What would be some of the defining characteristics of deposition as a result of a tsunami such as caused by an oceanic bolide impact? Would it still result in HCS and wave ripples except on a large scale? Similar to the mega ripples found in the channeled scablands.
Tsunamis don't often produce wave ripples or HCS because there aren't enough wave crests. They usually move lots of sediment at once and deposit it rapidly. Offshore deposits often consist of larger than average grains (sometimes boulders), commonly with turbidite characteristics. Onshore deposits consist of erosion and deposition of unusually large magnitude. You can find some examples by searching for tsunami deposits. The USGS pages are great.
Given that tsunami deposits seem to have identifiable characteristics. Are they, or can they be used in the field to help identify oceanic bolide impacts greater than 250 million years where crater evidence may have been removed by subduction of oceanic plates?
Tsunami can be caused by earthquakes and landslides as well as bolide impacts. Thus, we need more than tsunami deposits to identify old impacts. One thing geologists can see are "impact spherules", which are melted glass spheres that are formed during the impact. I have found a couple of layers of these spherules in rocks that are 2.5-2.6 billion years old, suggesting ancient meteorite impacts. Others have found similar layers. There have been lots of impacts in earth history!
Hello Dawn. Can these sed structures be indicative of lacustrine near-shore environments as well as marine near-shore environments? Or is their interpretation restricted to marine nearshore environments alone?
Wave and storm sed structures can form in any body of water large enough to have waves and currents. The processes are the same, so the sedimentary structures are similar. For example, Lake Superior can have waves that are several meters high. Add currents from storm run-up and a typical storm deposit will form.
Thank you for the reply. Love your vids. I'm an Earth science geek and proud of it!
If they would interest you, I have some debris flow videos posted to my channel that I obtained from the USGS. My favorite is the Clear Creek, Colorado video; really remarkable footage captured by a Denver TV crew just next to I-70 not far from the continental divide (a 35 second clip).
What would be some of the defining characteristics of deposition as a result of a tsunami such as caused by an oceanic bolide impact? Would it still result in HCS and wave ripples except on a large scale? Similar to the mega ripples found in the channeled scablands.
EvolutionaI 3 years ago
Tsunamis don't often produce wave ripples or HCS because there aren't enough wave crests. They usually move lots of sediment at once and deposit it rapidly. Offshore deposits often consist of larger than average grains (sometimes boulders), commonly with turbidite characteristics. Onshore deposits consist of erosion and deposition of unusually large magnitude. You can find some examples by searching for tsunami deposits. The USGS pages are great.
sumnerd 3 years ago
Given that tsunami deposits seem to have identifiable characteristics. Are they, or can they be used in the field to help identify oceanic bolide impacts greater than 250 million years where crater evidence may have been removed by subduction of oceanic plates?
EvolutionaI 3 years ago
Tsunami can be caused by earthquakes and landslides as well as bolide impacts. Thus, we need more than tsunami deposits to identify old impacts. One thing geologists can see are "impact spherules", which are melted glass spheres that are formed during the impact. I have found a couple of layers of these spherules in rocks that are 2.5-2.6 billion years old, suggesting ancient meteorite impacts. Others have found similar layers. There have been lots of impacts in earth history!
sumnerd 3 years ago
Hello Dawn. Can these sed structures be indicative of lacustrine near-shore environments as well as marine near-shore environments? Or is their interpretation restricted to marine nearshore environments alone?
bapyou 4 years ago
Wave and storm sed structures can form in any body of water large enough to have waves and currents. The processes are the same, so the sedimentary structures are similar. For example, Lake Superior can have waves that are several meters high. Add currents from storm run-up and a typical storm deposit will form.
sumnerd 4 years ago
Thank you for the reply. Love your vids. I'm an Earth science geek and proud of it!
If they would interest you, I have some debris flow videos posted to my channel that I obtained from the USGS. My favorite is the Clear Creek, Colorado video; really remarkable footage captured by a Denver TV crew just next to I-70 not far from the continental divide (a 35 second clip).
bapyou 4 years ago
Thanks! It was very nice, could you please talk next time about sandstone, and mudrocks provenance, please?
cecauende 4 years ago