Subject	Earth and Planetary Sciences
Specific subject area	Geology, mineralogy, petrography
Type of data	Tables, images, graphics
How data were acquired	Optical polarizing microscope: Nikon Optiphot2-Pol, equipped with AxioScope Digital Camera. Environmental Scanning Electron Microscopes (ESEM): FEI Quanta 200 FEG, equipped with an energy-dispersive X-ray spectrometer (EDS) for microchemical analyses. Electron Micro Probe (EMP): four wavelength dispersion spectrometers Cameca SX50 and Camebax Microbeam 799.
Data format	Raw, analyzed
Parameters for data collection	About 300 samples of igneous rock clasts were collected in the field, fifty-nine of which (very fresh samples) were selected and analysed. Representative polished thin sections were mounted in aluminum stub for ESEM observations and analysis; operating conditions were a 30 kV accelerating potential, 2–15 nA beam current, 10 mm working distance, 0˚ tilt angle, variable beam diameter, low vacuum mode, with a specimen chamber pressure set from 0.80 to 0.90 mbar. The same polished thin sections were metallized for EMP analysis performed with an electronic beam diameter of 5–7 µm, an acceleration voltage of 15 kV and a beam current of 10 nA. The electron beam was defocused, with a shortened accumulation time (from 100 s down to 50 s) to minimizes volatile migration and loss. The standards used were natural minerals and synthetic phases.
Description of data collection	Modal mineralogy and petrography were identified in thin section using an optical polarizing microscope. Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS) was used to verify the semi-quantitative elemental composition of mineral phases and glass. Chemical composition of selected mineral phases and glass was finally determined using wavelength dispersive spectroscopy on EMP.
Data source location	Val d'Aveto, 44° 36′ 51″ N, 9° 23′ 57″ E Petrignacola, 44° 30′ 32″ N, 10° 07′ 04″ E Campastrino, 44° 22′ 47″ N, 10° 17′ 37″ E
Data accessibility	With the article
Related Research Article	M. Mattioli, M. Lustrino, S. Ronca, G. Bianchini, Alpine subduction imprint in Apennine volcaniclastic rocks. Geochemical-petrographic constraints and geodynamic implications from Early Oligocene Aveto-Petrignacola Formation (N Italy), Lithos 134–135 (2012) 201–220 [4]. doi:10.1016/j.lithos.2011.12.017