La Celia (volcano)
Coordinates: 38 ° 28 ′ N , 1 ° 28 ′ W La Celia is a now eroded volcano from the southeast Iberian volcanic province that was active at the end of the Miocene . It consists of the rare lamproite rock jumillite .
description
The La Celia volcano is located about 1 kilometer west of the small town of La Celia , after which it was named, about 10 kilometers west of Jumilla in the province of Murcia . It is located at 650 msnm not far from the border with the province of Albacete and is associated with the Cenajo -Jumilla- Yecla fault .
La Celia was originally a conical volcanic structure, but it was removed down to its stump. Parts of the chimney and remains of lava flows and ejecta are still present. The brown, gray to dark green lava rock, which is massive in its interior, consists of jumillite , a madupite lamproit , more precisely an olivine diopside Richterite madupite lamproitic . It shows intense surface weathering. Mineralogically, olivine ( Forsterite Fo 86-88 ) and titanium-rich phlogopite can be recognized as phenocrystals in the jumillite of La Celia . The vitreous matrix contains diopside , sanidine , richterite , orthopyroxene , leucite , apatite and the opaque minerals hematite , ilmenite , picotite and hercynite .
The volcano La Celia forms part of a neogene volcanic field in the province of Murcia and in the province of Albacete with many eroded volcanic centers and lava flows. This also includes the Cancarix volcano . The volcanic field is drained by the Río Segura and the Río Mundo .
Chemical composition
Main and trace elements
| Oxide wt.% |
La Celia | Trace elements ppm |
La Celia |
|---|---|---|---|
| SiO 2 | 49.90 | Cr | 1170 |
| TiO 2 | 1.48 | Ni | 340 |
| Al 2 O 3 | 9.77 | Zn | 98.0 |
| Fe 2 O 3 | 5.43 (dead) | Rb | 253 |
| FeO | Sr | 1375 | |
| MnO | 0.10 | Zr | 628 |
| MgO | 11.90 | Ba | 3216 |
| CaO | 6.16 | V | 108 |
| Na 2 O | 0.92 | Nd | 163 |
| K 2 O | 5.33 | Sm | 31.1 |
| P 2 O 5 | 1.60 | Pb | 116 |
| LOI | 4.81 | Th | 114 |
| K / Na | 3.82 | ||
| K / Al | 0.59 | ||
| (Na + K) / Al | 0.75 |
The jumillite of the La Celia volcano is a metaluminous, mafic rock with an ultrapotassic character (K / Na> 3). The mesocrate volcanite belongs to the alkali rocks with a predominance of potassium . It is characterized by very high concentrations of MgO of almost 12 percent by weight and CaO is also quite high at 6 percent by weight. The rock, however, is depleted of Al 2 O 3 and Na 2 O .
In the case of trace elements, there is a clear accumulation of incompatible elements , in particular LILE such as strontium , barium and lead , but also HFSE such as uranium and thorium show high levels. The very high concentrations of chromium and vanadium are also remarkable .
Isotope ratios
The following initial ratios were determined for the radioisotopes of Sr, Nd and Pb:
| Isotopes | Ratio La Celia |
|---|---|
| 87 Sr / 86 Sr | 0.717191 |
| 143 Nd / 144 Nd | 0.512175 |
| 206 Pb / 204 Pb | 18.777 |
| 207 Pb / 204 Pb | 15.682 |
| 208 Pb / 204 Pb | 39.007 |
In the isotopes, 143 Nd / 144 Nd is low, but 87 Sr / 86 Sr is significantly increased. Their ratio lies in the enriched quadrant and approaches the values of upper crustal rocks, Atlantic sediments (from the continental edge of Northwest Africa) and also the value of the enriched mantle component EM 2 . A correspondence with the situation in Tuscany and the Western Alps can also be observed for these two parameters. The lead ratios, which overlap with the values for oceanic sediments and are very similar to the cordierite- rich lavas of south-east Spain, also correspond to Tuscany. The quite high 208 Pb / 204 Pb ratio is also striking .
Deposit and mineral discovery site
The apatite- rich volcanic rock was mined in two mines ( Nuestra señora del Carmen and La Mina-Caserío de La Celia ) for the production of artificial fertilizers in the 20th century because of its high phosphorus content. The mined rock was transported by rail to Minateda south of Hellín for further processing. These mining activities have now stalled for some time. The two mines are popular with mineral collectors, particularly because of the beautiful asparagus green fluoroapatite and the rare minerals warwickite and yuanfuliite . There are also analcime , augite , fluoro-richterite, hydroxyapatite , pseudobrookite , tridymite and wadeit .
Age
The jumillite of the La Celia volcano was dated in 2005 by Duggen and colleagues to be 6.76 ± 0.04 million years BP . It was therefore formed in the Messinium .
Individual evidence
- ↑ Conticelli, S. et al .: Trace elements and Sr-Nd-Pb isotopes of K-rich, shoshonitic and calc-alkaline magmatism of the Western Mediterranean Region: Genesis of ultrapotassic to calc-alkaline magmatic associations in a post-collisional geodynamic setting . In: Lithos . tape 107 , 2009, p. 68-92 .
- ↑ Duggen, S. et al .: Post-collisional transition from subduction to intraplate type magmatism in the westernmost Mediterranean: Evidence for continent-edge delamination of subcontinental lithosphere . In: Journal of Petrology . tape 46 , 2005, pp. 1155-1201 , doi : 10.1093 / petrology / egi013 .