Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula: the Alacón borehole
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| Format: | Artículo científico |
| Language: | en |
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Universitat de Barcelona
2004
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| author | F. Ortí |
| author_facet | F. Ortí |
| contents | Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula: the Alacón borehole F. Ortí J. Ma. Salvany Ciencias de la Tierra Salina Triassic Anhydrite Evaporites Iberian Chain The evaporite unit (the Lécera Formation), which was formed at the TriassicLiassic boundary in the AragonianBranch of the Iberian Chain, was studied at the 01 Alacón borehole (Alacón village, Teruel province),where it is mainly constituted by a thick (>300 m) succession of predominant sulphates (anhydrite, secondarygypsum and carbonate) overlain by brecciated carbonates. In the evaporite succession, a number of lithofacieswere recognized, which can be grouped into an ideal cycle, from base to top: (C1) massive to bandedcarbonate mudstone, (C2) alternation of carbonate and anhydrite laminae, (A1) alternation of anhydrite andcarbonate bands, (A2) clastic intercalations in the alternation of anhydrite and carbonate bands, (A3)laminated to banded anhydrite, (A4) bedded pseudomorphs, (A5) interstitial pseudomorphs, and (A6) massiveto nodular anhydrite. Fine-grained gypsum (anhydrite laminae and bands), bedded selenitic gypsum (beddedpseudomorphs), interstitial selenitic gypsum (interstitial pseudomorphs), and graded-nodular anhydrite (a particularfabric of nodular anhydrite) were the most outstanding depositional lithofacies. The evaporite successionexhibits a marked cyclicity: in the lower part the individual cycles are more similar to the ideal cycle and reflectdeeper water settings, whereas in the upper part they correspond to shallower water settings. The evaporite sedimentationmainly occurred in a subsiding coastal basin of the salina or lagoon type. In this setting, the subaqueousprecipitation of the carbonate and gypsum lithofacies was followed, in each cycle, by the interstitial growthof anhydrite in exposed conditions. As a whole, the evaporite succession reflects an infilling process. The conversioninto anhydrite of the selenitic gypsum -probably also of the rest of depositional gypsum lithofaciesstartedunder synsedimentary conditions and followed during shallow to moderate burial diagenesis. 2004 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50520405 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.4 Vol.2 |
| format | Artículo científico |
| id | redalyc_50520405 |
| institution | Redalyc |
| language | en |
| publishDate | 2004 |
| publisher | Universitat de Barcelona |
| spellingShingle | Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula: the Alacón borehole F. Ortí Ciencias de la Tierra Salina Triassic Anhydrite Evaporites Iberian Chain Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula: the Alacón borehole F. Ortí J. Ma. Salvany Ciencias de la Tierra Salina Triassic Anhydrite Evaporites Iberian Chain The evaporite unit (the Lécera Formation), which was formed at the TriassicLiassic boundary in the AragonianBranch of the Iberian Chain, was studied at the 01 Alacón borehole (Alacón village, Teruel province),where it is mainly constituted by a thick (>300 m) succession of predominant sulphates (anhydrite, secondarygypsum and carbonate) overlain by brecciated carbonates. In the evaporite succession, a number of lithofacieswere recognized, which can be grouped into an ideal cycle, from base to top: (C1) massive to bandedcarbonate mudstone, (C2) alternation of carbonate and anhydrite laminae, (A1) alternation of anhydrite andcarbonate bands, (A2) clastic intercalations in the alternation of anhydrite and carbonate bands, (A3)laminated to banded anhydrite, (A4) bedded pseudomorphs, (A5) interstitial pseudomorphs, and (A6) massiveto nodular anhydrite. Fine-grained gypsum (anhydrite laminae and bands), bedded selenitic gypsum (beddedpseudomorphs), interstitial selenitic gypsum (interstitial pseudomorphs), and graded-nodular anhydrite (a particularfabric of nodular anhydrite) were the most outstanding depositional lithofacies. The evaporite successionexhibits a marked cyclicity: in the lower part the individual cycles are more similar to the ideal cycle and reflectdeeper water settings, whereas in the upper part they correspond to shallower water settings. The evaporite sedimentationmainly occurred in a subsiding coastal basin of the salina or lagoon type. In this setting, the subaqueousprecipitation of the carbonate and gypsum lithofacies was followed, in each cycle, by the interstitial growthof anhydrite in exposed conditions. As a whole, the evaporite succession reflects an infilling process. The conversioninto anhydrite of the selenitic gypsum -probably also of the rest of depositional gypsum lithofaciesstartedunder synsedimentary conditions and followed during shallow to moderate burial diagenesis. 2004 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50520405 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.4 Vol.2 |
| title | Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula: the Alacón borehole |
| topic | Ciencias de la Tierra Salina Triassic Anhydrite Evaporites Iberian Chain |
| url | https://www.redalyc.org/articulo.oa?id=50520405 |