Large-Scale Seismogenic Deformation of A Carbonate Platform Straddling the Precambrian-Cambrian Boundary, Karatau Range, Kazakhstan

Heubeck, Christoph; K., None Ergaliyev E.; Evseev, Sergey

doi:10.2110/jsr.2013.76

Cited by 10 publications

(10 citation statements)

References 77 publications

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“…Smaller fitted fragments with irregular edges reflect in situ fragmentation and minor movement (cf. Chen et al, 2011;Heubeck et al, 2013). Swirled laminated matrix around larger clasts records soft-sediment deformation that was accompanied in part by rotation of rigid blocks within relatively unlithified layered sediment.…”

Section: Discussionmentioning

confidence: 99%

Estimates of large magnitude Late Cambrian earthquakes from seismogenic soft‐sediment deformation structures: Central Rocky Mountains

Myrow

Chen

2014

Sedimentology

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A variety of unusual early post‐depositional deformation structures exist in grainstone and flat‐pebble conglomerate beds of Upper Cambrian strata, western Colorado, including slide scarps, thrusted beds, irregular blocks and internally deformed beds. Thrusted beds up to tens of centimetres thick record thrust movement of a part of a bed onto itself along a moderate to steeply inclined (15° to 40°) ramp, locally producing hanging wall lenses with fault‐bend geometries. Thrust plane orientations are widely distributed, and in some cases nearly oppositely oriented in close proximity, indicating that they did not form as failures acted upon by gravity forces. Irregular bedded to internally deformed blocks are isolated on generally flat upper bedding surfaces. These features represent parts of beds that detached, moved up onto and some distances across, the laterally adjacent undisturbed bed surfaces. Deformation of thin intervals of mud on the ocean floor by moving blocks rules out the possibility of storm‐induced deformation, because the mud was not eroded by high shear stresses that would accompany the extremely large forces required to produce and move the blocks. Finally, internally deformed beds are characterized by large blocks, fitted fabrics of highly irregular fragments and contorted lamination, which represent heterogeneous deformation, such as brecciation and liquefaction. The deformation structures were produced by earthquakes linked to the reactivation of Mesoproterozoic, crustal‐scale shear zones in the central Rockies during the Late Cambrian. Analysis of the deformation structures indicates very large body forces and calculated earthquake‐generated ground motion velocities of ca 1·6 m sec−1. These correspond to moment magnitudes of ca 7·0 or more and a Mercalli Intensity of X+. These are the only known magnitude estimates of Phanerozoic (other than Quaternary) large‐intensity earthquakes for the Rocky Mountain region, and they are as large as, or larger than, previous estimates of Proterozoic earthquakes along these major shear zones of the central Rockies.

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Section: Discussionmentioning

confidence: 99%

Estimates of large magnitude Late Cambrian earthquakes from seismogenic soft‐sediment deformation structures: Central Rocky Mountains

Myrow

Chen

2014

Sedimentology

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“…Sedimentary rocks comprise a succession of dolostones (cf. Heubeck et al, ), overlain by bedded, dark‐colored cherts, the minable phosphorite units with an intercalated phosphate‐bearing siltstone and shale unit. The Upper Phosphorite is topped by a Fe‐Mn‐carbonate and dolostone horizon, which was deposited in a shallow marine archipelago setting (P. J. Cook & Shergold, ; Heubeck et al, ).…”

Section: Location and Sample Descriptionmentioning

confidence: 99%

“…The Upper Phosphorite is topped by a Fe-Mn-carbonate and dolostone horizon, which was deposited in a shallow marine archipelago setting (P. J. Cook & Shergold, 1986;Heubeck et al, 2013). The Cambrian Shabakty Fm.…”

Section: Location and Sample Descriptionmentioning

confidence: 99%

Radiogenic Sr and Stable C and O Isotopes Across Precambrian‐Cambrian Transition in Marine Carbonatic Phosphorites of Malyi Karatau (Kazakhstan)—Implications for Paleo‐environmental Change

Stammeier

Hippler

Nebel

et al. 2019

Geochem Geophys Geosyst

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The Precambrian‐Cambrian (PЄ‐Є) transition is a unique period in Earth's history known for the “Cambrian Explosion.” Here we present a continuous radiogenic and stable isotope (87Sr/86Sr, δ13CVPDB, carb, and δ18OVPDB, carb) and elemental (including rare earth elements) record across the PЄ‐Є transition, preserved in phosphatic and carbonate shallow‐water deposits from two sections (Koksu and Kyrshabakty) in Kazakhstan. Microstructure, trace, and rare earth elements concentrations reflect near‐primary preservation. δ13CVPDB, carb data (−12.1‰ to 3.3‰) record formation conditions at a time of severe geodynamic changes. Negative δ13CVPDB, carb at the PЄ‐Є boundary resemble the Basal Cambrian Carbon Anomaly. Average δ18OVPDB, carb values of −11.7 ± 3.8‰ are suggested to represent near‐primary signals and can be explained by isotopically lighter past sea water and elevated temperature during precipitation compared to present‐day conditions. Initial 87Sr/86Sr of the carbonate and phosphate fraction are in the range of 0.7086–0.7112 at the Koksu section and 0.7082–0.7136 at the Kyrshabakty section. This is in general agreement with the seawater 87Sr/86Sr evolution during the Early Cambrian. In this study, we present a refined 87Sr/86Sr seawater evolution, highlighting an extreme positive Sr isotope excursion at the PЄ‐Є transition, which is suggested to be indicative for enhanced continental weathering and an increase in nutrient runoff into shallow ocean waters. This extreme geodynamic event may have served as a driving force for enhanced biologic activity in the lead up to the Cambrian Explosion, where phosphatic shallow‐water deposits from Kazakhstan constitute a valuable paleo‐environmental archive.

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“…With different degrees of liquefaction (partial to complete), structures varied widely ranging from ductile deformation with the preservation of stratification to obliteration of stratification with complete liquefaction (cf. Heubeck et al 2013).…”

Section: Chaotically Associated Structuresmentioning

confidence: 99%

Earthquake-induced soft sediment deformation (SSD) structures from the Bilara limestone formation, Marwar basin, India

2019

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The Neoproterozoic Bilara limestone Formation of the Marwar Group, Rajasthan, India exposes metresthick layers of soft sediment deformation (SSD) structures at different stratigraphic levels which could be traced over hundreds of metres on the outcrop scale. The SSD structures include disharmonic folds, lowangle thrusts, distorted laminae, fluidisation pipes, slump and load structures, homogeneities, diapirs, etc. Whereas SSD structures suggesting tensional stress, viz., intrastriatal graben, fluidisation, slump, etc. dominate in the lower part of the Bilara succession, features implicating compression, viz., folds, lowangle thrust are prevalent in the uppermost part. Since SSD structures are mostly confined within the algal laminites, we interpret that enhanced micritic fluid pressure below early cemented algal carbonate played a major role in laminae deformation. Depending on the degree of lithification and pore-water pressure, deformation features formed either plastically or led to diapiric injection at enhanced pore water pressure. Separated by near-horizontal underformed strata, the SSD layers, traceable over hundreds of metres, are interpreted as products of seismic shacking. Considering the time frame of the Marwar basin, i.e., the Precambrian-Cambrian transition, the SSD horizons present within the Bilara succession may hold the potential for the correlation with SSD structures reported from the time-correlative stratigraphic successions present in erstwhile adjoining tectonic terrains, e.g., China, Siberia, etc.

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Large-Scale Seismogenic Deformation of A Carbonate Platform Straddling the Precambrian-Cambrian Boundary, Karatau Range, Kazakhstan

Cited by 10 publications

References 77 publications

Estimates of large magnitude Late Cambrian earthquakes from seismogenic soft‐sediment deformation structures: Central Rocky Mountains

Estimates of large magnitude Late Cambrian earthquakes from seismogenic soft‐sediment deformation structures: Central Rocky Mountains

Radiogenic Sr and Stable C and O Isotopes Across Precambrian‐Cambrian Transition in Marine Carbonatic Phosphorites of Malyi Karatau (Kazakhstan)—Implications for Paleo‐environmental Change

Earthquake-induced soft sediment deformation (SSD) structures from the Bilara limestone formation, Marwar basin, India

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