The relationships between the relative B-Li-Cl compositions of deep fluids and their entrapment depth were investigated by means of geochemical studies of fluid inclusions in foliation-parallel quartz veins using the crush-leach method and conventional petrology. Investigated samples were collected from the Sanbagawa metamorphic belt, SW Japan, covering the metamorphic grade from the pumpellyite-actinolite fades (300 degrees C/0.5 GPa) to the quartz-eclogite facies (550-650 degrees C/1.5-2.5 GPa). We took a special care on the relationship between arrangements of fluid inclusions and grain fabric of their host quartz to evaluate the entrapment timing of fluid inclusions. Our results show that quartz veins can be classified into three groups based on their fabrics: polygonal type (P-type), deformed-interlobate-grain type (DI-type) and pervasively-deformed-domain type (DD-type). P-type fabrics in the studied samples indicate textural development under the conditions of very low differential stress with relatively high temperature and free from subsequent brittle deformation, thus, corresponding fluid inclusions should have been trapped during the peak metamorphic stage or in the early stage of exhumation. On the other hand, fabrics of DI- and DD-type, such as largely deformed lamellae and undulatory extinction, are thought to be formed under high differential stress and low temperatures (<400 degrees C) during the later stage of exhumation. Fluid inclusions in DI-/DD-type veins are thought to be trapped in association with the later-stage deformation event and corresponding fluid infiltration. P-type veins tend to contain relatively high saline aqueous fluids (5-10 mass%(NaCleq)) and their compositions are mainly Na-Cl dominated. DI-/DD-type veins contain dilute aqueous fluid (<5 mass%(NaCleq)) and some of them are characterized by the dominance of HCO3 in anions. The relative B-Li-Cl compositions of the studied fluids are characterized by high (B + Li)/Cl ratio, which is characteristic of the Arima-type hydrothermal fluids, thought to be directly derived from the subducting-slab at the present fore-arc region of the Japanese island chain. The Li/B ratios of the studied fluids show a large variation from a low value of 0.02 in the pumpellyite-actinolite facies/DD-type sample to a high value of 1.99 in the eclogite facies/P-type sample. These results suggest that high-saline and B-Li-enriched fluids are supplied from subducting slabs to the hanging wall mantle wedge in the subduction zone. (C) 2015 Elsevier B.V. All rights reserved.