Besides many granitic xenoliths of volcanic rocks， their original granitic rocks and the host volcanic rocks ranging from basalt to andesite， all found in Southwest Japan， were petrographically examined before the detailed studies of zircons in them were made． The xenoliths can be divided into 6ve groups according to the degree of rock alteration．In the granitic xenoliths ma丘c minerals are most easily decomposed to produce mainly iron-ores and brown glass． The microperthitic texture of the original potash feldspar in the greater parts of the xenoliths disapPeared and this mineral is readily resorbed after the mafic rninerals． Plagioclase and quartz are more resistant to fusion：the former is commonly clouded to various extent with minute inclusions， and the latter is usually crackled， while vitrified plagioclase is apt to show 6ne mesh works of glass along its cleavages． Feldspar optics shows that potash feldspar and plagioclase in all the xenoliths are completely or incompletely converted to the high．temperature form．The observations described above may support the conclusion that the temperature attained by the granitic xenoliths in question should be between 500°and 573°in one example and above 500°to 700°and probably below about 900° in the others． ContentgYoshifumi KムRAKIDム ToMITA． The results of my investigation show that some of character changes in the zircons under consideration may be attributed to volcanic heating， an answer to these problems having been already discussed in paper I(ToMITA and KARAKIDA， 1958)． It is the purpose of this investigation to describe the modes of occurrence of granitic xenoliths collected from some volcanic丘elds in Southwest Japan；to examine the alteration of their main constituent minerals；to estimate the temperatures attained by the xenoliths on the basis of those observations． These description and discussion would serve as a fundamental knowledge for understanding the petrologic signi丘cance of the natural change in zircon characters which will be dealt with in a series of papers now in preparation．
Wooden anchors equipped with a pair of granitic anchor stones were found and recovered form a number of submerged wrecks located in Imari Bay of Takashima, Nagasaki Prefecture. These remains are from wrecked Mongolian warships that were involved in the second Mongol invasion of 1281. All the granitic anchor stones from different anchors are alkali granite, consisting mainly of microcline-micro-perthite and quartz with trace amounts of biotite and plagioclase. The CHIME (chemical Th-U-total Pb isochron method) age determination was carried out on zircons from the recovered granitic anchor stones to try to identify the original source area for the anchor stones. The CHIME zircon ages for 3 anchor stones from different anchors are 110±1Ma, 108±3Ma and 108±2Ma. The ages together with the Sr-poor nature of the bulk chemistry suggest that the anchor stones were derived from a leucocratic alkali granite body found close to Quanzhou, southeastern China. This result implies that the wrecked warships were constructed in Quanzhou and supports the view that the Moslem traders in Quanzhou contributed significantly to the second Mongol invasion by providing ships and seamen.
Wooden anchors equipped with a pair of granitic anchor stones were found and recovered form a number of submerged wrecks located in Imari Bay of Takashima, Nagasaki Prefecture. These remains are from wrecked Mongolian warships that were involved in the second Mongol invasion of 1281. All the granitic anchor stones from different anchors are alkali granite, consisting mainly of microcline-micro-perthite and quartz with trace amounts of biotite and plagioclase. The CHIME (chemical Th-U-total Pb isochron method) age determination was carried out on zircons from the recovered granitic anchor stones to try to identify the original source area for the anchor stones. The CHIME zircon ages for 3 anchor stones from different anchors are 110±1Ma, 108±3Ma and 108±2Ma. The ages together with the Sr-poor nature of the bulk chemistry suggest that the anchor stones were derived from a leucocratic alkali granite body found close to Quanzhou, southeastern China. This result implies that the wrecked warships were constructed in Quanzhou and supports the view that the Moslem traders in Quanzhou contributed significantly to the second Mongol invasion by providing ships and seamen.
The Ryδke metamorphic terrain of the Yanai area， Southwest Japan， consists of non-metamorphosed sediment zone， biotite schist zone， and banded gneiss， zone， and the older Ryδke granodiorites and the younger Ry6ke granites． Zircon overgrowths sometimes found iII the zircon concentrates from granitized banded gneisses and granitic rocks are divided into three七ypes according to mor-・ phological forms of core and she11： 0-A， O-B， and O-C． The relations between the overgrowth type and the enclosing rock type as well as characteristic・ features of each overgrowth type we．re examined in detail． These investigations． reveal that the zircon overgrowths were originated by mixing， in a broad sense， of sediments and granitic liquids and by the subsequent contamination of granitic magma， and that characters of the overgrowth may indicate the conditions of mixing and contamination．
