SciELO - Scientific Electronic Library Online

 
vol.33 issue2Stratigraphic revision and structure of Sierra Plomosa, ChihuahuaValidation of digestion and element separation methods and a new data reduction program (IsotopeHf®) for Lu-Hf isotope dilution analysis by MC-ICP-MS author indexsubject indexsearch form
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

  • Have no similar articlesSimilars in SciELO

Share


Revista mexicana de ciencias geológicas

On-line version ISSN 2007-2902Print version ISSN 1026-8774

Abstract

BRIGHT, Jordon; OREM, Caitlin A.; MEAD, Jim I.  and  BAEZ, Arturo. Late Pleistocene (OIS 3) paleoenvironmental reconstruction for the Térapa vertebrate site, northcentral Sonora, Mexico, based on stable isotopes and autecology of ostracodes. Rev. mex. cienc. geol [online]. 2016, vol.33, n.2, pp.239-253. ISSN 2007-2902.

The Térapa fossil vertebrate site, northcentral Sonora, Mexico, provides a rare opportunity to study the paleoenvironmental conditions present in northwestern Mexico during mid-Oxygen Isotope Stage (OIS) 3. Ostracode faun al assemblages and stable oxygen (δ18O) and stable carbon (δ13С) isotope values from ostracode calcite were used to reconstruct the seasonality of precipitation and vegetation cover at Térapa at 40-43 ka. The ostracode fauna was a non-analogue mix of temperate and tropical ostracode species composed of 13 species from 12 genera. The nearctic ostracodes Fabaeformiscandona caudata, Physocypria pustulosa, Cypridopsis vidua and the cosmopolitan ostracode Darwinula stevensoni dominate the assemblage. Two tropical ostracode genera, Chlamydotheca arcuata and Stenoсуpris sp., were present throughout the deposit and indicate that mean monthly summer temperatures were probably no more than 4°C to 6°C cooler than at present, based on available ecological information. Winter precipitation dominated the hydrologie cycle as evidenced by low ostracode δ18O values (-6‰ to -8‰ VPDB). Low ostracode δ13C values (-7‰ to -8‰ VPDB) suggest that local vegetation was dominated by C3 plants. A previous tooth enamel-based paleoenvironmental reconstruction at the same site favored a summer-dominated or evaporative hydrology and abundant C4 vegetation. The Térapa megafauna site exemplifies the need for multi-indicator paleoclimate reconstructions in desert environments where marked differences in the seasonality of precipitation and vegetation cover may occur.

Keywords : Sonora; OIS 3; paleoenvironment; ostracode; stable isotopes.

        · abstract in Spanish     · text in English     · English ( pdf )