## 2 Samples and Methods  
For this study, we selected 3 rock samples from the Telica volcano in Nicaragua (TEL02, TEL04B and TEL04K) and 3 samples from the Baru volcano in Panama (BAM, LCI, LCS) (Figure 1). The most mafic samples were selected, considering that Ol and Px are the most suitable for the study of noble gases (He, Ne, Ar) in FI. Rocks from Telica were taken from a suite of samples already studied by [72] for their petrography and mineral-rock composition. These samples belong to the 1982 eruption (TEL02) and to scoria fragments taken from the Scoria Telica Superior (STS) deposit on the west and south-west flanks of Telica (TEL04B, TEL04K). The 3 February 1982, eruption (VEI = 2) produced bombs that can be found at 500-1000 m distance from the NE crater rim [73; 74], and contain a mineral assemblage of Px > Ol, with dominant plagioclase and accessory magnetite [72]. The STS has a minimum age at 2150 \(\pm\) 150 yrs B.P. [74]. The STS samples are classified by [72], based on their stratigraphic positions. Samples TEL04B, TEL04K are dark to grey in colour, and are made up of small to medium size lapilli with minor fine ash. The fragments are highly vesicular with mineral assemblage similar to the February 1982 eruption [75]. TEL04B has large yellow Ol (>4-12 mm). It also contains larger Px [72]. Rocks from the Baru volcano were collected during field work in 2016. The analysed samples refer to some episode of the Pleistocene-to-Holocene effusive activity, and were chosen according to stratigraphic description and the petro-geochemistry of the lavas [12; 13]. The sample from La Cuesta Inferior (LCI) represents a basaltic andesite lava flow at the base of the La Cuesta unit, with an age of 0.213 Ma [13]. The flow is compact with grey colour groundmass, and porphyric fabric with some aggregates that contain less than 5-10% Ol of 1-4 mm diameter. Prismatic Px is found in similar proportions (5-8%). The sample from La Cuesta Superior (LCS) represents a basaltic andesite lava flow with columnar joints, for which previous studies establish an age of 0.122 Ma [13]. The sampling site is located on the eastern flank of the volcano, close to the Bajo Mono North exit (Lat. N 8 deg48'15.30''/Long. W 82 deg27''10.10'') and at an altitude of 1287 m. The LCS is the Upper layer of La Cuesta Unit, a voluminous, 13 m thick lava flow unit that outcrops along the \"Rio Caldera\" river in the Bajo Mono area. It exhibits columnar joints of 55 cm diameter, a compact aspect, a grey colour groundmass, and porphyic fabric with some aggregates that generally contain more Ol than LCI (10-12%). The Px crystals (5%) have euhedral prismatic shapes with a long axis of 5 mm. The Bambito unit (BAM) represents an andesite lava unit found NW of Baru, and has an approximate age of 0.122 to 0.011 Ma [13]. The sampling site is found between the Nuevo Bambito and Volcan villages, west of Cerro Aguacate, on road 418 along the Rio Chiriqui Viejo (Lat. N 8 deg49'46.98''/Long. W 82 deg36'53.36''). The rock was sampled at 1743 m altitude, and was taken from a slightly weathered massive outcrop. It contains very few ferromagnetism minerals, such as a 4-6% euhedral prismatic Px with a green-turquoise colour (no Ol was observed on thin sections). Major and trace element bulk-rock analyses of the Baru samples were performed at the Activation Laboratories (Ancaster, Canada) following preparation techniques and analytical procedures already described by [38; 46; 72; 76; 77]. Data are reported in Table S1. Rock fragments containing phenocrystals were prepared on Crystal Bond(tm) resin, then polished over one side for glass rim or distinct glass fragments. Ol and Px, separated by hand picking, were all prepared on different mounts after using abrasives and polishing down to 6-, 3-, and 1-um diamond powder fractions. Mineral chemistry was determined in the HPHT (high-pressure/high temperature) laboratory of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome, by using a JXA-8200 electron microprobe (EMPA).