Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

Gábor Botfalvai, J. Haas, Emese Réka Bodor, Andrea Mindszenty, A. Ősi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.

Original languageEnglish
Pages (from-to)659-678
Number of pages20
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume441
DOIs
Publication statusPublished - Jan 1 2016

Fingerprint

Santonian
sandstone
Hungary
vertebrate
vertebrates
mountains
Cretaceous
mountain
siltstone
paleosol
conglomerate
fill
fossils
terrestrial deposit
fossil
cross-bedding
crevasse
flash flood
claystone
river channel

Keywords

  • Anastomosing river
  • Csehbánya Formation
  • Fluvial deposits
  • Sedimentology
  • Upper Cretaceous
  • Vertebrates

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Palaeontology
  • Earth-Surface Processes
  • Oceanography

Cite this

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title = "Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehb{\'a}nya formation at the Ihark{\'u}t vertebrate locality (Bakony Mountains, Northwestern Hungary)",
abstract = "The Csehb{\'a}nya Formation (Santonian), exposed in the Ihark{\'u}t open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehb{\'a}nya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Ihark{\'u}t open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.",
keywords = "Anastomosing river, Csehb{\'a}nya Formation, Fluvial deposits, Sedimentology, Upper Cretaceous, Vertebrates",
author = "G{\'a}bor Botfalvai and J. Haas and Bodor, {Emese R{\'e}ka} and Andrea Mindszenty and A. Ősi",
year = "2016",
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TY - JOUR

T1 - Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

AU - Botfalvai, Gábor

AU - Haas, J.

AU - Bodor, Emese Réka

AU - Mindszenty, Andrea

AU - Ősi, A.

PY - 2016/1/1

Y1 - 2016/1/1

N2 - The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.

AB - The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.

KW - Anastomosing river

KW - Csehbánya Formation

KW - Fluvial deposits

KW - Sedimentology

KW - Upper Cretaceous

KW - Vertebrates

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U2 - 10.1016/j.palaeo.2015.10.018

DO - 10.1016/j.palaeo.2015.10.018

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VL - 441

SP - 659

EP - 678

JO - Palaeogeography, Palaeoclimatology, Palaeoecology

JF - Palaeogeography, Palaeoclimatology, Palaeoecology

SN - 0031-0182

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