Cretaceous and Paleogene geologic history of coastal Ecuador

Stratigraphy of the late Cretaceous–Paleogene deposits of the cordillera occidental of central ecuador: geodynamic implications

“…1), associated with a variety of sediments (Faucher and Savoyat 1973;Kehrer and Van der Kaaden, 1979;Feininger and Bristow, 1980;Mamberti, 2001;Kerr et al, 2002). However, the nature, age and accretion date of these oceanic terranes are poorly known and still debated.…”

“…However, the nature, age and accretion date of these oceanic terranes are poorly known and still debated. According to various authors, accretions took place in the Campanian (Lebrat et al, 1987;Aspden et al, 1992;Hughes and Pilatasig, 2002), the Late Paleocene (Daly, 1989;Jaillard et al, 1995;Reynaud et al, 1999), and/or the Eocene (Feininger and Bristow, 1980;Egüez, 1986;Bourgois et al, 1990;Spikings et al, 2001;Kerr et al, 2002). Most authors agree that the Cordillera Occidental of central Ecuador comprises a western island arc terrane (Macuchi terrane, Kehrer and Van der Kaaden, 1979;Baldock, 1982;Egüez, 1986;Hughes and Pilatasig, 2002), and an eastern oceanic terrane of oceanic floor to oceanic plateau nature (Lebrat et al, 1987; Pallatanga terrane of McCourt et al, 1998;Hughes and Pilatasig, 2002;Kerr et al, 2002).…”

Investigation of the Lead Isotope Signatures of Marine Sediments in Relation to the Lead Isotope Signatures of Northern Andean Ores

“…In coastal areas and the Western Cordillera there are widespread outcrops of Cretaceous to Eocene volcanic and plutonic rocks with a basic to intermediate composition (Lebras et al, 1987). The coastal rocks of Ecuador consist of three collections of rock types (Feininger and Bristow, 1980). These three groupings are the Piñon and San Lorenzo Formations, the Celica Formation, and the Macuchi Formation.…”

“…The dolerites are compositionally the same as the pillow lavas, but have a fine-grained ophitic texture (Lamb et al, 1997). The Piñon Formation (Figure 3), in particular, is considered by Feininger and Bristow (1980) to be a segment of the ocean floor. The San Lorenzo Formation is chemically very similar to the Piñon Formation; both are composed of the same rock types, but because of a difference in age, they are determined to be separate formations (Feininger and Bristow 1980).…”

“…The Piñon Formation (Figure 3), in particular, is considered by Feininger and Bristow (1980) to be a segment of the ocean floor. The San Lorenzo Formation is chemically very similar to the Piñon Formation; both are composed of the same rock types, but because of a difference in age, they are determined to be separate formations (Feininger and Bristow 1980). Like the Piñon Formation, the San Lorenzo Formation is composed of pillow basalts and dikes and sills of dolerite (Feininger and Bristow 1980).…”