Geochemistery of late Neoproterozoic Cap Carbonate from Banded Iron-formation In the Rizu seri (Zarand) of Kerman

Category Sedimentology
Group GSI.IR
Location The 25 Symposium of Geosciences
Author M.Kianian-A.Khakzad-I.Rasa-M.vosoughi Abedini
Holding Date 01 July 2007


Cap carbonates carbon isotope (13c) and Banded Iron formations are the basic events during global glaciations. In the study area. The variety of carbonates include medium to coarse (saddle dolomite ) grains of dolomites, are situated uppermost of sequence of Rizu Formation.

The sequence of Rizu seri Contains of vary lithology, Quartzite sandstone, Turbidite ( graywake) with association of ore minerals(magnetite- hematite- Jasper) , in form of Banded Iron- Formations, (BIFs) .

The existence of dropstones with hetrogenous grains (diamictite) within Fine matrix of carbonate are the indicators for glaciation episodes.

Chemical analyses showed that the

 values of carbonates in area are low , ranging Form- 2.65 to -6.79 permil versus PDB and- 6.48 to – 15.21per mil (PDB), respectively . Isotopically light carbon and oxygen were Correlated with increased concentrations of Iron, which reflects their deposition in a glaciomarine setting. The significant excursion of and high index of alteration (Fe/sr or Mn/sr) shows the alteration and diagentic processes.The depleted carbonates reflect climate changes from Glacial (icehouse) to greenhouse conditions, that deposited during sea- level rise after retrearing and diglaciation aftermath global glaciations, snowball Earth.

Key words: Glacial, cap carbonate, carbon Isotope, diamictite, dropstone