Relationships between crustal contamination and crystallisation in continental flood basalt magmas with special reference to the Deccan Traps of the Western Ghats, India

The Western Ghats represents a small part of the Deccan Traps continental flood basalt province that erupted about 65 million years ago. It is an area of outstanding scenic beauty and has attracted the attention of geologists, naturalists and geomorphologists for over a century. One of the unique habitats in the Western Ghats are the rocky plateaus. Previous studies have covered plant species composition, geological and geomorphological status of the rocky plateaus. An analytical study of microhabitats and associated therophytes of four rocky plateau sites was conducted. The study sites were Durgawadi Plateau, Naneghat Plateau which are basalt outcrops and Zenda plateau and Amba Plateau, which are laterite outcrops on the escarpment of the northern Western Ghats. The results revealed a correlation between basalt and lateritic rock outcrops as well as ephemeral plant elements. All four outcrops are similar in their nutrient status but the microhabitats of these plateaus are extremely different from each other.

Download Full-text

Resource utilization and beneficial aspects of invasive alien weeds with special reference to the Western Ghats, India.

Invasive alien plants: an ecological appraisal for the Indian subcontinent ◽

10.1079/9781845939076.0271 ◽

2011 ◽

pp. 271-281

Author(s):

R. R. Rao ◽

S Kavitha ◽

N. Sathyanarayana

Keyword(s):

Special Reference ◽

Resource Utilization ◽

Western Ghats ◽

The Western Ghats

Download Full-text

Geochemistry of Deccan Tholeiite Flows and Dykes of Elephanta Island: Insights into the Stratigraphy and Structure of the Panvel Flexure Zone, Western Indian Rifted Margin

Geosciences ◽

10.3390/geosciences10040118 ◽

2020 ◽

Vol 10 (4) ◽

pp. 118 ◽

Cited By ~ 2

Author(s):

Vanit Patel ◽

Hetu Sheth ◽

Ciro Cucciniello ◽

Gopal W. Joshi ◽

Wencke Wegner ◽

...

Keyword(s):

Western Ghats ◽

Normal Fault ◽

Flood Basalt ◽

Lava Flows ◽

Dyke Swarm ◽

Geochemical Data ◽

Current View ◽

Structural Framework ◽

Rifted Margin ◽

The Western Ghats

Elephanta Island near Mumbai is an important area for understanding the stratigraphic and structural framework of the Deccan flood basalt province in the tectonically disturbed Panvel flexure zone on the western Indian rifted margin. Elephanta exposes a west-dipping, 66–65 Ma sequence of tholeiitic lava flows and dykes. Geochemical correlations with the thick, horizontal, 66–65 Ma Western Ghats sequence to the east show that lava flows of the Khandala and Ambenali formations are present at Elephanta, with two lava flows probably being locally derived. The Elephanta tholeiites have experienced crystal fractionation and accumulation, particularly of olivine. They have εNd(t) ranging from +5.4 to −7.9 and (87Sr/86Sr)t from 0.70391 to 0.70784, with most tholeiites little contaminated by continental lithosphere, probably lower crust. Field and geochemical data indicate a normal fault along the central part of Elephanta with a 220 m downthrow, consistent with a domino-type block-faulted structure of Elephanta, and the surrounding area as previously known. Seventeen of the 20 analyzed Elephanta intrusions, striking ~N–S, belong to the Coastal dyke swarm of the western Deccan province. Several of these are probable feeders to the Ambenali Formation in the Western Ghats sequence, requiring reconsideration of the current view that the voluminous Wai Subgroup lavas of the Western Ghats were erupted without organized crustal extension. East–west-directed extensional strain was already active at 66–65 Ma along this future (62.5 Ma) rifted continental margin. A young (~62 Ma) ankaramite dyke on Elephanta Island is a probable feeder to the Powai ankaramite flow in the 62.5 Ma Mumbai sequence 20 km to the northwest.

Download Full-text

Late Jurassic continental flood basalt doleritic dykes in northwestern Cuba: remnants of the Gulf of Mexico opening

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.179.5.445 ◽

2008 ◽

Vol 179 (5) ◽

pp. 445-452 ◽

Cited By ~ 1

Author(s):

James Allibon ◽

Henriette Lapierre ◽

François Bussy ◽

Marc Tardy ◽

Esther M. Cruz Gàmez ◽

...

Keyword(s):

South America ◽

Gulf Of Mexico ◽

Late Jurassic ◽

Crustal Contamination ◽

Flood Basalt ◽

Upper Jurassic ◽

Continental Flood Basalt ◽

Continental Flood Basalts ◽

Accreted Terranes ◽

Eastern Cuba

Abstract Accreted terranes, comprising a wide variety of Late Jurassic and Early Cretaceous igneous and sedimentary rocks are an important feature of Cuban geology. Their characterization is helpful for understanding Caribbean paleo-geography. The Guaniguanico terrane (western Cuba) is formed by upper Jurassic platform sediments intruded by microgranular dolerite dykes. The geochemical characteristics of the dolerite whole rock samples and their minerals (augitic clinopyroxene, labradorite and andesine) are consistent with a tholeiitic affinity. Major and trace element concentrations as well as Nd, Sr and Pb isotopes show that these rocks also have a continental affinity. Sample chemistry indicates that these lavas are similar to a low Ti-P2O5 (LTi) variety of continental flood basalts (CFB) similar to the dolerites of Ferrar (Tasmania). They derived from mixing of a lithospheric mantle source and an asthenopheric component similar to E-MORB with minor markers of crustal contamination and sediment assimilation. However, the small quantity of Cuban magmatic rocks, similarly to Tasmania, Antarctica and Siberia differs from other volumetrically important CFB occurrences such as Parana and Deccan. These dolerites are dated as 165-150 Ma and were emplaced during the separation of the Yucatan block from South America. They could in fact be part of the Yucatan-South America margin through which the intrusive system was emplaced and which was later accreted to the Cretaceous arc of central Cuba and to the Palaeogene arc of eastern Cuba. These samples could therefore reflect the pre-rift stage between North and South America and the opening of the gulf of Mexico.

Download Full-text

The genus Drepanolejeunea (Spruce) Schiffn. (Lejeuneaceae; Marchantiophyta) in the Western Ghats with special reference to Kerala

Plant Science Today ◽

10.14719/pst.2020.7.3.789 ◽

2020 ◽

Vol 7 (3) ◽

Author(s):

V K Chandini ◽

B Mufeed ◽

Manju C Nair ◽

K P Rajesh

Keyword(s):

Special Reference ◽

Western Ghats ◽

New Records ◽

Present Survey ◽

The Family ◽

The Western Ghats

Diversity of the genus Drepanolejeunea (Spruce) Schiffn. of the family Lejeuneaceae in Kerala is discussed in detail. So far, 8 species have been reported from the Western Ghats, of which 6 occur in Kerala. This paper provides detailed descriptions of 5 of the species collected from Kerala during the present survey. Among these, Drepanolejeunea erecta (Steph.) Mizut. is new to the Western Ghats, D. fleischeri (Steph.) Grolle & Zhu, D. pentadactyla (Mont.) Steph. and D. ternatensis (Gottsche) Steph. are new records for Kerala.

Download Full-text

40Ar/39Ar dating of mineral separates and whole rocks from the Western Ghats lava pile: further constraints on duration and age of the Deccan traps

Earth and Planetary Science Letters ◽

10.1016/s0012-821x(00)00159-x ◽

2000 ◽

Vol 180 (1-2) ◽

pp. 13-27 ◽

Cited By ~ 170

Author(s):

C Hofmann ◽

G Féraud ◽

V Courtillot

Keyword(s):

Western Ghats ◽

Deccan Traps ◽

Lava Pile ◽

The Western Ghats

Download Full-text

U-Pb constraints on pulsed eruption of the Deccan Traps across the end-Cretaceous mass extinction

Science ◽

10.1126/science.aau2422 ◽

2019 ◽

Vol 363 (6429) ◽

pp. 862-866 ◽

Cited By ~ 85

Author(s):

Blair Schoene ◽

Michael P. Eddy ◽

Kyle M. Samperton ◽

C. Brenhin Keller ◽

Gerta Keller ◽

...

Keyword(s):

Mass Extinction ◽

Temporal Correlation ◽

High Volume ◽

Flood Basalt ◽

Deccan Traps ◽

Zircon Geochronology ◽

Mass Extinctions ◽

Continental Flood Basalt ◽

Environmental Deterioration ◽

Before And After

Temporal correlation between some continental flood basalt eruptions and mass extinctions has been proposed to indicate causality, with eruptive volatile release driving environmental degradation and extinction. We tested this model for the Deccan Traps flood basalt province, which, along with the Chicxulub bolide impact, is implicated in the Cretaceous-Paleogene (K-Pg) extinction approximately 66 million years ago. We estimated Deccan eruption rates with uranium-lead (U-Pb) zircon geochronology and resolved four high-volume eruptive periods. According to this model, maximum eruption rates occurred before and after the K-Pg extinction, with one such pulse initiating tens of thousands of years prior to both the bolide impact and extinction. These findings support extinction models that incorporate both catastrophic events as drivers of environmental deterioration associated with the K-Pg extinction and its aftermath.

Download Full-text

Mineralogy, geochemistry and 40Ar–39Ar geochronology of the Barda and Alech complexes, Saurashtra, northwestern Deccan Traps: early silicic magmas derived by flood basalt fractionation

Geological Magazine ◽

10.1017/s0016756818000924 ◽

2019 ◽

Vol 156 (10) ◽

pp. 1668-1690 ◽

Cited By ~ 6

Author(s):

Ciro Cucciniello ◽

Ashwini Kumar Choudhary ◽

Kanchan Pande ◽

Hetu Sheth

Keyword(s):

Magma Chamber ◽

Fractional Crystallization ◽

Mafic Magma ◽

Flood Basalt ◽

Deccan Traps ◽

Isotopic Data ◽

Continental Flood Basalt ◽

Basaltic Magmas ◽

Silicic Magmas ◽

Silicic Magmatism

AbstractMost continental flood basalt (CFB) provinces of the world contain silicic (granitic and rhyolitic) rocks, which are of significant petrogenetic interest. These rocks can form by advanced fractional crystallization of basaltic magmas, crustal assimilation with fractional crystallization, partial melting of hydrothermally altered basaltic lava flows or intrusions, anatexis of old basement crust, or hybridization between basaltic and crustal melts. In the Deccan Traps CFB province of India, the Barda and Alech Hills, dominated by granophyre and rhyolite, respectively, form the largest silicic complexes. We present petrographic, mineral chemical, and whole-rock geochemical (major and trace element and Sr–Nd isotopic) data on rocks of both complexes, along with 40Ar–39Ar ages of 69.5–68.5 Ma on three Barda granophyres. Whereas silicic magmatism in the Deccan Traps typically postdates flood basalt eruptions, the Barda granophyre intrusions (and the Deccan basalt flows they intrude) significantly pre-date (by 3–4 My) the intense 66–65 Ma flood basalt phase forming the bulk of the province. A tholeiitic dyke cutting the Barda granophyres contains quartzite xenoliths, the first being reported from Saurashtra and probably representing Precambrian basement crust. However, geochemical–isotopic data show little involvement of ancient basement crust in the genesis of the Barda–Alech silicic rocks. We conclude that these rocks formed by advanced (70–75 %), nearly-closed system fractional crystallization of basaltic magmas in crustal magma chambers. The sheer size of each complex (tens of kilometres in diameter) indicates a very large mafic magma chamber, and a wide, pronounced, circular-shaped gravity high and magnetic anomaly mapped over these complexes is arguably the geophysical signature of this solidified magma chamber. The Barda and Alech complexes are important for understanding CFB-associated silicic magmatism, and anorogenic, intraplate silicic magmatism in general.

Download Full-text