The geology of the northern Niigata area, northern Honshu, Japan, provides a template of the petroleum system including Miocene source rock and Pliocene －Pleistocene turbidite sandstone reservoirs that resulted in number of commercial fields in this particular area. In contrast, the Yamagata area to the north of northern Niigata is characterized by uplifted and dissected blocks of basement rocks and Miocene sedimentary covers, which permits easier access to lateral changes of Miocene lithofacies. Recent investigation on biosiliceous shale in these areas seems to be raising new ideas on source rock generation in the Miocene back-arc setting. Our intention includes tight reservoir exploration, a growing concept in this country, in the Miocene biosiliceous shale formations like in the Monterey Formation of the US Pacific coast. As pursuit of new ideas like this has to be inherited by young generation of petroleum geologists/engineers, promoting collaborative activities between the industries and educational sectors should be the most helpful foothold for our future to come.

On January 1^st, 2019, The city of Niigata marks the 150^th anniversary of the opening of Niigata port.

Throughout the history of Niigata, Niigata port has a crucial role to create the unique history and culture. In prehistoric time, Niigata port presumed already existed, even if water traffic was primitive era. “Kanbara-no-tsu” is the first set up port described at Engi-Shiki in 972 A.D. Then, “Nuttari-minato” port and “Niigata-no-tsu” port appeared from the 14th to the 16th century. As described three ports were located at the mouths of the Shinano river and the Agano river, these two rivers have the largest watershed area in Japan. In early modern ages, Niigata port became prosperous as a port of Kitamaebune cargo ships entrance and departure. In the period of Isolation, the end of the Edo era，foreign countries selected led to be forced to opening of Niigata port, however, due to the civil war, it opened later than the other ports.

After the Meiji era, Niigata thrived as a modern port and also as a gateway to the continent, but towards the end of WWII, the port lost all ability to function due to a naval mine blockade in the surrounding waters. After the war, the port regained its position as one of the Japanese most important ports. Today, many cultural assets from Port City Niigataʼs history remain including the traditional Ryoutei restaurants and Geisha culture that blossomed to welcome guests when Niigata flourished as a trading hub, former residences of wealthy merchants from that same period, and cultural assets related to praying for ship safety. Port City Niigata will continue to utilize these cultural legacies to better our city.

Chemical and isotopic compositions of formation waters from oil and gas fields in Niigata Prefecture, Japan, were examined to demonstrate their geochemical characteristics and stratigraphic change for each formation.

They have the following geochemical characteristics.

1） The formation waters are mainly composed of Na^＋ and Cl^－ ions.

2） Although they were originated from seawater （Kato and Kajiwara, 1986）, their SO₄^2－ and Mg^2＋ contents have decreased rapidly and their NH₄^＋, I^－ and HCO₃^－ contents which are derived from organic matter have

increased roughly in this order during burial diagenesis.

3） They have a relative narrow range of δD values between －15 and －3 ‰ and large variations of δ¹⁸O values from －4.8 to ＋1.6 ‰, similar to formation waters from oil and gas fields in Akita, Japan.

Their Cl^－ contents reach the maximum in the upper part of the Nishiyama Formation which is due to formation of authigenic minerals such as clay mineral and zeolite from volcanic glass, and decrease toward the underlying Shiiya and Teradomari formations. This decrease of Cl^－ content may be caused by release of waters from transformation of clay minerals and maturation of organic matter during burial of sediments.

Four geologists （Dr. Nakajima, Mr. Sagawa, Dr. Otsuka and Dr. Iki）, who were with Geological Survey of Japan at the middle to late Meiji era and had surveyed oil fields geologically, and a part of their contribution to petroleum exploration in Japan are presented in this paper.