Person:
Pieren Pidal, Agustín Pedro

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First Name
Agustín Pedro
Last Name
Pieren Pidal
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Estratigrafía
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Now showing 1 - 2 of 2
  • Item
    Datos bioestratigráficos de los materiales silúricos del Sinclinal de Herrera del Duque (Badajoz)
    (Geogaceta, 1990) Pieren Pidal, Agustín Pedro; Gutiérrez Marco, Juan Carlos
    The Silurian sequen ce in the Herrera del Duque syncline (Southern Central /berian zone) starts with 20 m. of black shales (Guadarranquejo Formation) which lay disconformably upon the Hirnantian diamictites (Gualija Formation). Within the black shales, eight graptolite horizons have been recorded (A-H) and two (/-1) at the base of the overlying sandy alternances. A Telychian (post-Turriculatus Zone) age for the Guadarranquejo Formation has been suggested, the L1andovery/Wenlock boundary Iying probably near its top.
  • Item
    The Triassic–Jurassic boundary in Asturias (northern Spain): Palynological characterisation and facies
    (Review of palaeobotany and palynology, 2006) Barrón López, Eduardo; Gómez Fernández, Juan José; Goy Goy, Antonio; Pieren Pidal, Agustín Pedro
    A palynological, biostratigraphic, sedimentological and sequence stratigraphy study of the Triassic–Jurassic transition in Asturias (northern Spain) was performed by logging and sampling the cores of two boreholes, the Cantavieyo and Vilorteo boreholes. Four lithological units were differentiated and correlated. The lower unit, composed of mudstones and evaporites deposited in coastal lake to subaerial sabkha and distal alluvial environments, correlated in part with the Upper Triassic Keuper facies present in most of western Europe. The middle unit of well bedded carbonates corresponds to the Solis Member of the Gijon Formation. This unit was deposited on a shallow, subtidal to inter- and supratidal carbonate platform influenced by storms and with interbedded distal fan-delta facies. The Triassic–Jurassic boundary has been located within the carbonates of the Solis Member, which contain a Hettangian ammonite, Caloceras pirondii (Reynés), in tempestitic carbonates attributed to the upper part of this unit. The upper unit, the Barzana Member, is composed of mudstones, evaporites and carbonates, respectively, deposited in distal alluvial environments, in supratidal sabkha environments, and on a shallow subtidal to intertidal platform. Overlying the upper unit, or as a time equivalent of the Barzana Member, the Fabares Member is composed of a carbonate breccia with a lutitic matrix, interpreted as formed by the dissolution of the evaporites of the Barzana Member and the collapse of the originally interbedded carbonates and mudstones. A total of 49 palynomorph taxa have been recorded: 20 spore taxa, 24 pollen taxa, 1 acritarch, 2 prasinophytes, and 2 dinoflagellate cysts. Three palynological assemblages (PA) have been distinguished. PA1, which is typically Rhaetian, corresponds to the Rhaetipollis germanicus Zone. PA2 can be Rhaetian and/or Hettangian in age. PA3, which is Hettangian in age, partly corresponds to the Kraeuselisporites reissingeri Zone. These zones have been correlated with similar zones in northwestern Europe. Palaeoecological analysis of the palynomorph assemblages indicates marked palaeofloral renewal, from diversified, Late Triassic xerophilous plants to an impoverished palaeofloral community at the Triassic–Jurassic transition. The latter was composed of a poorly diversified group of conifers and ferns. The arid climate of the Late Triassic was followed by a short, humid event of the beginning of the Hettangian, during which the renewal and important recovery of vascular cryptogams and conifers occurred. The later predominance of xerophilous species in the Hettangian indicates a recovery of arid climatic conditions. After the turnover at the end of the Triassic, and especially during the Hettangian, the recovery of new species is well marked. Of a total of 21 palynomorphs, 7 species did not surpass the base of the Triassic – Jurassic transition, 6 species appeared in this transition, and 22 species appeared in the Hettangian, marking an outstanding phase of recovery for the plants that generated the studied palynomorphs.