Comparación de la situación estratigráfica y la génesis del horizonte basal de bauxita-laterítica del paleosuelo en la Formación Shemshak de Alborz Central, secciones (Glandrood - Lavij - Vaz)
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J. Selva Andina Res. Soc.
Abstract
Este estudio analiza la distribución geográfica de la Formación Shemshak en el Alborz Central, comparando secuencias estratigráficas, litología, influencias tectónicas y ambientes depositacionales en las secciones de Glendrow, Lovej y Vaz. El objetivo es comprender las secuencias sedimentarias y los procesos geológicos del período Triásico-Jurásico. Se realizaron muestreos en secciones clave, cuyas ubicaciones fueron registradas mediante GPS. Se llevaron a cabo análisis mineralógicos y petrológicos en 100 secciones delgadas y muestras pulidas utilizando microscopía de luz transmitida y microscopía de reflexión petrográfica. Además, se analizaron diez muestras de la zona de bauxita-laterita y diez del horizonte laterítico en la base de la Formación Shemshak para identificar influencias climatológicas y eventos tectónicos, utilizando técnicas de FRX y DRX en la Organización Geológica de Irán, minas de Binalud. La presencia de un horizonte de bauxita-laterita es crucial para la reconstrucción de la geología regional, y los hallazgos indican que la Formación Elika subyace a la Formación Shemshak, depositada durante la fase orogénica Cimmeriana temprana. El desarrollo de la Formación Shemshak tuvo lugar en una cuenca de antepaís en transición hacia una cuenca de retroarco, compuesta por diversas rocas sedimentarias como conglomerados de cuarzo, cuarzarenitas, sublitarenitas, litarenitas, lutitas y arcillolitas, frecuentemente con intercalaciones de capas de carbón. Los datos palinológicos y de paleosuelos sugieren un ambiente depositacional que varía desde continental hasta deltaico costero. Las influencias tectónicas y climáticas, evidenciadas por discontinuidades y fallas orientadas este-oeste en Glendrow, desempeñaron un papel significativo en la configuración del ambiente sedimentario de la formación.
This study analyzes the geographic distribution of the Shemshak Formation in the Central Alborz, comparing stratigraphic sequences, lithology, tectonic influences, and depositional environments across the Glendrow, Lovej, and Vaz sections. The goal is to understand the sedimentary sequences and geological processes of the Triassic-Jurassic period. Sampling was carried out at key sections, with locations recorded via GPS. Mineralogical and petrological analyses were performed on 100 thin sections and polished samples using transmitted light microscopy and petrographic reflection. additionally, ten samples from the bauxite-laterite zone and ten from the base of the Shemshak Formation's laterite horizon were analyzed to identify climatological influences and tectonic events, using XRF and XRD at the Geological Organization of Iran, Binalud Mines. The presence of a bauxite-laterite horizon is crucial for reconstructing regional geology, with findings indicating that the Elika Formation underlies the Shemshak, deposited during the Early Cimmerian orogenic phase. The development of the Shemshak Formation occurred within a foreland basin transitioning into a back-arc basin, comprising diverse sedimentary rocks such as quartzite conglomerates, quartz arenites, sublitharenites, litharenites, mudstones, and claystones, often with coal interbeds. Palynological and paleosol data suggest a depositional environment from continental to coastal-deltaic. Tectonic and climatic influences, evidenced by discontinuities and east-west Glenrod faults, played a significant role in shaping the formation's sedimentary environment.
This study analyzes the geographic distribution of the Shemshak Formation in the Central Alborz, comparing stratigraphic sequences, lithology, tectonic influences, and depositional environments across the Glendrow, Lovej, and Vaz sections. The goal is to understand the sedimentary sequences and geological processes of the Triassic-Jurassic period. Sampling was carried out at key sections, with locations recorded via GPS. Mineralogical and petrological analyses were performed on 100 thin sections and polished samples using transmitted light microscopy and petrographic reflection. additionally, ten samples from the bauxite-laterite zone and ten from the base of the Shemshak Formation's laterite horizon were analyzed to identify climatological influences and tectonic events, using XRF and XRD at the Geological Organization of Iran, Binalud Mines. The presence of a bauxite-laterite horizon is crucial for reconstructing regional geology, with findings indicating that the Elika Formation underlies the Shemshak, deposited during the Early Cimmerian orogenic phase. The development of the Shemshak Formation occurred within a foreland basin transitioning into a back-arc basin, comprising diverse sedimentary rocks such as quartzite conglomerates, quartz arenites, sublitharenites, litharenites, mudstones, and claystones, often with coal interbeds. Palynological and paleosol data suggest a depositional environment from continental to coastal-deltaic. Tectonic and climatic influences, evidenced by discontinuities and east-west Glenrod faults, played a significant role in shaping the formation's sedimentary environment.
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Vol. 16, No. 2