Sr, Zr, and Ba (Croudace et al. 2006). Depending on the requirements, the duration of the analyses was defined as 8 s per 1 mm. The relative elemental abundances were measured as ‘counts per second (cps)’ and the element ratio profiles were utilized as proxies for paleoclimatic and paleoenvironmental reconstruction (Croudace et al. 2006).

Palynological analysis

For pollen analysis, approximately 20 g of paleosol material was taken from the samples. The seven samples were prepared according to the standard pollen preparation method (Cour 1974). First, 35% cold HCl acid and 47% cold HF acid were added to eliminate carbonate and silica, respectively. Then, ZnCl2 (density > 2.0) was used to separate the palynomorphs. The resting sediments were sieved using 200 μm and 10 μm nylon sieves. The final residue was mounted on glass with one drop of glycerin and fixed with a cover glass. Pollen grains are robust bioindicators (proxy) because the outer wall of the pollen, called the exine, is resistant to all kinds of weathering effects and acids. One inherent limitation in the examination of fossil pollen lies in its exclusive representation of plant taxa capable of producing pollen; nevertheless, certain pivotal species, notably Triticum and Pinus, not only offer insights into climatic conditions but also reliably signal anthropogenic influences. Plants generally exhibit a distribution according to temperature and precipitation changes. For this reason, pollen analysis allows the determination of past climate changes. Another feature of pollen is its morphological diversity. Each plant has a unique pollen morphology. This diversity of pollen makes it possible to conduct taxonomic studies by considering pollen grains. Palynological slides were studied under a light transmission microscope (Leica) at the Eurasia Institute of Earth Sciences Microscope Laboratory in the ITU using immersion oil with different lenses (X63 and X100). Palynomorphs were counted, with a minimum of 300 pollen grains, except for Pinus (pine tree) due to its prolific character. Only three samples were barren in terms of pollen grains, and were not included in the pollen diagram. Pinus species often produce a large number of pollen grains. Only three samples were barren in terms of pollen grains. A pollen atlas (Reille 1992) and pollen photographs were used for pollen identification. The results are displayed in a detailed pollen diagram generated using the TiliaIT program (version 2.0.41; Grimm, 1991–2020). Nonpollen palynomorphs (NPPs) are commonly encountered during routine pollen counting procedures (Shumilovskikh and van Geel 2020). The percentages of NPP were calculated based on the overall pollen count. To identify these palynomorphs, descriptions and illustrations were provided by Wolf (1966; 1967a, b), van Geel (1978, 2002), Ellis-Adam and van Geel (1978), Ellis and Ellis (1997), van Geel and van der Hammen (1978), van Geel and Aptroot (2006), Cugny et al. (2010), and Miola (2012).

Statistical analysis

Principal component analysis (PCA) is employed to construct composite proxy records by identifying the primary factors that govern the variability of the proxies. PCA was performed with PAST (Hammer 2001) software on the XRF data. PCA calculates new variables referred to as principal components, which are linear combinations of the original variables and can be interpreted meaningfully. The analysis was performed on a time axis that was evenly interpolated, spanning from 12,795 to 11,184 years BP. In the process of principal component analysis (PCA), the primary objective is to capture the greatest variance in the first principal component, followed by the second principal component which explains the maximum part of the remaining variance. This methodology involves operating on a correlation matrix derived from linear relationships between the variables under consideration. The fundamental principle behind PCA is to identify a set of multivariate constituents that effectively dominate the variability present in the original dataset. In more detail, the analysis is designed to extract patterns and structures within the data by transforming it into a new set of uncorrelated variables, known as principal components. PCA was applied to a dataset comprising 35 elements. The correlation matrix formed the basis for the analysis, allowing PCA to uncover and emphasize the most influential multivariate components that collectively account for the variability inherent in the original dataset.

Results

The dominant plant communities between approximately 11,126 years BP and 13,354 years BP consisted mainly of Artemisia steppes (14%) and herbaceous plants, including Asteraceae Cichorioideae (45.5%), Asteraceae Asteriodeae (5.9%), and Poaceae (13%) as shown in Fig. 4. At the beginning of the Holocene, a forest community was also present, comprising deciduous tree species such as deciduous Quercus (oak), Salix (willow), Juglans (walnut), Pinus (pine), Abies (fir), Olea (olive), and Juniperus (juniper). These species indicate the presence of forests in the area alongside the herbaceous and steppe vegetation ca. 11,126 years BP. In addition to pollen, nonpollen palynomorphs (NNPs) were also examined. The NNP community contained various elements, such as Pseudoschizaea, plant remains, Glomus, Anabea bacteria, and trilet spores. These nonpollen palynomorphs provide additional information about the environmental conditions and the diversity of microscopic organisms and plant remnants present during the studied time period.

Fig. 4
figure 4

A detailed pollen diagram of samples SK-1 and SK-3 showing the percentages of pollen from the recorded taxa

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The pollen analysis of section SK-3 provides insights into the vegetation and climate changes that occurred between the Younger Dryas (12,418 years BP) and the early Holocene (10,634 years BP) (Fig. 4). During the Younger Dryas, the dominant plant communities observed in the pollen analysis included those of the Artemisia steppes, Asteraceae Cichorioideae, Asteraceae Asteriodeae, and Poaceae families. At a depth of 12 m in the samples, Artemisia steppes comprised 44% of the vegetation. Herbaceous plants, specifically Asteraceae Cichorioideae, accounted for 38% to 41% of the plant population. The Poaceae family accounted for 16.1% of the plant composition, while the Asteraceae Asteriodeae family ranged from 7% to 12.9%. During the early Holocene, there was a decrease in the abundance of Artemisia steppes and Asteraceae Cichorioideae. Concurrently, the forest assemblages exhibited the presence of deciduous tree species such as Quercus and Salix. This indicates the coexistence of forests alongside herbaceous vegetation and steppes during that period. In addition to pollen analysis, the discovery of nonpollen palynomorphs (NNPs) provided additional insights into the presence of plant remains, including Glomus (a type of soil fungus) and Botryococcus algae. These NNP findings contribute to our understanding of the ecological dynamics and diversity of microscopic organisms and remnants during the early Holocene.

Figure 5 shows the total carbon, total organic carbon and total inorganic carbon results of samples SK-1, SK-2, and SK-3. In the SK-1 samples, there is a notable variation in total organic carbon (TOC) values from the lower to the upper levels. The lower portion of the SK-1 section has relatively lower TOC contents, approximately 0.3%. However, the TOC content increases significantly by 1% at depths of 6 m and 4.5 m, reaching values of 1.2% and 1.08%, respectively. Sample SK-2 has a low TOC content of 0.28%. In contrast, the SK-3 section has a higher TOC content, ranging between 1.42% (at 10 m depth) and 0.8% (at 12 m depth). However, the total inorganic carbon content ranged between 7.3% (at 10 m depth) and 8.2% (at 12 m depth) in sample SK-3 (Fig. 5).

Fig. 5
figure 5

Total carbon, total organic carbon and total inorganic carbon results for samples SK-1, SK-2, and SK-3

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The calculation of the ratio involves comparing the concentration of calcium (Ca) to the concentration of titanium (Ti) in sediment or soil samples. The XRF measurements identified a total of 35 chemical elements in the analyzed samples. A notable trend was observed in the Ca/Ti ratio. At 11,126 years BP, there was a general increase in the Ca/Ti ratio. However, an exception to this trend is observed at 13,354 years BP, where a distinct decrease in the Ca/Ti ratio is evident as illustrated in Fig. 6. The concentrations of silicon (Si), potassium (K), titanium (Ti), and iron (Fe) increase within the SK-3 sample at a depth of 10 m. Conversely, these same elements demonstrate a decrease in concentration in the SK-1 sample (4–4.5 m). Nickel (Ni), zinc (Zn), tin (Sn), and antimony (Sb) emerge as prominent elements in the X-ray fluorescence (XRF) profile (Fig. 7).

Fig. 6
figure 6

µ-XRF geochemical element and element-ratio profiles (Si, Ar, K, Ca, Ti, Mn, Fe, Sr, Ca/Ti, and Sr/Ti) for samples SK-1, SK-2, and SK-3

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Fig. 7
figure 7

µ-XRF geochemical element profiles (S, Cl, Cr, Co, Ni, Cu, Zn, Ga, Y, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Yb, W, Bi, U) for samples SK-1, SK-2, and SK-3

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Discussion

Vegetation and climate changes around the Göbekli Tepe inferred from multiproxy analysis

The pollen analysis obtained from the SK-1 samples provides information about vegetation and climatic changes between approximately 11,126 years BP and 13,354 years BP. During these periods, the region experienced a cold and dry climate at 13,354 years BP. The occurrence of Glomus during this period implies the occurrence of erosion activity. Glomus is a mycorrhizal fungus commonly found in association with plant roots, and its presence in the sediment record suggests the transportation and deposition of eroded materials (Anderson et al. 1984). Pseudoschizaea are algal spores, also known as the Concentricystes group, and may indicate soil erosion, does Glomus (Milanesi et al. 2006). In the Poaceae family, Triticum pollen has a low abundance. However, this provides information even though it is found in small amounts in the pollen record. Joly et al. (2007) suggested using biometric measurements to differentiate morphologically between pollen grains of wild grasses and cultivated grasses. A comparison of biometric characteristics, specifically the diameter of pollen grains and the diameter of the annulus, enabled differentiation between pollen grains of wild grasses found along the French West Atlantic seaboard and those of Cerealia-type grasses (Joly et al. 2007). These groups were classified based on a threshold value pair, specifically 47–11 μm (47 μm for grain diameter and 11 μm for annulus diameter). Grasses with measurements equal to or exceeding these threshold values were categorized as Cerealia type, while grasses with measurements smaller than these values were categorized as wild type. In this study, the length of Triticum pollen was measured to be 35.12 μm, while the annulus diameter was found to be 6.8 μm. According to the criteria established by Joly et al. (2007), the morphological measurements of Triticum (wheat) pollen in the pollen records around the Göbekli Tepe indicate that it belongs to the wild type category. The study carried out by Weide et al. (2018) is a systematic review that explores the exploitation of wild grasses during the Epipaleolithic and aceramic Neolithic periods in the Fertile Crescent. The focus is on understanding the role of wild grasses in subsistence economies during the emergence of cereal cultivation. One particular site, Chogha Golan, located in the central Zagros Mountains, was examined in that study. This site spans a time period of approximately 11.7 to 9.6 ka BP. The archaeobotanical data from Chogha Golan revealed the extensive use of various wild grasses for nearly 2,000 years. However, toward the end of the occupation period at Chogha Golan (approximately 9.8 ka BP), domesticated emmer grains replaced wild grasses as the primary food source. The study discusses the potential implications of this transition and suggests that the traditional concept of predomestication cultivation is insufficient for explaining the patterns observed at Chogha Golan. These findings align with the broader trends observed in the Zagros Mountains, where wild grasses were consistently gathered throughout the early Holocene. In contrast, in the Levantine corridor, there was a gradual shift from wild grasses to wild cereals following the end of the Pleistocene (Weide et al. 2018). According to the findings of Dietrich et al. (2019), the analysis of macroscopic and microscopic use-wear on tools at the Göbekli Tepe suggests that Neolithic inhabitants utilized standardized and efficient grinding tools, primarily for processing cereals. Phytolith analysis further confirmed the substantial presence of cereals at the site, compensating for the limited preservation of charred macroscopic remains. The observation of multicellular phytoliths indicated that they commonly originated from the husks and culms of Pooid grasses, including species such as Triticum and Hordeum. However, the occurrence of a small number of multicellular forms suggested that some phytoliths may have been mechanically destroyed during the grinding process due to various deposition and postdeposition factors. Sediments found within the rectangular buildings predominantly contained markers associated with the upper and middle parts of the plants. This pattern may indicate the presence of harvested cereals, as plants are typically gathered and transported in sheaves (Dietrich et al. 2019). Alternatively, it is possible that people were collecting and utilizing wild grasses instead of engaging in cereal harvesting activities.

Numerous studies based on pollen analysis have been performed to reconstruct paleoclimate changes in Anatolia. The majority of these palynological studies have been carried out in sizable lakes and marshes (van Zeist et al. 1975; van Zeist and Woldring 1978; Bottema and Woldring 1984; Sullivan 1989; van Zeist and Bottema 1991; Bottema 1995; Eastwood et al. 1999; Karadaş 2013). These studies have identified changes in vegetation over time and established chronological distinctions for certain periods. For instance, by examining the pollen records of Karamık Swamp and Lake Söğüt in the Göller region, alterations in vegetation over the past 20.000 years have been revealed (van Zeist et al. 1975). These findings indicate that a period of aridity occurred between 20.000 and 14.000 years BP, and was characterized by drought and the prevalence of steppe vegetation. After 14.000 years BP, there was a mingling of tree species amidst the steppes, indicating favorable conditions for tree growth and an increase in humidity. However, by 12.000 years BP, the climate once again became unsuitable for tree growth. Significant development of forest vegetation occurred only after 8500 years BP, likely due to a rise in humidity and temperature. Humidity levels reached their current state 6000 years BP ago, coinciding with the emergence of today's vegetation from 6000 years BP onwards. Between 6000 and 3000 years BP, minimal human impacts on vegetation were observed. However, in many pollen diagrams of the Middle-Late Holocene, a notable shift occurred 3000 years ago. During this period, there was a significant decrease in forest vegetation and an increase in pollen from agricultural products, indicating human influence (van Zeist et al. 1975).

In a paleoclimatic context, the Ca/Ti ratio is often used as a proxy for assessing changes in the intensity of chemical weathering and the availability of calcium in the environment. Calcium and strontium are more soluble and more easily leached from the soil by water than titanium is. Therefore, a higher Ca/Ti ratio suggests enhanced weathering and leaching, indicating wetter and more humid conditions. In contrast, a lower Ca/Ti ratio indicates reduced weathering and leaching, which can be associated with drier and more arid climatic conditions. This ratio is particularly useful for studying past changes in moisture availability, such as variations in precipitation and aridity. Nevertheless, the Sr/Ti ratio is primarily used as a proxy for understanding changes in weathering and erosion processes, which can be linked to climate variations. Therefore, a higher Sr/Ti ratio indicates intensified chemical weathering and higher rates of erosion. This is often associated with increased precipitation and wetter climatic conditions. Higher Ca/Ti and Sr/Ti ratios indicate wetter and milder conditions in the region during the early Holocene. This is supported by the presence of deciduous forests, including deciduous Quercus, Salix, and Juglans. Si, K, Ti, and Fe increase in SK-3 (at 10 m) which suggests that the influx of detritial material came from weathering conditions of the rock in the region. Principal component analysis (PCA) was applied to a dataset consisting of 35 elements derived from sediment samples. By analyzing the XRF data, significant changes are observed in the Ca/Ti and Sr/Ti ratios. Notably, the elements Ca, K, and Si exhibit strong correlations with Ti, implying their association with detrital input (Kylander et al. 2011). According to the PCA results, Ca, K, Si, and Ti grouped together, and exhibited similar patterns. This grouping underscores their interconnected behavior and reinforces the notion that these elements collectively contribute to the detrital input in the sediment (Fig. 8). However, detrital indicators such as Ti and Fe do not exhibit distinct trends in sediments. In particular, Fe emerges as the dominant signal, which is notably evident in sample SK-3 at a depth of 10 m. The dataset shows that the strongest positive PC1-loadings for the elements Ti, K, and Fe are separated from each other with negative loadings on their PCA2- axes. Ca has the most pronounced negative loadings on the PC1 axis possibly indicating subordinate source rock geology. This difference might be due to biomineralization or independent detrital input from bedrock (Fig. 8).

Fig. 8
figure 8

Biplot (PC1-PC2) showing element correlations and data point distributions of log-ratio transformed XRF element intensity data. The dataset shows that the strongest positive PC1-loadings for the elements Ti, K, and Fe are separated from each other with negative loadings on their PCA2- axes. Ca has the most pronounced negative loadings on the PC1 axis

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Furthermore, the ratio of total organic carbon (TOC)-total inorganic carbon (TIC) in sediments serves as an indicator of the input and maintenance of organic matter from both internal and external sources, and is primarily influenced by aquatic biology and terrestrial vegetation (Fischer and Wefer 1999). The observed increase in total organic carbon values aligns with the hypothesis of favorable environmental conditions. In the lower layers of the SK-1 sample, a notable decrease in TOC content is evident. This decrease, coupled with the analysis of the Ca/Ti and Sr/Ti ratios, points toward a climatic shift characterized by cold and arid conditions during that time. This interpretation is supported by the abundance of herbaceous vegetation and steppe species identified in the sediment, including Asteraceae Cichorioideae, Asteraceae Asteriodeae, Poaceae, and Artemisia. These botanical indicators collectively suggest a transition toward more arid and cooler environmental conditions at approximately 13,354 years BP. The correlation between TOC values, elemental ratios, and botanical indicators provides a comprehensive picture of the environmental changes that occurred during the specified timeframe. The decrease in TOC values suggested a potential decrease in organic matter, possibly influenced by the prevailing climatic conditions. The botanical composition further reinforces the idea of aridity, with the dominance of vegetation adapted to cold and arid environments. Conversely, in the upper strata of the SK-3 section, a substantial increase in the TOC content is noticeable. This suggests a higher organic carbon content in the sediments, indicating a potentially greater input of organic material during that period. The significant presence of deciduous Quercus trees further suggested this finding since deciduous tree species are recognized for their contribution to elevated organic matter levels in the environment. Taken together, these discoveries point toward a period of heightened organic productivity and the existence of deciduous forests in the upper layers of the SK-3 section during the early Holocene period around the Göbekli Tepe region. While this study aimed to investigate the impact of human-made changes during specific periods, attributing observed environmental changes solely to human activities may be challenging. Natural factors and climatic variability could also contribute to shifts in the paleoenvironment, and distinguish between anthropogenic and natural influences. Additionally, future studies could address these limitations and refine our understanding of the paleoenvironmental dynamics around the Göbekli Tepe.

Conclusions

At lower levels in the SK-1 section, there is a clear decrease in the TOC content, suggesting colder and drier climatic conditions based on the Ca/Ti and Sr/Ti ratios. The abundance of herbaceous plants and steppes supports this notion. Herbaceous plants dominate these landscapes, suggesting a relatively open and potentially more arid or cold environment. In contrast, in the upper layers of the SK-3 section, there is a significant increase in the TOC content, indicating a greater input of organic material. The presence of deciduous Quercus further confirms this observation, suggesting a period of heightened organic productivity and the presence of deciduous forests during the early Holocene. Moreover, morphological measurements of Triticum pollen in the pollen records from the Göbekli Tepe area indicate that it falls into the category of wild-type pollen.

The utilization of pollen grains preserved in sediments and around archaeological sites enables the long-term tracking of changes in ancient plant communities. This approach not only captures snapshots of historical vegetation but also facilitates the identification of shifts and trends in the composition of these communities over time. By combining various analytical techniques and focusing on different sections, this study enhances the understanding of the region's environmental history and contributes valuable data to broader discussions on paleoclimate and paleoecology. One promising avenue for future research involves a synergistic comparison of pollen record data with archaeological data, specifically archaeobotanical records. This collaborative approach holds substantial potential for advancing our understanding of past environments and human interactions with vegetation in the Göbekli Tepe. In the past, it was accepted that hunter-gatherer people abandoned nomadism and started farming, thus establishing the first cities. When the Göbekli Tepe was discovered, people understood that they had built temples before agriculture and urbanization, and human history was revised. Ongoing archaeological excavations in the region reveal new information every day. The data obtained in this study shed light on the vegetation and climate changes that occurred during that period in the region, which is important for revealing human history.