Marine Aragonite Sea-Floor Growths and Cements in Permian Phylloid Algal Mounds, Sacramento Mountains, New Mexico
Marine Aragonite Sea-Floor Growths and Cements in Permian Phylloid Algal Mounds, Sacramento Mountains, New Mexico
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新墨西哥州萨克拉门托山脉二叠纪叶状藻丘中的海洋文石海底生长物和胶结物
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发表时间：
1979
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影响因子：
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通讯作者：
J. M. Cys
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作者：
S. Mazzullo;J. M. Cys
摘要在新墨西哥州萨克拉门托山脉的浅水WolfCampian(二叠纪)叶状藻丘中，描述了一个迄今未见文献记载的海底文石类葡萄状藻类形成的例子。这些土丘的核心由呈低浮雕状矗立在海底的葡萄状文石块组成。这些块体的向上生长和结合形成了一个坚固的、网状的框架，内部空洞和类肉体之间的空洞同时被海洋沉积物和文石扇形胶结物填充。由此产生的无机边界岩成为后来叶状藻丘发育的底物。随后的藻类定居和同时期的文石沉淀也导致了无机-有机混合相的形成，其中藻类叶片包裹在海相文石中。以前的文石占整个丘状岩石的50%-85%。这些无机“礁石”的核心相在结构上，很可能在成因上与世界各地许多古生代的泥丘相似，这些泥丘被称为沃尔索尔土丘。叠层珊瑚礁和斑马石灰岩。以前的海相文石是由粗晶方解石假球的发散放射状马赛克所代表，通常被铁质“巴洛克”白云石取代。这种假自旋以射线晶体和复合晶体的形式出现，其中含有前驱体纤维文石的残留物。这种方解石有别于通常取代针状碳酸盐组构的放射状纤维马赛克。文石对方解石的矿物学稳定作用是在地下环境下发生的，其重结晶作用是在地下发生的。悬而未决的问题包括该文石的组构保持稳定成岩作用的机制，以及文石丰度与全新世生物礁的明显异常，其中镁方解石是主要的胶结矿物学。
ABSTRACT A heretofore undocumented example of aragonite botryoid formation on the sea floor is described from shallow-water Wolfcampian (Permian) phylloid algal mounds in the Sacramento Mountains of New Mexico. The cores of these mounds consisted of botryoidal aragonite masses that stood in low relief on the sea floor. The upward growth and coalescence of these masses created a solid, anastomosing framework of inter-botyroid and internal cavities that were simultaneously filled with marine sediment and aragonite fan cements. The resulting inorganic boundstone became the substrate for later phylloid algal mound development. Subsequent algal colonization and contemporaneous aragonite precipitation also resulted in the development of a mixed inorganic-organic facies wherein algal blades are encas d in marine aragonite. Former aragonite constitutes from 50-85% of the total mound rock. The core facies of these inorganic "reefs" are texturally and, most probably, genetically similar to the many Paleozoic mudmounds throughout the world known variously as Waulsortian mounds. Stromatactis reefs, and zebra limestones. The former marine aragonite is represented by divergent-radial mosaics of coarsely crystalline calcite pseudospar that commonly are replaced by ferroan "baroque" dolomite. This pseudospar occurs as ray-crystals and composite crystals with included relicts of the precursor fibrous aragonite. This species of calcite is distinct from the radiaxial-fibrous mosaics that commonly replace acicular carbonate fabrics. Mineralogic stabilization of the aragonite to calcite via paramorphic inversion is believed to have occurred in the subaerial environment, with recrystallization to pseudospar occurring in the subsurface. Unresolved problems include the mechanics of fabric-retentive stabilization diagenesis of this aragonite, and the apparent anomaly of aragonite abundance in contrast to Holocene reefs, in which Mg-calcite is the dominant cement mineralogy.