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Most of the quartz is detrital (part of the original sediments that formed the shale) rather than authigenic (crystallized within the shale after deposition). [9] Shales and other mudrocks contain roughly 95 percent of the organic matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale. Black ...
As is common during anoxic events, black shale deposition was widespread during the deoxygenation events of the Toarcian. [ 143 ] [ 18 ] [ 144 ] Toarcian anoxia was responsible for the deposition of commercially extracted oil shales, [ 145 ] particularly in China.
The Marcellus deposition produced a transgressive black shale, [51] because it was deposited in deepening conditions when the basin floor dropped as the mountains rose up. [115] Generalized geologic cross section of Catskill Delta magnafacies across western Pennsylvania and eastern Ohio. [63]
The new thought is that these ocean currents were slowed by blooms of microscopic marine primary producers, which allowed for the settlement of organic-rich sediments at the seafloor, producing many of the economically productive black shale beds that are present today. To this day it remains an intensely researched subject by scholars and ...
[77] [52] The resulting elevated levels of carbon burial would account for the black shale deposition in the ocean basins. [72] [78] The proto-North Atlantic in particular was a hotbed of carbon burial during OAE2 as it was in later, less severe anoxic events. [79]
OAE1a, as with other OAEs, exhibited widespread deposition of black shales rich in organic matter incapable of being decomposed on the seabed, as the anoxic conditions prohibited habitation of most microbial decomposers. [1] Black shale deposition begins during the C6 stage of OAE1a and lasted for around 0.4 Myr. [24]
The Hesseltal Formation or Blackcoloured Formation is a Late Cretaceous (late Cenomanian to early Turonian) geological formation from northern Germany.It consists of lithified marls and limestone, with a unique series of black shales deposited in anoxic conditions during the Cenomanian-Turonian boundary event.
"Middlesex Shale Formation – Sonyea Group". Shanan E. Peters & Noel A. Heim. Archived from the original on 2015-09-23; Schieber, J. (1999). "Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York". Journal of Sedimentary Research. 69 (4). SEPM Society for Sedimentary Geology: 909–925.