Stratigraphic Classification in Pre-Cambrian Rocks

Middle-Late Cambrian acritarchs from the Zardkuh area in the High Zagros Mountains, southern Iran: Stratigraphic and paleogeographic implications

The excellent preservation of the acritarchs, their great abundance, diversity and good stratigraphic control permit establishment of a detailed Middle and Late Cambrian acritarch biozonation. A total of 56 palynomorph species form the basis of 10 local acritarch assemblage zones. Assemblage zones I-II occur in the lower and middle parts of the Member C of the Mila Formation and suggest Early-m...

Clay and Sulfate-bearing Rocks in a Stratigraphic Sequence in Gale Crater

Introduction: Gale Crater is a ~150 km diameter impact crater located at 5.3°S, 137.7°E that contains a thick (>5 km) sequence of strata interpreted as sedimentary rocks [1]. Gale is one of four final candidate landing sites for the 2011 Mars Science Laboratory (MSL) rover. Recent data acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument show evidence for clay...

AGeochemical Classification for Feldspathic Igneous Rocks

In this paper we classify the range of feldspathic igneous rocks using five geochemical variables: the FeO/(FeOþMgO) ratio or Fe-index, the modified alkali^lime index, the aluminum-saturation index, the alkalinity index, and the feldspathoid silica-saturation index.The Fe-index distinguishes between melts that have undergone extensive iron enrichment during differentiation from those that have ...

Occurrence, Texture, and Classification of Igneous Rocks

Organic-Walled Microfossils from Earliest Cambrian or Latest Proterozoic Tindir Group Rocks, Northwest Canada

Allison, C.W. and Awramik, S.M., 1989. Organic-walled microfossils from earliest Cambrian or latest Proterozoic Tindir Group rocks, northwest Canada. Precambrian Res., 43: 253-294. Uppermost Tindir Group limestones exposed in the headwaters of Tindir Creek, Yukon Territory, Canada, contain a diverse and abundant microbiota of mineralized and organic-walled microfossils. Preserved primarily in c...