Department of Earth Sciences

University of Torino, Italy

Mélanges and mélange forming processes

Definition of the role played by tectonic, sedimentary (gravitational), and diapiric processes in the formation of mélanges (or chaotic rock units) in passive and active margins, and in ancient accretionary complexes. Particular interest is addressed to document and define: (i) the relationships between different mélange types, and geodynamic setting in which they formed; (ii) the criteria helpful for distinguishing different types of mélange forming processes and their superposition. This research is developed through the comparative analyses of different types of mélanges exposed in the Apennines and W-Alps in Italy, circum-Mediterranean region, Central Appalachians and Sierra Nevada (USA), Andean Precordillera (Argentina) and Cantabria Zone (Spain). The paper "Mélanges and mélange- forming processes: a historical overview and new concepts" by Festa et al. 2010 (International Geology Review, 52(10-12), 1040-1105) has been recognized as “High Cited Paper” and evaluated the #10 paper on 11542 articles in the category “Geology” of WEB OF SCIENCE for the period 2010 to 2014 (Web of Science Core Collection).

Advella Mélange (Pindos Mts.),

Greece (courtesy by Y. Dilek).

Convergent margins and subduction zones

Observations at modern convergent margins and accretionary wedge - subduction zone

systems throughout the world clearly show high degree of structural complexities and

variability in site-specific geometry, resulting in a complex segmentation along-strike as well

as along-dip. This research is devoted to the

definition of the structural setting and tectono-

stratigraphic evolution of convergent margins from subduction-related deformation to

collision and intra-continental deformation. It also focusses on the dynamics of the accretionary complexes, including the study of the MTDs (mass-transport deposits) and

their control on seismic behavior of shallow-leve megathrusts at the subduction plate interface, supported by the comparison between modern (ocean drilling from IODP projects) and fossil analoques. Main studied areas are Apennines in Italy, Western Alps, central Appalachians and northern Sierra Nevada in USA, and Crete in Greece. Figure modified from Festa et al. (2018) - Gondwana Research 60, p. 186-193.

Intra-oceanic tectonic and sedimentation relationships

Sunrise at the Corno Grande

(Gran Sasso Renge, Central

Apennines, Italy). (

from Vezzani

et al., 2010 GSA Spec Paper

469)

Tectono-stratigraphic evolution of sedimentary basins

Definition of the geometry, and kinematic of faulting in the Apennines and Alps,

based on detailed structural analysis, and field mapping. Particular attention

has been addressed to the multistage reactivation of inherited faults, and their control on

sedimentation.

The photograph above shows the panorama on the northern frontal scarp of the Gran

Sasso thrust belt is modified (from Vezzani et al. (2010) - GSA Special Paper 469).

Overturned contact between

massive serpeninite, brecciated

serpentinite and talc-chlorite

schist within an exhumed

detachment fault (Monviso

Ophiolte, W-Alps;

from Balestro

et al., 2016, Episodes

)

Aerial view eastward of the

increasing uplift in the Central

Apennines carbonate platform

(Italy).

(from Vezzani et al., 2010

GSA Spec Paper 469)

Ankara Mélange, Turkey.

Geological Mapping

Geologic mapping

represents the

principal tool that I

use in my

research to

convey a

complete

compilation of

information about

the structure and

stratigraphy of the

sectors I work on.

It addition to

scientific papers,

the

product

consists of maps

at different scales

(from 1:10.000 to 1:250.000) of different sectors of the Apennines thrust-and-fold belt.

(see

“

Geological Maps” section for more informations

Geological mapping is not always a

fundamental tool for my research, and I consider it integral to the professional development

of geoscientists, and particularly important as it applies to student understanding of spatial,

temporal, and complex relations in the Earth system.

The Figure is Sheet 1 of the Geolgical-structural Map of the Central-Southern Apennines

(Italy) at 1:250,000 scale by Vezzani et al. (2010) - GSA Spec Paper 469

Structural scheme of Central -

Southern Apennines , Italy.

(from

Vezzani et al., 2010 GSA Spec

Paper 469)

preserved remnants of extensional detachment faults associated to Ocean Core Complex

(OCC) in eclogite facies Western Alpine metaophiolite units. Particular attention is addressed

to the role played by preserved intra-oceanic structures in controlling the subsequent

tectonic evolution of Western Alps during subduction, obduction, collision and exhumation

stages.

Main studied areas are the Western Alps, Sierra Nevada in California,

and Crete. These studies have been awarded by IUGS (International Union of Geological

Sciences) with the

EPISODES Best Paper Award 2016

in recongition of the paper:

“Pre-Alpine extensional tectonics of a peridotite-localized Oceanic Core Complex in Late

Jurassic, High-Pressure Monviso Ophiolite (Western Alps)” by Balestro, G., Festa, A., Dilek,

Y., Tartarotti, P. Episodes, 38 (4), 266-282.

Figure modified from Balestro et al. (2016) - Episodes 38, p. 266-282.

Normal fault in lacustrine

deposits (Sulmona basin, Central

Apennines, Italy).