Wednesday, October 27, 2010

Fossils In Amber From Eocene Cambay Basin India

This story is being covered by a number of science news outlets. Science Daily covers it here. The link to the paper in PNAS is here.

Cambay basin in which these fossils were found is a cratonic rift basin that formed beginning mid-late Cretaceous as India broke away from Africa and then Madagascar and finally from Seychelles. The fossils have been found in near shore deposits rich in lignite and shale which contains fossil wood as well. The graphic below shows the configuration of continents in early Cretaceous.

 The Cambay basin formed along the eastern continental margin of the evolving Indian continent, its orientation following ancient Precambrian mobile belt trends, ancient weak zones of the crust along which fragments of Gondwanaland broke. The figure below shows the position of the Cambay basin among other Indian sedimentary basins.

Source: Geotimes

 After its breakup from Gondwanaland the Indian subcontinent drifted northeastwards as a seemingly isolated block for tens of millions of years  until it slammed into Asia, initial contact beginning perhaps around 50 million years or so.

The preserved insect fossils date from a time just before or at the beginning of contact between India and Asia when there would have been island chains or perhaps the first land bridges between the two continents. They don't show similarities with fauna of Madagascar or Africa the two fragments of Gondwana that India most recently broke away from.  Instead they show similarities with fauna from the Eocene in N. Europe, Asia, to recent Australiaasia  and the Miocene to recent of Americas suggesting faunal exchange between these continents by early Cenozoic times.

Perhaps oceanic currents were favorable in bringing flotsam and jetsam to Indian shores from these continents and along with it an exchange of insect passengers. The faunal similarities from this time period between India and other continents though might be restricted to small animals like insects which could perhaps survive long journeys on rafts. Interesting to speculate whether larger animals groups like reptiles and early mammals from India show some degree of Cretaceous and Early Cenozoic endemism.

The amber in which these fossils insects are entombed has been shown to be chemically similar to Dipterocarpaceae, a family of hardwood trees, implying that these types of broad leaf forests were present during the early Eocene and evolved perhaps even earlier.

The Early Cenozoic was a period of global warm climate and the evolutionary radiation of several groups of social insects took place during this time. The variety of insect fossils preserved in the Cambay shale reflects this diversification.

Tuesday, October 26, 2010

I Can't Get No Satisfaction

I just had to put this up.

NPR's Fresh Air interviews Rolling Stones Keith Richards:

In an interview on Fresh Air, Richards recounts how he woke up just long enough to record the famous opening riff of "Satisfaction" on a cassette player he'd placed next to his bed.

"I go to bed as usual with my guitar, and I wake up the next morning, and I see that the tape is run to the very end," Richards tells Terry Gross. "And I think, 'Well, I didn't do anything. Maybe I hit a button when I was asleep.' So I put it back to the beginning and pushed play and there, in some sort of ghostly version, is [the opening lines to 'Satisfaction']. It was a whole verse of it. And after that, there's 40 minutes of me snoring. But there's the song in its embryo, and I actually dreamt the damned thing."

Einstein had dreamy thoughts about the relativistic nature of space-time. Keith Richards dreamt up the most famous guitar riff in rock and roll.

Creativity is a funny beast.

Monday, October 25, 2010

Back From The Lesser Himalayas

I am back after several days of hiking in the Mukteshwar area of Uttarakhand. I'll be writing a more geology oriented post in a few days but let me first put up a few photos to give you an idea about the place.

It was beautiful.. there is no other word to describe it.. take a look.

Sunrise over Nanda Devi (extreme left).. height 25,643 feet

Temple on a hill..

Walking trail....

Tea break during a long hike..

A British era cottage...where I was staying..

October hillside.. with cherry blossoms..

The trip was too short...ain't that always the problem with holidays .. :)  There are lots of trails and places I still want to explore. I will definitely be going back.

Tuesday, October 12, 2010

Going Hiking In The Lesser Himalayas

I'll be of the radar for the next couple of weeks or so. First to Delhi for some work and then off to Mukteshwar, a small temple town in the Kumaon region of the Himalayas for a few days of hiking and recreation.

Mukteshwar falls in what is known as the Lesser Himalayas. As the name suggest it reflects the physiography of the region as compared to the Greater Himalayas. Overall the Lesser Himalayas as not as rugged and high as the Greater Himalayas. There are geological differences as well.

I've put below a rough sketch of the major litho-tectonic provinces of the Himalayan orogen. These represent the roughly WNW-ESE trending deformed blocks of the Indian plate as the Indian shelf broke up along major faults during the India-Asia collision.

From Delhi I'll be traveling on the Quaternary alluvium until I cross the Himalayan frontal thrust which brings into contact the Quaternary alluvium with the  Neogene Siwalik mountains - remnants of the Cenozoic foreland basin that formed in front of the rising Himalayas.

I will then cross the Main Boundary Thrust, which places the Lesser Himalayas over the Siwaliks. The Lesser Himalayas are made up of Proterozoic to Paleozoic rocks (geological division - the Lesser Himalayan sequence) and represent the basement and metamorphosed cover of the Indian shelf. Beyond that in thrust contact along the Main Central Thrust are the Greater Himalayas which are also made up of the Proterozoic basement and Paleozoic metamorphosed cover of the Indian shelf (geological division -Greater Himalayan crystalline complex).

The Greater Himalayas are generally of higher metamorphic grade and may represent the exhumation of a deeper crustal level.

Beyond that.. tectonically juxtaposed with the Greater Himalayas along the South Tibetan Detachment are the Tethyan Himalayas which are composed of mostly unmetamorphosed Paleozoic to Eocene sedimentary cover deposited on the Indian shelf. Beyond that is the zone of collision known as the Indus-Tsangpo suture and beyond that .... the Asian plate.

I've been able to draw only the Himalayan Frontal Thrust and the Main Boundary Thrust with some confidence. I am not well versed enough to pick out the other boundaries between the provinces from a satellite image. But I think I've got the general placement of the provinces correct.

As I mentioned, Mukteshwar falls in the physio-graphic province of the Lesser Himalayas.... but geologically..?

I'll write about it in more detail with some maps and cross sections when I return. There is somewhat of a surprise regarding the geology and structure around Mukteshwar.

The night train from Delhi will put me in the Siwalik foothills by dawn. Its an early morning drive from there up to Mukteshwar which is at an altitude of around 7200 feet.

I hope to catch the sunrise as I drive up the Cenozoic alluvial fans that make up the Siwaliks and cross over into the Proterozoic metasediments of the Lesser Himalayas...

Wednesday, October 6, 2010

China And Rare Earths

On Point Radio invites geologist Anthony Mariano to talk about rare earth elements, their geological distribution and applications and why China currently dominates the rare earth market.

Very briefly... China dominates because of cheap labor and a willingness until of late to tolerate environmental degradation that accompanies mining and processing of rare earth deposits... but listen to the talk for details of how this came to be.

Christine Parthemore, the other guest talks on U.S. national security and policy implications of China's rare earth market domination.

The geological context of these deposits in China varies depending on geography. The inner Mongolia deposits are within  carbonatite like bodies and veins that are intrusive and replace dolomites and shales (see here and here). In southern China the rare earths occur as ions adsorbed on clays, which are a weathered residual deposit derived from a  mostly granitic source.

Quite a good discussion.

Monday, October 4, 2010

A New Version Of Bhuvan Has Been Released

The Indian Space Research Organization has released a new beta version of Bhuvan a web mapping tool which serves images of India and the rest of the world taken from various Indian remote sensing satellites. It is available in 2D and 3D versions.

The new versions looks a little slicker and cleaner than its predecessor. But 5.8 meters is the highest resolution imagery available via Bhuvan while Google Maps and Google Earth both have long started serving 1 meter or so images of Indian cities and hinterland.

In case you are wondering why, here is the Remote Sensing data policy of the Government of India:

Government prescribes the following guidelines to be adopted for dissemination of satellite remote sensing data in India:

All data of resolutions up to 5.8 m shall be distributed on a nondiscriminatory basis and on “as requested basis”.

With a view to protect national security interests, all data of 5.8 m and better than 5.8 m resolution images will be screened by the appropriate agency before distribution so that images of sensitive areas are excluded.
a. Data of 5.8m and up to 1m resolution can be distributed to users after screening and ensuring that the sensitive areas are excluded.

b. Data of 1m resolution and better will also be screened as above and the following procedure will be followed for its distribution.
i. Government users can obtain the data without any further clearance.
ii. Private sector agencies, recommended by at least one Government agency for use of 1 m and better resolution data for supporting development activities, can obtain it without any further clearance.
iii. Private, foreign and other users can obtain the data after further clearance from an inter-agency High Resolution Image Clearance Committee (HRC).
iv. Specific requests for data of sensitive areas, by any user, can be distributed only after obtaining clearance from HRC.
v. Specific sale/non-disclosure agreements to be concluded between NRSC and users for data of 1 m resolution and better.

What this means is that under the current policy scenario, high resolution (1 meter or so) images collected from Indian satellites will not be available via open access free web mapping tools like Bhuvan. The only users of this high res imagery will be those who have obtained clearances for images of pre-defined geographic extent to be viewed in specialized GIS and Remote Sensing software.

This will severely limit the user base of Bhuvan and Indian imagery:

For example-

1) That means despite a developer API for Bhuvan being available there will likely be few takers especially for designers of urban applications.

2) And Bhuvan for the mobile market?... all those location apps, business listings, navigation already available via Google..?... forget it.. can't be done when your street and neighborhood looks like an undifferentiated granular blob.

3) Additional India specific thematic layers..?... many already  available at other free web mapping apps like Geocommons, India Biodiversity PortalBhoosampada, and  Census India Web Mapping.

unless there is a policy shift with regards to availability of high resolution images... I don't see the point of Bhuvan..