塔里木盆地西克尔地区中奥陶统鹰山组生物礁沉积特征

Sedimentary Characteristics of Yingshan Reefs of Middle Ordovician in Xike'er Area, Tarim Basin

在塔里木盆地中奥陶统鹰山组上段中发现生物礁(丘),造礁生物主要为Calathium,其次为钙藻、苔藓虫、海绵等。生物礁发育于开阔台地内隆起部位,属于台内点礁,形成于海退的大背景下,但未见暴露痕迹。礁体无礁前、礁后和礁翼之分,但自下而上可划分出礁基、礁核和礁盖3个亚相,礁基以棘屑灰岩为主,礁核以Calathium障积岩、藻-托盘粘结障积岩、缝洞及沟道充填物为主,礁盖以亮晶砂屑灰岩为主。生物礁演化经历了5个阶段,发育2个生态群落。

The reefs （bioherm） or baffle reefs were discovered in upper Yingshan formation of the Middle Ordovician. The reef-building organism composes of Calathium, calcium algae, bryozoan, sponge, etc., dominated by Calathium. The reefs occur on the uplift of open platform, and were formed in regressive background without exposure signs and the division of reef front, reef behind and reef flank, but can be divided into reef base, reef core and reef cover. Reef base is dominated by echinoderm grainstone; reef core by Calathium bafflestone, algae-Calathium bafflestone, fractures, hole-groove filled substance, and reef cover by sparite ealearenite. The reefs undergo five stages of evolutions and develop two ecological communities.