福建地质特点的新认识

NEW LIGHT ON THE CHARACTERISTICS OF THE FUKIEN GEOLOGY

"福建地质的特点和问题"一文的写成,距现在已年余.在1958年中南京大学地质系、北京地质勘探学院、长春地质勘探学院学生先后来福建进行实习,填了颇多图,得到不少成果.那一年中,各县也都成立县地地质勘察队,遍地找矿,也搜集了很多新资料.那年底,福建师范学院地理系师生参加支援南平、福安两专区钢铁生产中的找矿工作,也看到些地质现象.更主要的,省地质局的队伍扩大了工作面,找到有希望的新矿种和不少矿点.总之,那一年中,

The new light on the characteristics of the Fukien geology is based on the new materials collected in 1958. The so-called pre-Sinian series of North Fukien with the exception of the existence of the pre-Devonian etamorphism, are mostly new metamorphosed rocks, partly of the Jurassic coal series and partly of the Mesozoic volcanic series.In fact, since the Upper Paleozoic time, the metamorphic activity in Fukien has by no means been weak. The limestone of Upper Carboniferous and of the Lower Permian were affected.Within the geological formations of the Devonian to the Permian, there were ferriginous and manganese sediments. These sediments may, thru etamorphic processes or weathering, form ore deposits.Since Devonian, the geologic structure of Fukien is chiefly in the form of faulting. The existence and the form of the Caledonian movement are still not clear.The early or middle Hercynian movement is evident. Between the Upper Paleozoic and Mesozoic, there was a break in the nature of mountain-making movement. This Pfalzian movement was very strong.All movements after the Pfalzian and even thru the period of the new tectonic movement, are but post-humous movements. Since the Pfalzian movement the tectonic framework of the Fukien area is established.From Mesozoic, all continental formations as well as the eruptions of the volcanic series of the western portion of Fukien were deposited or outpoured following the trends of faultings. From now on, the trends are dominantly NNE and NE, but in some places like the Shaowu area, the trend is mainly NW. The faultings determine the lattice orientation of the river system of the province.The late Hercynian movement and the Ninchen movement (between the Upper Jurassic and the Lower Cretaceous), both very strong in North Fukien, possibly caused the sub-regional (Dynamo-thermal type) metamorphic phenomenon, although a part of it was due to stress metamorphism.The knowledge of the intrusive activities of the Archaeozoic or Proterozoic as well as the post Cretaceous is still not certain. Generally speaking, there were definite granite intrusions during the time of Hercynian and Ninchen movements. But the granite intrusions between the Lower Cretaceous and Lower Tertiary need to beproved.Skarns formed from the Upper Paleozoie limestone are widely exposed in the North Fukien area. The existence of the late Hercynian granite is relatively definite. The above mentioned facts make the discovery of the blinded ore connected with the mineral deposits of the Hypogene skarns very hopeful.It has found, of suitable grade for the multiple utilization, the paragenesis of 10 to 20 kinds of the rare metals and the dispersive elements, among the different ore minerals.From the geotectonic point of view, Southwest Fukien is a structural unit with the pre-Devonian series as the bed rock, and the Upper Paleozoic series as a single overlying stratum. These overlying strata were not very much affected by the metamorphism. Here the granite intrusions as well as the faults were not very strong. It is a rather weak 'activizing platform'.Northwest Fukien is another geotectonic unit. It has double overlying strata namely, the Upper Paleozoic and Mesozoic series. The faults were strong. The granite intrusions were extremely strong. The over-lying strata were widely metamorphosed. It is a strong 'activizing platform'. The eastern longitudinal strip of Fukien is covered by double overlying strata composed of the Upper Paleozoic and Mesozoic series. The Mesozoic eruption-sedimentary series was carried on under the sea. This reflects the fact that there was a strong down-warping during the Mesozoic time. This is a special evidence of a strong activizing area, and therefore it must be a strong 'activizing platform', also with extremely strong faults and granitic activities, but it is not indicated by the wide metamorphism.Regarding the minerogenetic zones, it is an unsettled question. Possibly such zones are located in the transitional belts or the boundaries of different geotectonic units, or geologic areas, and also commonly along the fault zones. In Fukien these boundaries and the structural breaks usually coincide with each other.The fault zones are closely related to the endogenic ore deposits, especially where the fault line cuts thru limestone of the upper Paleozoic and the sediments of other periods. It is the place where we look for ores.