Ophiolites mapping in the Taro Valley (Central Italy) by using an LWIR airborne TASI-600 survey: preliminary results on the Roccamurata complex

In the framework of the INAL/BRIC research contract #ID57 (2016) different remote sensing technologies, from proximal to remote (from airborne to satellite), and processing classification technique have been exploited to detect both manmade materials containing asbestos and natural occurring asbestos (NOA) formations.

Asbestos minerals show characteristic spectral features in the LWIR spectral regions centered at about 9.6 µm. The VNIR-SWIR spectral region was well explored by multi and hyperspectral airborne, while the LWIR spectral range, at present, is still less explored for the detection and identification of the NOA. The LWIR range should have a high potential as asbestos minerals absorption feature are far from the ones of the other minerals commonly associated with them (e.g., carbonates).

The area surveyed by the multispectral LWIR airborne TASI-600 corresponds to a peridotitic ophiolite of great thickness and extension referring to the ophiolitic complex (i.e. including Roccamurata) along the banks of the Taro river [1], [3]. The ultramafic rock outcrops occurring in the Taro Valley (Italy), belong to the External Ligurid Units of the Northern Apennines within Cretaceous-Eocene sedimentary formation [2]. These ultramafic rocks formations include natural asbestos minerals that have a high potential hazard to human health if inhaled [3].

The airborne survey has been carried out using the airborne hyperspectral TASI-600 sensor acquiring 32 spectral bands in the 8.0 - 11.5 µm spectral range with a spectral resolution of 100 nm. The airborne survey was performed on a test area NW to the Borgo Val di Taro town along the Taro Valley for about 50 km2 at an altitude of about 1000 m a.s.l.. The survey covers two quarries of massive ophiolites (almost serpentine) on which samples have been collected in view of a further spectral and chemical analysis.

This communication will present the preliminary results of multispectral LWIR TASI survey performed on the Roccamurata study area in terms of: (i) radiometric and geometric correction; (ii) LST, by using a split window technique, and emissivity calculation by using a TES algorithm (iii) a preliminary result of the serpentine mapping compared with the available 2016 geological map (http://www.isprambiente.gov.it/Media/carg/note_illustrative/216_Borgo_Val_di_Taro.pdf).

• [1] Boschetti, T., & Toscani, L. (2008). Springs and streams of the Taro–Ceno Valleys (Northern Apennine, Italy): reaction path modeling of waters interacting with serpentinized ultramafic rocks. Chemical Geology, 257(1-2), 76-91.
• [2] Marroni, M., Molli, G., Montanini, A., Ottria, G., Pandolfi, L., & Tribuzio, R. (2002). The external Ligurian units (Northern Apennine, Italy); from rifting to convergence of a fossil ocean-continent transition zone. Ofioliti, 27(2), 119-131.
• [3] Gaggero, L., Crispini, L., Isola, E., & Marescotti, P. (2013). Asbestos in natural and anthropic ophiolitic environments: a case study of geohazards related to the Northern Apennine ophiolites (Eastern Liguria, Italy). Ofioliti, 38(1), 29-40.
• [4] Beghè, D., Dall’Asta, L., Garavelli, C., Pastorelli, A. A., Muscarella, M., Saccani, G., ... & Chetta, A. (2017). Sarcoidosis in an Italian province. Prevalence and environmental risk factors.PloS one,12(5), e0176859.