Where is deccan traps

At the end of the Cretaceous, Rajahmundry was in a shallow estuarine environment, which presented a chance that marine microfossils could be present. We were successful discovering the first direct link between Deccan Traps and the KTB mass extinction. Within a year two other teams independently discovered planktic foraminifera in intertrappean sediments in central India Jhilmili, Madhya Pradesh.

These new discoveries and improved age dating have now brought Deccan volcanism to front and center in the mass extinction debate.

Increasingly, scientists are recognizing the importance of Deccan volcanism and their global effects are being investigated. Deccan Volcanism is no longer the unspoken elephant in the room, but rapidly emerging as the critical and even most likely cause for the KTB mass extinction.

Here we highlight the scientific discoveries by our multi-disciplinary international team of investigators that have revitalized the mass extinction debate and opened the way for new studies across disciplines to evaluate the role of Deccan volcanism in the KTB mass extinction. This hotspot is still active today and last erupted on April 7, The DVP is one of the largest volcanic eruptions in Earth history and today covers an area of , km2, or about the size of France, or Texas.

The original size prior to erosion is estimated to have been at least twice as large. The volume of lava extruded is estimated to have been about 1. Photo by Jyotiranjan Ray. This is how many compound pahoehoe flows of the Deccan look. Compare with c. Some 17 flow units are seen. Modified from Walker Compare with a and b. Figure 6. Map of the Dediapada dyke swarm in the Narmada-Satpura region of the Deccan after Krishnamacharlu, This is one of the large, spectacular oriented dyke swarms of the Deccan Traps.

Geochemical studies of these dykes are currently underway. Elevations are in metres. Internal age progression? None exists within the Deccan Figure 3. However, a this activity is not minor; large volumes of lava are emplaced in the subsurface along the west coast, and there is a scarcity of geochronological data.

In comparison, the Western Ghats section has been heavily sampled and dated. It is not. For example, according to prevalent views the plume head was all consumed in a quick phase around 66 — 65 Ma, and the predicted 60 Ma volcanic basement to the south of India, on top of the Maldives Ridge, should have formed from the narrow — km wide plume tail.

It is not clear how this plume tail could produce basalt in Bombay, 1, km to the north, at Suggestions such as northward dragging of the plume tail by the plate are ad hoc , and such drag and tilting would make impossible any systematic age progression in the first place. Enriched mantle: plume or continent? Smith proposed that ocean-island volcanism is derived from enriched continental mantle delaminated from a continent rifted along an ancient suture see also Lithospheric delamination page.

However such compositions may instead mark involvement of shallow-level, enriched continental mantle. However, if continental mantle is introduced into the oceanic mantle, e. Mahoney et al.

They opined that some of these may represent pre-Deccan oceanic seamounts. The associated intrusions were emplaced in continental shelf-and-slope-type marine sediments along the northern margin of India.

Nevertheless, the analyzed intrusions are located within the boundary of the Indian continental mantle, and the true oceanic seamounts may not have been far from the northern margin of India. Continental mantle delaminated during the early stages of India-Seychelles breakup could have migrated northward ahead of India and fed the seamounts built on oceanic lithosphere. The continent followed behind, and when it converged upon Asia it simply overrode these seamounts. This is a better explanation for the observations than the plume model.

The rocks analyzed by Mahoney et al. It may be explained by southward crack propagation through the oceanic lithosphere see below. The Cambay triple junction and other fiction.

This geophysical feature may even be a recent post-Deccan development Sheth , a. Pre-volcanic lithospheric uplift, or lack thereof? Pre-volcanic lithospheric uplift of up to a few kilometres is an essential prerequisite for all thermal models such as the plume model. This is yet another issue on which specialists of different flood basalt provinces have come to diametrically opposed conclusions e. Pachmarhi is on the Satpura horst between the Tapi and Narmada rifts.

The very youthful landscape e. The same is true of the Deccan plateau region, where the Deccan-basement contact is in the subsurface over vast areas.

Major rivers draining the Deccan plateau are of the antecedent type, i. The uplift of the Western Ghats is post-volcanic and recent possibly Miocene and younger , and not pre-volcanic uplift produced by a plume Sheth , a. There are two possible interpretations: 1 Pre-volcanic lithospheric uplift occurred and then completely decayed and was overprinted by post-volcanic uplift. This is what plume proponents advocate. Option 2 is more plausible, and there is in fact actual support for it in the form of an uplifted, extensive planation surface below the Deccan lavas in central India Dixey , ; see Sheth , a.

Note that the Western Ghats rise much higher in southern India the region little or not affected by Deccan volcanism than they do in the Deccan plateau region Figure 7. Figure 7. The main elements of the physiography of the Indian peninsula.

The Western Ghats escarpment is shown by the heavy broken line. Note the pronounced easterly drainage. Palaeolatitudes: true polar wander or crack propagation? To explain this significant discrepancy in the framework of the plume model, some workers have proposed true polar wander TPW of the Earth's mantle e. Such speculation indicates well the extent of special pleading permitted within the plume model.

Burke has questioned this postulated TPW. I propose a much simpler alternative to the TPW, illustrated by the schematic diagram shown in Figure 8b. This is that the systematically changing palaeolatitudes between the Deccan and ODP Site 33 Ma indicate southward crack propagation in a northward-moving plate with the condition that the northward plate motion was faster than the southward crack propagation.

The situation shown in Figure 8b is for a plate in the southern hemisphere. A similar progression occurs between times T2 and T3. Thus, although the crack tip propagates southward , the palaeolatitudes systematically become more northerly. Additional thoughts. I propose instead that the breakup occurred because of prolonged continental extension and an eventual ridge jump.

One interesting question is whether eclogite, a mantle rock more fusible than peridotite, could have been a source in part for the Deccan lavas. Also, the Narmada zone that crosses India has been proposed as an ancient suture between the southern Dharwar and northern Aravalli protocontinents e. Such an ancient suture may have contained trapped, eclogitized oceanic crust. Foulger et al. If eclogite constituted a major source for the Deccan, mantle fertility and not high mantle temperatures are implicated see also Yaxley , The interplay of the Deccan rift zones is responsible for this.

They are not arranged radially, are much older than the Deccan, being of at least Jurassic age, and certainly were not produced by whatever produced the Deccan. The presence of several such major rifts means that lithospheric control Anderson , c , and lithospheric extension Sheth , were important in Deccan volcanism.

The nearly circular outcrop of the Deccan proper does not reflect a spherical plume head beneath, but simply results from the confluence of numerous rift zones and the continental margin in west-central India. In conclusion , a non-plume, plate-tectonic model involving continental breakup and related mantle convection and decompression melting, is suitable for the Deccan. If radial, focused flow of the upper mantle occurs instead of vertical flow as in the plume model , a potentially unlimited volume of the mantle is available for processing.

The plume model was proposed for the Deccan more than 30 years ago, when little was known about the Deccan and about the plume mode of convection.

Today we know a lot more about the Deccan, and the plume model becomes less tenable as our knowledge grows. The originators and champions of the plume model had little or no personal knowledge of the Deccan, and their broad generalizations should have been put to critical tests by regional experts on the Deccan. The tendency has been to assume a plume origin and infer the plume properties and characteristics based on whatever is required by the observations, but if volatiles, mantle fertility, continental geology, and dynamic, evolving plates are considered, one no longer needs mantle plumes Sheth, b.

The new voices asking for new explanations e. The plume model for the Deccan has been around for over thirty years, and has failed.

We live in interesting times. The Deccan beyond the plume hypothesis. Anderson, D. Enriched asthenosphere and depleted plumes. The helium paradoxes. AGU Geodyn. Age of the Deccan Traps using Re- Os systematics. Earth Planet. Anil Kumar, Pande, K. A contact between two lava flows passes through the knees of this statue. Small features such as these suggest that slow emplacement of flows during eruptions lasting months or years. Geologists have postulated that the Deccan Trap volcanism is associated with a deep mantle plume or hot spot.

The plume or hot spot caused the continent to break apart. India has drifted north, away from the hot spot which is now under Reunion. Bhattacharji, S. Beane, J. Krishnan, M. Geological Survey of India, p. Officer, C. Rampino, M. Self, S. White, R. Skip to main content.