92 research outputs found
The sedimentary record of the exhumation of a granite intrusion into a collisional setting: the lower Gonfolite Group, Southern Italy.
No full textA provenance study of a post-collisional transgressive sequence (Molare Formation, Italy) through integrated facies analysis, mineral chemistry and Ar/Ar dating.
No full textCretaceous evolution of the Andean margin between 36°S and 40°S latitude through a multi-proxy provenance analysis of Neuquén Basin strata (Argentina)
No full textDuring the Cretaceous, the Neuquén Basin transitioned from an extensional back-arc to a retroarc foreland basin. We present a multi-proxy provenance study of Aptian to Santonian (125–84 Ma) continental sedimentary rocks preserved in the Neuquén Basin used to resolve changes of sediment drainage pattern in response to the change in tectonic regime. Sandstone petrology and U–Pb detrital zircon geochronology constrain the source units delivering detritus to the basin; apatite U–Pb and fission track dating further resolve provenance and determine the age and patterns of exhumation of the source rocks. Sandstone provenance records a sharp change from a mixed orogenic source during Aptian time (ca. 125 Ma), to a magmatic arc provenance in the Cenomanian (ca. 100 Ma). We interpret this provenance change as the result of the drainage pattern reorganisation from divergent to convergent caused by tectonic basin inversion. During this inversion and early stages of contraction, a transient phase of uplift and basin erosion, possibly due to continental buckling, caused the pre-Cenomanian unconformity dividing the Lower from Upper Cretaceous strata in the Neuquén Basin. This phase was followed by the development of a retroarc foreland basin characterised by a volcanic arc sediment provenance progressively shifting to a mixed continental basement provenance during Turonian-Santonian (90–84). According to multi-proxy provenance data and lag times derived from apatite fission track analysis, this trend is the result of a rapidly exhuming source within the Cordillera to the west, in response to active compressional tectonics along the western margin of South America, coupled with the increasing contribution of material from the stable craton to the east; this contribution is thought to be the result of the weak uplift and exhumation of the foreland due to eastward migration of the forebulge.Fil: Di Giulio, Andrea. Universita di Pavia; ItaliaFil: Ronchi, Ausonio. Universita di Pavia; ItaliaFil: Sanfilippo, Alessio. Universita di Pavia; ItaliaFil: Balgord, Elizabeth A.. University of Arizona; Estados UnidosFil: Carrapa, Barbara. University of Arizona; Estados UnidosFil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin
Thermal history of the Epiligurian Marzabotto wedge‐top basin records the tectonic development of the Northern Apennines (Italy)
No full textApatite fission track (AFT) and U-Th/He analyses (AHe) of detrital minerals from Eocene to Pliocene siliciclastic deposits in the Northern Apennines were here applied to constrain the tectono-thermal history of the wedge-top Epiligurian Marzabotto Basin (EMB). Detrital AFT age populations from Eocene to Miocene strata cluster between similar to 71 and similar to 58 Ma. AHe ages show a quite variable single grain age distribution ranging from similar to 104 to similar to 7 Ma indicating some degree of post-depositional thermal resetting. Thermal modelling of AFT and AHe data indicates that the EMB experienced a maximum temperature of similar to 90 degrees prior to Oligocene-to-Pliocene cooling. We interpret the Oligocene-Early Miocene cooling signal to represent rock uplift associated with growth of the Apennines orogenic wedge and the late Miocene-Quaternary cooling to track frontal accretion in the orogenic wedge concomitant with rollback-driven extension
Facies analysis, Ar/Ar dating and mineral chemestry: tools for studying paleogeography in a subsiding collisional belt (Ligurian Alps, Italy).
No full textThe early stages of the Alpine collision: An image derived from the upper Eocene-lower Oligocene record in the Alps-Apennines junction area
No full textThe upper Eocene-lower Oligocene sediments deposited in the eastern part of the Tertiary Piedmont Basin in northern Italy provide a complete record of the unroofing of the Alpine orogenic prism during the early stages of exhumation in the Ligurian sector. From late Priabonian till late Rupelian time, the sediments in the study area were derived from two different sources, one characterised by white micas with Si7 pfu and Eocene-Oligocene 40 Ar/ 39 Ar ages (32-50 Ma). The first source is considered to be indicative of low-pressure metamorphic rocks that covered the HP rocks of the Ligurian Alps, and were completely eroded by Chattian time. From this time on, the study area started to record the first input from western Alpine sources characterised by a larger span of ages with a more frequent Eoalpine signal. Thus, sediments deposited in the eastern part of the Tertiary Piedmont Basin contain the only available evidence of rocks belonging to high crustal levels in the Alpine orogenic prism that were not affected by the Alpine overprint. These data also provide time constraints to the poorly dated first conglomerates deposited in this area. 40 Ar/ 39 Ar geochronology reveals a minimum age of 33±1.4 Ma for the Pianfolco Conglomerates in the type locality, and of 31.4±3.5 Ma for the Borbera Conglomerates
Tectonic evolution of the Cretaceous back-arc to foreland Neuquén Basin (Argentina) through a detrital multi-proxy provenance study.
No full textProvenance of Oligocene synorogenic sediments of the Ligurian Alps (NW Italy): inferences on belt age and cooling history
No full textMiddle Eocene-Early Miocene sedimentary evolution of the Western Lombardy South Alpine foredeep (Italy).
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Unexpected thermal history of a syn-collisional basin revealed by geo- and thermochronology: the case of the Tertiary Piedmont Basin (Western Alps, Italy)
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