Early Ordovician conodonts from the ullum volcanic center, Argentine precordillera: Biostratigraphy, geothermometry and preservation

2021 ◽  
pp. 103504
Author(s):  
M.J. Mango ◽  
G.G. Voldman ◽  
G.L. Albanesi
Keyword(s):  
Volcanic Center ◽  
Early Ordovician ◽  
Argentine Precordillera

Lower Ordovician graptolite biozonation and lithofacies of southern Bolivia: relevance for palaeogeographic interpretations

2004 ◽  
Vol 141 (3) ◽  
pp. 287-299 ◽  
Author(s):  
SVEN O. EGENHOFF ◽  
JÖRG MALETZ ◽  
BERND-DIETRICH ERDTMANN
Keyword(s):  
South America ◽  
Basin Evolution ◽  
Early Ordovician ◽  
The Pacific ◽  
Lower Ordovician ◽  
Lithostratigraphic Units ◽  
Faunal Succession ◽  
Argentine Precordillera

The interpretation of the lithofacies and basin evolution of the early Ordovician of southern Bolivia is based on a number of sections on an E–W transect. Lithostratigraphic units are extremely diachronous and only the available data on the graptolite biostratigraphy enabled an interpretation of the basin evolution. The newly proposed graptolite biozonation includes the biozones of Rhabdinopora flabelliformis, Adelograptus sp., Araneograptus murrayi, Hunnegraptus copiosus, Tetragraptus phyllograptoides, Expansograptus protobalticus, Expansograptus holmi, Baltograptus minutus, Azygograptus lapworthi and Isograptus victoriae. Isograptus victoriae is the first isograptid identified from Gondwanan South America. The early Ordovician succession of southern Bolivia is the most complete one documented from South America and can be used as a standard for this continent. The faunas are most easily correlated with the faunal succession of Scandinavia and without doubt belong to the Atlantic graptolite faunal province. They show distinct differences from coeval faunas of the Argentine Precordillera, referable to the Pacific faunal province.

scholarly journals A lowermost Ordovician tabulate-like coralomorph from the Precordillera of western Argentina: a main component of a reef-framework consortium

2016 ◽  
Vol 91 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Marcelo G. Carrera ◽  
Ricardo A. Astini ◽  
Fernando J. Gomez
Keyword(s):  
Microbial Consortium ◽  
Early Cambrian ◽  
Migration Routes ◽  
Early Ordovician ◽  
New Finding ◽  
Argentine Precordillera ◽  
Reef Mounds ◽  
And Migration ◽  
Main Component ◽  
A New Species

AbstractAlthough putative corals of uncertain affinities occur in the early Cambrian, the earliest definite tabulate corals have not been described prior to the Early Ordovician in North America. This paper reports a new finding of a tabulate-like coralomorph forming part of biostratigraphically well-constrained reef mounds in the latest Cambrian–Early Ordovician La Silla Formation in the Argentine Precordillera. The oldest record of the coralomorph genus Amsassia is reported and a new species, A. argentina, is erected. The discovery of this genus in the lowermost Ordovician modifies the previously proposed paleogeographic distribution and patterns of origination and migration routes of this coral-like organism. Amsassia argentina n. sp. constitutes a main framework builder together with a complex microbial consortium. This oldest occurrence of Amsassia as a reef builder represents a new record of a skeletal organism in the gap of metazoan reef constructors after the demise of archaeocyaths in the late early Cambrian.

Biogeography of Ordovician sponges

1999 ◽  
Vol 73 (1) ◽  
pp. 26-37 ◽  
Author(s):  
Marcelo G. Carrera ◽  
J. Keith Rigby
Keyword(s):  
North American ◽  
New South ◽  
New South Wales ◽  
Late Ordovician ◽  
Published Data ◽  
Middle Ordovician ◽  
Biogeographic Patterns ◽  
Early Ordovician ◽  
South Wales ◽  
Argentine Precordillera

Sponges have an unrealized potential importance in biogeographic analysis. Biogeographic patterns determined from our analysis of all published data on distribution of Ordovician genera indicate Early Ordovician sponge faunas have relatively low diversity and are completely dominated by demosponges. Early Ordovician (Ibexian) faunas are characterized by the widespread co-occurrence ofArchaeoscyphiaand the problematicCalathium.This association is commonly found in biohermal structures. Middle Ordovician faunas show an increase in diversity, and two broad associations are differentiated: Appalachian faunas (including Southern China and the Argentine Precordillera) and Great Basin faunas.Late Ordovician faunas show important changes in diversity and provincialism. Hexactinellid and calcareous sponges became important and new demosponge families appeared. Four Mohawkian-Cincinnatian associations are recognized here, including: 1) Midcontinent faunas; 2) Baltic faunas; 3) New South Wales faunas; and 4) Western North American (California and Alaska) faunas. However, two separate biogeographic associations are differentiated based on faunal differences. These are a Pacific association (western North American and New South Wales) and an Atlantic association (Midcontinent Laurentia and Baltica).Distribution of sponge genera and migration patterns are utilized to consider paleogeographic dispositions of the different continental plates, climatic features, and oceanic currents. Such an analysis points to close paleogeographic affinities between the Argentine Precordillera and Laurentian Appalachian faunas. However, significant endemicity and the occurrence of extra-Laurentian genera suggest a relative isolation of the Precordillera terrane during the Late Ibexian-Whiterockian. The study also shows a faunal migration from the Appalachian region to South China during the Middle Ordovician and the migration of faunas from Baltica to Laurentia in the Late Ordovician. The occurrence of Laurentian migrants in New South Wales during the Late Ordovician could be related to inferred oceanic current circulation between these two areas, although other paleogeographic features may be involved.

Silent Canyon volcanic center, Nye County, Nevada

1968 ◽  
Author(s):  
Donald C. Noble ◽  
K.A. Sargent ◽  
H.H. Mehnert ◽  
E.B. Ekren ◽  
F.M. Byers
Keyword(s):  
Volcanic Center ◽  
Nye County
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