II.3. Intermediate igneous rocks

DIORITE

Appearance: Dark, medium to coarse-grained intrusive igneous rock, the intrusive equivalent of andesite. The mineral of this rock type is similar with the gabbros, but the anorthite content of plagioclase is usually less than 50 mol%. It usually can be found in subduction zones.

Mineral content:

Essential minerals: Ca-Na plagioclase, amphibole, less biotite and pyroxene (clino- and/or orthopyroxene). Among the mafic minerals amphibole prevails,

Accessory minerals: minor amount of quartz, alkali-feldspar or olivine and feldspathoids, as well as apatite, magnetite, garnet

Secondary minerals: chlorite, sericite, epidote

Rock types:

further varieties of diorites are defined based on the occurrence of quartz or feldspathoids and considering the relative amount of alkali feldspar and plagioclase: quartz-monzodiorite and foid-diorite, foid-bearing diorite, foid-bearing monozodiorite and foid-monzodiorite

Figure II.96. – Diorite

Locations in the Carpathian-Pannonian region: Central-Slovakian volcanic complex, such as in the deeply eroded central part of the Stiavnica, Kremnica and Javorie volcanoes

ANDESITE

Appearance: Dark, grey or red, fine-grained often medium to highly prophyritic volcanic rock. It is common rock type of subduction zones.

Mineral content:

Essential minerals: Ca-Na plagioclase, amphibole, pyroxene (clino- and/or orthopyroxene), occasionally biotite.

Accessory minerals: apatite, magnetite, garnet

Secondary minerals: chlorite, sericite, epidote, carbonat minerals

Rock types:

Figure II.97. – Andesite (Szanda, Cserhát)

Figure II.98. – Typical, grey and red andesite from the Visegrád Mts. Although they have different appearance, they are similar petrographically and geochemically. They could be derived from the same collapsed lava dome and now are the main constituents of block- and ash flow deposits (Thirring-cliffs, Visegrád Mts., photo: Szabolcs Harangi)

Figure II.99. – Typical microscopic photos of plagioclase- and pyroxene-phyric andesite from Bér, Cserhát. Left with one nicol, right with crossed nicols.

Figure II.100. – Typical microscopic photos of plagioclase-phyric andesite from Zsuny, Cserhát. Left with one nicol, right with crossed nicols.

Figure II.101. – Typical microscopic photos of amphibole- and plagioclase-phyric andesite from the Visegrád Mts.. Left with one nicol, right with crossed nicols.

Figure II.102 – A simiplified cross-section of a subduction zone, where most of the andesites are formed via fractional crystallization of primitive mantle-derived high-Al basalts and/or by mixing of mantle-derived mafic and crustal silicic magmas.

Figure II.103. – Characteristic andesite lava rocks: block lava in Nea Kameni, Santorini (left, photo: Szabolcs Harangi) and steep-sided fresh lava dome emerged from the remnant of an old, collapsed lava dome remnant (Soufriére Hills, Montserrat,photo: Richard Roscoe)

Figure II.104. – Characteristic andesite lava rocks: the andesitic lava dome of the Unzen, Japan with a block- and ash flow deposit in the front (photo: Richard Roscoe).

Locations in the Carpathian-Pannonian region: Eastern-Bükk (Triassic), Zala basin, Velence Mts. and Recsk (Eocene-Oligocene); Miocene-Pliocene andesites: Pohorje, Visegrád Mts., Börzsöny; Central-Slovakian volcanic complex (Stiavnica, Kremnica, Javorie, Polyana), Cserhát, Mátra, Cserehát, Tokaj-Slanec Mts., Vihorlat, Gutin, Calimani, Gurghiu, Harghita, Apuseni, Mecsek, basement of the Great Hungarian Plain

Figure II.105. – Locations of the Triassic (orange), Eocebe-Oligocene (blue) and Miocene-Pliocene andesites (black) in the Carpathian-Pannonian region.

Triassic andesite:

Figure II.106. – Typical microscopic photos of andesite from Polgárdi. The rock is strongly altered. Scarn mineralization belongs to this subvolcanic andesite body. Left with one nicol, right with crossed nicols.

Figure II.107. – Typical microscopic photos of andesite from Polgárdi. The rock is strongly altered. Scarn mineralization belongs to this subvolcanic andesite body. Left with one nicol, right with crossed nicols.

Eocene-Oligocene andesites:

Figure II.108. – Typical microscopic photos of andesite from Nadap (Velence Mts.). Left with one nicol, right with crossed nicols.

Figure II.109. – Typical microscopic photos of andesite from Nadap (Velence Mts.). Left with one nicol, right with crossed nicols.

Figure II.110. – Typical microscopic photos of andesite from Kanázsvár (Recsk, Mátra). Left with one nicol, right with crossed nicols.

Figure II.111. – Typical microscopic photos of andesite from Kanázsvár (Recsk, Mátra). Left with one nicol, right with crossed nicols.

Miocene-Pliocene andesites

Visegrád Mts. and Börzsöny (13-16 Ma)

Figure II.112. – Locations of Miocene andesitic rocks in the Northern Pannonian basin.

Figure II.113. – Miocene andesites: a deeply eroded volcano (Keserűs volcano, Visegrád Mts) from the viewpoint of Dobogókő (photo: Szabolcs Harangi).

Figure II.114. – Miocene andesites: rhyodacitic pyroclastic flow deposit and accretionary lapilli-bearing tuff, the oldest volcanic products of the Visegrád Mts. (Holdvilág-valley; photo: Szabolcs Harangi).

Figure II.115. – Miocene andesites: block- and ash flow deposits of nuée ardentes in the Thirring cliffs (Visegrád Mts.; photos: Szabolcs Harangi)

Figure II.116. – Miocene andesites: The Castle hill at Visegrád is composed of huge rock avalanche deposits formed by flank collapse of an andesite volcano (Visegrád Mts.; photos: Szabolcs Harangi)

Figure II.117. – Typical microscopic photos of pyroxene-andesite from Dömörkapu (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.118. – Typical microscopic photos of pyroxene-andesite from Dömörkapu (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.119. – Typical microscopic photos of the red andesite from Vadálló-kövek (Visegrád Mts.). Amphiboles show total opacitization. Left with one nicol, right with crossed nicols.

Figure II.120. – Typical microscopic photos of the red andesite from Vadálló-kövek (Visegrád Mts.). Amphiboles show total opacitization. Left with one nicol, right with crossed nicols.

Figure II.121. – Typical microscopic photos of the light grey amphibole andesite from Vadálló-kövek (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.122. – Typical microscopic photos of the light grey amphibole-andesite from Vadálló-kövek (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.123. – Typical microscopic photos of amphibole-andesite from Holdvilág-árok (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.124. – Typical microscopic photos of amphibole-andesite from Holdvilág-árok (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.125. – Typical microscopic photos of pyroxene-andesite from Prépost-hegy (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.126. – Typical microscopic photos of pyroxene-andesite from Prépost-hegy (Visegrád Mts.). Left with one nicol, right with crossed nicols.

Figure II.127. – Andesites from Börzsöny: Typical microscopic photos of amphibole-andesite from Királyrét. Left with one nicol, right with crossed nicols.

Figure II.128. – Andesites of Börzsöny: Typical microscopic photos of amphibole-oxiandesite from Királyrét. Left with one nicol, right with crossed nicols.

Figure II.129. – Andesites of Börzsöny: Typical microscopic photos of amphibole-andesite from Hártókút. Left with one nicol, right with crossed nicols.

Figure II.130. – Andesites of Börzsöny: Typical microscopic photos of amphibole-andesite from Hártókút. Left with one nicol, right with crossed nicols.

Figure II.131. – Andesites from Börzsöny: Typical microscopic photos of a hypersthene biotite-amphibole andesite from Peres hill. Left with one nicol, right with crossed nicols.

Figure II.132. – Andesites from Börzsöny: Typical microscopic photos of a hypersthene biotite-amphibole andesite from Peres hill. Left with one nicol, right with crossed nicols.

Figure II.133. – Andesites from Börzsöny: Typical microscopic photos of a hypersthene andesite from Nagy-Sas hill. Left with one nicol, right with crossed nicols.

Figure II.134. – Andesites from Börzsöny: Typical microscopic photos of a hypersthene andesite from Nagy-Sas hill. Left with one nicol, right with crossed nicols.

Figure II.135. – Andesites from Börzsöny: Typical microscopic photos of the amphibole-pyroxene andesite from Nagy-Inóc. Left with one nicol, right with crossed nicols.

Figure II.136. – Andesites from Börzsöny: Typical microscopic photos of the amphibole-pyroxene andesite from Nagy-Inóc. Left with one nicol, right with crossed nicols.

Stiavnica-Kremnica volcanic complex (10-16 Ma)

Figure II.137. – Andesites from Central-Slovakia: Typical microscopic photos of the garnet-bearing amphibole andesite from Breziny. Left with one nicol, right with crossed nicols.

Figure II.137. – Andesites from Central-Slovakia: Typical microscopic photos of the garnet-bearing amphibole andesite from Breziny. Left with one nicol, right with crossed nicols.

Figure II.138. – Andesites from Central-Slovakia: Typical microscopic photos of the pyroxene andesite from Ladzany. Left with one nicol, right with crossed nicols.

Figure II.139. – Andesites from Central-Slovakia: Typical microscopic photos of the pyroxene andesite from Ladzany. Left with one nicol, right with crossed nicols.

Figure II.140. – Andesites from Central-Slovakia: Typical microscopic photos of the amphibole andesite from Ihráč. Left with one nicol, right with crossed nicols.

Figure II.141. – Andesites from Central-Slovakia: Typical microscopic photos of the amphibole andesite from Ihráč. Left with one nicol, right with crossed nicols.

Figure II.142. – Andesites from Central-Slovakia: Typical microscopic photos of the pyroxene andesite from Hrušov. Left with one nicol, right with crossed nicols.

Figure II.143. – Andesites from Central-Slovakia: Typical microscopic photos of the pyroxene andesite from Hrušov. Left with one nicol, right with crossed nicols.

Figure II.144. – Andesites from Central-Slovakia: Typical microscopic photos of the basaltic andesite from Vlci Vrch. Left with one nicol, right with crossed nicols.

Figure II.145. – Andesites from Central-Slovakia: Typical microscopic photos of the basaltic andesite from Vlci Vrch. Left with one nicol, right with crossed nicols.

Cserhát (13-16 Ma)

Figure II.146. – Locations of the andesitic volcanic rocks (red) in the Cserhát

Figure II.147. – Columnar jointed andesites (Szanda and Bér; photos: Szabolcs Harangi)

Figure II.148. – Andesitic lava flows and silicic pyroclastic deposits at Sámsonháza (photo: Szabolcs Harangi)

Figure II.149. – Andesites from Cserhát: Typical microscopic photos of the pyroxene andesite from Szanda. Left with one nicol, right with crossed nicols.

Figure II.150. – Andesites from Cserhát: Typical microscopic photos of the pyroxene andesite from Szanda. Left with one nicol, right with crossed nicols.

Figure II.151. – Andesites from Cserhát: Typical microscopic photos of the pyroxene andesite from Bercel. Left with one nicol, right with crossed nicols.

Figure II.152. – Andesites from Cserhát: Typical microscopic photos of the pyroxene andesite with large plagioclase phenpcryst from Bercel. Left with one nicol, right with crossed nicols.

Figure II.153. – Andesites from Cserhát: Typical microscopic photos of the crystal-rich pyroxene andesite from Bér. Left with one nicol, right with crossed nicols.

Figure II.154. – Andesites from Cserhát: Typical microscopic photos of the crystal-rich pyroxene andesite from Bér. Left with one nicol, right with crossed nicols.

Figure II.155. – Andesites from Cserhát: Typical microscopic photos of the pyroxene andesite from Buják. Left with one nicol, right with crossed nicols.

Figure II.156. – Andesites from Cserhát: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Buják. Left with one nicol, right with crossed nicols.

Figure II.157. – Andesites from Cserhát: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Zsuny. Left with one nicol, right with crossed nicols.

Figure II.158. – Andesites from Cserhát: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Zsuny. Left with one nicol, right with crossed nicols.

Mátra (13-17 Ma)

Figure II.159. – Andesites from Mátra: Typical microscopic photos of the andesite from Csákánykő. Left with one nicol, right with crossed nicols.

Figure II.160. – Andesites from Mátra: Typical microscopic photos of the andesite from Csákánykő. Left with one nicol, right with crossed nicols.

Figure II.161. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Károlyvár. Left with one nicol, right with crossed nicols.

Figure II.162. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Károlyvár. Left with one nicol, right with crossed nicols.

Figure II.163. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric amphibole andesite from Nagyátalkő. Left with one nicol, right with crossed nicols.

Figure II.164. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric amphibole andesite from Nagyátalkő. Left with one nicol, right with crossed nicols.

Figure II.165. – Andesites from Mátra: Typical microscopic photos of th epyroxene andesite from Sás-tó. Left with one nicol, right with crossed nicols.

Figure II.166. – Andesites from Mátra: Typical microscopic photos of the pyroxene andesite from Sás-tó. Left with one nicol, right with crossed nicols.

Figure II.167. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric amphibole andesite from Tar. Left with one nicol, right with crossed nicols.

Figure II.168. – Andesites from Mátra: Typical microscopic photos of the plagioclase-phyric amphibole andesite from Tar. Left with one nicol, right with crossed nicols.

Karancs (15-16 Ma)

Figure II.169. – The exposed subvolcanic andesite body of Karancs

Figure II.170. – Andesites from Karancs: Typical microscopic photos of the garnet-bearing amphibole andesite from Farkaslyuk. Note the inclusion-rich large garnet phenocryst. Left with one nicol, right with crossed nicols.

Figure II.171. – Andesites from Karancs: Typical microscopic photos of the garnet-bearing amphibole andesite from Farkaslyuk. Left with one nicol, right with crossed nicols.

Figure II.172. – Andesites from Karancs: Typical microscopic photos of the garnet-bearing amphibole andesite from Siatoros. Left with one nicol, right with crossed nicols.

Figure II.173. – Andesites from Karancs: Typical microscopic photos of the garnet-bearing amphibole andesite from Siatoros. Note the inclusion-rich large garnet phenocryst. Left with one nicol, right with crossed nicols.

Tokaj Mts. (10-16 Ma)

Figure II.174. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Mulató hill. Left with one nicol, right with crossed nicols.

Figure II.175. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Mulató hill. Left with one nicol, right with crossed nicols.

Figure II.176. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric banded andesite from Mulató hill. Left with one nicol, right with crossed nicols.

Figure II.177. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric banded andesite from Mulató hill. Left with one nicol, right with crossed nicols.

Figure II.178. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Fony. Left with one nicol, right with crossed nicols.

Figure II.179. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Fony. Left with one nicol, right with crossed nicols.

Figure II.180. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Regéc. Left with one nicol, right with crossed nicols.

Figure II.181. – Andesites from Tokaj Mts.: Typical microscopic photos of the plagioclase-phyric pyroxene andesite from Regéc. Left with one nicol, right with crossed nicols.

MONZONITE

Appearance: Light coloured medium- to coarse-grained intrusive rock with less than 20% quartz and approximately the same amount of plagioclase and alkali feldspar, respectively. The mafic minerals are represented by clinopyroxene, orthopyroxene, amphibole and biotite. In rare monzonite variety, felspathoids could occur instead of quartz. It is the intrusive equivalent of tracybasalt and latite. It is formed mostly at subduction zones.

Mineral content:

Essential minerals: Ca-Na plagioclase ≈ K-feldspar, amphibole, pyroxene, biotite

Accessory minerals: quartz (<20%) or feldspathoid, apatite, magnetite, zircon

Secondary minerals: chlorite, sericite, epidote

Figure II.182. – Monzonite

Figure II.183. – Monzonite (Mórágy)

Locations in the Carpathian-Pannonian region: Mórágy

TRACHYANDESITE

Appearance: Light-grey, often aphyric or slightly to medium porphyritic fien-grained volcanic rock. Plagioclase and alkali feldspar occur in approximately the same amount and it could contain minor amount of quartz or feldspathoid. The mafic minerals are represented mostly by pyroxene or amphibole with less biotite (mostly in latite). It is formed at subduction and collision zones (the famous 1815 Tambora eruption was fed by tracyandesitic magma), but could occur also in intra-plate settings zones (e.g. mugearites).

Mineral content:

Essential minerals: Ca-Na plagioclase ≈ K-feldspar, amphibole, pyroxene, biotite

Accessory minerals: quartz (<20%) or feldspathoid, apatite, magnetite, zircon

Secondary minerals: chlorite, sericite, epidote

Rock types:

Locations in the Carpathian-Pannonian region: Gleichenberg (Styrian-basin), Balatonmária (in borehole) and Pásztori (in boreholes)

Figure II.184. – Typical microscopic photos of a latite from Gleichenberg. It contains large plagioclase phenocrysts and pyroxene and biotite microphenocrysts. Left with one nicol, right with crossed nicols.

Figure II.185. – Typical microscopic photos of a latite from Gleichenberg. It contains large plagioclase and biotite phenocrysts and pyroxene and biotite microphenocrysts. Left with one nicol, right with crossed nicols.

Figure II.186. – Typical microscopic photos of a latite from Balatonmária-1 borehole (at 394 m). It contains clinopyroxene phenocrysts and strongly opacitized biotites. Left with one nicol, right with crossed nicols.

Figure II.187. – Typical microscopic photos of a latite from Balatonmária-1 borehole (at 394 m). It contains clinopyroxene phenocrysts and strongly opacitized biotites. Left with one nicol, right with crossed nicols.

Figure II.188. – Typical microscopic photos of a latite from Balatonmária-1 borehole (at 438 m). It contains clinopyroxene phenocrysts and strongly opacitized biotites. Left with one nicol, right with crossed nicols.

Figure II.189. – Typical microscopic photos of a latite from Balatonmária-1 borehole (at 438 m). It contains clinopyroxene phenocrysts and strongly opacitized biotites. Left with one nicol, right with crossed nicols.

SYENITE

Appearance: Light coloured, medium- to coarse-grained intrusive igneous rock, where alkali feldspar prevails. The mafic minerals are represented by small amount of pyroxenes (usually aegirineaugite and aegirine), amphibole and biotite. Plagioclase occurs also in small amount. Quartz or feldspathoid could be found in minor amount. It is the intrusive equivalent of trachyte and phonolite. It is formed mostly in continental rift zones.

Mineral content:

Essential minerals: K-feldspar >> Ca-Na plagioclase, amphibole, pyroxene, biotite

Accessory minerals: quartz or felspathoid, titanite, apatite, magnetite, zircon

Secondary minerals: chlorite, sericite

Rock types:

Quartz-syenite or nepheline-syenite depending on the occurrence of quartz (Si-saturated variety) or feldspathoids (Si-undersaturated variety)

Locations in the Carpathian-Pannonian region: Ditró (nepheline- and sodalite-syenite=ditróite; Jurassic), Moravian-Silesian Beskidy (Czech Republic; Early Creataceous, it has close relationship with the Early Cretaceous alkali basalt – phonolite suite of the Mecsek Mts.).

Figure II.190. – Syenite

Figure II.191. – Sodalite-bearing syenite (ditróite) from Ditró.

TRACHYTE

Appearance: Light coloured, porphyritic volcanic rocks. The trachytic texture means that feldspar crystals are aligned in one direction. Among the feldspars, alkali feldspars prevail over plagioclases. The mafic minerals are represented by pyroxenes, amphiboles and/or biotite. Some trachyte varieties contain quartz or feldspathoids. Trachytes are most commonly associated with ocean island and continental rift magmatism and evolve by crystal fractionation of alkali basalt magmas.

Mineral content:

Essential minerals: K-feldspar >> Ca-Na plagioclase, amphibole, pyroxene, biotite

Accessory minerals: quartz or felspathoid, titanite, apatite, magnetite, zircon

Secondary minerals: chlorite, sericite

Rock types:

Quartz-trachyte or alkali trachyte depending on the occurrence of quartz (Si-saturated) or feldspathoids (Si-undersaturated variety)

Locations in the Carpathian-Pannonian region: Pásztori (in borehole).

Figure II.192. – trachyte

Figure II.193. – trachyte

PHONOLITE

Appearance: Light-grey-grey, often aphyric or slightly porphyritic volcanic rock. K-feldspar (sanidine or anorthoclase) prevails in this rocks that show often perthitic texture. The mafic minerals are alkali pyroxene (aegirinaugite and aegirine), alkali amphibole and rarely biotite. It contains typically feldpathoids such as nepheline or leucite. They could occur also as phenocrysts. Its name – singing rock- refers to the clinking sound given by the rock when the hammer hits it. Phonolite is commonly found in continental rift zones (e.g., Kilimanjaro; East African rift zone; Laacher-see, Eifel, Germany; Massif Central, Czech Republic) and in ocean islands (e.g., Teide, Tenerife, Canary islands; St. Helena). It forms by crystal fractionation of basanitic parental magma.

Mineral content:

Essential minerals: K-feldspar (sanidine) >> Ca-Na plagioclase, nepheline or leucite, alkali pyroxene, rarely alkali amphibole and biotite

Accessory minerals: titanite, sodalite, apatite, magnetite, zircon

Secondary minerals: analcime, chlorite, sericite

Locations in the Carpathian-Pannonian region: Köves hill and Szamár hill, Máza valley (Eastern Mecsek)

Figure II.194. – Phonolite (Mecsek)

Figure II.195. – Typical microscopic photos of the phonolite from Szamár hill, Mecsek Mts. Left with one nicol, right with crossed nicols.

Figure II.196. – Teide in Tenerife (Canary islands) a huge phonolitic volcano (left) and typical phonolitic lava flows (coulee; right) (photos: Szabolcs Harangi)

Figure II.197. – Typical thick phonolitic obsidian lava flow at the fott of the Teide. (photos: Szabolcs Harangi)

Figure II.198. – The Devils Tower in Wyoming (USA) with its spectacular columnar jointing is composed by phonolite.