Provenance, tectonic setting and source-area weathering of the lower Cambrian sediments of the Parahio valley in the Spiti basin, India

Abstract

The geochemical study of siliciclastic rocks from the Lower Cambrian of Parahio Valley has been studied to describe the provenance, chemical weathering and tectonic setting. The K 2 O/Al 2 O 3 ratio and positive correlation of Co (r = 0.85), Ni (r = 0.86), Zn (r = 0.82), Rb (r = 0.98) with K 2 O reflects that the presence of clay minerals control the abundances of these elements and suggests a warm and humid climate for this region. The chondrite normalized REE pattern of the samples is equivalent to upper continental crust, which reflects enriched LREE and flat HREE with negative Eu anomaly. The tectonic setting discriminant diagram log[K 2 O/Na 2 O] vs. SiO 2 ; [SiO 2 /Al 2 O 3 ] vs. log[K 2 O/Na 2 O]; [SiO 2 /20]-[K 2 O+Na 2 O]-[TiO 2 +Fe 2 O 3 +MgO] indicates transitional tectonic setting from an active continental margin to a passive margin. The discriminant function plot indicates quartzose sedimentary provenance, and to some extent, the felsic igneous provenance, derived from weathered granite, gneissic terrain and/or from pre-existing sedimentary terrain. The CIA value indicates low to moderate degree of chemical weathering and the average ICV values suggests immature sediments deposited in tectonically active settings. The A-CN-K diagram indicates that these sediments were generated from source rocks of the upper continental crust.

Mineralogical and geochemical characteristics of the iron–duricrust deposit in Adi-Daero area, northwestern Tigray, Ethiopia: implication for the origin and controlling factors

“…The marked variation in ΣREE contents in the iron-rich duricrust is due to heavy mineral concentrations or mineralogical variations. A positive correlation between ΣLREE/ΣHREE and Al 2 O 3 (r = 0.87) (Table 3) confirms that clay minerals (kaolinite) are the principal factors controlling REE abundances (Abedini and Calagari 2014;Pandey and Parcha 2017). However, the negative correlation between ΣLREE/ ΣHREE and Fe 2 O 3 (r = −0.89) implies role of Fe oxyhydroxides in REE scavenging is negligible.…”

“…Furthermore, decomposition of ferromagnesian minerals, which are hosts of Mn and Mg during weathering, is attributed to the depletion of Mn and Mg as they are released into the weathering solutions (Abedini and Calagari 2013; Gebru et al 2019). The relatively elevated values of CaO and MgO in the clay-rich horizon suggest that kaolinite is the chief scavenging agent for them (Pandey and Parcha 2017). This has been shown with a positive correlation between SiO 2 –CaO ( r = 0.53) and SiO 2 –MgO ( r = 0.99) (Table 3).…”

Petrography and geochemistry of the Proterozoic sandstones of Somanpalli Group from Pomburna area, Eastern Belt of Pranhita–Godavari Valley, central India: Implications for provenance, weathering and tectonic setting

“…REE patterns and the size of the Eu anomaly are also used to study the sources of sedimentary rocks (Taylor and McLennan 1985). Generally, low LREE/HREE ratios and small/absence of Eu anomalies are indicative of basic rock source, whereas higher ratio (La/Y) and negative Eu (Eu/Eu*) anomaly indicates the silicic igneous rock sources and marine depositional environments (Cullers 1994;Pandey and Parcha 2017) (figure 9). The samples of the Pomburna sandstones show high ratio of LREE/HREE and negative Eu anomaly (figure 9B), which supports the silicic rock source and marine depositional environment.…”

“…The tectonic setting discriminant diagrams proposed by many authors can provide reliable results for siliciclastic rocks because they are not too much affected by post-depositional weathering/ metasomatism/metamorphism (McLennan et al 1993). Bhatia (1983), Bhatia and Cook (1986), Roser and Korsch (1986) Pandey and Parcha (2017). Bhatia (1983) and Roser and Korsch (1986) proposed tectonic setting discrimination fields for sedimentary rocks by using SiO 2 content and K 2 O/Na 2 O ratios to identify the tectonic setting of unknown basins.…”

“…The original composition of weathered source rocks has a dominant control on the makeup of terrigenous sediments, and therefore, geographic and stratigraphic variations in provenance can provide important constraints on the tectonic evolution of the region (e.g., Clift et al 2000;McLennan et al 2003;Rahman and Suzuki 2007;Absar et al 2009;Absar and Sreenivas 2015;Nagarajan et al 2017;Tawfik et al 2017;Zaid 2017). The geochemistry of clastic sedimentary rocks is widely studied to the tectonic setting, weathering, source rock compositions, provenance and 1 diagenesis (Dickinson and Suczek 1979;Nesbitt and Young 1982;Bhatia 1983;Roser and Korsch 1986;McLennan 1989;Condie 1993;Armstrong-Altrin et al 2004;Absar et al 2009;Moosavirad et al 2011;Saeed et al 2011;Randive 2012;Zaid 2012Zaid , 2015Sharma et al 2013;Srivastava et al 2013;Absar and Sreenivas 2015;Absar et al 2016;Madhavaraju et al 2016;Nagarajan et al 2017;Pandey and Parcha 2017;Periasamy and Venkateshwarlu 2017;Zaid 2017). The chemical composition of clastic sedimentary rocks is a function of a complex relationship of several variables, including the source rock composition, the extent of weathering, transportation and diagenesis (Taylor and McLennan 1985;Bhatia and Cook 1986;Roser and Korsch 1986;…”