BIOEROSION ON SPINICAUDATA SHELLS FROM A FRESHWATER PALEOLAKE (TRIASSIC), MENDOZA, ARGENTINA

BUSTOS ESCALONA, EVELYN L.; MANCUSO, ADRIANA CECILIA; BENAVENTE, CECILIA ANDREA

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2019

0883-1351

Bioerosion by microorganismsis referred as microbioerosion. In aquatic systems, microbioerosion affectsvarious substrates, most commonly relatively soluble ones such as sulfates,phosphates and carbonates. However, the record of microbioerosion in fossilcalcareous organisms in lake environments is limited. In the North of MendozaProvince, at the locality Paramillos de Uspallata, Triassic sedimentary rocks outcrop.The Agua de la Zorra Formation is characterized by deposition in a deltaic andlacustrine system. This study assesses possible bioerosion by microorganisms onspinicaudata shells from the lacustrine succession and discusses theirpreservation potential in lacustrine environments. Spinicaudatans from the Aguade la Zorra Fm. were analyzed under binocular magnifying glass and scanningelectron microscope. Of traces, casts, product of microbioerosion, were assignedas trace Types 1 and 2. The traces found were compared with traces generated bycyanobacteria, bacteria, chlorophyte and fungi that inhabit fresh and brackishwater environments. Microbioerosion takes place in a post-mortem state and enhancesdissolution of the spinicaudata shells. The latter, together with bias inextraction methodologies and sampling, would explain the rarity of spinicaudatanswith traces of bioerosion in the lacustrine record.