Abstract Devastating earthquakes and tsunamis capable of causing catastrophic damage to human societies and economies have frequently occurred on and around the Japanese islands. Because Japan is a long and narrow island arc in the Pacific Ocean located at the junction of four plates (the Eurasian and Philippine Sea Plates in the SW and the North America and Pacific Plates in the NE), it has probably suffered the highest number of earthquake and tsunami events anywhere in the world. Hence, geological and geoinformation investigations are supremely important, not only for understanding the geological development of Japan but also for forecasting the risks associated with geohazards and securing the safety of human lives and infrastructures. For these reasons, the Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (GSJ-AIST) has been conducting marine geological surveys since 1974 and, as of the end of 2019, produced a Marine Geology Map Series consisting of 90 geological maps. In addition, a coastal zone research project that aims to connect marine, coastal and land area geoinformation seamlessly was launched in 2008 to survey areas that have not yet been investigated, and six maps of geologically distinct areas have already been published based on that collected data.

Abstract The bonanza-grade, low-sulfidation epithermal Hishikari gold deposit is located in the Plio-Pleistocene volcanic area of southern Kyushu, Japan. The concealed veins were discovered in 1981 and the mine has since produced 5.462 million metric tons (Mt) of ore averaging 44.3 g/t Au (242 t Au) from 1985 to the end of 2018, at which time reserves were 7.98 Mt at 20.9 g/t Au. The Hishikari deposit consists of the Honko, Sanjin, and Yamada ore zones, which occur in a NE-trending area 2.8 km long and 1.0 km wide. The veins are hosted by basement sedimentary rocks of the Cretaceous Shimanto Supergroup and by overlying Hishikari Lower Andesites of Pleistocene age. Sinter occurs about 100 m above the Yamada ore zone. Temperature-controlled hydrothermal alteration zones occupy an area of >5 km long and 2 km wide. The Honko and Sanjin veins occur within a chlorite-illite alteration zone (paleotemperature >230°C), whereas the Yamada veins occur within an interstratified clay mineral zone (150°–230°C). The marginal alteration comprises quartz-smectite (100°–150°C) and cristobalite-smectite (<100°C) zones. Ore-grade veins are located between –60- and 120-m elev, with the paleowater table over the Honko-Sanjim veins at ~300-m elev. Overall, the Ag/Au wt ratio is about 0.6. Vein-forming minerals consist of quartz, adularia, and clay minerals plus truscottite, with electrum and minor pyrite, chalcopyrite, naumannite, galena, and sphalerite. The major veins formed from repeated episodes of boiling and strong fluid flow inferred from bands of quartz, adularia, and smectite with bladed quartz, columnar adularia, and truscottite.