中文摘要:根据物质组分、盐矿物种类、剖面结构和厚度将含盐系划分为Ⅰ、Ⅱ、Ⅲ级韵律，分别描述了各级韵律的剖面特征，也讨论了其形成机理。本文着重将Ⅲ级韵律分为钠镁盐一钾镁盐型、杂卤石一钠镁盐型、钙芒硝一杂卤石型、石盐一钙芒硝型、硬石膏一石盐型和硬石膏型，并按上述各型在剖面中的不同组合从下向上划分为Ⅱ1一Ⅱ44个韵律，归纳了Ⅱ级韵律中剖面结构类型所指示的卤水演化的共同特征和沉积阶段，正是这种沉积阶段性，既滞留了卤水浓缩期的K+，也聚积了淡化期补给的K+，为钾矿层的形成提供了K+来源。本文还指出，赋存钾矿层的I级韵律的盐亚段上部，应是我国东部中、新生代类似凹陷中找钾目的层段。
Abstract:Dawenkou depression is situated at the west end of Wenmeng faulted basin in the middIe of Luxi uplift, where large amounts of anhydrite, gypsum, halite, polyhalite and langbeinite are found in the upper part of 2nd-member of Eocene-Oligocene Wenkou Formation. The rhythm is well developed within the Dawenkou salt deposit, and can be divided into three orders according to mineral composition, mineral types and thickness of the salt section. Order-Ⅰis composed of upper and lower potions of argiliaceous Iimestone and the anhydrite-halite sequence in the middle which can be further divided into three parts, i. e., anhydrite above the halite, halite and anhydrite below the halite. The thickness of Order-Ⅰcall reach 500m, and its development is thought to be mainly controlled by the evolution of the basin and the activities of the contemporaneous faults. The rhythms of Order-Ⅲ occur within the anhydrite-halite sequence, formed by alternate halite layers and desalinated layers, with the halite layers varying from 0.1m to 18.6m and the desalinated layers from 0.34m to 48m in thickness. According to the assemblages, quantities and types of minerals, especially minerals with high solubility, the rhythms of Order-Ⅲcan be classified into six types: (1)sodium-magnesium salt-potassium-magnesium salt type; (2) polyhalite-sodium-magnesium salt type; (3)glauberite-polyhalite type; (4) hatite-glauberite type; (5)anhydrite-halite type and (6)anhydrite type. Of them, the sodium-magnesium salt-potassium magnesium salt type is most highly concentrated; in the section, sodium-magnesium salt, halite, glauberite, anhydrite, argillaceous limestone are symmetrically distributed with the potassium-magnesium salt at the center. Each rhythm of Order-Ⅲranges from several to ten or even teens of meters. The density of the rhythms of Order-Ⅲdiffers from place to place, even within a short distance, suggesting that the formation of these rhythms was affected by the local depositional conditions. The rhythms of Order-Ⅱis formed by the regular distribution rhythms of order-Ⅲwith different textural types in the salt section. For example, four kinds of rhythms of Order-Ⅱcan be observed in drill hole ZK8: Rhythm-Ⅱ1 lies at the bottom of the anhydrite-halite sequence, and is composed of anhydrite-halite type, halite-glauberite type and glauberite-polyhalite type; Rhythm-Ⅱ2 lies over Rhythm-Ⅱ1, and is made up of halite-gtauberite type, glauberite-polyhalite type, and polyhalite-sodium-magnesium salt type; Rhythm-Ⅱ3 overlies Rhythm-Ⅱ2, and consists of glauberite-polyhalite type, halite-glauberite type, polyhalite-sodium-magnesium salt type, and sodium-magnesium salt-potassium-magnesium salt type. Rhythm-Ⅱ4 occurs in the upper part of the anhydrite-halite sequence and comprises merely polyhalite-sodium magnesium type. It can be concluded that the rhythm of Order-Ⅱ represents a change from desalination through concentration to another cycle of desalination，indicating peculiar deposition stages in the brine evolution, which are also discussed in this paper. The textural types, spatial distribution and evolution stages of variant rhythms in the salt section alll indicate that the potassium ore bed composed mainly of langbeinite results from the cyclic change from desalination to concentration．It is just this cyclic process that retains potassium in the brine and accumulates the potassium supplied during the desalination. This results in the formation of the potassium ore bed in the upper part of the rhythms of Order-Ⅰ.It is also considered that many Meso—Cenozoic salt deposits similar to Rhythm-Ⅱ3 in geological setting and depositional conditions in Eastern China might provide suitable potassium resources.
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引用文本：
朱忠德.1988.山东大汶口盐矿盐类沉积的韵律特征和沉积阶段[J].矿床地质,7(1):87~96.1988.Rhythm characteristics and depositional stages of salts in Dawenkou depression 0f Shandong province[J].Mineral Deposits7(1):87~96
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