Mount Hasan ( tr, Hasan Dağı) is a

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

Anatolia Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

. It has two summits, the high eastern Small Hasan Dagi and the high Big Hasan Dagi, and rises about above the surrounding terrain. It consists of various volcanic deposits, including several

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

s, and its activity has been related to the presence of several faults in the area and to regional tectonics. Activity began in the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

and continued into the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

; a mural found in the

archeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology and ...

Çatalhöyük Çatalhöyük (; also ''Çatal Höyük'' and ''Çatal Hüyük''; from Turkish ''çatal'' "fork" + ''höyük'' "tumulus") is a tell of a very large Neolithic and Chalcolithic proto-city settlement in southern Anatolia, which existed from app ...

have been controversially interpreted as showing a volcanic eruption or even a primitive

map A map is a symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. Many maps are static, fixed to paper or some other durable medium, while others are dynamic or interactive. Although ...

. It was the second mountain from the south in the

Byzantine beacon system In the 9th century, during the Arab–Byzantine wars, the Byzantine Empire used a semaphore system of beacons to transmit messages from the border with the Abbasid Caliphate across Asia Minor to the Byzantine capital, Constantinople. According to ...

used to warn the Byzantine capital of

Constantinople la, Constantinopolis ota, قسطنطينيه , alternate_name = Byzantion (earlier Greek name), Nova Roma ("New Rome"), Miklagard/Miklagarth (Old Norse), Tsargrad ( Slavic), Qustantiniya (Arabic), Basileuousa ("Queen of Cities"), Megalopolis (" ...

of incursions during the

Arab–Byzantine wars The Arab–Byzantine wars were a series of wars between a number of Muslim Arab dynasties and the Byzantine Empire between the 7th and 11th centuries AD. Conflict started during the initial Muslim conquests, under the expansionist Rashidun an ...

Etymology

The modern name of Mount Hasan is widely accepted to be in dedication to Ebu'l-Gazi (El-Hasan), brother of Ebu'l-Kasım during the reign of the

Anatolian Seljuks fa, سلجوقیان روم () , status = , government_type = Hereditary monarchyTriarchy (1249–1254) Diarchy (1257–1262) , year_start = 1077 , year_end = 1308 , p1 = B ...

. It is hypothesized that Mount Hasan’s name was “''Argeos''” or “''Argaios''”, but this name belongs to

Mount Erciyes Mount Erciyes ( tr, Erciyes Dağı), also known as Argaeus ( Greek: ) is a volcano in Turkey. It is a large stratovolcano surrounded by many monogenetic vents and lava domes, and one maar. The bulk of the volcano is formed by lava flows of an ...

. Another hypothesis is that it was simply called ''Árgos'', (

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

: Ἄργος) as well as Argeiopolis Mons. Mount Hasan was named ''Athar'' during the

Hittites The Hittites () were an Anatolian people who played an important role in establishing first a kingdom in Kussara (before 1750 BC), then the Kanesh or Nesha kingdom (c. 1750–1650 BC), and next an empire centered on Hattusa in north-centra ...

period.

Geography and geomorphology

Mount Hasan lies in the Anatolian plateau, between the Taurus Range and the

Pontic Mountains The Pontic Mountains or Pontic Alps (Turkish language, Turkish: ''Kuzey Anadolu Dağları'', meaning North Anatolian Mountains) form a mountain range in northern Anatolia, Turkey. They are also known as the ''Parhar Mountains'' in the local Turki ...

, and its and

's silhouettes dominate the landscape and rise high above the surrounding terrain. The city of

Aksaray Aksaray (, Koine Greek: Ἀρχελαΐς ''Arhelays'', Medieval Greek: Κολώνεια ''Koloneya'', Ancient Greek: Γαρσάουρα ''Garsaura'') is a city in the Central Anatolia Region, Turkey, Central Anatolia region of Turkey and the ca ...

lies northwest from Mount Hasan, while the settlements of

Helvadere Helvadere is a town (''belde'') and municipality in the Aksaray District, Aksaray Province, Turkey. Its population is 2,564 (2021). Geography Helvadere is on the western slopes of Mount Hasan at about . It is south of Aksaray. History ...

, Uluören, Dikmen and Taşpınar lie clockwise from north to northwest around the volcano. In addition, there are seasonal settlements on the volcano which are associated with summer

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or swine ...

s. Mount Hasan is part of a larger volcanic province in Central Anatolia known as the Central Anatolian or

Cappadocian Cappadocian Greeks also known as Greek Cappadocians ( el, Έλληνες-Καππαδόκες, Ελληνοκαππαδόκες, Καππαδόκες; tr, Kapadokyalı Rumlar) or simply Cappadocians are an ethnic Greek community native to the ...

Volcanic Province., which includes

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

s, monogenetic

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

s and

stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...

es such as

, Mount Hasan, Karacadağ and Melendiz Dağ with an area of about -. Volcanism took place during the

Plio-Pleistocene The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5&nbs ...

and into the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

. The volcano has two summits, the high eastern Small Hasan Dagi/ and the high Big Hasan Dagi/; both are located within a

and consist of

lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on ...

s and

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

s. Big Hasan Dagi has two nested craters with an wide and high inner cone that is the source of a

. Fossil

rock glacier Rock glaciers are distinctive geomorphological landforms, consisting either of angular rock debris frozen in interstitial ice, former "true" glaciers overlain by a layer of talus, or something in-between. Rock glaciers are normally found at high ...

s are found on the volcano. The volcano as a whole rises almost around the surrounding terrain and covers an area of with of rocks. The terrain of Mount Hasan is formed by

phreatomagmatic Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions cont ...

breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...

lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...

deposits,

s and

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

deposits. The pyroclastic flow deposits occur in the form of fans or valley flows, when they were channelled by topography. The northern flanks also feature two debris avalanche deposits with hummocky surfaces. The volcanics of Mount Hasan have been subdivided into a "hot flow" unit, a "Mt. Hasan ashes" unit and into a lava unit.

Cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s and accompanying lava flows also occur around Mount Hasan, they are part of a

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic volcano family that forms

parasitic vent A parasitic cone (also adventive cone or satellite cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the volcano. These fractures occur ...

s. These include the cone/maar and a lava flow field at which covers an area of and was produced by

fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive eruption, explosive activity. The vent is often a few metres wide an ...

s. Many of the cones around Mount Hasan have been grouped as the Hasandağ-Karacadağ volcanic field.

Geology

As a consequence of the

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

and eventual closure of the Neo-Tethys and continental collision between

Arabia The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate. ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

moves westward between the

North Anatolian Fault The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral strike-slip fault in northern Anatolia, and is the transform boundary between the Eurasian Plate and the Anatolian Plate. The fault extends westward fro ...

and the

East Anatolian Fault The East Anatolian Fault ( tr, Doğu Anadolu Fay Hattı) is a major strike-slip fault zone in eastern Turkey. It forms the transform type tectonic boundary between the Anatolian Plate and the northward-moving Arabian Plate. The difference in t ...

. This movement and the resulting tectonic deformation of Anatolia are responsible for volcanism in Central Anatolia which has been ongoing for the past 10 million years; this volcanism is defined as "post-collisional". Further, volcanism at Mount Hasan has been related to the Tuz Gölü Fault and its intersection with the Karaman-Aksaray faults; the former of these is one of two major fault systems in Central Anatolia which influence volcanism there, and volcanic products of Mount Hasan have been deformed by the fault. The Hasandag fault branches off the Karaman-Aksaray fault and cuts between the two summits of Mount Hasan. The westerly Mount Hasan, central and easterly form a

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...

, which is surrounded by plains and whose summits reach heights of over . Of these mountains, is more heavily eroded compared to the steep cones of Hasan and like is of early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58lineament ''See also Line (geometry)'' A lineament is a linear feature in a landscape which is an expression of an underlying geological structure such as a fault. Typically a lineament will appear as a fault-aligned valley, a series of fault or fold-ali ...

with and the Karapınar Field. The

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

in Central Anatolia is formed by magmatic,

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

and ophiolitic rocks, the former of which are of

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

age; it crops out at scattered sites and in the Kirshehir and Nigde massifs. The surface however consists mainly of

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

volcanic rocks, which are formed both by

volcaniclastic Volcaniclastics are geologic materials composed of broken fragments ( clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

material and individual volcanoes. Central Anatolia has undergone uplift, for which several mechanisms have been proposed.

Composition

Mount Hasan has produced volcanic rocks with compositions ranging from

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

but the dominant components are

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...

and

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

which define an older

tholeiitic The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma ...

and a younger

calc-alkaline The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic mag ...

or alkaline suite. These rocks in turn include

amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common e ...

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...

clinopyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...

ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

, orthopyroxene,

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...

pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

in the form of augite,

bronzite Bronzite is a member of the pyroxene group of minerals, belonging with enstatite and hypersthene to the orthorhombic series of the group. Rather than a distinct species, it is really a ferriferous variety of enstatite, which owing to partial a ...

diopside Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...

hypersthene Hypersthene is a common rock-forming inosilicate mineral belonging to the group of orthorhombic pyroxenes. Its chemical formula is . It is found in igneous and some metamorphic rocks as well as in stony and iron meteorites. Many references have f ...

and salite, and

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

. The older volcanic stages have produced

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Amer ...

while dacite appears only in the most recent stage.

Obsidian Obsidian () is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter elements s ...

also occurs in the most recent stage although it is not an important component while most of the rocks are

porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all ...

. The basaltic family includes both

and

alkali basalt Alkali basalt or alkali olivine basalt is a dark-colored, porphyritic volcanic rock usually found in oceanic and continental areas associated with volcanic activity, such as oceanic islands, continental rifts and volcanic fields. Alkali basalt ...

s with augite,

hornblende Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks ...

, orthopyroxene,

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

s and

. Magma mixing processes appear to be the most important mechanisms involved in the genesis of Mount Hasan

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

s, which are derived from the mantle with participation of crustal components. Evidence of fractional crystallization has been encountered in the most recent stage rocks and more generally plays a role in the genesis of Hasan magmas although it does not explain all of the compositional traits. Older volcanic stages also show evidence of

influence while the more recent magmas are more indicative of intraplate processes, the effects of crustal extension and of the presence of water. In general, various sources have been proposed for the magmas of the Central Anatolian province.

Ecology and hydrology

Oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

forests occur on Mount Hasan. Annual precipitation is about . Between October/November and May, the mountain is frequently covered by

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

due to the common precipitation at that time and when it melts the water mostly infiltrates into the permeable rocks, making the volcano a principal groundwater recharge area in the region. Additionally, volcanics of Mount Hasan form a major

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

and the Melendiz River passes north and northeast of the volcano.

Eruption history

Mount Hasan has been active for the last 13 million years, with the , Paleo-Hasan, Mesovolcano and Neovolcano stages during the

, Miocene-

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

; the older two stages might actually not be part of Mount Hasan at all. Aside from the

felsic In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, whi ...

central vent volcanism, basaltic volcanism also took place at Mount Hasan throughout its activity; this activity has been dated to 120,000, 65,000 and the most recent event 34,000 years ago. This volcanism however is not part of the actual Mount Hasan system. The main edifice has produced about of magma every millennium. is the oldest (13 million years) volcanic structure, it is among the oldest volcanoes of the Central Anatolian volcanic province. This volcano is a small sized volcano with a

which crops out on the southwestern side of Mount Hasan. It grew over sediments to a present-day elevation of ; today it is eroded, partly buried by the younger Hasan volcanics and disrupted by

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

ing. About 7 million years ago the Paleovolcano began to grow north of ; it too is buried by more recent volcanics but part of its deposits crop out on the northwestern flank of Mount Hasan in the form of ignimbrites, lahars and lava flows. The Paleovolcano also formed a caldera which produced the rhyolitic Dikmen-Taspinar Ignimbrites; formerly the Cappadocian

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

s were in general attributed to volcanism at Mount Hasan, Mount Erciyes and Göllü Dag. The

activity gave rise to the Mesovolcano and Neovolcano, with the former centered between the two present-day summits. This volcano produced ignimbrites, lava domes and lava flows and eventually a

; it too has been dissected by faulting which probably also influenced the development of the volcano and its activity probably occurred between 1 and 0.15 million years ago. Finally, the Neovolcano grew within the caldera, producing various kinds of deposits; these include

s with accompanying

deposits,

in the rim of the Mesovolcano caldera that probably formed through the interaction of intruding

with water in the caldera, 700,000 years ago

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

flows and ignimbrites accompanied by the formation of another, caldera, and finally

andesitic Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

lava flows and lava domes which form the two main summits. Small Mount Hasan is probably older as it is more heavily eroded while the morphology of Big Hasan Dagi is fresher although its pyroclastic flow deposits are heavily incised. Dates of 33,000 and 29,000 years ago have been obtained on the summit domes and ages of 66,000±7,000 years on the most recent

monogenetic volcano A monogenetic volcanic field is a type of volcanic field consisting of a group of small monogenetic volcanoes, each of which erupts only once, as opposed to polygenetic volcanoes, which erupt repeatedly over a period of time. The small monogenetic ...

south of Mount Hasan. Tephras found in the

Konya Konya () is a major city in central Turkey, on the southwestern edge of the Central Anatolian Plateau, and is the capital of Konya Province. During antiquity and into Seljuk times it was known as Iconium (), although the Seljuks also called it D ...

plain and in a lake of the

Turkish Lakes Region The Turkish Lake District or Turkish Lakeland ( tr, Göller Yöresi) is an area with a series of shallow tectonic lakes within the folds of the Taurus Mountains in Southwestern Anatolia, TurkeyDominic Whiting (2001) "Turkey Handbook", p. 439/ref> ...

have been attributed to Mount Hasan. The debris flow from Mount Hasan occurred 150,000-100,000 years ago and a number of

s were emplaced during the last 100,000 years.

Holocene and present activity

Eruptions occurred 8,970 ± 640, 8,200, less than 6,000 years ago and 0 ± 3,000 years ago; the first emplaced

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...

on the summit, the penultimate of these formed a lava dome on the northern flank while the last formed a lava flow on Mount Hasan's western foot. A shift in

s around Mount Hasan may be linked to the older eruptions.

Hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

activity also occurs at Mount Hasan, with

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

s and water vapour emissions observed on the summit.

Magnetotelluric Magnetotellurics (MT) is an electromagnetic geophysical method for inferring the earth's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ra ...

imaging has found evidence of a

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upw ...

at depth and of a possible hydrothermal system. A seismic swarm occurred southwest of Mount Hasan in 2020 next to a

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

that was active 2000 years ago, and reportedly there are frequent explosions within the volcano.

Possible portrayal of an eruption in a mural from Çatalhöyük

mural A mural is any piece of graphic artwork that is painted or applied directly to a wall, ceiling or other permanent substrate. Mural techniques include fresco, mosaic, graffiti and marouflage. Word mural in art The word ''mural'' is a Spani ...

discovered in

has been interpreted as showing a volcanic eruption, commonly linked to Mount Hasan, and this mural has even been interpreted as being the oldest known

. The interpretation of the mural showing a volcanic eruption has been contested however as an alternative interpretation is that the "volcano" shown in the mural is actually a

leopard The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...

and the "village" a set of random geometric motifs. The map interpretation is also contested. If the mural indeed shows an eruption, it probably occurred only a short time before the mural was drawn.

Radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...

has yielded ages of about 7,400 - 6,600 years

BCE Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the or ...

for Çatalhöyük and

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

has produced evidence for explosive eruptions during the time that Çatalhöyük was inhabited. The recorded eruption probably was a lava dome eruption and a possible although disputed reconstruction of a mural recording the eruption is in

Museum of Anatolian Civilizations The Museum of Anatolian Civilizations ( tr, Anadolu Medeniyetleri Müzesi) is located on the south side of Ankara Castle in the Atpazarı area in Ankara, Turkey. It consists of the old Ottoman Mahmut Paşa bazaar storage building, and the Kurş ...

Ankara Ankara ( , ; ), historically known as Ancyra and Angora, is the capital of Turkey. Located in the central part of Anatolia, the city has a population of 5.1 million in its urban center and over 5.7 million in Ankara Province, maki ...

. The discovery of this mural has drawn attention to the volcano and has led to efforts to date the eruptive activity of Mount Hasan.

Importance during ancient history

Mount Hasan was used as a source for

. The

Byzantine The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...

city of

Mokissos Mokissos or Mokisos ( grc, Μωκισσός or Μωκησός) or Mokison (Μωκισόν) was a town of ancient Cappadocia. The Romans called the city Mocisus or Mocissus, and Mocisum, and after the city was rebuilt by the Byzantine Emperor Justi ...

was located on Mount Hasan. The mountain is considered to be the second beacon of the

, which was used to relay information from the

Taurus Mountains The Taurus Mountains ( Turkish: ''Toros Dağları'' or ''Toroslar'') are a mountain complex in southern Turkey, separating the Mediterranean coastal region from the central Anatolian Plateau. The system extends along a curve from Lake Eğirdir ...

to the Byzantine capital

References

Sources

* * * * * * * * * * * * * * * * * * * *

External links

* *
Niğde
{{DEFAULTSORT:Hasan, Mount Mountains of Turkey Stratovolcanoes of Turkey Landforms of Aksaray Province Three-thousanders of Turkey Calderas of Turkey Pliocene stratovolcanoes Pleistocene stratovolcanoes Holocene stratovolcanoes