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台地相剖面不同时期海平面早期上升相对快慢的评估方法
A Method Evaluating the Relative Rate of Early-stage Rise in Cycles of Sea-level Changesat a Platform Section Based on the Stratum Thickness
【摘要】 理论推导结果表明 ,在无剥蚀且沉积速率 (VS)和压缩比 (C)不变的条件下 ,碳酸盐台地相剖面点处三极相对海平面早期上升速度 (VR1 )与三级沉积层序厚度 (Sd)、海侵体系域及陆架边缘体系域厚度 (Td +Md)和老空间增量 (Δko)之间 ,具有近似关系式 :VR1 ≈CVSSd +ΔkoTd +Md.据此 ,可应用剖面层序地层比值R( =Sd +ΔkoTd +Md) ,来定量化评估台地相剖面中无剥蚀、无凝缩段若干三级沉积层序所代表的不同时期相对海平面早期上升的相对快慢 ;当某个或某些沉积层序的R值相对于其它沉积层序的R值较大时 ,则表明这个或这些沉积层序形成时期的相对海平面早期上升相对较快 ,反之亦然 ;R值相差越大则评估结论越可靠
【Abstract】 If the sedimentary rate (VS) and compressive ratio (C) are constant without erosive actions in the sedimentary process, it can be deduced that there is an approximate relation represented by VR1≈CVSSd+ΔkoTd+Md, in which VR1 is the rise rate of the early stage in the 3rdgrade cycle of relative sealevel changes; Sd the thickness of the 3rdgrade depositional sequence at a platform section;Td and Md respectively the thickness of transgression systems tract and shelfmargin systems tract in the sequence; and Δko the increment of old space. Based on the deductive results, we can make use of the value of ratio R(=Sd+ΔkoTd+Md) to evaluate the relative rate of earlystage rise in the different 3rdgrade cycles of relative sealevel changes. The R values of different sequences in a platform section without concentrative deposition and erosive evidence might respectively represent the different rates of earlystage rise in different cycles. And the bigger the R value is, the faster the rise rate may be.
【Key words】 carbonate platform; sequence stratigraphy; sea_level changes; rise rate; evaluating method;
- 【文献出处】 南京大学学报(自然科学版) ,Journal of Nanjing University (Natural Sciences) , 编辑部邮箱 ,2004年06期
- 【分类号】P731
- 【被引频次】1
- 【下载频次】85