摘要
哈拉阿拉特组是西准噶尔地区重要的石炭纪海相地层,岩性组合二分性明显:灰绿色为主的火山岩、火山碎屑岩夹灰岩透镜体与灰黑色为主的正常碎屑岩、火山碎屑岩夹少量生物碎屑灰岩。长期以来均认为前者在上,后者在下。根据该组层型剖面中的地层产状、层劈关系、冲刷构造和粒序层理,认为该剖面并未发生倒转,应是火山岩、火山碎屑岩夹灰岩透镜体在下,正常碎屑岩、火山碎屑岩夹生物碎屑灰岩整合覆在其上。根据`哈拉阿拉特组内所发现的化石材料,认为该组是西准噶尔地区一跨早—晚石炭世的岩石地层单位,下石炭统-上石炭统的界线位于该组下段上部。在克拉玛依西北部达尔布特蛇绿混杂岩带与达尔布特断裂之间新识别出的哈拉阿拉特组地层,其中含有早石炭世晚期至晚石炭世的化石,前人用这些材料来确定包古图组和太勒古拉组的时代是错误的,目前包古图组和太勒古拉组尚无可延续到晚石炭世的古生物依据。
The Hala＇alate Formation is a marine Carboniferous unit in the western Junggar Basin. It con- sists of two lithological associations：1） gray-green volcanic rocks and pyroclastic rocks, intercalated with limestone lenses, 2） gray-black clastic rocks, pyroclastic rocks and several intervals of bioclastic lime- stones. Many researchers considered that the volcanic association overlies the clastic association. Our in- vestigation of the stratotype section shows that the Hala＇alate Formationfor is not an overturned sequence, and this conclusion is based on stratigraphic observations, the relationship between bedding and cleavage, and sedimentary features such as scouring structures and graded bedding. Thus the clastic rocks with pyro- clastic rocks and a few bioclastic limestones overlie conformably the volcanic rocks with pyroclastic rocks and limestone lenses. The Hala＇alate Formation occurs between the Daerbute ophiolitic mélange belt and the Daerbute Fault in northwestern Karamay, and it contains late Early to early Late Carboniferous fos- sils. These fossils were mistakenly used to determine the age of the Baogutu and Tailegula formations. As far as we know, there is no paleontological evidence supporting a Late Carboniferous age for the Baogutu and Tailegula formations. To conclude, the Hala＇alate Formation is an Early-Late Carboniferous lithos- tratigraphic unit in the western Junggar Basin, and the Lower-Upper Carboniferous boundary lies in the upper part of the lower Hala＇alate Formation.
出处
《地层学杂志》
CSCD
北大核心
2014年第3期290-298,共9页
Journal of Stratigraphy
基金
新疆1/25万<铁厂沟镇幅>(L45C002001)和<克拉玛依市幅>(L45C003001)区调修测(1212011120502)
西准噶尔克拉玛依后山地区深部地质调查试点项目(1212011220245)
国家自然科学基金(No.41290260
41072252)
高等学校博士学科点专项科研基金项目(20120145110012)联合资助
关键词
岩石地层
生物地层
地层层序
哈拉阿拉特组
石炭系
西准噶尔
新疆
lithostratigraphy
biostratigraphy
stratigraphic sequence
Hala＇alate Formation
Carboniferous
western Junggar
Xinjiang
