The runoff of the Huanghe contains a great amount of suspended load and forms the high-density underflows (hyperpycnal currents) at the river mouth. The sediments over the subaqneous delta are mainly transported by th...The runoff of the Huanghe contains a great amount of suspended load and forms the high-density underflows (hyperpycnal currents) at the river mouth. The sediments over the subaqneous delta are mainly transported by the underflow. The sediment texture gradually get fining seawards, which relates to the attenuation of the hyperpycnal currents and hypopycnal plumes. Being hydraulically equivalent to the medlum-silt-sized quartz, which is the dominant component in the sediments, the clastic mica concentrates on the delta. The maximum thickness of the subaqueous delta is about 16m and the period of accumulation lasted from 12 to 16 years, therefore its sedimentary rate ranges from 110 to 130 cm/a.展开更多
In capturing a snapshot of 150 years(1872-2022)of research on deep-water processes,deposits,settings,triggers,and deformation,the following 22 topics are selected:(1)H.M.S.Challenger expedition(1872-1876):The discover...In capturing a snapshot of 150 years(1872-2022)of research on deep-water processes,deposits,settings,triggers,and deformation,the following 22 topics are selected:(1)H.M.S.Challenger expedition(1872-1876):The discovering of the“Challenger Deep”by the H.M.S.Challenger in the Mariana Trench has been the single most important achievement in deep-water research.(2)Five pioneers amid 50 notable contributors:R.A.Bagnold,J.E.Sanders,G.D.Klein,F.P.Shepard,and C.D.Hollister.(3)Mass transport:Mass-transport deposits(MTD)are the most important deep-water facies in terms of volume,geohazards,and petroleum reservoirs.(4)Gravity flows:There are six basic types,namely(a)hyperpycnal flows,(b)turbidity currents,(c)debris flows,(d)liquefied/fluidized flows,(e)grain flows,and(f)thermohaline contour currents.Sandy debrites are the most important petroleum reservoir facies.Despite their popularity,turbidites are not an important reservoir facies.(5)Kelvin-Helmholtz(KH)waves:Turbidites,related to KH waves,with internal hiatus are not qualified to function as predictive facies models;nor are they fit for stratigraphic correlations.(6)High-density turbidity currents(HDTC):Misclassification of density-stratified gravity flows with laminar debris flows and turbulent turbidity currents as HDTC is flawed.Experimental generation of density-stratified gravity flows in flume studies has debunked the concept of HDTC.(7)Classification of turbidites:Contrary to the popular groupthink,turbidites are exclusive deposits of turbidity currents.(8)Bottom currents:The four basic types of deep-marine bottom currents are:(a)thermohaline-induced geotropic contour currents,(b)wind-driven bottom currents,(c)tide-driven bottom currents(mostly in submarine canyons),and(d)internal wave/tide-driven baroclinic currents.(9)Classification of contourites:Contrary to the popular groupthink,contourites are the exclusive deposits of thermohaline-induced geotropic contour currents.(10)Tidal currents in submarine canyons:Their velocity measurements have been the single most important achievement in deep-water process sedimentology.(11)Modern and ancient systems:There is a dichotomy between rare observations of turbidity currents in modern settings and overwhelming cases of interpretations of ancient turbidites in outcrops and cores.The reason is that turbidity currents are truly rare in nature,but the omnipotent presence of turbidites in the ancient rock record is the manifestation of groupthink induced by the turbidite facies model(i.e.,the Bouma Sequence).(12)Internal waves and tides:Despite their ubiquitous documentation in modern oceans,their ancient counterparts in outcrops are extremely rare.This is another dichotomy.(13)Hybrid flows:They are commonly developed by intersecting of down-slope gravity flows with along-slope contour currents.However,they are often misapplied to down-slope flow transformation of gravity flows.(14)Density(sediment)plumes:Deflected sediment plumes by wind forcing are common.Despite their importance in provenance studies,they are not adequately studied.(15)Hyperpycnal flows:They occur near the shoreline,next to the plunge point;but are of no relevance in deep-water environments.However,their importance in deep-marine settings is overhyped in recent literature.(16)Omission of erosional contact and internal hiatus:In order to promote genetic facies models that must not contain internal hiatuses,some researchers selectively omit internal hiatuses observed by the original authors.(17)Triggers of sediment failures:There are 22 types,but short-term triggers,such as earthquakes and meteorite impacts are more important than the conventional long-term trigger known as Eustasy.(18)Tsunami waves:Despite their sedimentologic importance,there are no reliable criteria for recognizing tsunami deposits in the ancient rock record.(19)Soft-Sediment Deformation Structures(SSDS):Although most SSDS are routinely interpreted as seismites,not all SSDS are caused by earthquakes.There are 10 other mechanisms,such as sediment loading,which can trigger liquefaction that can develop SSDS.(20)The Jackfork Group,Pennsylvanian,Ouachita Mountains,USA:Our reinterpretation of this classic North American flysch turbidites as MTD and bottomcurrent reworked sands has resulted in the longest academic debate with 42 printed pages in the AAPG Bulletin history since its founding in 1917.(21)Basin-floor fan model,Tertiary,North Sea:Our examination of nearly 12,000 ft(3658 m)of conventional core from Paleogene and Cretaceous deep-water sandstone reservoirs cored in 50 wells in 10 different areas or fields in the North Sea and Norwegian Sea reveals that these reservoirs are predominantly composed of MTDs,mainly sandy slumps and sandy debrites,and bottom-current reworked sands.Our core-seismic calibration debunked the conventional wisdom(groupthink)that basin-floor fans are composed of sandy turbidites in a sequence-stratigraphic framework.(22)Turbidite groupthink:A case study in illustrating how turbidite groupthink functions,without sound scientific methods,on the basis of published information on modern turbidity currents in Bute Inlet(fjord and estuary),British Columbia,Canada.This compendium is hybrid in composition between an atlas(with 108 figures)and a review article(with 348 references).The author admonishes scientists against deep-sea groupthink and provides a roadmap for future researchers by identifying potential topics for research involving density plumes,internal waves,tidal currents,tsunami waves,sediment deformation,and lowstand braid deltas.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘The runoff of the Huanghe contains a great amount of suspended load and forms the high-density underflows (hyperpycnal currents) at the river mouth. The sediments over the subaqneous delta are mainly transported by the underflow. The sediment texture gradually get fining seawards, which relates to the attenuation of the hyperpycnal currents and hypopycnal plumes. Being hydraulically equivalent to the medlum-silt-sized quartz, which is the dominant component in the sediments, the clastic mica concentrates on the delta. The maximum thickness of the subaqueous delta is about 16m and the period of accumulation lasted from 12 to 16 years, therefore its sedimentary rate ranges from 110 to 130 cm/a.
文摘In capturing a snapshot of 150 years(1872-2022)of research on deep-water processes,deposits,settings,triggers,and deformation,the following 22 topics are selected:(1)H.M.S.Challenger expedition(1872-1876):The discovering of the“Challenger Deep”by the H.M.S.Challenger in the Mariana Trench has been the single most important achievement in deep-water research.(2)Five pioneers amid 50 notable contributors:R.A.Bagnold,J.E.Sanders,G.D.Klein,F.P.Shepard,and C.D.Hollister.(3)Mass transport:Mass-transport deposits(MTD)are the most important deep-water facies in terms of volume,geohazards,and petroleum reservoirs.(4)Gravity flows:There are six basic types,namely(a)hyperpycnal flows,(b)turbidity currents,(c)debris flows,(d)liquefied/fluidized flows,(e)grain flows,and(f)thermohaline contour currents.Sandy debrites are the most important petroleum reservoir facies.Despite their popularity,turbidites are not an important reservoir facies.(5)Kelvin-Helmholtz(KH)waves:Turbidites,related to KH waves,with internal hiatus are not qualified to function as predictive facies models;nor are they fit for stratigraphic correlations.(6)High-density turbidity currents(HDTC):Misclassification of density-stratified gravity flows with laminar debris flows and turbulent turbidity currents as HDTC is flawed.Experimental generation of density-stratified gravity flows in flume studies has debunked the concept of HDTC.(7)Classification of turbidites:Contrary to the popular groupthink,turbidites are exclusive deposits of turbidity currents.(8)Bottom currents:The four basic types of deep-marine bottom currents are:(a)thermohaline-induced geotropic contour currents,(b)wind-driven bottom currents,(c)tide-driven bottom currents(mostly in submarine canyons),and(d)internal wave/tide-driven baroclinic currents.(9)Classification of contourites:Contrary to the popular groupthink,contourites are the exclusive deposits of thermohaline-induced geotropic contour currents.(10)Tidal currents in submarine canyons:Their velocity measurements have been the single most important achievement in deep-water process sedimentology.(11)Modern and ancient systems:There is a dichotomy between rare observations of turbidity currents in modern settings and overwhelming cases of interpretations of ancient turbidites in outcrops and cores.The reason is that turbidity currents are truly rare in nature,but the omnipotent presence of turbidites in the ancient rock record is the manifestation of groupthink induced by the turbidite facies model(i.e.,the Bouma Sequence).(12)Internal waves and tides:Despite their ubiquitous documentation in modern oceans,their ancient counterparts in outcrops are extremely rare.This is another dichotomy.(13)Hybrid flows:They are commonly developed by intersecting of down-slope gravity flows with along-slope contour currents.However,they are often misapplied to down-slope flow transformation of gravity flows.(14)Density(sediment)plumes:Deflected sediment plumes by wind forcing are common.Despite their importance in provenance studies,they are not adequately studied.(15)Hyperpycnal flows:They occur near the shoreline,next to the plunge point;but are of no relevance in deep-water environments.However,their importance in deep-marine settings is overhyped in recent literature.(16)Omission of erosional contact and internal hiatus:In order to promote genetic facies models that must not contain internal hiatuses,some researchers selectively omit internal hiatuses observed by the original authors.(17)Triggers of sediment failures:There are 22 types,but short-term triggers,such as earthquakes and meteorite impacts are more important than the conventional long-term trigger known as Eustasy.(18)Tsunami waves:Despite their sedimentologic importance,there are no reliable criteria for recognizing tsunami deposits in the ancient rock record.(19)Soft-Sediment Deformation Structures(SSDS):Although most SSDS are routinely interpreted as seismites,not all SSDS are caused by earthquakes.There are 10 other mechanisms,such as sediment loading,which can trigger liquefaction that can develop SSDS.(20)The Jackfork Group,Pennsylvanian,Ouachita Mountains,USA:Our reinterpretation of this classic North American flysch turbidites as MTD and bottomcurrent reworked sands has resulted in the longest academic debate with 42 printed pages in the AAPG Bulletin history since its founding in 1917.(21)Basin-floor fan model,Tertiary,North Sea:Our examination of nearly 12,000 ft(3658 m)of conventional core from Paleogene and Cretaceous deep-water sandstone reservoirs cored in 50 wells in 10 different areas or fields in the North Sea and Norwegian Sea reveals that these reservoirs are predominantly composed of MTDs,mainly sandy slumps and sandy debrites,and bottom-current reworked sands.Our core-seismic calibration debunked the conventional wisdom(groupthink)that basin-floor fans are composed of sandy turbidites in a sequence-stratigraphic framework.(22)Turbidite groupthink:A case study in illustrating how turbidite groupthink functions,without sound scientific methods,on the basis of published information on modern turbidity currents in Bute Inlet(fjord and estuary),British Columbia,Canada.This compendium is hybrid in composition between an atlas(with 108 figures)and a review article(with 348 references).The author admonishes scientists against deep-sea groupthink and provides a roadmap for future researchers by identifying potential topics for research involving density plumes,internal waves,tidal currents,tsunami waves,sediment deformation,and lowstand braid deltas.
