Asociación de espículas cámbricas de la Formación Empozada, Precordillera de Mendoza.

BERESI M.S. AND HEREDIA S.E

AMEGHINIANA

Revista Asociación Paleontológica Argentina

Lugar: Buenos Aires; Año: 1995 vol. 32 p. 401 - 405

0002-7014

    ABSTRACT We have collected spicule sponges and sclerites of chancelloriids in carbonate facies of the San Isidro, Precordillera of Mendoza, western Argentina. The allochthonous assemblage consists of spicules and skeletal nets collected in diverse carbonate olistoliths from the slope facies of the Mendoza Precordillera. The Cambrian carbonate blocks were derived from the collapse and/or fragmentation of the shallow, outer platform and slope facies. These blocks were reworked and deposited in Ordovician clastic slope sequences of the Empozada Formation. Sclerites of the Chancelloria Walcott and other dissociated spicules identified as Kiwetinokia, occur in the Middle Cambrian bioclastic wackestones of the San Isidro (Glossopleura Zone) and in the dark mudstones from the San Martín (agnostids from the Upper Middle Cambrian) olistoliths of the Lower Member of the Empozada Formation. In the Upper Cambrian, a La Cruz olistolith (Proconodontus tenuiserratus Zone) of the Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera. We have collected spicule sponges and sclerites of chancelloriids in carbonate facies of the San Isidro, Precordillera of Mendoza, western Argentina. The allochthonous assemblage consists of spicules and skeletal nets collected in diverse carbonate olistoliths from the slope facies of the Mendoza Precordillera. The Cambrian carbonate blocks were derived from the collapse and/or fragmentation of the shallow, outer platform and slope facies. These blocks were reworked and deposited in Ordovician clastic slope sequences of the Empozada Formation. Sclerites of the Chancelloria Walcott and other dissociated spicules identified as Kiwetinokia, occur in the Middle Cambrian bioclastic wackestones of the San Isidro (Glossopleura Zone) and in the dark mudstones from the San Martín (agnostids from the Upper Middle Cambrian) olistoliths of the Lower Member of the Empozada Formation. In the Upper Cambrian, a La Cruz olistolith (Proconodontus tenuiserratus Zone) of the Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera. identified as Kiwetinokia, occur in the Middle Cambrian bioclastic wackestones of the San Isidro (Glossopleura Zone) and in the dark mudstones from the San Martín (agnostids from the Upper Middle Cambrian) olistoliths of the Lower Member of the Empozada Formation. In the Upper Cambrian, a La Cruz olistolith (Proconodontus tenuiserratus Zone) of the Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera. Isidro (Glossopleura Zone) and in the dark mudstones from the San Martín (agnostids from the Upper Middle Cambrian) olistoliths of the Lower Member of the Empozada Formation. In the Upper Cambrian, a La Cruz olistolith (Proconodontus tenuiserratus Zone) of the Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera. the Upper Middle Cambrian) olistoliths of the Lower Member of the Empozada Formation. In the Upper Cambrian, a La Cruz olistolith (Proconodontus tenuiserratus Zone) of the Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera. Empozada Formation can be found isolated hexactines, pentactines and monaxons. Isolated stauractines, anchoring and diagonally arranged spicules, are also present in this assemblage. Demosponges have very limited record in the Cambrian of the Precordillera. Anthaspidellid sponges have been reported from the San Martín olistolith (Empozada Formation). This olistolith represents an outer platform. These unidentifiable fragments of trabs and dendroclone spicules represent the only Cambrian occurrences of anthaspidellids known thus far in South America. The occurrence of these spicules sponges in both the platform and slope facies of the Precordillera are useful in providing help for paleoenvironmental and paleogeographical interpretations. Additionally, these sponge and spicule assemblages aid in the ongoing discussion of the relationships between the east and the west facies during the Cambrian and Ordovician of the Precordillera.