塔里木盆地塔中32井中上奥陶统内潮汐沉积

塔里木盆地塔中32井的中、上奥陶统钻遇厚度为1 462 m。它是一套巨厚的深灰色泥岩、页岩与灰色砂岩、粉砂岩互层夹少量灰岩的地层。其中深灰色泥岩、页岩最多；砂岩和粉砂岩主要分布于上部和下部，中部砂岩和粉砂岩较少；鲕粒灰岩数量少，主要夹于深灰色泥页岩中。这些砂岩和鲕粒灰岩既可单独成层，但更常见它们与深灰色泥页岩组合成薄互层。薄互层中发育脉状、波状和透镜状层理，并普遍发育交错层理和双向交错纹理。这些特征表明砂岩和鲕粒灰岩为深水斜坡上的内潮汐沉积的产物。这些内潮汐沉积进一步划分为4种类型：双向交错纹理细砂岩型、单向交错层和双向交错纹理中-细砂岩型、韵律性砂泥岩薄互层型和鲕粒灰岩型。它们具有5种垂向沉积层序，在剖面上常形成多旋回韵律性沉积组合。

INTERNAL-TIDE DEPOSITS OF THE MIDDLE AND UPPER ORDOVICIAN IN WELL TZ 32, TARIM BASIN

Based on a comprehensive study of cores and various data, the authors considered that the sandstones and oolitic limestones in the Middle and Upper Ordovician of Well TZ32 in the Tarim Basin were mainly origin of internal-tide deposits. The thickness of Middle and Upper Ordovician drilled in Well TZ32 is 1 462 m and is mainly composed of alternating beds of dark-gray mudstones and/or shales and gray sandstones and/or siltstones interbedded with minor limestones, in which the dark-gray mudstones and/or shales are the most. Sandstones and siltstones are mainly concentrated in the upper and lower parts. Oolitic limestones are rare and interbedded in the dark-gray mudstones and/or shales. These sandstones and oolitic limestones can form beds alone, but more commonly, form thin alternate beds with dark-gray mudstones and/or shales in which flaser, wavy and lenticular bedding are well-developed, and cross bedding and bi-directional cross laminations are also well-developed. According to the sedimentary background and the characteristics of lithology and sedimentary structure combination, these sandstones and oolitic limestones are explained as the products of internal-tide deposits on deep water slope. These internal-tide deposits can-be classified into four basic types according to their features, i.e. , bi-directional cross-laminated fine-grained sandstone, unidirectional cross-bedded and bidirectional cross-laminated medium-grained to fine-grained sandstone, rhythmic thin alternating beds of sandstone and mudstone, and oolitic limestone. These internal-tide deposits possessed five types of vertical successions and formed rhythmic deposit combinations with cyclicity in the vertical section.