本文選題：薄層石灰?guī)r + 米蘭柯維奇旋回��； 參考：《地球科學(xué)進(jìn)展》2017年03期

【摘要】：高旋回性薄層石灰?guī)r一般沉積于斜坡和深水盆地環(huán)境中,良好地保存了有關(guān)天文旋回的信息,具有重要的研究意義。鄂爾多斯盆地西緣內(nèi)蒙桌子山地區(qū)中奧陶統(tǒng)達(dá)瑞威爾階克里摩里組下段發(fā)育韻律性極好的薄層石灰?guī)r與頁巖,是較為理想的研究層位。在詳細(xì)的野外觀察和測(cè)量的基礎(chǔ)上,結(jié)合石灰?guī)r稀土元素及其他相關(guān)微量元素測(cè)試結(jié)果,對(duì)克里摩里組下段薄層狀石灰?guī)r的垂向沉積序列進(jìn)行詳細(xì)分析,結(jié)果如下:(1)薄層石灰?guī)r由4種垂向序列(旋回束)組成,分別為向上變薄序列、向上變厚序列、雙向序列和波動(dòng)序列;(2)在剖面上可劃分出145個(gè)薄層石灰?guī)r與極薄層頁巖對(duì)、33個(gè)旋回束和7個(gè)超旋回束;(3)(La/Nd)_N值和Mn/Fe值總的變化趨勢(shì)一致,從下到上呈減小趨勢(shì),但波動(dòng)較大;(4)稀土元素總量和銪異常值曲線具有良好的鏡像關(guān)系,與(La/Nd)_N值具有耦合關(guān)系;(5)石灰?guī)r晶粒大小曲線、V/Cr和V/(V+Ni)值曲線形態(tài)相似,變化一致,總體上從下到上由小變大再變小,與(La/Nd)_N值曲線總體上具有相似性,但局部常出現(xiàn)鏡像關(guān)系。依據(jù)沉積序列的類型、在剖面上的分布及各參數(shù)在垂向上的關(guān)系,在已有研究成果基礎(chǔ)上可以得出以下結(jié)論:(1)雙向序列可能受控于等深流強(qiáng)度(米蘭柯維奇旋回),向上變薄序列與波動(dòng)序列可能受控于海平面的變化,向上變厚序列可能受控于構(gòu)造作用;(2)受米蘭柯維奇旋回控制的等深流作用貫穿整個(gè)沉積,反映的沉積時(shí)限不少于2.9 Ma;(3)垂向上沉積演化受控于次級(jí)沉積控制因素構(gòu)造作用和海平面上升,兩者在垂向上交替作用,共反映出2個(gè)構(gòu)造活躍階段。
[Abstract]:High cycle thin layer limestone is generally deposited in the environment of slopes and deep water basins, which keeps the information of astronomical cycles well, which is of great significance in research. The lower member of the Middle Ordovician Darivier Tikimori formation in the Taijiaoshan area of Inner Mongolia on the western margin of Ordos Basin is an ideal study horizon because of its excellent rhythmic development of thin layer limestone and shale. On the basis of detailed field observation and measurement, combined with the test results of rare earth elements and other related trace elements in limestone, the vertical sedimentary sequence of thin layer limestone in the lower member of the Klimoli formation is analyzed in detail. The results are as follows: (1) Thin-layer limestone consists of four vertical sequences (cyclic bundles), which are the upward thinning sequence and the upward thickening sequence, respectively. Two-way series and wave sequence; (2) 145 thin layer limestone and polar thin shale pairs, 33 cyclic beams and 7 supercyclic beams can be divided into two sections; (3) the total variation trend of (La / ND) N value and mn / Fe value is the same, and the trend is decreasing from bottom to top. (4) the curve of the total amount of rare earth elements and the abnormal value of europium has a good mirror relation, which is coupled with the value of (La / ND) N, (5) the curve of V _ (r) Cr and V / (V _ (Ni) of limestone grain size curve is similar in shape and the variation is consistent. On the whole, from small to up, it changes from small to large and then becomes smaller, which is similar to (La / ND) N value curve as a whole, but there is a mirrored relation in some places. According to the type of sedimentary sequence, the distribution on the section and the relation of parameters in vertical direction, Based on the existing research results, the following conclusions can be drawn: (1) the bidirectional sequence may be controlled by the intensity of the isothermal current (Milankovich cycle), the upward thinning sequence and the wave sequence may be controlled by the sea level change. The upward thickening sequence may be controlled by tectonic processes; (2) the isothermal current controlled by the Milankovich cycle runs through the whole deposition, (3) the vertical sedimentary evolution is controlled by the tectonic processes of secondary sedimentary control factors and sea level rise, which alternates vertically, reflecting two tectonic active stages.
【作者單位】： 昆明理工大學(xué)國土資源工程學(xué)院;
【基金】：國家自然科學(xué)基金面上項(xiàng)目“阿拉善地塊東南緣與鄂爾多斯盆地西緣中、上奧陶統(tǒng)濁流演化及其與內(nèi)波相互作用研究”(編號(hào)41272119)資助~~
【分類號(hào)】：P534.42
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本文編號(hào)：2071562