Petrology and geochemistry of Mesozoic igneous rocks, Bükk Mountains, Hungary

H. Downes, Gy Pantó, P. Árkai, M. F. Thirlwall

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Basic and ultrabasic igneous rocks of the Jurassic Szarvaskő complex (southwestern Bükk Mountains, NE Hungary) have previously been interpreted as dismembered fragments of a Mesozoic ophiolitic sequence comprising mainly gabbroic sills intruded into deep-water terrigenous shales. Abundant extrusive pillow basalts, layered ultramafics and plagiogranite bodies are also present. Gabbros and basalts showing slight LREE depletion ( Ce YbN=0.84-0.93) and very slight negative Eu anomalies (0.92-0.98) are considered to be close to liquid compositions, while some gabbros with the lowest overall REE abundances and positive Eu anomalies ( Eu Eu* = 1.14-1.29) are regarded as plagioclase+clinopyroxene cumulates. The REE characteristics of the most primitive rocks are very similar to those of N-type MORB. Differentiated magmas show negative Eu anomalies and increasing REE enrichment, consistent with fractionation of plagioclase and clinopyroxene. In most rocks from the Szarvaskő complex, strong enrichment is seen in Ba, Rb and K, compared with the values for MORB. Age-corrected ε{lunate}Srt-values of the Szarvaskő complex range from -0.2 (basic rocks) to + 36.4 (evolved rocks). The ε{lunate}Ndt-values vary between +6.4 (basic rocks) and +3.3 (evolved rocks). The variation in ε{lunate}Ndt is probably not due to alteration or metamorphism, since simple REE patterns indicate REE immobility, and is considered to be caused by contamination during magmatic fractionation. The high and variable ε{lunate}Srt-values could be due to transfer of radiogenic Sr from the surrounding sediments during very low-grade regional Alpine metamorphism. It is suggested that the basic magmas of the complex were probably originally MORB-like, but during evolution in a shallow magma chamber, they became contaminated by terrigenous sediments. The nearby Triassic Darnó Hill complex is much more strongly altered, does not show the same depletion in LREE, and has lower ε{lunate}Ndt-values. It is considered to have been formed in a different tectonic setting, possibly a continental margin or oceanic island.

Original languageEnglish
Pages (from-to)201-215
Number of pages15
JournalLithos
Volume24
Issue number3
DOIs
Publication statusPublished - 1990

Fingerprint

Petrology
Igneous rocks
Geochemistry
petrology
igneous rock
geochemistry
Rocks
rare earth element
mountain
mid-ocean ridge basalt
rock
Fractionation
anomaly
clinopyroxene
plagioclase
Sediments
metamorphism
fractionation
basalt
plagiogranite

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Petrology and geochemistry of Mesozoic igneous rocks, Bükk Mountains, Hungary. / Downes, H.; Pantó, Gy; Árkai, P.; Thirlwall, M. F.

In: Lithos, Vol. 24, No. 3, 1990, p. 201-215.

Research output: Contribution to journalArticle

Downes, H. ; Pantó, Gy ; Árkai, P. ; Thirlwall, M. F. / Petrology and geochemistry of Mesozoic igneous rocks, Bükk Mountains, Hungary. In: Lithos. 1990 ; Vol. 24, No. 3. pp. 201-215.
@article{deab1fd5483d4003a048e663885edb62,
title = "Petrology and geochemistry of Mesozoic igneous rocks, B{\"u}kk Mountains, Hungary",
abstract = "Basic and ultrabasic igneous rocks of the Jurassic Szarvaskő complex (southwestern B{\"u}kk Mountains, NE Hungary) have previously been interpreted as dismembered fragments of a Mesozoic ophiolitic sequence comprising mainly gabbroic sills intruded into deep-water terrigenous shales. Abundant extrusive pillow basalts, layered ultramafics and plagiogranite bodies are also present. Gabbros and basalts showing slight LREE depletion ( Ce YbN=0.84-0.93) and very slight negative Eu anomalies (0.92-0.98) are considered to be close to liquid compositions, while some gabbros with the lowest overall REE abundances and positive Eu anomalies ( Eu Eu* = 1.14-1.29) are regarded as plagioclase+clinopyroxene cumulates. The REE characteristics of the most primitive rocks are very similar to those of N-type MORB. Differentiated magmas show negative Eu anomalies and increasing REE enrichment, consistent with fractionation of plagioclase and clinopyroxene. In most rocks from the Szarvaskő complex, strong enrichment is seen in Ba, Rb and K, compared with the values for MORB. Age-corrected ε{lunate}Srt-values of the Szarvaskő complex range from -0.2 (basic rocks) to + 36.4 (evolved rocks). The ε{lunate}Ndt-values vary between +6.4 (basic rocks) and +3.3 (evolved rocks). The variation in ε{lunate}Ndt is probably not due to alteration or metamorphism, since simple REE patterns indicate REE immobility, and is considered to be caused by contamination during magmatic fractionation. The high and variable ε{lunate}Srt-values could be due to transfer of radiogenic Sr from the surrounding sediments during very low-grade regional Alpine metamorphism. It is suggested that the basic magmas of the complex were probably originally MORB-like, but during evolution in a shallow magma chamber, they became contaminated by terrigenous sediments. The nearby Triassic Darn{\'o} Hill complex is much more strongly altered, does not show the same depletion in LREE, and has lower ε{lunate}Ndt-values. It is considered to have been formed in a different tectonic setting, possibly a continental margin or oceanic island.",
author = "H. Downes and Gy Pant{\'o} and P. {\'A}rkai and Thirlwall, {M. F.}",
year = "1990",
doi = "10.1016/0024-4937(90)90032-V",
language = "English",
volume = "24",
pages = "201--215",
journal = "Lithos",
issn = "0024-4937",
publisher = "Elsevier",
number = "3",

}

TY - JOUR

T1 - Petrology and geochemistry of Mesozoic igneous rocks, Bükk Mountains, Hungary

AU - Downes, H.

AU - Pantó, Gy

AU - Árkai, P.

AU - Thirlwall, M. F.

PY - 1990

Y1 - 1990

N2 - Basic and ultrabasic igneous rocks of the Jurassic Szarvaskő complex (southwestern Bükk Mountains, NE Hungary) have previously been interpreted as dismembered fragments of a Mesozoic ophiolitic sequence comprising mainly gabbroic sills intruded into deep-water terrigenous shales. Abundant extrusive pillow basalts, layered ultramafics and plagiogranite bodies are also present. Gabbros and basalts showing slight LREE depletion ( Ce YbN=0.84-0.93) and very slight negative Eu anomalies (0.92-0.98) are considered to be close to liquid compositions, while some gabbros with the lowest overall REE abundances and positive Eu anomalies ( Eu Eu* = 1.14-1.29) are regarded as plagioclase+clinopyroxene cumulates. The REE characteristics of the most primitive rocks are very similar to those of N-type MORB. Differentiated magmas show negative Eu anomalies and increasing REE enrichment, consistent with fractionation of plagioclase and clinopyroxene. In most rocks from the Szarvaskő complex, strong enrichment is seen in Ba, Rb and K, compared with the values for MORB. Age-corrected ε{lunate}Srt-values of the Szarvaskő complex range from -0.2 (basic rocks) to + 36.4 (evolved rocks). The ε{lunate}Ndt-values vary between +6.4 (basic rocks) and +3.3 (evolved rocks). The variation in ε{lunate}Ndt is probably not due to alteration or metamorphism, since simple REE patterns indicate REE immobility, and is considered to be caused by contamination during magmatic fractionation. The high and variable ε{lunate}Srt-values could be due to transfer of radiogenic Sr from the surrounding sediments during very low-grade regional Alpine metamorphism. It is suggested that the basic magmas of the complex were probably originally MORB-like, but during evolution in a shallow magma chamber, they became contaminated by terrigenous sediments. The nearby Triassic Darnó Hill complex is much more strongly altered, does not show the same depletion in LREE, and has lower ε{lunate}Ndt-values. It is considered to have been formed in a different tectonic setting, possibly a continental margin or oceanic island.

AB - Basic and ultrabasic igneous rocks of the Jurassic Szarvaskő complex (southwestern Bükk Mountains, NE Hungary) have previously been interpreted as dismembered fragments of a Mesozoic ophiolitic sequence comprising mainly gabbroic sills intruded into deep-water terrigenous shales. Abundant extrusive pillow basalts, layered ultramafics and plagiogranite bodies are also present. Gabbros and basalts showing slight LREE depletion ( Ce YbN=0.84-0.93) and very slight negative Eu anomalies (0.92-0.98) are considered to be close to liquid compositions, while some gabbros with the lowest overall REE abundances and positive Eu anomalies ( Eu Eu* = 1.14-1.29) are regarded as plagioclase+clinopyroxene cumulates. The REE characteristics of the most primitive rocks are very similar to those of N-type MORB. Differentiated magmas show negative Eu anomalies and increasing REE enrichment, consistent with fractionation of plagioclase and clinopyroxene. In most rocks from the Szarvaskő complex, strong enrichment is seen in Ba, Rb and K, compared with the values for MORB. Age-corrected ε{lunate}Srt-values of the Szarvaskő complex range from -0.2 (basic rocks) to + 36.4 (evolved rocks). The ε{lunate}Ndt-values vary between +6.4 (basic rocks) and +3.3 (evolved rocks). The variation in ε{lunate}Ndt is probably not due to alteration or metamorphism, since simple REE patterns indicate REE immobility, and is considered to be caused by contamination during magmatic fractionation. The high and variable ε{lunate}Srt-values could be due to transfer of radiogenic Sr from the surrounding sediments during very low-grade regional Alpine metamorphism. It is suggested that the basic magmas of the complex were probably originally MORB-like, but during evolution in a shallow magma chamber, they became contaminated by terrigenous sediments. The nearby Triassic Darnó Hill complex is much more strongly altered, does not show the same depletion in LREE, and has lower ε{lunate}Ndt-values. It is considered to have been formed in a different tectonic setting, possibly a continental margin or oceanic island.

UR - http://www.scopus.com/inward/record.url?scp=0025223592&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025223592&partnerID=8YFLogxK

U2 - 10.1016/0024-4937(90)90032-V

DO - 10.1016/0024-4937(90)90032-V

M3 - Article

AN - SCOPUS:0025223592

VL - 24

SP - 201

EP - 215

JO - Lithos

JF - Lithos

SN - 0024-4937

IS - 3

ER -