Abstract:
Recently，a new locality of the Cambrian Balang Fauna was discovered in Lazhizhai village，Jianhe，Guizhou，Southwest China．The Balang Lagerst?tte of the new locality contains abundant fossil material．Based on measured geological section and fossils collected in the field，two fossil enrichment beds were discovered in Lazhizhai section of the Balang Formation， which were named as the Lower Fossil Bed and the Upper Fossil Bed respectively．According to the two fossil beds’sedimentary petrology characteristics， fossil assemblages，fossil abundance and fossil taphonomic characters and so on，there are some differences for fossil assemblage and burial characteristics of the two beds．For the Lower Fossil Bed，a diversified fossil assemblage and well-preserved fossils mainly occur in the sedimentary event layer，which are represented by trilobites， Naraoia，Isoxys， Tuzoia of arth- ropods，palaeoscolecidan Wronascolex，echinoderm Guizhoueocrinus and sponges，especially， non-mineralized fossil individuals with soft body．These characters suggest that the living animals have been buried in situ by the rapid deposition of lithic fragments in an outer shelf environment．It indicates that these organisms were preserved by the model of autochthonous burial to form fossil assemblages．For the Upper Fossil Bed，the fossil assemblage mainly consisted of trilobites and fragments of their cephalic and thoracic segments， and a small exoskeleton of Naraoia and valves of Isoxys，their complete individuals little， only fragmented left valves or just fragments and few fossil numbers． Fossils mainly preserved in background layer by environment of static water sedimentation，a lot of organisms were accum- ulated in the matrix and organism bodies pre-burial underwent exposure for a long time on the sea bed， and then，sedimentary lithic fragments continually accumulated and compressed to form fossil enrichment bed， in which shell bodies are preserved by model of near autochthonous burial to form fossil assemblages．
