Funnel-shaped, breccia-filled clastic dykes in the Late Cambrian Chaomidian Formation (Shandong Province, China)
49
Citation
15
Reference
10
Related Paper
Citation Trend
Keywords:
Breccia
Grainstone
Funnel
Breccia
Impact structure
Basement
Cite
Citations (53)
The concentric structural feature known as the Ames Hole, or Ames Crater, located on the northern shelf of the Anadarko Basin, contains several heterogeneous and uniquely associated hydrocarbon reservoirs, as well as a locally thick (crater-filling) Middle Ordovician (Simpson shale) source rock. Critical diagnostic structural and morphological features, along with petrographic and shock metamorphism evidence, strongly support an impact origin of the structure. Principle crater reservoirs include extremely brecciated, fractured, and faulted, Cambro-Ordovician Arbuckle Group dolomites, PreCambrian granodiorites, devitrified pseudo-pyroclastic (impact melt) rocks, and a rather homogenous, dolomitic ejectafallout breccia, which is present along the rim and flanks of the crater. Stratigraphic trapping of hydrocarbons associated with the presence of reservoir-quality ejecta-fallout lithologies unconformably present in the upper portion of the Arbuckle Group, and in reworked, arkosic/dolomitic impact-related lithofacies within the overlying basal Simpson Group, may exist both locally and regionally relative to the Ames Crater. Recognition and regional correlation of Arbuckle ejecta-failout breccias, and arkosic/dolomitic (reworked) Simpson clastics, requires a thorough understanding of the genesis, distribution, structural complexities, and petrographic/petrophysical properties associated with various Ames Crater lithofacies. Calibration of log-rock characteristics of ejecta-fallout reservoir lithofacies from key crater rim wells provides the basis for field-wide and regional inferences about lithologies, reservoir quality, and related production characteristics. An awareness and understanding of impact-related Ames Crater Arbuckle and Simpson lithofacies should lead to refinement of regional Lower and Middle Ordovician stratigraphy, and create renewed exploration strategies for potential stratigraphic traps.
Breccia
Lithology
Cite
Citations (0)
The prehistoric but geomorphically pristine North Long John rock avalanche of the Inyo Mountains piedmont, California, formed by the catastrophic collapse and disintegration of a 500 × 1000 m range-front bedrock slab. This failure rapidly produced and transferred ~25 million cubic metres of new sediment to the piedmont, where it was deposited in a trough between two coalesced alluvial fans. The avalanche consists of nearly monolithologic (aplitic), unstratified, very angular, muddy, cobble, pebble gravel with boulders concentrated at the top and outer margins. The deposits are clast supported except in the lower central zone. Coarse clasts exhibit crackle-breccia fabric, and the voluminous equant pebbles are the disaggregated products of these clasts. The avalanche deposits are distributed in a U-shaped body with paired lateral levees 10-60 m high that extend 1560 m from the range front to a 108 m high distal snout. Each levee contains three segments that, along with the snout, overlap and extend progressively farther downslope from the inside of each other in a telescoped pattern. The most proximal deposits are the remnant sole sheared off where the avalanche intersected the piedmont, whereas the remainder was deposited as an ensuing grain flow. The radial alignment of the long axes of coarse clasts in the upper levees indicate that particle-particle interaction took place during flowage, and that clasts were pushed towards the margins. Part of the northern second levee borders a sharp and vertical, 10-18 m high scarp cleanly sliced through older fan deposits. This scarp was cut by the leading edge of the avalanche, which rapidly bulldozed away ~0.5 million cubic metres of fan deposits in the flow path. A southward cross-tilt resulted from the avalanche turning south due to interference with higher fan deposits on the north side. Friction from this interference restricted avalanche runout to 1.6 km, 25-33% of the distance predicted by empirical data from case studies lacking flow-path obstructions.
Cobble
Imbrication
Bedrock
Breccia
Alluvial fan
Mass wasting
Cite
Citations (26)
Sedimentation
Cite
Citations (8)
Breccia
Conglomerate
Diamictite
Grainstone
Cite
Citations (34)
Abstract Some limestone breccias and conglomerates from the Furongian (Late Cambrian) Chaomidian Formation (Shandong Province, China) were investigated in order to understand the depositional and deformational processes induced by storms. The sediments under study occur in a hummocky cross-stratified peloidal grainstone layer. The limestone conglomerates consist of well-rounded clasts that are mostly flat-lying or imbricated, and have erosional bases. They formed by surface reworking (erosion and rip-up) of thin-bedded grainstones by storm waves and currents. The limestone breccias consist of subangular to subrounded clasts of grainstone, which are often associated with small-scale grainstone clastic dykes. The breccias and dykes resulted from subsurface soft-sediment deformation (i.e., differential liquefaction and fluidization of heterogeneously cemented carbonate grains), most likely triggered by storm-wave loading. The limestone breccias and conglomerates bear important implications for understanding the reworking mechanisms of storms on ancient carbonate platforms
Grainstone
Breccia
Wackestone
Cite
Citations (11)
Scoria
Breccia
Lapilli
Phreatomagmatic eruption
Cinder cone
Turbidity current
Pyroclastic fall
Cite
Citations (6)
Pumice
Breccia
Bedrock
Drumlin
Cite
Citations (109)
ABSTRACT During the early Upper Jurassic, widespread deep‐sea radiolarites were deposited in most parts of the Northern Limestone Alps. In the formation described (Tauglboden‐Schichten), these pelagic sediments interfinger with local‐source clastic material. Depending on the topography and the kind of material, either slides and slumps, mudflows, grain flows or turbidity currents operated and formed slump‐folded beds, mud‐flow breccias, fluxoturbidites or turbidites. A breccia had been traced over an area of 20 km 2 . Its variation is described in terms of lithological columns, bed thicknesses, maximum grain sizes and grain orientations. It forms a tongue‐shaped body, which was probably a part of a submarine fan. The fluxoturbidites of the proximal area grade distally on three sides into turbidites within 3–5 km. The clastic material consists of marls and limestones of Rhaetian and Jurassic age. It was probably derived from a tectonically uplifted palaeo‐high by an interplay of tectonics and gravity. The clastics were deposited on submarine fans bordering this high. In its lithology the formation closely resembles certain marginal facies of flysch troughs.
Breccia
Flysch
Lithology
Turbidity current
Lithostratigraphy
Marl
Cite
Citations (46)
Breccia
Grainstone
Cite
Citations (43)