6533b870fe1ef96bd12d0422
RESEARCH PRODUCT
Proterozoic Tectonostratigraphy and Paleogeography of Central Madagascar Derived from Detrital Zircon U‐Pb Age Populations
Alan S. CollinsAlan S. CollinsCarla B. ChokelStephen B. DeoreoBert De WaeleBert De WaeleJoseph L. WoodenJoseph L. WoodenRónadh CoxDrew S. ColemanAlfred KrönerAlfred Krönersubject
ProvenancebiologyProterozoicTectonostratigraphyMetamorphic rockGeochemistryGeologybiology.organism_classificationSedimentary depositional environmentPaleontologyStromatoliteClastic rockGeologyZircondescription
Abstract Detrital zircon U‐Pb ages determined by SHRIMP distinguish two clastic sequences among Proterozoic metasedimentary rocks from central Madagascar. The Itremo Group is older: zircon data, stromatolite characteristics, and carbon isotope data all point to a depositional age around 1500–1700 Ma. The Molo Group is younger, deposited between ∼620 Ma (the age of the youngest zircon) and ∼560 Ma (the age of metamorphic overgrowths on detrital cores). Geochronologic provenance analysis of the Itremo Group points to sources in East Africa as well as local sources in central and southern Madagascar but provides no evidence for a detrital contribution from northern and eastern Madagascar nor from southern India. Detrital zircon and sedimentologic similarities between rocks of the Itremo Group and the Zambian Muva Supergroup suggest a lithostratigraphic correlation between the two. The Molo Group has a strong 1000–1100 Ma detrital signature that also indicates an east African provenance and suggests a Neoprot...
year | journal | country | edition | language |
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2004-07-01 | The Journal of Geology |