BLDGBLOG has an interview with Abraham Van Luik, a geoscientist with the U.S. Department of Energy.
Its a long interview about isolating nuclear waste. Yucca mountain and its geology feature prominently.
Definitely worth reading.
Thursday, November 5, 2009
Teaching Human Evolution In Pakistan Can Be Dangerous
Kenneth Chang of New York Times has written an interesting summary on the teaching and acceptance of evolution across Muslim countries and among Muslim immigrants in many western nations.
Atomic physicist Pervez. A Hoodbhoy went through a dramatic moment while lecturing at a university in Pakistan:
Its scary that this took place not at some isolated madrassa but at a national university. Overall acceptance of evolution - especially human evolution - is low in Muslim countries. The technological advancement engulfing these countries is not necessarily paralleled by a more scientific mindset among citizenry. Religious beliefs are playing a large role in driving a wedge between the two. Turkey is a great example. Just 2-3 decades ago creationism was not a factor affecting science education in Turkey. Today, the influence of Islamic parties is greater in society, evolution teaching is diluted at the school level and creationist textbooks are influencing biology syllabus.
The article does not mention Muslims in India but I doubt if attitudes towards evolution are significantly different among Indian Muslims.
And I wonder what the break up would be according to educational level and how it compared to Hindus.
Atomic physicist Pervez. A Hoodbhoy went through a dramatic moment while lecturing at a university in Pakistan:
Pervez A. Hoodbhoy, a prominent atomic physicist at Quaid-e-Azam University in Pakistan, said that when he gave lectures covering the sweep of cosmological history from the Big Bang to the evolution of life on Earth, the audience listened without objection to most of it. “Everything is O.K. until the apes stand up,” Dr. Hoodbhoy said.
Mentioning human evolution led to near riots, and he had to be escorted out. “That’s the one thing that will never be possible to bridge,” he said. “Your lineage is what determines your worth.”
Mentioning human evolution led to near riots, and he had to be escorted out. “That’s the one thing that will never be possible to bridge,” he said. “Your lineage is what determines your worth.”
Its scary that this took place not at some isolated madrassa but at a national university. Overall acceptance of evolution - especially human evolution - is low in Muslim countries. The technological advancement engulfing these countries is not necessarily paralleled by a more scientific mindset among citizenry. Religious beliefs are playing a large role in driving a wedge between the two. Turkey is a great example. Just 2-3 decades ago creationism was not a factor affecting science education in Turkey. Today, the influence of Islamic parties is greater in society, evolution teaching is diluted at the school level and creationist textbooks are influencing biology syllabus.
The article does not mention Muslims in India but I doubt if attitudes towards evolution are significantly different among Indian Muslims.
And I wonder what the break up would be according to educational level and how it compared to Hindus.
Monday, November 2, 2009
End Cretaceous: How Many Impacts? How Many Iridium Anomalies?
Looking over the recent GSA geoblogosphere page I was alerted to a presentation by Shankar Chatterjee and colleagues on the Shiva crater, a hypothetical impact crater that Chatterjee claims is of end Cretaceous age and is likely responsible along with the Deccan volcanism for the mass extinction. He suggests that the Chicxulub impact event in Mexico also timed to the end Cretaceous did not alone cause the mass extinction.
Here is the abstract. The talk apparently got a skeptical reception. Chatterjee envisions the following scenario. The meteor hit the Indian continental plate and maybe initiated rifting between Seychelles and India.
Source: Chatterjee- Proc 30th Int. Geol. Congr. Vol 26, pp - 31-54
The crater is now broken up along the rift. Part of the structure lies along the Indian west coast and part of it along the Seychelles margin.
The argument is at present based mostly on the geometry and structure of the basins and rifted margins matching what a meteorite hit will produce if it hit the crust at a shallow angle from the southwest.
But according to what I have read so far there is little direct local evidence of this being an impact crater. There is no core recovered from the supposed impact site and so no information available on whether the features that are seen at the Chicxulub crater in Mexico i.e. impact melt rock, high pressure quartz phases, chaotic breccia, tsunami deposits and so on are present at this site too. Also Chatterjee has not given as far as I know a convincing account of why various models of continental rifting, flood volcanism and denudational isostacy are inadequate explanations of the continental margin geology of west India and the Seychelles.
Yet, end Cretaceous always fascinates.
Chatterjee think this impact occurred either simultaneously with the Chicxulub impact or it post-dates the impact in Mexico. I found this view point very interesting for the response it drew from Gerta Keller who is a strong proponent of the theory that the Chicxulub impact was not the primary cause of the K-T extinction. She is pushing for the Deccan volcanics being the real culprit.
Keller has been quoted rejecting Chatterjee's theory, saying there is no evidence for such an impact in Indian deposits. But she leaves a big question unanswered, one that is prompted by her own work and theory.
How do you explain the iridium anomaly associated with many K-T boundary sediments?
Keller contends that the Chicxulub impact took place about 300,000 years before the K-T boundary (read the debate here). The iridium anomaly at the K-T boundary is widely acknowledged - including Keller - to be of meteorite impact origin. In a previous paper she has proposed the possibility of multiple impacts to account for this iridium anomaly, even naming the Shiva crater as a potential candidate for a second impact site.
Now she seems to be against the Shiva impact theory and cites a lack of local evidence in Indian continental deposits for the Shiva impact event, but see....let me add an intriguing possibility... the Deccan volcanics complicate the stratigraphy and everything depends on the exact timing of the impact. If the impact did not coincide with deposition of sediments and instead took place during eruptions, then all that evidence could be lost..obliterated within the lava flows. At end Cretaceous in the Indian continent these events, volcanism and sedimentation phases, alternated over periods of tens to a few hundred thousand years, and how can one be sure if the impact didn't coincide with a period of non-deposition and volcanism?
Given Keller's strong stance that there was no single smoking gun for the K-T mass extinction its a little bizarre that she is now dissing Chatterjee's hypothesis so readily and apparently rooting for the Deccan volcanics as the smoking gun!
So one impact definitely but how many more? ...still unanswered..
The most sympathetic view of Chatterjee's hypothesis was from The Economist who suggested that if the Shiva impact post-dates the Chicxulub impact, there should be two stratigraphically separated iridium enriched layers. The article pointed out to the Anjar deposits in west India as a site which might contain these two iridium anomalies.
I followed up on the work on the Anjar sediments. These are lacustrine (lake deposits) inter-trappean sediments i.e. they are sandwiched between Deccan volcanic layers. Magnetostratigraphy indicates the sediments to be deposited in the latest Maastrichtian (the uppermost division of the Cretaceous) within the magnetic zone 29R (R- reversed magnetic field), which contains the K-T boundary at many locales. There are three iridium enriched layers each occurring below a clay rich bed.
Sounds like an ideal candidate in support of multiple impacts.
...Except there seems to be no evidence that these iridium anomalies are due to meteorite impacts or that they encompass the K-T boundary. Geochemical analysis shows that the section lacks the negative carbon isotope excursion that is characteristic of the K-T event found in terrestrial deposits elsewhere (see here). There is evidence in the form of high temperature low pressure cristobalite ( a variety of quartz) in the clay beds associated with the iridium (see here) that these could represent leaching and enrichment from a alkali volcanic tuff. Impact deposits should contain high pressure varieties of quartz.
Early alkali Deccan volcanics along the western margin of the rifted Indian continent are known to be enriched in iridium (see here) and leaching and secondary enrichment could form concentrated iridium layers.
Finally the sediment above the iridium enriched layers contain dinosaur egg shells and late Cretaceous ostracods (see here). Along with sedimentological features this indicates that the iridium layers at Anjar predate the K-T extinction significantly and were formed in the early part of magnetic cron 29R.
It does not appear that these particular iridium layers are a result of the Shiva impact if it did occur. These deposits are well within the impact fallout zone for the Shiva impact and should have contained direct impact evidence like shocked quartz.
So....looks like many iridium layers but not all of them associated with the K-T boundary or with meteor impacts.
The Chicxulub impact and the Deccan volcanism overlapped. The stratigraphy of end Cretaceous is going to be messy and it won't be possible to sort out events that took place with a few tens of thousands of years of each other and tie them to either an impact or volcanism. If there was a second impact its record could easily be amalgamated with that of volcanism and very hard to resolve within Indian continental deposits as an independent event .
Direct drilling and study of the recovered core from the Bombay High basin basement which is supposed to be the impact site should decide the issue
...if and when that data comes around.
My head is reeling with these details and nuances. I'll leave readers to sort through the evidence.
Here is the abstract. The talk apparently got a skeptical reception. Chatterjee envisions the following scenario. The meteor hit the Indian continental plate and maybe initiated rifting between Seychelles and India.
The crater is now broken up along the rift. Part of the structure lies along the Indian west coast and part of it along the Seychelles margin.
The argument is at present based mostly on the geometry and structure of the basins and rifted margins matching what a meteorite hit will produce if it hit the crust at a shallow angle from the southwest.
But according to what I have read so far there is little direct local evidence of this being an impact crater. There is no core recovered from the supposed impact site and so no information available on whether the features that are seen at the Chicxulub crater in Mexico i.e. impact melt rock, high pressure quartz phases, chaotic breccia, tsunami deposits and so on are present at this site too. Also Chatterjee has not given as far as I know a convincing account of why various models of continental rifting, flood volcanism and denudational isostacy are inadequate explanations of the continental margin geology of west India and the Seychelles.
Yet, end Cretaceous always fascinates.
Chatterjee think this impact occurred either simultaneously with the Chicxulub impact or it post-dates the impact in Mexico. I found this view point very interesting for the response it drew from Gerta Keller who is a strong proponent of the theory that the Chicxulub impact was not the primary cause of the K-T extinction. She is pushing for the Deccan volcanics being the real culprit.
Keller has been quoted rejecting Chatterjee's theory, saying there is no evidence for such an impact in Indian deposits. But she leaves a big question unanswered, one that is prompted by her own work and theory.
How do you explain the iridium anomaly associated with many K-T boundary sediments?
Keller contends that the Chicxulub impact took place about 300,000 years before the K-T boundary (read the debate here). The iridium anomaly at the K-T boundary is widely acknowledged - including Keller - to be of meteorite impact origin. In a previous paper she has proposed the possibility of multiple impacts to account for this iridium anomaly, even naming the Shiva crater as a potential candidate for a second impact site.
Now she seems to be against the Shiva impact theory and cites a lack of local evidence in Indian continental deposits for the Shiva impact event, but see....let me add an intriguing possibility... the Deccan volcanics complicate the stratigraphy and everything depends on the exact timing of the impact. If the impact did not coincide with deposition of sediments and instead took place during eruptions, then all that evidence could be lost..obliterated within the lava flows. At end Cretaceous in the Indian continent these events, volcanism and sedimentation phases, alternated over periods of tens to a few hundred thousand years, and how can one be sure if the impact didn't coincide with a period of non-deposition and volcanism?
Given Keller's strong stance that there was no single smoking gun for the K-T mass extinction its a little bizarre that she is now dissing Chatterjee's hypothesis so readily and apparently rooting for the Deccan volcanics as the smoking gun!
So one impact definitely but how many more? ...still unanswered..
The most sympathetic view of Chatterjee's hypothesis was from The Economist who suggested that if the Shiva impact post-dates the Chicxulub impact, there should be two stratigraphically separated iridium enriched layers. The article pointed out to the Anjar deposits in west India as a site which might contain these two iridium anomalies.
I followed up on the work on the Anjar sediments. These are lacustrine (lake deposits) inter-trappean sediments i.e. they are sandwiched between Deccan volcanic layers. Magnetostratigraphy indicates the sediments to be deposited in the latest Maastrichtian (the uppermost division of the Cretaceous) within the magnetic zone 29R (R- reversed magnetic field), which contains the K-T boundary at many locales. There are three iridium enriched layers each occurring below a clay rich bed.
Sounds like an ideal candidate in support of multiple impacts.
...Except there seems to be no evidence that these iridium anomalies are due to meteorite impacts or that they encompass the K-T boundary. Geochemical analysis shows that the section lacks the negative carbon isotope excursion that is characteristic of the K-T event found in terrestrial deposits elsewhere (see here). There is evidence in the form of high temperature low pressure cristobalite ( a variety of quartz) in the clay beds associated with the iridium (see here) that these could represent leaching and enrichment from a alkali volcanic tuff. Impact deposits should contain high pressure varieties of quartz.
Early alkali Deccan volcanics along the western margin of the rifted Indian continent are known to be enriched in iridium (see here) and leaching and secondary enrichment could form concentrated iridium layers.
Finally the sediment above the iridium enriched layers contain dinosaur egg shells and late Cretaceous ostracods (see here). Along with sedimentological features this indicates that the iridium layers at Anjar predate the K-T extinction significantly and were formed in the early part of magnetic cron 29R.
It does not appear that these particular iridium layers are a result of the Shiva impact if it did occur. These deposits are well within the impact fallout zone for the Shiva impact and should have contained direct impact evidence like shocked quartz.
So....looks like many iridium layers but not all of them associated with the K-T boundary or with meteor impacts.
The Chicxulub impact and the Deccan volcanism overlapped. The stratigraphy of end Cretaceous is going to be messy and it won't be possible to sort out events that took place with a few tens of thousands of years of each other and tie them to either an impact or volcanism. If there was a second impact its record could easily be amalgamated with that of volcanism and very hard to resolve within Indian continental deposits as an independent event .
Direct drilling and study of the recovered core from the Bombay High basin basement which is supposed to be the impact site should decide the issue
...if and when that data comes around.
My head is reeling with these details and nuances. I'll leave readers to sort through the evidence.
Wednesday, October 28, 2009
Cambrian Explosion: This Time Its The Calcium That Did It
Geological processes and evolution - 4
A short article in Science Daily describes research that suggests that a buildup of calcium in the oceans in the early Cambrian provided the necessary trigger for the Cambrian "explosion" - the pronounced expansion and diversification of multicellular groups of animals. Some of the best examples of this evolutionary radiation is preserved in deposits like the Burgess Shale and the Chengjiang strata.
Here is the one sentence summary-
There is deja vu when I read another ultimate causative explanation for the Cambrian explosion. Over the years you could write a similar sentence but substitute the word calcium with the sudden increase in oxygen, the warming of the earth following the thawing of the snowball earth, the increase in shallow shelf areas following marine transgression, all proposed as a one point explanations of this evolutionary phase in earth history.
Reading the press release you get a sense that the Cambrian explosion coincided with the origin of multicelluarity. Take this sentence:
Its important to make a distinction here between the origin of a system and its subsequent diversification. Groups like fungi, plants and animals have evolved multicellularity independently of each other. Whatever triggered single celled animals to assemble into multicellular ones (metazoans), that transition did not happen in the Cambrian but much before in the late Proterozoic maybe as much as 50 -100 million years before.
The original study recognizes this point but it gets lost in the press release.
There is a good and improving fossil record of metazoans from the late Proterozoic Ediacaran fauna and other types of fossil preservation that indicates that molecular mechanisms for cell to cell signaling and cell adhesion must have evolved well before the Cambrian. Multicellularity in animals originated long before the Cambrian explosion occurred and long before the rise of calcium in Cambrian sea-water.
The figure below summarizes the current fossil record of the evolution of metazoans. The Cambrian "explosion" corresponds with the Chengjiang fauna.
Source: On The Origin of Phyla
Explanations of the origin of metazoans and subsequent evolutionary radiations like the Cambrian explosion involve long and intertwined causal chains. A rise in oxygen by late Proterozoic may have favored larger body size and one solution to achieve this large size was to aggregate into colonies of cells which eventually became integrated as one organism. The marine transgressions by late-Proterozoic early Cambrian expanded available shallow marine shelf areas and created large and diverse ecologic niches for evolutionary diversification to take place. The evolution of predation would have set forth selective pressures for skeletonization. Many organisms would have taken opportunistic advantage of the rise of calcium in sea-water to boost skeletal production. Likewise calcium may have provided stability for even larger masses of cells to aggregate.
There were many geological and ecological factors at play feeding of each other that were responsible for one of the major transitions in the history of life. Insisting on just one cause as the most important to the exclusion of others is too simplistic.
A short article in Science Daily describes research that suggests that a buildup of calcium in the oceans in the early Cambrian provided the necessary trigger for the Cambrian "explosion" - the pronounced expansion and diversification of multicellular groups of animals. Some of the best examples of this evolutionary radiation is preserved in deposits like the Burgess Shale and the Chengjiang strata.
Here is the one sentence summary-
The researchers succeeded to show that the massive and sudden surge in the calcium concentration of the Cambrian seawater -- that is believed to be the result of volcanically active mid-ocean ridges -- not only initiated the buildup of calcified shells, but was also mandatory for the aggregation and stabilization of multicellular sponge structures. This allows, on the other hand, to formulate a novel theory where the geologically induced increase of marine calcium might be the key for understanding the Cambrian Explosion of Life.
There is deja vu when I read another ultimate causative explanation for the Cambrian explosion. Over the years you could write a similar sentence but substitute the word calcium with the sudden increase in oxygen, the warming of the earth following the thawing of the snowball earth, the increase in shallow shelf areas following marine transgression, all proposed as a one point explanations of this evolutionary phase in earth history.
Reading the press release you get a sense that the Cambrian explosion coincided with the origin of multicelluarity. Take this sentence:
However, the causes of its origin have been the subject of debate for decades, and the question of what was the trigger for the single cell microorganisms to assemble and organize into multicellular organisms has remained unanswered until now.
Its important to make a distinction here between the origin of a system and its subsequent diversification. Groups like fungi, plants and animals have evolved multicellularity independently of each other. Whatever triggered single celled animals to assemble into multicellular ones (metazoans), that transition did not happen in the Cambrian but much before in the late Proterozoic maybe as much as 50 -100 million years before.
The original study recognizes this point but it gets lost in the press release.
There is a good and improving fossil record of metazoans from the late Proterozoic Ediacaran fauna and other types of fossil preservation that indicates that molecular mechanisms for cell to cell signaling and cell adhesion must have evolved well before the Cambrian. Multicellularity in animals originated long before the Cambrian explosion occurred and long before the rise of calcium in Cambrian sea-water.
The figure below summarizes the current fossil record of the evolution of metazoans. The Cambrian "explosion" corresponds with the Chengjiang fauna.
Source: On The Origin of Phyla
Explanations of the origin of metazoans and subsequent evolutionary radiations like the Cambrian explosion involve long and intertwined causal chains. A rise in oxygen by late Proterozoic may have favored larger body size and one solution to achieve this large size was to aggregate into colonies of cells which eventually became integrated as one organism. The marine transgressions by late-Proterozoic early Cambrian expanded available shallow marine shelf areas and created large and diverse ecologic niches for evolutionary diversification to take place. The evolution of predation would have set forth selective pressures for skeletonization. Many organisms would have taken opportunistic advantage of the rise of calcium in sea-water to boost skeletal production. Likewise calcium may have provided stability for even larger masses of cells to aggregate.
There were many geological and ecological factors at play feeding of each other that were responsible for one of the major transitions in the history of life. Insisting on just one cause as the most important to the exclusion of others is too simplistic.
Saturday, October 24, 2009
The Latest Numbers On Arctic Oil and Gas Potential
Some interesting readings I came across on hydrocarbon resources and challenges over the last few days.
Geology.com has published a report by the Energy Information Administration on the latest estimates of undiscovered technically recoverable oil and gas resources of the Arctic basins.
And the number is large - about 400 billion barrels of oil equivalent or about 20 odd percent of the world's undiscovered resources. This is an estimate based on occurrence of geologically favorable conditions in various Arctic basins. These are resources or potential. They will be or rather a fraction of these will be added to reserves only when someone drills and more directly estimates the amount of hydrocarbons that can be economically recovered.
We won't be running out of oil and gas or other fossil fuels like coal soon, geologically, and BP's chief executive officer Tony Hayward thinks that in 2030 fossil fuels will still be meeting 80% of the world's energy needs. He explains his position in a speech given at the Oil and Money conference, London. The title of the conference conjures up images of greedy petro-oligarchs doing everything to maintain a vice-like grip on the supremacy of fossil fuels, but the changeover to renewables won't be easy given the enormous gap that exists between the contributions from fossil fuels and renewables to our energy mix. India for example generates 70% of its electricity from coal and has plans to build plenty of coal fired power plants in the near future. The contribution of solar and wind to power generation in India is currently negligible. The U.S generates about 46% of power from coal and the contribution of non-hydro renewables to power generation is just 3%.
If fossil fuels are going to be an important if slowly declining part of our energy mix for some time to come then Geoffrey Styles of Energy Outlook argues that we rethink our reluctance to pursue low emissions strategies like carbon capture and sequestration (CCS). He writes on not just the technological and economic challenges facing CCS but also a public backlash against it based on - he thinks - a lack of education among the public about geological principles and the efficacy and safety of CCS.
Plenty to think about as the Copenhagen climate change summit nears.
Geology.com has published a report by the Energy Information Administration on the latest estimates of undiscovered technically recoverable oil and gas resources of the Arctic basins.
And the number is large - about 400 billion barrels of oil equivalent or about 20 odd percent of the world's undiscovered resources. This is an estimate based on occurrence of geologically favorable conditions in various Arctic basins. These are resources or potential. They will be or rather a fraction of these will be added to reserves only when someone drills and more directly estimates the amount of hydrocarbons that can be economically recovered.
We won't be running out of oil and gas or other fossil fuels like coal soon, geologically, and BP's chief executive officer Tony Hayward thinks that in 2030 fossil fuels will still be meeting 80% of the world's energy needs. He explains his position in a speech given at the Oil and Money conference, London. The title of the conference conjures up images of greedy petro-oligarchs doing everything to maintain a vice-like grip on the supremacy of fossil fuels, but the changeover to renewables won't be easy given the enormous gap that exists between the contributions from fossil fuels and renewables to our energy mix. India for example generates 70% of its electricity from coal and has plans to build plenty of coal fired power plants in the near future. The contribution of solar and wind to power generation in India is currently negligible. The U.S generates about 46% of power from coal and the contribution of non-hydro renewables to power generation is just 3%.
If fossil fuels are going to be an important if slowly declining part of our energy mix for some time to come then Geoffrey Styles of Energy Outlook argues that we rethink our reluctance to pursue low emissions strategies like carbon capture and sequestration (CCS). He writes on not just the technological and economic challenges facing CCS but also a public backlash against it based on - he thinks - a lack of education among the public about geological principles and the efficacy and safety of CCS.
Plenty to think about as the Copenhagen climate change summit nears.
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