The black unit including a biotic extinction was caused by oceanic anoxic event. Crisis that deepwater keeled foraminifera encountered represents a ferocious anoxia in deep marine environment .
黑层段是大洋缺氧造成的结果，生物大量灭绝，深层水具旋脊有孔虫的所遭受的危机反映出当时海洋深层水体严重缺氧的特征；
The black unit including a biotic extinction was caused by oceanic anoxic event. Crisis that deepwater keeled foraminifera encountered represents a ferocious anoxia in deep marine environment .
黑层段是大洋缺氧造成的结果，生物大量灭绝，深层水具旋脊有孔虫的所遭受的危机反映出当时海洋深层水体严重缺氧的特征；
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