William Cavazza

The TRANSMED Atlas. The Mediterranean Region from Crust to Mantle

One - Printed Volume.- 1 The Mediterranean Area and the Surrounding Regions: Active Processes, Remnants of Former Tethyan Oceans and Related Thrustbelts.- Abstract.- 1.1 Introduction.- 1.2 Mediterranean Fold-and-thrust Belts.- 1.3 Mediterranean Marine Basins.- 1.4 Geological-geophysical Baseline.- 1.4.1 Heat Flow.- 1.4.2 Crustal and Lithospheric Structure.- 1.4.3 Gravity.- 1.4.4 Magnetic Field.- 1.4.5 Seismicity.- 1.4.6 Geodetic Data.- 1.4.7 Stress Field.- 1.5 Global Dynamics and Active Processes Exemplified in the Mediterranean.- 1.5.1 Subduction of the Eastern Mediterranean Lithosphere beneath the Calabrian and Aegean.- 1.5.2 Rifting and Passive Margin Development in Back-arc Regions and Other MediterranRelated to Tectonic Wedges, Tilted Blocks and Sedimentary Loadingean Domains.- 1.5.3 Mud and Salt Diapirism (Eastern Mediterranean Ridge, Alboran Sea, Nile Delta).- 1.5.4 Sea-level Changes, Salinity Crisis, Flooding (Messinian Mediterranean versus Pleistocene Black Sea).- 1.6 Record of Ancient Dynamics of the Tethyan Oceans, Ophiolitic Sutures, Mantle Tomography versus Paleogeography of the Mediterranean Realm.- 1.6.1 Collisional vs. Intracontinental Thrust Belts and Oceanic Sutures.- 1.6.2 Plate Dynamics and Palinspastic Restorations: Demise of the Concept of a Single Tethys.- 1.6.3 Cenozoic Magmatism in the Mediterranean Region.- 1.7 Conclusions.- Acknowledgements.- 2 A Tomographic View on Western Mediterranean Geodynamics.- Abstract.- 2.1 Introduction.- 2.2 The Global Tomography Model BS2000.- 2.3 Interpretation of Model BS2000 for the Western Mediterranean Mantle.- 2.3.1 Alps, Apennines, and the Western Mediterranean.- 2.3.2 The Betic-Rif and Alboran Region.- 2.4 Analysis: the Geodynamic Evolution of the Western Mediterranean.- 2.4.1 Tomographic Evidence for Slab Roll-back.- 2.4.2 Northern Apennines and Alpine-Tethys Subduction.- 2.4.3 Slab Detachment beneath the Central-southern Apennines.- 2.4.4 Calabria Subduction.- 2.4.5 The North African Margin.- 2.4.6 Betic-Rif and Alboran Region: I. Subduction and Roll-back of Predominantly Oceanic Lithosphere.- 2.4.7 Betic-Rif and Alboran Region: II. Development of Arc Geometry and Subduction Roll-back.- 2.4.8 Synthesis of Tomographic Constraints on the Geodynamic Evolution of the Western Mediterranean Region.- 2.5 Summary.- Acknowledgements.- Appendix 1 (CD-ROM).- Appendix 2 (CD-ROM).- 3 The TRANSMED Transects in Space and Time: Constraints on the Paleotectonic Evolution of the Mediterranean Domain.- Abstract.- 3.1 Introduction.- 3.2 The Western Tethys Main Plate Tectonic Constraints.- 3.2.1 The East Mediterranean-Neotethys Connection.- 3.2.2 The Apulia-Adria Problem.- 3.3 The Geodynamic Evolution of Greater Apulia and Surrounding Regions.- 3.3.1 Paleotethys Evolution (Figs. 3.2-3.6).- 3.3.2 Cimmerian Events and Triassic Marginal Oceans (Figs. 3.6-3.9).- 3.3.3 The Jurassic Oceans: Alpine Tethys, Central Atlantic and Vardar (Figs. 3.8-3.11).- 3.3.4 The Cretaceous Oceans: North Atlantic and the Pyrenean Domain (Figs. 3.10-3.14).- 3.4 The TRANSMED Transects in Space and Time.- 3.4.1 Transects I-II-III West.- 3.4.2 Transects IV-V-VI.- 3.4.3 Transects III East, VII and VIII.- 3.5 Conclusions.- Acknowledgements.- Appendix 3 (CD-ROM).- References: Preface, Chapters 1, 2 and 3.- References: CD-ROM.- Transect I: Iberian Meseta - Guadalquivir Basin - Betic Cordillera - Alboran Sea - Rif - Moroccan Meseta - High Atlas - Sahara Domain.- Transect II: Aquitaine Basin - Pyrenees - Ebro Basin - Catalan Coastal Ranges - Valencia Trough - Balearic Promontory - Algerian Basin - Kabylies - Atlas - Saharan Domain.- Transect III: Massif Central - Provence - Gulf of Lion - Provencal Basin - Sardinia - Tyrrhenian Basin - Southern Apennines - Apulia - Adriatic Sea - Albanian Dinarides - Balkans - Moesian Platform.- Transects IV, V and VI: The Alps and Their Forelands.- Transect VII: East European Craton - Scythian Platform - Dobrogea - Balkanides - Rhodope Massif - Hellenides - East Mediterranean - Cyrenaica.- Transect VIII: Eastern European Craton - Crimea - Black Sea - Anatolia C2014 Cyprus - Levant Sea - Sinai - Red Sea.

Calabria-Peloritani terrane and northern Ionian Sea

This chapter provides a synthesis of the past and current state of the knowledge on geological structure and evolution of the Calabria-Peloritani terrane and the northern (N) Ionian Sea. A general introduction to the study area is followed by a brief overview of past interpretations, a description of its main tectono-stratigraphic units, and a new interpretation of its evolution in terms of terrane analysis and accretion history. The term Calabria-Peloritani Arc, traditionally found in the literature, is discontinued because it refers to the present-day morphological curvature of the terrane in map view, but it is confusing if geologically defined.

Apatite fission-track data for the Miocene Arabia-Eurasia collision

The collision between the Eurasian and Arabian plates along the 2400-km-long BitlisZagros thrust zone isolated the Mediterranean from the Indian Ocean and has been linked to extension of the Aegean, rifting of the Red Sea, and the formation of the North and East Anatolian fault systems. However, the timing of the collision is poorly constrained, and estimates range from Late Cretaceous to late Miocene. Here, we report the fi rst apatite fi ssiontrack (AFT) ages from the Bitlis-Zagros thrust zone. The AFT samples are distributed over the 450 km length of the Bitlis thrust zone in southeast Turkey and include metamorphic rocks and Eocene sandstones. Despite the disparate lithology and large distance, the AFT ages point consistently to exhumation between 18 and 13 Ma. The AFT ages, along with a critical appraisal of regional stratigraphy, indicate that the last oceanic lithosphere between the Arabian and Eurasian plates was consumed by the early Miocene (ca. 20 Ma). The results imply that Aegean extension predated the Arabia-Eurasia collision.

A comparison of fluvial megafans in the Cordilleran (Upper Cretaceous) and modern Himalayan foreland basin systems

The Campanian–Maastrichtian Hams Fork Conglomerate Member of the Evanston Formation in northeastern Utah and southwestern Wyoming consists of a widespread (>10 000 km 2 ) boulder to pebble, quartzitic conglomerate that was deposited by east-southeastward–flowing, gravelly braided rivers on top of the frontal part of the Sevier fold-thrust belt and in the adjacent foredeep of the Cordilleran foreland basin. In northeastern Utah the conglomerate was deposited in a lobate fan-shaped body, up to 122 m thick, that trends southeastward away from its principal source terrane in the southern end of the Willard thrust sheet. The Willard sheet contains thick Proterozoic quartzite units that produced highly durable clasts capable of surviving long-distance fluvial transport. Although the main source of sediment for the Hams Fork Conglomerate was the Willard sheet, the active front of the thrust belt lay 40–50 km to the east along the Absaroka thrust system. Displacement along the Absaroka system uplifted and topographically rejuvenated the Willard sheet, and antecedent drainages carried detritus from hinterland source terranes into the proximal foreland basin. Although topographic ridges associated with fault-propagation anticlines along frontal thrusts locally influenced transport directions, they provided relatively little sediment to the Hams Fork Conglomerate. Lithofacies, paleocurrent, and isopach data indicate that the Hams Fork Conglomerate was deposited in fluvial megafans and stream-dominated alluvial fans, similar in scale and processes to megafans and alluvial fans in southern Nepal and northern India that are forming along the proximal side of the Himalayan foreland basin system. The Himalayan fluvial megafans have areas of 10 3 –10 4 km 2 , slopes of 0.05°–0.18°, and are deposited by large transverse rivers that are antecedent to frontal Himalayan structures and topography. The main fluvial channels on the upper parts of the megafans are anastomosed and braided at bankfull stage but commonly have braided thalwegs at low-flow stage. Downstream, these channels become predominantly braided and meandering and ultimately merge with the axial Ganges trunk river system. Stream-dominated alluvial fans in the Himalayan foreland basin system fringe the topographic front of the fold-thrust belt in the intermegafan areas. These fans have areas of ∼10 2 km 2 and slopes of ∼0.5°. The proximal parts of both types of fans are dominated by extremely coarse (boulder-cobble) bedload that is in transit mainly during the monsoon. The prevalence of fluvial megafans in the modern and Miocene Himalayan foreland and in the Upper Cretaceous–lower Tertiary stratigraphic record of the Cordilleran foreland suggests that these types of deposits may be the volumetrically largest gravel accumulations in nonmarine foreland basin systems.

The Mediterranean Area and the Surrounding Regions: Active Processes, Remnants of Former Tethyan Oceans and Related Thrust Belts

The Mediterranean domain provides a present-day geodynamic analog for the final stages of a continent-continent collisional orogeny. Over this area, oceanic lithospheric domains originally present between the Eurasian and African-Arabian plates have been subducted and partially obducted, except for the Ionian basin and the southeastern Mediterranean. A number of interconnected, yet discrete, Mediterranean orogens have been traditionally considered collectively as the result of an “Alpine” orogeny, when instead they are the result of diverse tectonic events spanning some 250 Myr, from the late Triassic to the Quaternary. To further complicate the picture, throughout the prolonged history of convergence between the two plates, new oceanic domains have been formed as back-arc basins either (i) behind active subduction zones during Permian-Mesozoic time, or (ii) associated with slab roll-back during Neogene time, when during advanced stages of lithospheric coupling the rate of active subduction was reduced. The closure of these heterogenous oceanic domains produced a system of discrete orogenic belts which vary in terms of timing of deformation, tectonic setting and internal architecture, and cannot be interpreted as the end product of a single Alpine orogenic cycle.

Upper Messinian siliciclastic rocks in southeastern Calabria (southern Italy): palaeotectonic and eustatic implications for the evolution of the central Mediterranean region

Abstract The Messinian stratigraphy of eastern Calabria (southern Italy) is characterised by a threefold subdivision: (1) a pelite section with local limestone and gypsum, deposited in a restricted-marine environment, is unconformably, or disconformably, overlain by (2) coarse-grained alluvial conglomerate, which is in turn locally overlain by (3) a thin and discontinuous ribbon-shaped sedimentary body of sandstone and pelite, commonly displaying a shallow-marine to continental progradational trend. The basal unconformity/disconformity, coarse grain-size, and abrupt compositional-sedimentological change of unit 2 with respect to unit 1 can be explained as a response to tectonic instability and out-of-sequence thrusting in the Calabrian orogenic wedge, possibly induced by isostatic back-tilting of the wedge following the desiccation of the Mediterranean Sea. This mechanism could explain widespread late Messinian thrusting and syntectonic sedimentation along the Apenninic–Maghrebian orogenic belt. The uppermost Messinian continental to shallow-marine siliciclastic deposits of unit 3 crop out today at elevations of up to 300 m. Similar, age-equivalent sedimentary deposits can be traced along the Apennines and the Sicilian Maghrebides, thus, indicating that the Mediterranean area was flooded before deposition of the Trubi Formation, the base of which is traditionally regarded as marking the reestablishment of marine conditions in the Mediterranean region.

An Oligocene ductile strike-slip shear zone: The Uludağ Massif, northwest Turkey—Implications for the westward translation of Anatolia

The Uludag Massif in northwest Turkey represents an exhumed segment of an Oligocene ductile strike-slip shear zone that is over 225 km long and has ~100 km of right-lateral strike-slip displacement. It forms a faultbounded mountain of amphibolite-facies gneiss and intrusive Oligocene granites. A shear-zone origin for the Uludag Massif is indicated by: (1) its location at the tip of the active Eskisehir oblique-slip fault, (2) pervasive subhorizontal mineral lineation in the gneisses with a right-lateral sense of slip, (3) foliation with a consistent strike, (4) the presence of a subvertical synkinematic intrusion, and (5) the alignment of the Eskisehir fault, synkinematic metagranite, and the strike of the foliation and mineral lineation. The shear zone nucleated in amphibolite-facies gneisses at peak pressure-temperature (P-T) conditions of 7.0 kbar and 670 °C, and it preserves Eocene (49 Ma) and Oligocene (36–30 Ma) Rb/Sr muscovite and biotite cooling ages. The shear zone was active during the latest Eocene and Oligocene (38–27 Ma), as shown by the crystallization and cooling ages from synkinematic granite. A 27 Ma postkinematic granite marks the termination of shear-zone activity. The 20–21 Ma apatite fi ssion-track (AFT) ages indicate rapid exhumation during the early Miocene. A 14 Ma AFT age from an Uludag gneiss clast deposited in a neighboring Neogene basin shows that the shear zone was on the surface by the late Miocene. Results of this study indicate that during the Oligocene, crustal-scale right-lateral strikeslip faults were transporting crustal fragments from Anatolia into the north-south– extending Aegean; this implies that the westward translation of Turkey, related to the Hellenic slab suction, started earlier than the Miocene Arabia-Eurasia collision.

Heterogeneous Distribution of Calcite Cement at the Outcrop Scale in Tertiary Sandstones, Northern Apennines, Italy

Calcite cement derived intraformationally in seven stratigraphic units of marine origin (five submarine-fan deposits and two shelf deposits) is distributed heterogeneously at the outcrop scale. Sandstone beds intercalated with calcareous shale older than Pliocene tend to be completely cemented, whereas stacked sandstone beds that lack shale interbeds have calcite cement in the form of tightly cemented concretions that make up only 10-30% of a bed. The abundance and distribution of concretions, with few exceptions, are irregular and unpredictable. Concretion shapes include spheres (<1 m diameter), oblate and prolate spheroids (<1.5 m), tabular forms (to 8 m long), and irregular forms. Patterns of concretions within beds are remarkably varied and include both random and uniform spacing; preference for either the top, middle, or bottom of beds; preference for faults that cut bedding at a high angle; and localization around shale rip-up clasts. There is no preference of concretions for shell-rich layers. Some formations have cement patterns specific to that formation, whereas other formations have different patterns at different outcrops. Most formations have more than one cement pattern in an outcrop. The lack of strong textural (grain size, graded bedding) or compositional controls on the localization of calcite cement suggests the preeminence of highly localized hydrologic factors in determining the spatial distribution of authigenic pore-filling calcite. Spherical concretions grew by diffusive supply of intraformationally derived components, whereas prolate and elongate concretions grew chiefly under the influence of advective supply. Faults apparently served as fluid conduits and were selectively cemented. In general, only sandstones intercalated with shale are totally cemented. This indicates that shales were a major source of cement components for these sandstones at least.

Cenozoic sedimentation and paleotectonics of north-central New Mexico: Implications for initiation and evolution of the Rio Grande rift

The Rio Grande rift is one of the major late Cenozoic continental rifts of the world, sharing most geophysical, geochemical, and geological characteristics with other rifts. Cenozoic evolution of the rift was synchronous with lithospheric plate interactions along and under the western North American margin: Paleocene-Eocene: Laramide primarily amagmatic compression related to flat-slab subduction; Oligocene: intermediate to silicic volcanism related to collapse of the slab; Miocene to present: rifting related to complex plate interactions overprinted on the previous history. Cenozoic paleogeographic and paleotectonic characteristics are consistent with a passive-mantle mode of rifting. North-central New Mexico provides a unique opportunity to constrain models for rift initiation and evolution. It is one of the few locations within any rift where excellently exposed pre-rift and syn-rift basin fill has been studied thoroughly enough to allow detailed paleogeographic reconstruction for almost the entire Cenozoic. Cenozoic paleogeography for the study area is summarized as follows: (1) Eocene (58-37 Ma): a single amagmatic sedimentary basin (El Rito-Galisteo) trended northwest-southeast with Laramide basement uplifts on three sides; (2) early to late Oligocene (37-28 Ma): intermediate magmatism with volcaniclastic aprons derived from the San Juan and Ortiz-Cerrillos volcanic fields, and residual Laramide uplifts; (3) late Oligocene-early Miocene (28-21 Ma): initiation of bimodal volcanism with widely dispersed volcaniclastic aprons derived from the predominantly silicic San Juan and Latir volcanic fields; (4) early to middle Miocene (21-15 Ma): continued volcaniclastic dispersal from silicic volcanic centers, concurrent with initiation of block faulting to form half grabens, internal drainage, and erosion of Phanerozoic strata and Precambrian basement; (5) middle to late Miocene (15-8 Ma): continued deepening of half grabens, widespread exposure of Precambrian terranes, formation of complex depositional environments in basin centers, and continued bimodal volcanism; (6) late Miocene to present (8-0 Ma): concentration of extension in central grabens linked by accommodation zones, major bimodal volcanism (for example, Taos Plateau and Jemez Mountains), regional uplift, and integration of Rio Grande drainage. Dispersal patterns, petrofacies analysis, K-Ar ages, and chemical analyses of volcanic clasts provide details concerning three primary volcanic centers: (1) San Juan Mountains (27-29 m.y., high-K andesite and rhyodacite); (2) Latir volcanic field (25-28 m.y., high-K andesite and rhyolite); and (3) the previously unrecognized Servilleta Plaza center (22-23 m.y., latite, high-K andesite and rhyodacite), which may have been a southern extension of the Latir field. These three volcanic centers provided detritus to the following units, respectively: (1) Esquibel Mbr. of Los Pinos Fm., upper Abiquiu Fm., middle Picuris Fm., Bishops Lodge Mbr. of Tesuque Fm. and volcaniclastic units in the northern Albuquerque basin (Zia and Abiquiu); (2) Cordito Mbr. of Los Pinos Fm. and uppermost Abiquiu Fm.; and (3) Chama-El Rito Mbr. of Tesuque Fm and upper Picuris Fm. Use of petrofacies (1. Esquibel, 2. Cordito, and 3. Plaza) simplifies the chaos of stratigraphic nomenclature and promotes regional correlations of poorly exposed units.

Differential diagenesis of sedimentary components and the implication for strontium isotope analysis of carbonate rocks

Geochemical analyses of various components foraminifera, coccoliths and siliciclastic fractions of limestone and marl . samples from the marine Trubi Formation Early Pliocene of southern Italy revealed subtle diagenetic contamination. The coccolith fraction is altered from its original value both in its trace element Sr rCa, MgrCa, FerCa, MnrCa, NarCa all