National Academies Press: OpenBook

Effects of Past Global Change on Life (1995)

Chapter: Caravaca, Spain

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Suggested Citation:"Caravaca, Spain." National Research Council. 1995. Effects of Past Global Change on Life. Washington, DC: The National Academies Press. doi: 10.17226/4762.
Page 82

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CRETACEOUS-TERTIARY (K/T) MASS EXTINCTION: EFFECT OF GLOBAL CHANGE ON CALCAREOUS 82 MICROPLANKTON (top of P1a) that marks the initial recovery of the ecosystem at El Kef (Figure 4.9). The N. parvulum abundance peak is followed by abundance peaks in Futyania petalosa (Toweius petalosus), Praeprinsius of P. dimorphesus, and Octolithus multiplus (Perch-Nielsen, 1981). Caravaca, Spain The planktic foraminiferal assemblages that dominate during the latest Maastrichtian at Caravaca (as well as Agost) are similar to those at El Kef, although species abundance varies significantly (Figure 4.10; Canudo et al., 1991). The K/T boundary is characterized by the same species datums as well as lithological and geochemical markers (Robin et al., 1991), but the boundary clay is much thinner (7 cm) than at El Kef (50 cm). Species abundances are variable across the boundary. Heterohelix navarroensis, H. glabrans, and H. globulosa decline in abundance 5 to 10 cm below the boundary, whereas H. globulosa, Pseudotextularia costulata, P. kempensis, Globigerinelloides aspera, and G. yaucoensis remain the same or increase in the boundary clay. All Cretaceous species, except G. cretacea, decline to <2% immediately above the clay layer. As indicated earlier, this sharp faunal change marks a short hiatus (Figure 4.3), and part of the anomalous abundance increase in P0 may be due to reworking of Cretaceous taxa. Nevertheless, these relative abundance changes suggest ecological disturbances beginning prior to the K/T boundary and continuing into the earliest Tertiary (7-cm clay layer). At Caravaca and El Kef, similar sequences of rapidly evolving and changing dominant planktic foraminiferal components are present in the earliest Tertiary, including the maximum abundances of P. longiapertura, P. eugubina, and Woodringina (Canudo et al., 1991). However, because the earliest Tertiary at Caravaca is more condensed Figure 4.10 Percentage CaCO3, δ13C values, and abundance of dominant planktic foraminiferal species (percent) across the K/T boundary at Caravaca, SE Spain. Note the presence of abundant Cretaceous specimens in the boundary clay (Zone P0).

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What can we expect as global change progresses? Will there be thresholds that trigger sudden shifts in environmental conditions—or that cause catastrophic destruction of life?

Effects of Past Global Change on Life explores what earth scientists are learning about the impact of large-scale environmental changes on ancient life—and how these findings may help us resolve today's environmental controversies.

Leading authorities discuss historical climate trends and what can be learned from the mass extinctions and other critical periods about the rise and fall of plant and animal species in response to global change. The volume develops a picture of how environmental change has closed some evolutionary doors while opening others—including profound effects on the early members of the human family.

An expert panel offers specific recommendations on expanding research and improving investigative tools—and targets historical periods and geological and biological patterns with the most promise of shedding light on future developments.

This readable and informative book will be of special interest to professionals in the earth sciences and the environmental community as well as concerned policymakers.

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