Facies and integrated stratigraphy of the Upper Turonian (Upper Cretaceous) Großberg Formation south of Regensburg (Bavaria, southern Germany)
Facies and integrated stratigraphy of the Upper Turonian (Upper Cretaceous) Großberg Formation south of Regensburg (Bavaria, southern Germany)
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雷根斯堡（德国南部巴伐利亚州）南部上图伦阶（上白垩统）Großberg 组的相和综合地层
DOI：
10.2478/v10263-012-0032-9
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发表时间：
2012
影响因子：
1.1
通讯作者：
M. Wilmsen
中科院分区：
文献类型：
--
作者：
B. Niebuhr;Nadine Richardt;M. Wilmsen
里根斯堡地区（德国南部巴伐利亚州多瑙河白垩纪群）的上土龙格罗斯堡组平均厚度为20-25 m，由桑迪生物碎屑碎屑岩和钙质砂岩组成，富含苔藓虫、蛇虫和双壳类（牡蛎、蛤类、单壳类）。已识别出8种相类型，这些相类型表征了向南倾斜的同斜斜坡上的沉积：内部斜坡亚环境的特征是具有遮蔽的浅滩间区域的高能沙波沉积（桑迪生物碎屑岩和颗粒岩、生物碎屑砂岩）。在中斜坡环境中，生物扰动砂岩、钙质砂岩、钙质砂岩和粉砂岩以及生物扰动砂岩、生物扰动杂砂岩和碎屑岩占主导地位。Grosberg组的碳酸盐颗粒组合描述了一种具有温水影响指标的温带苔藓岩相。推断盈余的陆源营养物质导致富营养化的条件下，有利于Grosberg坡道的异源动物群落。由于整体岩石δ 13 C值亏损且无趋势，碳稳定同位素地球化学无法对Grosberg组的地层标定做出显著贡献，这可能是由具有亏损δ 13 C DIC值和同沉积和早期成岩碳酸盐相的低δ 13 C值的浅水水相造成的。然而，强烈富集的骨骼方解石δ 13 C值支持Grosberg组与Turonian中晚期正Hitch Wood同位素事件（北方德国的Hyphantoceras事件）的相关性。这一解释得到了生物地层学数据和从Mytiloides striatoconcentricus带到My下游的范围的支持。scupini带以inoceramid双壳类为标志。Grosberg组的底部和顶部都具有不整合的特征。底部的层序边界SB Tu 4是主要的区域侵蚀面（里根斯堡地区下伏Kagerhoh组的侵蚀截短，Bodenwohr地区北部和东北部罗丁组Seugast段底部的河流切割）。这表明，这种不整合对应于一个主要的海平面下降，在许多其他白垩纪盆地以下的Hitch Wood或Hyphantoceras事件。Grosberg组的海侵和高位与河流Seugast段的沉积和边缘海相“Veldensteiner Sandstein”上覆到Frankische Alb上的过程相伴随。Grosberg组顶部的不整合面（晚Turonian SB Tu 5晚期）由含铁坚硬地面和δ 13 C值强烈亏损的下伏带指示。下Hellkofen组（最上部的Turonian-Lower Coniacian）较深的海相泥灰岩的突然叠加可能与波希米亚地块西南缘的反转构造有关。
The Upper Turonian Grosberg Formation of the Regensburg area (Danubian Cretaceous Group, Bavaria, southern Germany) has a mean thickness of 20–25 m and consists of sandy bioclastic calcarenites and calcareous sandstones which are rich in bryozoans, serpulids and bivalves (oysters, rudists, inoceramids). Eight facies types have been recognized that characterize deposition on a southward dipping homoclinal ramp: the inner ramp sub-environment was characterized by high-energy sandwave deposits (sandy bioclastic rud- and grainstones, bioclastic sandstones) with sheltered inter-shoal areas. In mid-ramp settings, bioturbated, glauconitic, calcareous sand- and siltstones as well as bioturbated, bioclastic wacke- and packstones predominate. The carbonate grain association of the Grosberg Formation describes a temperate bryomol facies with indicators of warm-water influences. An inferred surplus of land-derived nutrients resulted in eutrophic conditions and favoured the heterozoan communities of the Grosberg Ramp. Carbon stable isotope geochemistry cannot significantly contribute to the stratigraphic calibration of the Grosberg Formation due to the depleted and trendless bulk-rock δ 13 C values, probably resulting from a shallow-water aquafacies with depleted δ 13 C DIC values and low δ 13 C values of syndepositional and early diagenetic carbonate phases. However, strongly enriched skeletal calcite δ 13 C values support a correlation of the Grosberg Formation with the mid-Late Turonian positive Hitch Wood isotope event ( Hyphantoceras Event of northern Germany). This interpretation is supported by biostratigraphic data and a range from the Mytiloides striatoconcentricus Zone into the lower My. scupini Zone is indicated by inoceramid bivalves. Both the base and top of the Grosberg Formation are characterized by unconformities. Sequence boundary SB Tu 4 at the base is a major regional erosion surface (erosional truncation of the underlying Kagerhoh Formation in the Regensburg area, fluvial incision at the base of the Seugast Member of the Roding Formation in the Bodenwohr area towards the north and northeast). It is suggested that this unconformity corresponds to a major sea-level drop recognized in many other Cretaceous basins below the Hitch Wood or Hyphantoceras Event. The transgression and highstand of the Grosberg Formation is concomitant to the deposition of the fluvial Seugast Member and the onlap of the marginal-marine “Veldensteiner Sandstein” onto the Frankische Alb. The unconformity at the top of the Grosberg Formation (late Late Turonian SB Tu 5) is indicated by a ferruginous firm-/ hardground and an underlying zone of strongly depleted δ 13 C values. The abrupt superposition by deeper marine marls of the lower Hellkofen Formation (uppermost Turonian–Lower Coniacian) may be connected with inversion tectonics at the southwestern margin of the Bohemian Massif.
Bodenwöhrer Senke（德国巴伐利亚多瑙河白垩系群）晚塞诺曼阶-早期土伦阶相发育和海平面变化
影响因子：
1.8
作者：
Richardt;Wilmsen;Niebuhr
通讯作者：
Niebuhr
明斯特兰南部（德国西北部）下上白垩统标准剖面：碳稳定同位素和层序地层学
影响因子：
2.2
作者：
Richardt;Wilmsen
通讯作者：
Wilmsen