Banca de DEFESA: MARCIANA LEANDRO DE LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARCIANA LEANDRO DE LIMA
DATE: 15/12/2025
TIME: 14:00
LOCAL: Videoconferência
TITLE:

TAPHONOMY OF FOSSIL PLANTS IN QUATERNARY TUFA DEPOSITS OF THE CHAPADA DO APODI REGION (RN), SEMIARID NORTHEASTERN BRAZIL

KEY WORDS:

Quaternary; Paleoclimate; Carbonate; Biostratinomy; Felipe Guerra

PAGES: 59
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The Quaternary period in the Brazilian semi-arid region was characterized by changes in temperature and physiognomy. One way to document these changes is through the study of fossil leaves in Quaternary tufa deposits. These fossils record a past environment that was more humid than the present and aid in reconstructing their depositional settings. The present study aimed primarily to analyze the taphonomy of phytoclastic accumulations in Quaternary tufas from the Chapada do Apodi region (Rio Grande do Norte). The analyses included three fossil deposits and three active deposits, to establish taphonomic and paleoenvironmental comparisons. The following aspects were considered: degree of packing, fragmentation, orientation, and origin of the phytolith fossils. The tufas from “Caverna dos Sicários” consist of dense packages of leaf impressions without preferred orientation, preserving anatomical details. The tufas from “Igreja de Nossa Senhora do Perpétuo Socorro” exhibit zones with phytoherms and others with phytoclasts. The phytoclastic tufas are composed of dispersed packages of leaf impressions arranged horizontally. The tufas from “Livramento” are formed by dense packages of leaf impressions, sometimes horizontally aligned and sometimes chaotically arranged. All fossil assemblages were interpreted as parautochthonous, presenting a higher number of mesophilic leaves, absence of fragmentation from mechanical transport, and orientation of the leaf blade. The taphonomic analysis of the active deposits “Cachoeira da Caripina”, “Cachoeira do Roncador” and “Ramal Apodi” showed that plants do not influence the final architecture of the tufa. This finding could indicate differences in water availability, vegetation, and climate between the Quaternary and the present, as supported by palynological, isotopic, and paleontological studies. Finally, the interpretation of fossil deposits as parautochthonous contrasts with previous views that phytoclastic tufas are solely allochthonous in origin. Thus, it is suggested that the term “parautochthonous” as used in taphonomy, be incorporated into the definition of phytoclastic tufas. 

 

COMMITTEE MEMBERS:
Presidente - 1283832 - ALINE MARCELE GHILARDI
Externa à Instituição - FRESIA SOLEDAD RICARDI TORRES BRANCO - UNICAMP
Externo à Instituição - HERMINIO ISMAEL DE ARAUJO JUNIOR - UERJ