Southern Italian Apennines Research Articles

Mitochondrial DNA Variability in Italian and East European Wolves: Detecting the Consequences of Small Population Size and Hybridization

Abstract: The Italian wolf (Canis lupus) population has declined continuously over the last few centuries and become isolated as a result of the extermination of other populations in central Europe and the Alps during the nineteenth century. In the 1970s, approximately 100 wolves survived in 10 isolated areas in the central and southern Italian Apennines. Loss of genetic variability, as suggested by preliminary studies of mitochondrial DNA (mtDNA) sequences, hybridization with feral dogs, and the illegal release of captive, non‐native wolves are considered potential threats to the viability of the Italian wolf population. We sequenced 546 base pairs of the mtDNA control region in a comprehensive set of Italian wolves and compared them to those of dogs and other wolf populations from Europe and the Near East. Our data confirm the absence of mtDNA variability in Italian wolves: all 101 individuals sampled across their distribution in Italy had the same, unique haplotype, whereas seven haplotypes were found in only 26 wolves from an outbred population in Bulgaria. Most haplotypes were specific either to wolves or dogs, but some east European wolves shared haplotypes with dogs, indicative of hybridization. In contrast, neither hybridization with dogs nor introgression of non‐native wolves was detected in the Italian population. These findings exclude the introgression of dog genes via matings between male wolves and female dogs, the most likely direction of hybridization. The observed mtDNA monomorphism is the possible outcome of random drift in the declining and isolated Italian wolf population, which probably existed at low effective population size during the last 100–150 years. Low effective population size and the continued loss of genetic variability might be a major threat to the long‐term viability of Italian wolves. A controlled demographic increase, leading to recolonization of the historical wolf range in Italy, should be enforced.

Gravity-Accommodated ‘Structural Wedges’ Along Thrust Ramps: A Kinematic Scheme of Gravitational Evolution

In active geodynamic areas, such as the Italian Southern Apennines, the specific structural conditions have a profound effect on both the superficial and deep gravitational evolution of slopes. Chain sectors commonly exhibit structural complexities due to the superimposition, in space and time, of diverse tectonic stress fields. In this paper, attention is focused on particular structural configurations, connected to the tectonic quaternary phases that have affected the Southern Apennines, constituting a peculiar type of lateral spread gravitational deformations – which have not been previously described.

Deformation history of a synorogenic sedimentary wedge, northern Cilento area, southern Apennines thrust and fold belt, Italy

In the northern Cilento area of the southern Italian Apennines, a deformed turbiditic succession of Langhian to lower Tortonian age (the Cilento unit) unconformably overlies tectonic units (Liguride and Sicilide) derived from an oceanic accretionary complex and, to the east, overlies Mesozoic–Cenozoic carbonates belonging to the Apulian continental paleomargin. The turbiditic succession, representing the sedimentary infill of a Miocene foreland basin developed over the flexured southwestern margin of the Apulian plate, shows a complete record of the deformation at the macroscopic and mesoscopic scales. Structures postdating synsedimentary (slump) features in the Cilento unit include Neptunian dikes and extensional veins perpendicular to bedding, all related to high pore-fluid pressures associated with burial. Early tectonic structures consist of minor thrust faults, often conjugate and at a low angle to bedding, produced by initial layer-parallel shortening. The main regional structure mapped in the area consists of a moderately inclined to recumbent (hinterland-vergent) backfold. This structure probably developed by shortening of the strata caught between shear surfaces that cut obliquely across bedding, within the framework of a noncoaxial progressive deformation. The main shear surface constituting the upper boundary to the shear zone is represented by a regional backthrust which brings Mesozoic-Cenozoic carbonates onto the terrains of the Cilento unit, forming a triangle zone where backfolding of the latter occurred. Minor open domes and basins deform both limbs of the main regional structure, probably as a result of progressive shear deformation and, possibly, of deformation above underlying thrust culminations. It appears that high pore-fluid pressures must have been important not only during the development of pretectonic (i.e., burial-related) structures, but also during the main tectonic deformation. Abnormally high fluid pressures, reducing the effective stress and favoring intergranular movements, suppressed cleavage formation and pervasive strain during the main folding event. Later in the deformation sequence, a decrease in pore-fluid pressure probably favored local cleavage development during refolding. The deformation sequence outlined above provides a case history of the structural evolution of synorogenic clastic deposits progressively deformed and incorporated within a thrust belt. This study, documenting the deformation of a sedimentary wedge dominated by backfolding associated with hinterland-vergent reimbrication, should contribute to a better understanding of the wide range of deformation sequences and processes characterizing the tectonic evolution of thrust-belt–foredeep systems.

Strain analysis in Jurassic argillites of the Monte Sirino area (Lagonegro Zone, southern Apennines, Italy) and implications for deformation paths in pelitic rocks

Analysis of strain in Jurassic argillites forming part of the folded and thrusted sedimentary succession of the Lagonegro basin (southern Italian Apennines) has been carried out using ellipsoid-shaped ‘reduction’ spots as strain markers. Most of the determined finite strain ellipsoids are of oblate type and show a peculiar distribution of the maximum extension direction (X), with maxima either subparallel or subperpendicular to the local fold axes. Using the strain matrix method, two different deformation histories have been considered to assist the interpretation of the observed finite strain pattern. A first deformation history involved vertical compaction followed by horizontal shortening (occurring by a combination of true tectonic strain and volume loss), whereby all strain is coaxial and there is no change in the intermediate axis of the strain ellipsoid. By this type of deformation sequence, which produces a deformation path where total strain moves from the oblate to the prolate strain field and back to the oblate field, prolate strain ellipsoids can be generated and may be recorded where tectonic deformation has not been large enough to reverse pretectonic compaction. This type of deformation history may be of local importance within the study area (i.e. it may characterize some fold hinge regions) and, more generally, is probably of limited occurrence in deformed pelitic rocks. A second deformation sequence considered the superposition of pre-tectonic compaction and tectonic strain consisting of initial layer-parallel shortening followed by layer-parallel shear (related to flexural folding). Also in this instance, volume change during tectonic deformation and tectonic plane strain have been assumed. For geologically reasonable amounts of volume loss due to compaction and of initial layer-parallel shortening, this type of deformation history is capable of producing a deformation path entirely lying within the oblate strain field, but still characterized by a changeover, during deformation, of the maximum extension axis (X) from a position parallel to the fold axis to one perpendicular to it. This type of deformation sequence may explain the main strain features observed in the study area, where most of the measured finite strain ellipsoids, determined from the limb regions of flexural folds, display an oblate shape, irrespective of the orientation of their maximum extension direction (X) with respect to the local structural trends. More generally, this type of deformation history provides a mechanism to account for the predominance of oblate strains in deformed pelitic rocks.

Structural geology and the dissection of alluvial fan sediments by mass movement: An example from the southern Italian apennines

This paper describes how mass movement is dissecting a relict alluvial fan at the margin of the margin Sele Valley graben in southern Italy. Rock mass structure and neotectonics are treated here, not as controls upon fan sedimentation, but as a fundamental cause of the instability of inactive fan sediments. We use detailed geological and geomorphological mapping and interpretation to show how faulting and stratigraphic variations have created slump features, subsidence zones, scarpettes and cemented colluvium aprons in the vicinity of the fan. Recent faulting in the study area has influenced the concentration of groundwater and thus the stability of sedimentary formations, including those of the fan. In addition, movement in the plastic clays underlying the alluvial sediments causes the latter to break up and erode, although an olistolith embedded in a deeper layer of arenaceous flysch stabilizes parts of the fan. We use structural analysis of discontinuity planes in the adjacent limestone massif to reconstruct fault movements and the configuration of the local stress field, which we then relate to land form and surface instability phenomena. Hence, we demonstrate that neotectonics, rather than pseudo-gravitational faulting, are responsible for the distinctive morphology of the fan as mass movement continues to dismatle it.

Extensional Tectonics and the Birth of the Lagonegro Basin (Southern Italian Apennines)

Extensional Tectonics and the Birth of the Lagonegro Basin (Southern Italian Apennines)