Provenance analysis of the Oligocene turbidites (Andaman Flysch), South Andaman Island: A geochemical approach

Abstract

The Oligocene-aged sandstone-shale turbidites of the Andaman Flysch are best exposed along the east coast of the South Andaman Island. Previously undocumented sandstone-shale geochemistry, investigated here, provides important geochemical constraints on turbidite provenance. The average 70.75 wt% SiO 2 , 14.52 wt% Al 2 O 3 ,8. 2w t %F e 2 O t 3 +MgO and average 0.20 Al 2 O 3 /SiO 2 and 1.08 K 2 O/Na 2 Or a t i o s in sandstones, compare with quartzwackes. The shale samples have average 59.63 wt% SiO 2 , 20.29 wt% Al 2 O 3 , 12.63 wt% Fe 2 O t 3 +MgO and average 2.42 K 2 O/Na 2 O and 0.34 Al 2 O 3 /SiO 2 ratios. Geochemical data on CaO-Na 2 O-K 2 O diagram fall close to a granite field and on K 2 O/Na 2 O-SiO 2 diagram within an active continental margin tectonic setting. The range and average values of Rb and Rb/Sr ratios are consistent with acid-intermediate igneous source rocks, while the values and ratios for Cr and Ni are with mafic rocks. Combined geochemical, petrographic and palaeocurrent data indicate a dominantly plutonic-metamorphic provenance with a lesser contribution from sedimentary and volcanic source, which is possibly the Shan-Thai continental block and volcanic arc of the northeastern and eastern Myanmar. Chemical index of alteration (CIA) values suggests a moderate range of weathering of a moderate relief terrane under warm and humid climate.

Hydrogeochemical characterization and water quality evaluation for drinking and irrigation purposes of coastal aquifers of Middle Andaman

“…These extensive hill ranges are enveloped by dense forests, while the coastal margin includes saline marshes, salt-affected patches, and undulating uplands. The predominant rock types in this region consist of sandstone, breccias, or conglomerates, with varying proportions of siliciclastic and cemented calcium carbonates [34,39]. The major geomorphic units in the area encompass "low to moderately high steep hills, intermontane narrow valleys, and gently sloping narrow to moderately wide coastal plains" (Figure 3) (https://bhuvan-app1.nrsc.gov.in/thematic/thematic/index.php).…”

Mineralogy and geochemistry of sands along the Manzanillo and El Carrizal beach areas, southern Mexico: implications for palaeoweathering, provenance and tectonic setting

“…However, among other trace elements, the REE, Th, Sc, Co and Cr are most considered for provenance study, since they are least affected by secondary processes like diagenesis and metamorphism (Cullers and Podkovyrov, ). Similarly, interpretations based on a combination of petrography and geochemistry data are considered as a suitable method to infer the provenance of clastic sediments (Madhavaraju et al ., ; El‐Anwar and El‐Wekeil, ; Armstrong‐Altrin et al ., ; Bandopadhyay and Ghosh, ; Zaid et al ., ; Ramachandran et al ., ).…”