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王成源 (Wang,2 0 0 0 )和金玉 (Jin,2 0 0 0 )提出了关于乐平统底界定义的不同论点。为了对此进行独立的验证 ,卡尔加里大学微体古生物实验室对采自华南广西来宾地区瓜达鲁普统 -乐平统界线地层的牙形类化石大块样品进行了处理。结果如下 :1.Jinogondolella和 Clarkina在样品中没有共生 ;2 .由 Jinogondolella granti演化为Clarkina postbitteri 的变化发生在层 115 - 6 i;3.C.postbitteri 的首次出现层位 (FAD)在蓬莱滩剖面位于层 115 - 6 i上部 ;4.这个变化标志着一个显著的生物信号和一个重要的点断演化事件。Jinogondolella granti演化为 Clarkinapostbitteri的事件很可能是受瓜达鲁普统与乐平统之交的海平面降至最低水位所触发和控制。层 115 - 6 i下部为较浅水相颗粒灰岩 ,代表瓜达鲁普统末期层序高位域之顶或上覆层序低位域之底部。作为 Clarkina属的第一个代表 ,Clarkina postbitteri是界线地层中最易识别的种之一 ,而 Clarkina postbitteri带的识别较容易和稳定一致。Clarkinapostbitteri和 Clarkina dukouensis可以通过基于锯齿型式 ,居群和个体发育的分类体系来加以稳定地区分。Clarki-na p ostbitteri和 Clarkina dukouensis之间的过渡是渐变的 ,其间的分界点只能人为地确定。如果采用这
Wang Chengyuan (Wang, 2000) and Jin Yujiao (Jin, 2000) put forward different opinions on the definition of the Leping floor. To independently validate this, large samples of tetrochemical fossils collected from the strata of the Guadalupe-Leping Line in the Laibin area of southern Guangxi are processed at the University of Calgary’s Microplankton Laboratory. The results are as follows: 1.Jinogondolella and Clarkina have no symbiosis in the sample; 2.The evolution from Jinogondolella granti to Clarkina postbitteri occurs at layer 115-6 i; 3. The first occurrence horizon (FAD) of C.postbitteri is at Penglaite section Located on top of layers 115-6 i; 4. This change marks a significant biological signal and an important point-break evolution event. The evolution of Jinogondolella granti into Clarkinapostbitteri is most likely triggered and controlled by the sea level drop to a minimum at Guadalupe and Lepong. The lower part of the layers 115 - 6 i is a shallower water-phase grain limestone, representing the bottom of the top or overlying low sequence of the uppermost sequence of Guadalupe. As the first representative of the genus Clarkina, Clarkina postbitteri is one of the most recognizable species in the boundary stratigraphy, while the Clarkina postbitteri band is easier and more consistent in its identification. Clarkinapostbitteri and Clarkina dukouensis can be stably distinguished by a classification system based on sawtooth type, population and individual development. The transition between Clarki-na p ostbitteri and Clarkina dukouensis is gradual, and the demarcation point between them can only be determined artificially. If you adopt this