Based on detailed measurement in the field and a comprehensive analysis of carbonate microfacies,the Pennsylvanian reefal microfacies characteristic and sedimentary environment from Longjiangdong,Guangxi,China are ana...Based on detailed measurement in the field and a comprehensive analysis of carbonate microfacies,the Pennsylvanian reefal microfacies characteristic and sedimentary environment from Longjiangdong,Guangxi,China are analyzed. The twelve carbonate microfacies have been recognized including micritic / microsparitic limestone,peloidal / aggregate-grain grainstone,bioclastic wackestone / packstone,laminated mudstone,boundstone,bioclastic wackestone / packstone with single shell,coral framestone / bafflestone,bioclastic packstones /grainstones with abundant benthic foraminifera or crinoids,wackestone / mudstone with calcispheres,bioclastic packstone / grainstone,unname reef-building organism framestone and brachiopod grainstone. In addition,four facies have been identified including open platform facies,restricted platform facies,coral reefal facies and shoal facies. According to analysis of microfacies combination and facies evolution,three stages and three reef units during the reef formation process have been noted. The evolution of each stage indicates a repeating fluctuation of the sea-level,but the water energy is still relatively low overall,which represents frequent changes of paleoclimate in the early Late Carboniferous.展开更多
Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism ...Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism in harbor and bays. Car- bonates of the Paleogene Kalatar Formation in southwest Tarim Basin yield abundant serpulid fossils, which, together with oyster fossils, constitute the characteristic fossil assemblage of the Kalatar Formation. Other common fossils include bivalves, gastropods, ostracods, echinoderms, and bryozoans. Lithologies that yielded serpulid fossils are characterized by micritic bio- clastic limestone, sandy limestone, and shelly limestone, indicating a semi-restricted to open shallow marine environment with medium to low water energy. The research data about serpulids and their fossil materials from China are relatively rare. Based on the studies of tbssils taxonomy, community palaeoecology, and fossil taphonomy, this paper analyzed and studied the types, occurrence, distribution, and morphological characteristics of serpulids and their palaeoecological features in the Kalatar For- mation. Two serpulid community compositions were recognized in the Kalatar Formation, including a rock-forming Ditrupa community and a cluster-growth Propomatoceros community. The Ditrupa community was distributed in coastal environment of the west Kunlun piedmont, lived on sandy hard substrates with little mud, and rarely occurred in lagoon and tidal settings. The Propomatoceros community occurred in offshore middle carbonate ramp in the piedmont of the south Tianshan Moun- tains and in offshore shelf in the piedmont of the west Kunlun Mountains. According to the analysis on the host-rock litholo- gies, preservation and symbionts, it is inferred that serpulids in the Kalatar Formation grew on the oyster shell or other hard substrate, and they did not form reefs or bioherms.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20120042110027,20110042120043)the National Natural Science Foundation of China(No.41202018)
文摘Based on detailed measurement in the field and a comprehensive analysis of carbonate microfacies,the Pennsylvanian reefal microfacies characteristic and sedimentary environment from Longjiangdong,Guangxi,China are analyzed. The twelve carbonate microfacies have been recognized including micritic / microsparitic limestone,peloidal / aggregate-grain grainstone,bioclastic wackestone / packstone,laminated mudstone,boundstone,bioclastic wackestone / packstone with single shell,coral framestone / bafflestone,bioclastic packstones /grainstones with abundant benthic foraminifera or crinoids,wackestone / mudstone with calcispheres,bioclastic packstone / grainstone,unname reef-building organism framestone and brachiopod grainstone. In addition,four facies have been identified including open platform facies,restricted platform facies,coral reefal facies and shoal facies. According to analysis of microfacies combination and facies evolution,three stages and three reef units during the reef formation process have been noted. The evolution of each stage indicates a repeating fluctuation of the sea-level,but the water energy is still relatively low overall,which represents frequent changes of paleoclimate in the early Late Carboniferous.
基金supported by National Natural Science Foundation of China(Grant Nos. 40872078,40976030)Knowledge Innovation Program of South China Sea Institute of Oceanology (Grant No. LYQY200806)the Research Project of Tarim Oilfield Company (Grant No. 41009080051)
文摘Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism in harbor and bays. Car- bonates of the Paleogene Kalatar Formation in southwest Tarim Basin yield abundant serpulid fossils, which, together with oyster fossils, constitute the characteristic fossil assemblage of the Kalatar Formation. Other common fossils include bivalves, gastropods, ostracods, echinoderms, and bryozoans. Lithologies that yielded serpulid fossils are characterized by micritic bio- clastic limestone, sandy limestone, and shelly limestone, indicating a semi-restricted to open shallow marine environment with medium to low water energy. The research data about serpulids and their fossil materials from China are relatively rare. Based on the studies of tbssils taxonomy, community palaeoecology, and fossil taphonomy, this paper analyzed and studied the types, occurrence, distribution, and morphological characteristics of serpulids and their palaeoecological features in the Kalatar For- mation. Two serpulid community compositions were recognized in the Kalatar Formation, including a rock-forming Ditrupa community and a cluster-growth Propomatoceros community. The Ditrupa community was distributed in coastal environment of the west Kunlun piedmont, lived on sandy hard substrates with little mud, and rarely occurred in lagoon and tidal settings. The Propomatoceros community occurred in offshore middle carbonate ramp in the piedmont of the south Tianshan Moun- tains and in offshore shelf in the piedmont of the west Kunlun Mountains. According to the analysis on the host-rock litholo- gies, preservation and symbionts, it is inferred that serpulids in the Kalatar Formation grew on the oyster shell or other hard substrate, and they did not form reefs or bioherms.
